Phytate and oxalate intakes of young children in Chakaria ...

Phytate and oxalate intakes of young

children in Chakaria, Bangladesh

Supervisor: Dr. Gail Goldberg

Candidate number: 107918

Word count: From Introduction to Conclusion 8753

Submitted in part fulfilment of the requirements for the degree of MSc in

Nutrition for Global Health

9 September 2014

MSc Project Report

2013-2014

i

Table of Contents List of Figures............................................................................................................................. ii

List of Tables .............................................................................................................................. ii

ABSTRACT ................................................................................................................................ v

ACKNOWLEDGEMENTS ......................................................................................................... vi

Acknowledgement of academic support ............................................................................... vi

Acknowledgement of other support ...................................................................................... vi

CONTRIBUTION OF OTHERS ................................................................................................vii

1. INTRODUCTION ................................................................................................................ 8

2. METHODS ........................................................................................................................ 11

2.1 Literature review............................................................................................................. 11

2.1.1 Search strategy ........................................................................................................... 11

2.1.2 Selection criteria.......................................................................................................... 13

2.2 Calculations .................................................................................................................... 14

2.2.1 Converting all data to milligram/100gram (mg/100g).............................................. 14

2.2.2 Converting water values for standardization........................................................... 15

2.2.3 Collection of recipes for calculation of values for composite dishes ...................... 16

2.2.4 Calculation of recipes with assumed changes in weight: ....................................... 16

2.2.5 Calculation of recipes with unknown changes in weight or weight of the cooked

dish:................................................................................................................................... 18

2.2.6 Calculation of mean value for foods with more than one values: ........................... 19

2.3 Dietary Data Analysis..................................................................................................... 19

3. RESULTS ......................................................................................................................... 19

3.1 Literature searching for phytate and oxalate values ..................................................... 19

3.2 Dietary intake in terms of phytate and oxalate .............................................................. 20

3.3 Contribution of different foods to phytate and oxalate................................................... 23

4. DISCUSSION.................................................................................................................... 31

4.1 Findings from literature review....................................................................................... 31

ii

4.2 Findings from dietary analysis ....................................................................................... 33

4.3 Limitations ...................................................................................................................... 35

4.4 Conclusion and Recommendations ............................................................................... 37

REFERENCES......................................................................................................................... 38

List of Figures

Figure 3-1 The main sources of phytate intake among all participants .................................. 24

Figure 3-2 The main sources of oxalate intake among all participants .................................. 25

List of Tables

Table 2-1 List of databases searched for phytate and oxalate values ................................... 12

Table 2-3 Format used literature review for the sources of information on phytate and

oxalate content of foods........................................................................................................... 13

Table 2-4 Example of weight of portion sizes used for recipe calculation .............................. 17

Table 2-5 Calculation of phytate and oxalate content in Brinjal/Aubergine Fry...................... 17

Table 3-1 Summary of availability of information on phytate and oxalate content of foods ... 20

Table 3-2 List of 9 foods with both unavailable phytate and oxalaet values .......................... 20

Table 3-3 Mean daily intake of calcium, phosphorus, zinc, iron phytate and oxalate in the

different study groups .............................................................................................................. 21

Table 3-4 Mean intake of calcium, phosphorus, zinc, iron phytate and oxalate per 1000 kcal

of food energy in the different study groups ............................................................................ 22

Table 3-5 Mean intake of calcium, phosphorus, zinc, iron phytate and oxalate per kg body

weight in the different study groups ......................................................................................... 23

Table 3-6 List of foods with their phytate and oxalate values (mg/100g) and sources of

information…………………………………………………………………………………………...25

Table 4-1 A few sources of information on phytate and oxalate content of food ................... 32

Table 4-2 Dietary intake in studies of rickets children and controls (adapted from Dr.

Ahmed’s thesis and revised, updated) .................................................................................... 34

iii

iv

GLOSSARY

AR Active Rickets children

AR-VC Village Controls for Active Rickets children

AEC Anion Exchange Chromatography

BDNAR Bone Deformity not Active Rickets children

BDNAR-VC Village Controls for Bone Deformity not Active Rickets

children

DINO Diet In Nutrients Out

DW Dry Weight

FAO Food and Agriculture Organization of the United Nations

FW Fresh Weight

G Gram

HNR Human Nutrition Research

HPLC High-performance liquid chromatography

icddr,b International Centre for Diarrhoeal Disease Research,

Bangladesh

MRC Medical Research Council

Mg milligram

NFPCSP National Food Policy Capacity Strengthening

Programme

OA Oxalic acid/oxalate

PA Phytic acid/phytate

SARPV Social Assistance for Rehabilitation of Vulnerable

People (an NGO in Bangladesh)

v

ABSTRACT

Background: A recent case-control study of the aetiology of rickets in Chakaria, Bangladesh

by MRC Human Nutrition Research (HNR), showed that calcium intakes of children were

very low (~150mg/day in cases and <300mg/day in controls) and mostly came from fish and

cereals. Calcium obtained from cereals and other plant foods is not very bioavailable

because the phytate and oxalate contents are likely to be high. This issue has not been

considered in previous studies of rickets in Bangladesh. The purpose of my project was to

derive phytate and oxalate values for all the foods consumed, and calculate the individual’s

daily intakes. The hypothesis was that phytate and oxalate content of diets of young children

in Chakaria, Bangladesh are high, particularly in children with rickets.

Methods: Data from prospective 24-hour weighed dietary records containing 117 different

foods were used. The project had four stages:1) literature searching; 2) deriving values in

foods as eaten; 3) adding these to the food composition database at HNR and calculating

individual daily total intakes using Diet In Nutrients Out software; 4) analysis of phytate and

oxalate intake in cases and controls.

Results: Phytate and oxalate content of 80 and 76 foods respectively were derived.

Mean±SD intake of phytate was 48.6±13.9 and median (25th, 75th percentile) intake of

oxalate was 1.8 (0.7 and 4.2). Children with rickets had significantly higher mean phytate

intake per 1000 kcal and per kg body weight than controls ([6.5±3.8g, p=0.03]; [6±0.1g,

p=0.007]). There were no significant differences in oxalate intake.

Conclusions: The published data on phytate and oxalate contents of foods, typically

consumed in South Asia are very limited. The diets of young children in Chakaria are very

low in calcium and other minerals and relatively high in phytate and oxalate. The implications

of this warrant further investigation.

vi

ACKNOWLEDGEMENTS

Acknowledgement of academic support

First of all, I would like to thank my supervisor Dr. Gail Goldberg (HNR and LSHTM) for her

remarkable supervision and thorough support. I admire her for her enduring patience,

intellectual freedom and nudging from time to time which have made it possible for me to

complete the study within 3 months. I am also truly grateful to Dr. Sophie Moore (LSHTM) for

her excellent mentoring and support during the proposal development, Dr. Alan Dangour

(LSHTM) for his support and encouragement, Dr. Birdem Amoutzopoulos (HNR) for her

support during literature review and write up stage of this dissertation. I am indebted to Dr.

Sonia Ahmed (HNR) for her valuable insights, sharing data, supporting and encouraging me

throughout my M.Sc. I remember Mr. Darren Cole (HNR), Ms. Nida Ziauddeen (HNR), and

Mrs. Susan Jones (HNR) with immense gratitude. I am truly grateful to Dr. Elaine Ferguson

(LSHTM) for sharing her unpublished literature review to support my dissertation. My

heartfelt thanks go to Dr. Ann Prentice, Director, MRC-HNR, UK for allowing me as a visiting

student and The Commonwealth Scholarship Commission, UK who funded my M.Sc.

studentship and project.

Acknowledgement of other support

I would like to thank my parents, in laws and family for always inspiring me for higher

education and to dream high and for their advice and support throughout the tenure. Thanks

to my aunt Dr. Krishna Datta for her advice, immense support and encouragement. Thanks

to my husband, Subir Kumar Chowdhury and thanks to our son Amiya Gahan Chowdhury for

being with me and supporting in every possible way in the most difficult times. This thesis is

dedicated to my family for their contribution to my M.Sc.

vii

CONTRIBUTION OF OTHERS

I thought of the idea that was refined by my supervisor who also helped me in writing the

protocol. The data I used in the project were collected by Dr. Sonia Ahmed as part of her

PhD thesis and given to me fully cleaned by her. Dr, Elaine Ferguson shared a database of

findings of literature review. I worked with my supervisor to define a data analysis plan,

literature review plan. Ms. Nida Ziauddeen entered the data into the Bangladeshi DINO, at

HNR database, transformed and transferred the data into excel spreadsheet for further

analysis. I conducted the literature review, analysis of dietary data, and reanalysis of mineral

intake data and wrote the report. My supervisor read advanced draft of the report and fed

back comments.

8

1. INTRODUCTION

The bone disorder most clearly related to nutrition is rickets. It is a disease of growing

children. Rickets is characterised by a delay in or failure of mineralisation at the unfused

growth plates of the long bones. This results in deformation of the growth plates, a reduction

in linear growth, the development of bone deformities [1]. The associated morbidity and

burden of disease, and economic and social implications are considerable. Still vitamin D

deficiency is the main cause in many parts of the world, however, prevalence of nutritional

rickets is higher in economically disadvantaged parts of the world where vitamin D deficiency

is uncommon because of abundance of sunlight [2]. Reports from Africa and Asia, including

the Chakaria region of Bangladesh suggest that there may be other aetiological factors

involved including chronically low dietary calcium intake, anaemia, and other features of

malnutrition and infections [3-5]. The National Rickets Survey in Bangladesh, 2008 showed

that the prevalence of rachitic children was 0.99% [6]. Recent reports have suggested that

the presentation of rickets in Bangladesh is more like the calcium deficiency rickets in Africa

compared to classical vitamin D deficiency type [5].

Rickets studies in Bangladesh so far have assessed food intakes at the household, and not

an individual level, and no studies have included both cases and matched control groups. A

case control study in 148 children has recently been conducted by Dr. Sonia Ahmed, a PhD

student in the Nutrition and Bone Health Group at MRC Human Nutrition Research in

Cambridge, supervised by Dr. Ann Prentice and Dr. Gail Goldberg [9]. Predictors of

childhood rickets in Bangladesh. PhD, University of Cambridge) in collaboration with icddr,b

and an NGO, SARPV in Bangladesh. Dietary intake data (prospective 24 hour weighed

records) results showed that the calcium intakes were very low (approximately 150 mg/day

in cases and less than 300 mg/day in controls) and mostly came from fish and cereals.

Calcium intake has always been poor in Bangladesh. In the recent years, production of rice

has substantially increased. A recent report of the National Food Policy Capacity

Strengthening Programme has suggested that the food quantity, quality, diversity and

regularity is still challenged, the country is becoming more food secure though [10]. Crop

rotation, diversity and milk production has reduced. The diet has become more monotonous

and imbalanced than it was three decades ago (personal observation). Food consumption

habits have shifted from calcium rich indigenous small fishes to cheap de-boned large fishes

[9]. It is of further potential concern that the calcium obtained from other foods is not very

bioavailable because the phytate and oxalate contents of the diets are likely to be high.

These dietary inhibitors have not been considered in previous studies of rickets in

Bangladesh at all.

9

Phytate and oxalate, regarded as ‘antinutrients’, are the two most important diet related

factors which influence bioavailability of minerals, such as – calcium, phosphorus, zinc and

iron which are crucial for bone nutrition . Phytate (or phytic acid) which is also known as

inositol hexaphosphate has a strong negative nutritional impact on absorption of minerals.

Phytate or phytic acid from plant products inhibits calcium absorption by complexing calcium

in the intestine. Foods which are high in fibre, for example, seeds and grains are rich in

phytate, the storage form of phosphate [7]. Another important chelator (ions and molecules

which bind metal ions) is oxalic acid or oxalate that binds which is also one of the most

common ‘anti nutritional’ factors present in abundance in green leafy vegetables. Oxalate

from certain vegetables affects the bioavailability of calcium by forming very stable

complexes in the body [8].

There is very little information from Bangladeshi and Indian food composition tables about

the content of phytate and oxalate in foodstuffs. Most of the data are from individual raw

foods and not foods as eaten or found in composite dishes. For Dr. Ahmed’s project

conducted in Bangladesh, new food codes for the composition of cooked foods and recipes

consumed in the study were created from literature sources and used in a bespoke version

of MRC-HNR’s DINO (Diet In Nutrients Out) programme [9]. Phytate and oxalate values

have not yet been included in the database.

Hypothesis statement:

Phytate and oxalate content of diets of young children in Chakaria, Bangladesh are high,

and may therefore impact on the bioavailability of minerals, and potentially explain some of

the aetiology of rickets in this region.

Overall Aim of the project:

Overall aim of my project was to derive phytate and oxalate values for the foods consumed

and calculate the individual’s daily intakes to inform future analysis.

Specific Aims:

Specific aims of the project were to conduct literature searching, including grey literature and

other sources of information; gain a good understanding of food composition table, individual

foods for example fruits, vegetables, all cereals, legumes, pulses and composite dishes, the

knowledge to convert values from raw to cooked foods and also apply these to composite

dishes and recipes, to enter values per 100g into the bespoke food composition tables held

at HNR, to use the ‘DINO’ programme to calculate daily intakes of phytate and oxalate in

10

children with rickets and matched controls; and consider the potential impact on calcium and

other mineral availability and bone health.

11

2. METHODS

Phytate, phytic acid and phytin mean the same and so do oxalate, oxalic acid. Different

literature have used different names. For consistency, I have used phytate and oxalate

throughout the report. The current project used data from 24 hour weighed dietary records

collected for dietary assessment as a part of the case control study on young children aged

1.0 to 10.9 year old in Chakaria, Bangladesh. Chakaria is a south east coastal sub-district of

Cox’s Bazar, a district of Chittagong, one of the seven division of Bangladesh. The project

was carried out in three stages- in the first stage literature searching for information on

phytate and oxalate content in Bangladeshi foods and information on intake was done. After

that, calculation of individual daily total intake of above study subjects was conducted using

DINO (Diet In Nutrients Out), a software for dietary analysis, developed by Mr. Darren Cole

at MRC-HNR[9]. Finally, preliminary analysis for comparison of intake between different

study groups was carried out.

2.1 Literature review

A literature review was conducted including electronic databases, journal sites, books,

theses. Another source of information on phytate content of foods was an extensive

literature review conducted by Dr. Elaine Ferguson at LSHTM (unpublished). Literature

searching in the present study was done in three parts. Firstly, sources were searched for

studies of rickets in Bangladesh which included dietary assessment to generate phytate and

oxalate intake. Secondly, literature was searched for phytate and oxalate content of different

food items and composite dishes consumed in Bangladesh. Thirdly, databases were

reviewed for information on the effect of food processing (for example: dehulling, soaking,

blanching, boiling, roasting, autoclaving, traditional cooking) on phytate and oxalate present

in foods.

2.1.1 Search strategy

The databases PubMed (http://www.ncbi.nlm.nih.gov/pubmed/), Web of Science

(http://isiwebofknowledge.com/products_tools/multidisciplinery/webofscience/), google

scholar (http://scholar.google.co.uk/), google books (http://books.google.com/) were used

predominantly for abstracts, articles, chapters of books. The terms searched were ‘phytate’,

‘phytic acid’, ‘oxalate’, ‘oxalic acid’, ‘antinutrients’, ‘food composition table’, ‘content’, ‘food

analysis’. Titles of articles and available abstracts were skimmed for relevance. To identify

additional, relevant articles, reference lists of abstracts reviewed in this current study were

searched. For less familiar foods, taxonomic names were used for searching (for example,

Shapla flower- nymphaea nouchali, Pat Shak - corchorus capsularis etc). Google

12

(http://www.google.co.uk/) was very helpful in finding images of foods, indigenous recipes,

and to have a general idea on specific foods.

The following data banks were searched for phytate and oxalate values:

Table 2-1 List of databases searched for phytate and oxalate values

Databank Links PA OA

Australia http://www.foodstandards.gov.au/science/monitoringnutrients/nutrientables/nuttab/Pages/default.aspx

No Yes

Denmark http://www.foodcomp.dk/v7/fcdb_search.asp No No

Canada http://w ebprod3.hc-sc.gc.ca/cnf-fce/index-eng.jsp No Yes

Czech version 4.13 http://www.czfcdb.cz/en/search-food-data/food-name/ No No

Finland http://www.fineli.f i/index.php?lang=en No No

France http://www.afssa.fr/TableCIQUAL/ No No

Germany http://www.bls.nvs2.de/index.php?id=1&L=1 No No

Netherlands http://nevo-online.rivm.nl/ProductenZoeken.aspx No No

New zealand http://www.foodcomposition.co.nz/foodfiles No No

Norw ay http://www.matvaretabellen.no/?language=en No No

Sw eden http://www7.slv.se/Naringssok/SokLivsmedel.aspx No No

Turkey http://www.turkomp.gov.tr/ No No

USDA (USA) http://ndb.nal.usda.gov/ndb/search/list No No

EUROFIR (all UK databases) http://www.eurofir.org/?page_id=96 No No

FAO-INFOODS http://www.fao.org/infoods/infoods

Yes No

*PA=Phytic acid/phytate, *OA=Oxalic acid/oxalate

Besides phytate and oxalate values, sources were searched for effect of food processing on

phytate and oxalate content in foods using the terms ‘food processing’, ‘domestic food

processing’, ‘dehulling’, ‘soaking’, ‘blanching’, ‘boiling’, ‘roasting’, ‘autoclaving’, ‘traditional

cooking’, ‘effect on antinutrients’, ‘phytate’, ‘oxalate’.

Supplements of McCance and Widdowson’s ‘The Composition of Foods’, Nutritive Value of

Indian Foods, Food Phytates, Handbook of Food Toxicology, Essentials of Food and

Nutrition-Volume 1 were some of the books searched for phytate, oxalate values and effect

of food processing [11-20].

13

2.1.2 Selection criteria

Studies published in peer-reviewed journals with an abstract and if the title included

information on specific food content were searched. Abstracts were scanned for information

on specific foods analysed, coverage of parameter of interest (phytate and oxalate), intake

value of phytate and oxalate, information on composite dishes. Studies were included if they

reported specific foods, geographical source of foods, seasonality, forms of phytate and

oxalate, analysis method (HPLC, ion exchange chromatography etc.), unit of value reported

(gram/100 gram, milligram/100 gram etc), parallel (single or multiple sample) used or not,

also if they reported values of mass/dry matter, water/moisture. Data on phytate and oxalate

were very limited. It was not possible to do this strict selection for most of the foods.

Table 2-2 Example of format used literature review for the sources of information on phytate and oxalate content of foods

Author Journal Food Origin of

food

PA/

OA

Analysis

method

Parallel

sample

DW/FW Moisture

content

Wilson et

al

(1982)[21]

JAFC Carambo

la,

Spinach

Florida PA HPLC yes DW No

Wang et

al.

(2008)[22]

FC Field

Peas

Canada PA aec yes DW Not

reported

Norhaizan

et al.

(2009)[23]

MJN Rice,

cereal

products,

wheat

products

Malaysia OA AEC yes Not

reported

Not

reported

Chan et al.

(2007)[24]

JFCA Rice,

instant

noodles,

peanut,

mung

beans

Indonesia PA HPLC Not

reported

DW Yes

JAFC- Journal of Agriculture and Food Chemistry, JFCA-Journal of Food Composition and

Analysis, MJN-Malaysian Journal of Nutrition, FC-Food Chemistry

DW-Dry weight, FW-Fresh weight

14

Most of the local/indigenous food items which were usually consumed raw, for example,

fruits, nuts, vegetables (such as cucumber) were collected from the FAO-INFOODS-

Bangladesh database and Nutritive Value of Indian Foods [20, 25]. FAO-INFOODS was the

most recent database of Bangladeshi raw foods published in 2013. Food items consumed in

Bangladesh and India are similar. ‘Nutritive Value of Indian foods’ includes foods which are

common in both Bangladesh and India. A lot of food was included in the review done by

Ferguson et al with a very few from Bangladesh and matching the criteria which had been

set for the present study. Table 2-2 shows some of the literature which had been reviewed

for information:

A major limitation of using these sources of information was that they included values of raw

foods only, not cooked food or composite dishes. In addition, they did not include retention

factors for phytate and oxalate. Retention factor can be described as the percentage

adjustments in the phytate and oxalate that account for the effect of cooking on them.

Retention of phytate and oxalate in the cooked dishes depends on the cooking method and

duration of cooking, moisture content of raw ingredients, type of food etc. This is a vast area

of research in Nutrition and food science which could not be included in the calculation of a

number of foods due to lack of reliable literature on Bangladeshi foods.

For a few raw foods, cooked and composite dishes and ethnic recipes, the most reliable

supplements of McCance and Widdowson’s ‘The Composition of Foods’ were used [11-16]

all food items and dishes, their phytate and oxalate values, sources of information has been

attached in the Appendix section.

2.2 Calculations

For the calculation of phytate and oxalate values, the food item which corresponded most

closely with the food consumed in Dr. Ahmed’s study was chosen from different sources. In

an spreadsheet information on phytate content (mg/100g) with source of information, oxalate

content (mg/100g) with source of information, water content (g/100g) were included. All the

values were per 100 g of edible portion or ‘as eaten’ as usually listed in Food Composition

Tables. Originally, for those foods which were consumed but not in the literature, the best

alternative by considering food type, general characteristics was chosen by Dr. Ahmed. For

example, Tara, which a tuber, listed in the food diary was replaced by Colocasia Stem,

another tuber [20].

2.2.1 Converting all data to milligram/100gram (mg/100g)

It was found that different sources of literature reported values of phytate and oxalate using

different units, for example, g/100g, mg/100g. Conventionally values expressed in food

15

composition tables for dietary assessment are mg/100g. Therefore the values which had

been collected were converted to phytate and oxalate in mg/100g.

The formula, used to convert g/100g to mg/100g was:

g/100g*1000=mg/100g

For example, raisins had 0.01 gram of phytic acid per 100 grams of edible portion. So, this

value of 0.01 gram was converted to 10 milligram of phytic acid per 100 grams of edible

portion of raisins by following the above mentioned formula.

2.2.2 Converting water values for standardization

In order to ensure a single way of reporting, all the collected values, converted and

expressed in mg/100g were calculated using a formula for water values for standardization.

The formula used was as followed:

For example,

Phytate value of Paratha (A fried flat bread made with wheat flour) per 100 gram of edible

portion=320mg

Water content per 100g of edible poriton in the source of information=32.3g

Water content per 100g of edible poriton in original dataset=30g

Final phytate value per 100g edible portion= [320*(100-30)]/(100-32.3)=331mg

Final phytate

value per 100g

edible portion=

[(phytate value per 100g edible portion*(100-water content of the

food in original dataset)]

(100-water content of the food in the source of information)

Final oxalate

value per 100g

edible portion =

[(oxalate value per 100g edible portion*(100-water content of the

food in original dataset)]

(100-water content of the food in the source of information)

16

Similarly,

Oxalate value of Kamranga/Carambola/Star fruit per 100g of edible portion=300mg

Water content per 100g of edible poriton in the source of information=92.5g

Water content per 100g of edible poriton in original dataset=92g

Final oxalate value per 100g edible portion=[300*(100-92.5)]/(100-92)=282mg

2.2.3 Collection of recipes for calculation of values for composite dishes

There is a paucity of data on contents of phytate and oxalate in composite dishes. Recipes

for listed composite dishes were collected from supplements of McCance and Widdowson’s

‘The Composition of Foods’, Dr. Ahmed’s records collected during 24 hour weighed dietary

assessment and different websites. All the records were crossmatched with Dr. Ahmed’s

findings of recipes which she filed for future use to ensure a reliable, consistent source of

amount of each ingredient to include in calculation when new values were to be added.

Calculation of values using the same recipes was done to ensure consistency among

nutrients and other values.

2.2.4 Calculation of recipes with assumed changes in weight:

For the composite dishes for which no data was available, ingredients of the dish with the

amount of each ingredient had been listed from recipes. Composition of cooked dishes was

calculated based on the content of phytate and oxalate of the ingredients and the changes in

weight on cooking due to evaporation of water or to its gain by absorption (for example, rice).

Foods like Noodles, pasta, macaroni, vermicelli gain weight by absorption of water by 35 to

50%. Their cooked weight is more than the raw weight. About 757 grams of vermicelli, milk,

sugar, almond yield 1138 grams of cooked vermicelli. On the other hand, mixed vegetables

loose water due to evaporation. About 1409 grams of mixed vegetables turn to 838 grams of

cooked mixed vegetable by losing around 24% of weight. Contribution of each ingredient

towards the total recipe’s phytate and oxalate content was calculated using the formula

documented in McCance and Widdowson’s ‘The Composition of Foods’ - sixth summary

edition [11].

The weights of the raw ingredients were used to calculate the total amounts of phytic acid

and oxalic acid in the raw dish. For weight calculation of individual ingredients in a recipe, I

had to find out portion sizes (e.g. 1 level teaspoon, 1 heaped teaspoon, 1 cup, 1 glass)

which I collected from the book ‘Food Portion Sizes’-2nd edition [26]. A few examples of

portion sizes for recipe calculation have been shown in Table 2-3.

17

Total phytate and oxalate content were then calculated by adding the contribution of each

ingredient together. An example of the calculation of antinutrient contents of the cooked dish

is shown in Table 2-4. The method of calculation was taken from McCance and

Widdowson’s ‘The Composition of Foods’ -sixth summary edition [11].

Table 2-3 Example of weight of portion sizes used for recipe calculation

Items Portion size Weight in gram

Salt 1 level teaspoon 5

Spices Dried, 1 teaspoon 3

Sugar 1 heaped teaspoon 6

Egg, hen’s No shell, size 1 67

Oil 1 tablespoon 11

Oil 1 teaspoon 3

Table 2-4 Calculation of phytate and oxalate content in Brinjal/Aubergine Fry

Ingredients Amounts contributed

Amount in Recipe g

Phytic acid mg Oxalic Acid mg

Oil 22 0 0

Onion 24 0 0.2

Green chillies 8 0.6 5.4

Turmeric powder 1 0 0

Coriander powder 1 0 0

Coriander leaves 5 0 2.4

Brinjal (Aubergine) 114 3.4 20.5

Total in recipe (a) 175 4.0 28.5

Cooked weight (b) 102

Weight loss on cooking (c) =a-b 73

% weight loss on cooking (d) =c/a x 100 41.71

Phytic acid and oxalic acid content of cooked dish (per 100g) (e)

=a/b x100 0.1 0.3

18

Formula used for phytate and oxalate content of cooked dish were as follows. These

formulas were used in the calculation shown in Table 2-4. I need to conduct similar

calculation for atleast 48 composite dishes for either phytate or oxalate values.

Phytate content of cooked dish per 100g

= Total phytate content of raw ingredients/Weight of cooked dish*100

Oxalate content of cooked dish per 100g

= Total oxalate content of raw ingredients/Weight of cooked dish*100

2.2.5 Calculation of recipes with unknown changes in weight or weight of the cooked

dish:

If the weight of the cooked dish was not known, a recipe was calculated from the raw

ingredients and the weight was estimated by using the % weight change from a similar

recipe as follows (provided that all the weight change can be attributed to water). For

example, for beef curry with radish, 30% weight loss was estimated from other recipes of

meat and vegetable. Then the weight of cooked beef curry with radish was calculated using

the following formula:

Weight of

cooked dish =

Weight of raw ingredients x (100 -% weight loss of similar dish)

100

Weight of beef curry= 1730g x (100-30)/100 = 1211g

For recipes which gain weight on cooking, for example vermicelli, a weight gain of 50% was

estimated from other recipes of vermicelli:

Weight of

cooked dish =

Weight of raw ingredients x (100 + % weight loss of similar dish)

100

Weight of vermicelli= 575g x (100+50)/100=862.5g

19

2.2.6 Calculation of mean value for foods with more than one values:

After converting all values to mg/100g, foods were tabulated in an excel spreadsheet. There

were foods for which values were available from various papers, books. For those foods,

from individual values a mean value was calculated.

2.3 Dietary Data Analysis

Dietary data analysis was carried out using the software Bangladesh DINO at MRC-HNR

which was originally developed for Dr. Sonia Ahmed’s Bangladesh Rickets Project by Mr.

Darren Cole [9]. There were two steps followed for dietary analysis. Firstly, values were

added to the food composition database. Intakes of Bangladeshi foods that had been

calculated as described from dietary records had been loaded to the the Bangladeshi DINO

by Mr. Darren Cole and Ms. Nida Ziauddin so that analysis can be re-run to include phytate

and oxalate values. The outputs were exported in an Excel spreadsheet which were then

imported to StataSE 13 (16bits) for data analysis.

The original analysis in Dr. Ahmed’s thesis included 143 subjects. In the current study, I

have analysed dietary intake data of 124 study subjects, 48 active rickets subjects with their

matched controls and 76 bone deformity not active rickets subjects with their matched

controls. I have not included siblings as they were from the same households of the study

subjects and consumed same food items and composite dishes as the other study subjects

did. They did not add any new food to the list. Data on intake of calcium, phosphorus, iron

and zinc were taken from Dr. Ahmed’s PhD thesis and reanalysed. To report normally

distributed variables, mean ± 1SD values were used. For positively skewed variables,

median with 25th and 75th percentile values were used. Paired t-test for comparing matched

pairs and two sample Student’s t-tests were used to determine the significance of

differences between two groups of normally distributed continuous variables. The Wilcoxon

Rank Sum test or Mann-Whitney test, a distribution-free alternative to the t-test was used for

continuous variables which were not normally distributed. The p-value threshold used in this

study was set at ≤0.05 in order to demonstrate a statistical significance.

3. RESULTS

3.1 Literature searching for phytate and oxalate values

Literature searching was done to derive phytate and oxalate content of 117 Bangladeshi

foods. Table 3-1 presents the summary of availability of information on phytate and oxalate

content of foods. Phytate content was found for 80 foods and dishes (68.4%) and oxalate for

20

76 foods and dishes (65%). Information on oxalate and phytate content were not available

for 12 (10.2%) and 16 (13.6%) foods items and composite dishes, respectively. Among

these, for 9 food items neither phytate and nor oxalate values could be found (e.g. Tara,

sweet pumpkin). A list of these 9 foods are presented in table 3-2. There were 25 foods

which did not have phytic acid or oxalic acid in them (Table 3-1).

Table 3-1 Summary of availab ility of information on phytic acid and oxalic acid content of foods

Status of information Information on phytic acid content

Information on oxalic acid content

Values found 80 (68.4%) 76 (65.0%)

Values not found 12 (10.2%) 16 (13.6%)

Not applicable 25 (21.4%) 25 (21.4%)

Total no. of foods 117 117

Table 3-2 List of 9 foods with both unavailable phytic acid and oxalic acid values

Food Items Food groups

Fruits gums/jellies eg lychee (artificial) Sugar confectionery, sweet and savoury snacks

Patti, purchased Sugar confectionery, sweet and savoury snacks

Tara Vegetables

Sweet pumpkin Vegetables

Fruit juice eg orange (artificial, made up from concentrate)

Beverages

Taam Fruit

Sugar cane Sugar confectionery, sweet and savoury snacks

Chicken with sweet pumpkin White meat and dishes

Shapla flower Vegetables

3.2 Dietary intake in terms of phytate and oxalate

In the current study, dietary data from the 24 hour weighed food intake measurements of

124 children aged 1.0 to 10.9 years were analysed for mean daily intake of phytate and

oxalateper 1000 kcal and per kg body weight of study children and compared among

different groups children with Active Rickets (AR), children with Bone Deformity not Active

21

Rickets (BDNR), and their respective village controls. Mean bodyweight (kg) of these

children was 9.65(1.74) for AR, 12.4 (3.51) for AR-VC, 11.4 (2.71) for BDNAR and 12.9

(3.99) BDNAR-VC. In terms of body weight (kg), AR was significantly heavier than the AR-

VC children (p=0.002) and BDNAR children (p=0.0003). Data on weight (kg) of study

children and on intake of minerals important for bones (calcium, phosphorus, iron and zinc)

have been taken from Dr. Ahmed’s PhD thesis [9] and presented along with Phytate and

oxalate values in Table 3-3, Table 3-4, Table 3-5.

Table 3-3 Mean daily intake of calcium, phosphorus, zinc, iron phytate and oxalate in the different study groups

Nutrient intake mg per day

AR AR-VC AR vs AR-VC

BDNAR BDNAR-VC BDNAR

vs BDNAR-VC

AR

vs BDNAR

n=24 n=24 p n=38 n=38 p p

Calcium 156

(80.1)

323

(249.0)

0.005 239

(166.0)

254

(221.8)

0.7 0.3

Phosphorus 322

(112.5)

424

(155.2)

0.009 380

(158.1)

403

(167.6)

0.3 0.1

Iron 4.3

(2.0)

5.8

(3.5)

0.08 5.0

(2.8)

5.4

(3.1)

0.5 0.3

Zinc 3.5

(1.6)

4.1

(1.5)

0.1 4.1

(2.8)

4.4

(1.8)

0.4 0.4

Phytate 318

(90.1)

319.5 (111.5)

0.5 339.5 (206.2)

402.6

(178.3)

0.09 0.68

*Oxalate 15.6 (7.7, 25.1)

18.6 (6.3, 49.5)

0.7 9.0 (4.2, 22.1)

12.4 (4.4, 45.8)

0.3 0.2

Normally distributed data; the results are mean (SD). p-values of the paired t-test for AR vs AR-VC and BDNR vs BDNR-VC and 2 sample t-test for AR vs BDNAR are presented. Significant difference at p≤0.05 between groups is denoted by a bold p-value. *Non-normally distributed data; the results are median (25th percentile, 75th percentile). Mann-Whitney test p-values are presented. Data on bone mineral is adapted from Dr. Ahmed’s PhD thesis and reanalysed with her permission [9]. Data did not show any difference after reanalysis.

AR children had lower mean daily intake of phytate than their controls [-1.5(21.4) g, p=0.5].

A similar pattern was seen in BDNAR children and their controls [-63.1(27.9) g, p=0.09].

None of the mean differences were significant. Mean daily intake of minerals were lower in

22

both AR and BDNR groups compared to their respective controls. Significant differences

were found between calcium and phosphorus intake of AR and their controls.

Table 3-4 and Table 3-5 present phytate intake per 1000 kcal of food energy and per kg

body weight, respectively. AR had significantly higher mean phytate intake per 1000 kcal

than their controls [6.5 (3.8) g, p=0.03]. The difference was more significant when phytate

intake was presented per kg body weight [6 (0.12) g, p=0.007]. On the contrary, intake of

minerals per 1000 kcal were lower in AR compared to the other groups.

Table 3-4 Mean intake of calcium, phosphorus, zinc, iron phytate and oxalate per 1000 kcal of food energy in the

different study groups

Nutrient

intake per

1000 kcal of

food energy

AR AR-VC AR vs

AR-VC

BDNR BDNR-VC BDNR

vs

BDNR-

VC

AR

vs

BDNR

n=24 n=24 P n=38 n=38 p p

Calcium 185 (85.7) 345 (266.0) 0.007 288 (202.8) 249 (160.2) 0.4 0.02

Phosphorus 378 (74.2) 446 (102.5) 0.02 427 (87.8) 405 (76.7) 0.2 0.03

Iron 3.9 (2.7) 6.1 (4.2) 0.04 5.3 (4.6) 6.0 (4.9) 0.4 0.2

Zinc 4.1 (1.1) 4.3 (0.8) 0.4 4.4 (1.3) 4.4 (0.8) 0.9 0.3

Phytate 51.7 (14.8) 45.2 (11.0) 0.03 47 (14.2) 50.4 (13.7) 0.96 0.27

*Oxalate 21.1 (9.3,

28)

20.3 (6.6, 44) 0.84 9.3 (5.4,

22.6)

14.4 (4.8,

37.4)

0.34 0.13

Normally distributed data; the results are mean (SD). The paired t-test and 2 sample t-test p-values

are presented. Significant difference at p≤0.05 between groups is denoted by a bold p-value.

*Non-normally distributed data; the results are median (25 th percentile, 75th percentile). Mann-Whitney

test p-values are presented. Data on bone mineral data is adapted from Dr. Ahmed’s PhD thesis and

reanalysed with her permission [9]. Data did not show any difference after reanalysis.

Significant differences were seen among AR vs AR-VC in their calcium and phosphorus

intake [-160 (180.3) g, p=0.007] and [68 (28.3)g, p=0.02] respectively. Moreover, intake of

these two minerals were found significantly lower in AR when compared with BDNR (p=0.02,

p=0.03 respectively).

23

Table 3-5 Mean intake of calcium, phosphorus, zinc, iron phytate and oxalate per kg body weight in the different

study groups

Nutrient

intake mg per

kg body

weight

AR AR-VC AR

vs

AR-

VC

BDNR BDNR-VC BDNR

vs

BDNR-

VC

AR

vs

BDNR

n=24 n=24 p n=38 n=38 P p

Calcium 16 (8.0) 29 (23.3) 0.02 21 (15.2) 19 (12.7) 0.4 0.1

Phosphorus

mg

34 (10.6) 45 (18.7) 0.3 33 (11.2) 36 (14.1) 0.3 0.8

Iron 0.5 (0.2) 0.5 (0.3) 0.5 0.4 (0.2) 0.4 (0.2) 0.7 0.7

Zinc 0.4 (0.1) 0.3 (0.1) 0.7 0.3 (0.2) 0.3 (0.1) 0.8 0.6

Phytate 33.3 (9.12) 27.3 (8.4) 0.007 28.6 (13.2) 31.5(13.7) 0.15 0.07

*Oxalate 1.7 (0.7, 2.7) 1.4 (0.6, 3.7) 0.9 0.8 (0.4,

1.9)

1.0 (0.4, 2.6) 0.4 0.06

Normally distributed data; the results are mean (SD). The paired t-test and 2 sample t-test p-values are

presented. Significant difference at p≤0.05 between groups is denoted by a bold p-value.

*Non-normally distributed data; the results are median (25 th percentile, 75th percentile). Mann-Whitney

test p-values are presented. Data on bone mineral is taken from Dr. Ahmed’s PhD thesis and

reanalysed with her permission [9]. Data did not show any difference after reanalysis.

The data of oxalate intake was not normally distributed. So, instead of presenting mean with

SD, median intake of oxalate of the different study groups with 25th and 75th percentile

values are presented in Table 3-4 and Table 3-5. Oxalate intake per 1000 kcal of food

energy was higher in AR compared to their controls, BDNAR and their controls. However,

there were no significant difference between AR and AR-VC (median difference 0.08,

p=0.84), BDNR and BDNR-VC (median difference -5.1, p=0.34) or between AR and BDNR

(median difference 11.8, p=0.13). Similar pattern was seen when the oxalate intake was

presented per kg body weight.

3.3 Contribution of different foods to phytate and oxalate

In this section, the contribution of different food groups to intake of phytate and oxalate are

shown. For phytate intake, all foods were divided into seven food groups: rice, wheat

products, vegetables, legumes, fruits and nuts, confectionary and beverages. For oxalate

intake, foods were divided into six food groups: rice, wheat products, vegetables, legumes,

fruits and nuts and confectionary. In both the groups rice includes white boiled rice and

puffed rice. Figure 3.1 shows the distribution of phytate sources among all participants.

24

Vegetables on their own and part of composite dishes were the greatest contributor of phytic

acid (31%) followed by rice (24%). Confectionary was the third contributor [17% of total

confectionary intake was broken down into biscuits (11%), homemade cake (3%), purchased

sponge cake (1%), chanachur/chevra, a popular snacks in Bangladesh which is a mixture of

dried lentil, rice flakes and roasted peanuts (2%)]. It should be noted that most of the

confectionary items were made of wheat flour (e.g. cake, biscuit). Considering rice, wheat

and legumes together it can be shown that 41% phytic acid came from these three sources.

Fruits and nuts contributed only 10% with a very low contribution of beverages for example,

tea (<1%).

Figure 3-1 The main sources of phytate intake among all participants

Figure 3.2 presents the distribution of sources of oxalate among all participants. Vegetables

were again found to be the greatest contributor (52%, about 16% came from mixed

vegetable curry, raw and roasted vegetables, and the rest from leafy vegetables, and other

composite dishes prepared with vegetables, fish, meat or egg) followed by rice (27%). Fruits

and nuts was the third contributor (10%). Results show that almost two third of the oxalic

acid came from vegetables and fruits. Wheat products and confectionary contributed a very

little to the intake of oxalic acid (1% and 4% respectively).

Rice24%

Wheat products10%

Vegetables31%

Legumes7%

Fruits and Nuts10%

Confectionary17%

Beverage1%

25

Figure 3-2 The main sources of oxalate intake among all participants

A detail list of 117 foods which I have derived phytate and oxalate values for has been

attached herewith. List of foods with water content (g), phytate content (g/100g) and source

of information, oxalate acid content (g/100g) and source of information have been included

here (Table 3-6):

Table 3-6 List of foods with their phytate and oxalate values (mg/100g) and sources of inform ation

Food

Number Food Name

Water

(g)

Phytate

(mg/100g)

*Phytate

Source

Oxalate

(mg/100g)

*Oxalate

Source

1001 White rice, boiled 69.9 55.54 1 0.34 1

1002 Puffed rice (muri) 14.7 47 6 0.00 6

1003 Biscuits 1 142.15 4 - Not

available

1004 Curry, mung bean dahl,

Bengali 83 225.17 7 0.05 7

1005

Curry, lentil, red/masoor dahl,

with vegetable oil

(mushari/moshuar dal/dahl)

50 46.62 7 1.37 7

1006 Eggs, chicken, boiled 75 - Not

applicable -

Not

applicable

1007 Sponge cake, purchased 14 30 4 - Not

Available

1008 Boiled sweets eg lozenge,

lollypop/lollipop 13 -

Not

applicable -

Not

Available

Rice27%

Wheat products1%

Vegetables52%

Legumes6%

Fruits and Nuts10%

Confectionary4%

26

Food

Number Food Name

Water

(g)

Phytate

(mg/100g)

*Phytate

Source

Oxalate

(mg/100g)

*Oxalate

Source

1009 Fruits gums/jellies eg lychee

(artificial) 14 -

Not

available -

Not

Available

1010 Paratha 30 330.87 4 0.00 6

1011 Roti 41 402.77 4 0.00 6

1012 Naan roti (with ghee/butter) 27 112.78 4 0.00 6

1013 Bun 33 67.08 4 0.00 6

1014 Jellabi 24.9 89.25 7 0.00 7

1015 Cucumber, raw 96.3 0 6 15.00 6

1016 Spinach bhaji 85 4.58 7 575.15 7

1017 Cabbage fry/bhaji 81 20.32 5 3.13 6

1018 Bhaji, green bean fry (bean

vaji/Sheem) 76 22.86 5 8.91 7

1019 Fried rice (with potato) 72 44.33 7 2.39 7

1020 Pitha (pancake type made

with wheat) 70 15.9 4 0.00 6

1021 Noodles with egg 74 22.67 7 2.51 7

1022 Chanachur/chevda (bombay

mix) 3.8 119.75 4 10.54 7

1023 Potato curry 67 14.67 5 20.47 8

1024 Potato and okra curry 78 13.82 7 21.03 7

1025 Potato mash with mustard

seeds 75 25 3 17.86 7

1026 Potato daal/dahl 85 9.57 5 14.54 7

1027 Daal/dahl (chana/boot) 73 238.04 7 1.44 7

1028 Pelom/Shimer Bichir

Daal/Dahl 78.7 24.36 7 6.91 7

1029 Fried egg/omelette 65 - Not

applicable -

Not

applicable

1030 Cake, homemade with wheat,

oil, coconut and sugar 37 62.68 4 0.00 4

1031 Cake homemade with flour,

sugar and oil 38 53.84 4 0.00 4

1032 Goja 66 31.5 7 0.00 7

1033 Ghee, butter 0 - Not

applicable -

Not

applicable

1034 Sugar, white 0.4 - Not

applicable -

Not

applicable

1035 Shemai (plain, NO almonds or

coconut) 70 5.5 7 0.00 7

1038 Beguni (aubergine and lentils) 45 250.91 5 11.80 5

1040 Piaju 75 368.98 5 1.35 5

27

Food

Number

Food Name

Water

(g)

Phytate

(mg/100g)

*Phytate

Source

Oxalate

(mg/100g)

*Oxalate

Source

1041 Chick peas, roasted 10.7 515.25 1 3.00 6

1042 Shimer seed, roasted 11.5 136 6 0.00 6

1043 Patti, purchased 50 - Not

Available -

Not

Available

1044 Vegetables with gravy 91 4.41 7 1.18 7

1045 Prawn curry with vegetables 89.8 2.41 7 11.95 7

1047 Curried vegetables with egg 86 0.63 7 4.49 7

1048 Kul - plum pickle 89 2.45 7 1.10 7

1049 Tea, black, infusion ONLY 100 2 12 - Not

available

1050 Sweetcorn, corn on the cob,

roasted 61.7 54.1 6 9.00 6

1051 Tara 85.6 - Not

available -

Not

Available

1053 Yam with spinach 79 142.88 7 1.39 7

1054 Yam with spinach and shimer

seed 77.7 158.06 7 6.15 7

1055 Yam with spinach and prawn 78 158.06 7 6.01 7

1056 Pat spinach (shak) 67.4 17.06 7 130.44 7

1057 Radish with spinach 87 6.6 7 1.39 7

1058 Brinjal fry/curry 86 3.9 7 27.91 7

1059 Pumpkin (misti kumra) 90 - Not

Available -

Not

Available

1060 Fruit juice eg orange (made up

from concentrate) 94.9 -

Not

Available -

Not

Available

1061 Vegetable curry 88 0.53 7 13.11 7

1062 Banana 70.1 4 6 0.00 6

1063 Kamranga/ Carambola/

Starfruit 91.9 -

Not

available 282.56 2

1064 Amloki/ Amla/ Gooseberry 81.8 8 1 296.00 6

1065 Guava 81.7 16.15 6 15.07 6

1066 Apple 84.6 0 1 9.22 1

1067 Pai namala (betfol) 80.8 13 6 200.00 6

1068 Ugli fruit/ Jambura/ Grapefruit 92 - Not

available 0.00 2

1069 Taam 77.2 - Not

Available -

Not

Available

1070 Coconut flesh ONLY 36.3 69.07 2 - Not

Available

1071 Anar gula/ Pomegranate 80.9 11.52 6 13.37 6

28

Food

Number Food Name

Water

(g)

Phytate

(mg/100g)

*Phytate

Source

Oxalate

(mg/100g)

*Oxalate

Source

1072 Olive 82 - Not

available -

Not

Available

1073 Boroi/ Indian plum/ Jujuba 73.2 6.56 10 8.82 10

1074 Sugar cane 90.2 - Not

Available -

Not

Available

1075 Fish with gravy 71.5 - Not

applicable -

Not

applicable

1076 Fish, fried 65.4 - Not

applicable -

Not

applicable

1077 Fish cooked with vegetables 80.8 0.92 7 6.82 7

1078 Vegetables cooked with small

fish 79.7 2.33 7 4.87 7

1079 Fish curry with potato 67.5 3.05 7 7.21 7

1080 Bata fish 63.3 - Not

applicable -

Not

applicable

1081 Bata fish with shem bichi curry 83.4 0.26 7 2.64 7

1082 Tangra fish 68.8 - Not

applicable -

Not

applicable

1084 Kaski fish 83.5 - Not

applicable -

Not

applicable

1085 Kaski fish with brinjal curry 72.7 2.3 7 4.87 7

1086 Nailotika fish (Tilapia) 68.8 - Not

applicable -

Not

applicable

1089 Loitta/ Lota fish 70.4 - Not

applicable -

Not

applicable

1090 Mango, ripe 81 0 6 26.00 6

1091 Milk powder eg Dano 3 - Not

applicable -

Not

applicable

1095 Bele fish fry 65.4 - Not

applicable -

Not

applicable

1099 Hilsa with potato 59.1 3.05 7 7.21 7

1101 Dried prawn (chingree sutki)

with radish and brinjal curry 76 0.61 7 5.51 7

1102 Dried prawn (chingree sutki)

curry 76 -

Not

applicable -

Not

applicable

1103 Dried fish (Churi shootki) curry 79.5 - Not

applicable -

Not

applicable

1104 Liver curry (Beef Kolija) 73 - Not

applicable -

Not

applicable

1106 Meat curry 76 - Not

applicable -

Not

applicable

29

Food

Number Food Name

Water

(g)

Phytate

(mg/100g)

*Phytate

Source

Oxalate

(mg/100g)

*Oxalate

Source

1107 Beef with radish curry 78 0.31 7 2.01 7

1108 Beef curry 76 - Not

applicable -

Not

applicable

1109 Chicken with pumpkin 79 - Not

Available -

Not

available

1110 Chicken curry with potato 78 4.59 7 3.15 7

1112 Chicken skin with radish and

green banana curry 79 2.81 7 0.64 7

1113 Chicken curry (chicken meat

and gravy) 79 -

Not

applicable -

Not

applicable

1114 Crab bhuna 76 - Not

applicable -

Not

applicable

1115 Chocolate, milk 4 - Not

applicable -

Not

applicable

1116 Vermicilli made with water 68 5.5 7 0.00 7

1117 Vermicilli made with milk and

coconut 61 7.74 7 0.00 7

1118 Milk, cow 87.5 - Not

applicable -

Not

applicable

1119 Yam, boiled (with spices) 74 64.18 7 20.12 7

1120 Tamarind, green 20.9 5.74 10 1.55 10

1121 Lichi/Lychee 84.1 0 6 19.00 6

1122 Puagula 23 74.68 8 0.00 8

1123 Nimki 24 74.68 8 0.00 8

1124 Ice cream (sugar, coconut,

water) 41 -

Not

applicable -

Not

applicable

1125 Samosa/samucha 51.3 31.75 8 4.32 8

1126 Chotpoti 87 238.82 7 3.96 7

1127 Chips/Crisps, ready bought 2 95 11 - Not

Available

1128 Papaya 90.8 4 6 1.00 6

1129 Shapla flower 49.1 - Not

available -

Not

available

1130 Orange 87.6 1 6 10.00 6

1131 Chewing gum 0 - Not

applicable -

Not

applicable

1132 Radish, raw 94.4 0 6 9.00 6

1133 Jackfruit 76.2 17 6 27.00 6

1134 Peanuts 6 747.61 2 160.00 9

30

*Source Denotes

Food Composition Table for Bangladesh-FAO-INFOODS, 2013 1

Fruit and Nuts. 1st supplement to 5th edition of M&W the Composition of foods.UK. 1992 2

Vegetables, herbs and spices. 5th supplement to 4th edition of M&W the Composition of

foods.UK. 1992

3

Cereals and cereal products. 3rd supplement to 4th edition of M&W the Composition of

foods.UK. 1988

4

Vegetable dishes. 2nd supplement to 5th edition of M&W the Composition of foods.UK. 1992 5

Nutritive Value of Indian Foods , 1989 6

Calculated from recipe used in Dr. Sonia Ahmed’s PhD theses, 2014 7

Immigrant Foods, Second supplement to M&W the Composition of foods.UK. 1989 8

Journal of Food Composition and Analysis 19 (2006) 340-347 9

Journal of Food, Agriculture and Environment Vol. 10(1):16-19.2012

10

Journal of Food Composition and Analysis 17 (2004) 217–226 11

World Rev Nutr Diet. 1987;52:235-59. 12

31

4. DISCUSSION

The current study was aimed to provide novel data which can be used in the assessment of

dietary intakes in rural Bangladesh. Prospective weighed 24-hour records of dietary intake of

children collected in Chakaria, Bangladesh was used for this study [9]. An extensive

literature review was done to find phytate and oxalate content of Bangladeshi foods listed

from the dietary assessment of 1.0 to 10.9 month old children. Data were analysed to get

information on intake of phytate and oxalate, main contributory foods. In this section, I have

compared the findings with other available data from Bangladesh and other parts of the

world. I have also included limitations of this study and recommendations for the direction of

future research.

4.1 Findings from literature review

Databases from different parts of the world, papers published in peer reviewed journals,

books, food composition tables of different countries were reviewed in a structured way

which confirmed the paucity of data on phytic acid oxalic acid. There were specific hurdles

which I had to cross in doing this literature searching.

There was a limited number of published data in Bangladesh on food composition.

Most of the food composition tables either did not have information on phytate or

oxalate content, or did not include specific foods which I was looking for. There was

no single food composition table which included all the foods. A recently published

food composition table (FCT) of Bangladesh which is methodically done and

available in FAO-INFOODS website [9]. This FCT included phytate and oxalate

values of only around 70 raw foods which did not cover all foods recorded in my

study, neither cooked items nor composite dishes. As a result I had to look for other

sources from different countries, information on foods grown in a different climate,

soil. ‘Nutritive Value of Indian Foods’ was one of the other source which provided

phytate and oxalate values of raw vegetables which was reported to be eaten raw in

the dietary data and some of the raw vegetables which was used for recipe

calculation and most of the fruits, spices, herbs and condiments [20]. I collected

information of raw foods, put the values in recipe and converted them to cooked

values.

Phytate and oxalate values of foods which was available in other sources either did

not match the search criteria or not analysed using standard method.

At the beginning of searching, I aimed to collect phytate and oxalate values on a

specific food from the source from which Dr. Ahmed collected other nutrient values.

However, it was possible for only a very few number of foods. The other issue was

32

the availability of information on both phytate and oxalate value from a single source.

As mentioned in the methodology, the majority of the phytate values of composite

dishes were collected from supplements of McCance and Widdowson’s ‘The

Composition of Foods’ [11-16]. However, these supplements do not provide oxalate

values of composite dishes or vegetables. They only give oxalate values of certain

fruits most of which are not available or consumed in Bangladesh. For oxalate values

of composite dishes I followed the same recipe which Dr. Ahmed followed in her PhD

thesis, collected oxalate values mostly from other sources, put them in the recipe and

calculated the cooked value of oxalate. Using two different sources of foods which

was analysed separately would definitely leave a chance for variability.

There were a number of foods for which no information was available in any of the

sources aforementioned. For these foods, I had to select sources of foods from other

countries, for example, tamarind and Jujuba was of Nigerian origin, yam leaves were

from Africa, tea was from USA etc, grown under different environment and treatment.

There was no way of comparing values of these foods with same foods grown in

Bangladesh.

Table 4-1 A few sources of information on phytic acid (PA) and oxalic acid (OA) content of food

Author Food items Raw/

cooked

Origin of food PA value OA value Water

content

Shaheen et al.

2013

Rice, maize, wheat,

legumes, vegetables,

fruits

Raw Bangladesh Yes Yes Yes

Holland et al.

1992

Fruits and nuts Raw - Yes Yes Yes

Holland et al.

1992

Vegetable dishes cooked - Yes No Yes

Gopalan et al.

1989

Rice, maize, wheat,

legumes, fruits,

vegetables, condiments

Raw India Yes No Yes

Amoo et al. 2012 Tamarind, jujube Raw Nigeria Yes Yes Yes

Judprasong et al.

2006

Vegetables, cereals,

legumes

Raw,

boiled

Thailand No Yes Yes

Ferguson et al,

2007

Rice, peanut,

mungbean

Raw,

cooked

Indonesia Yes No Yes

33

4.2 Findings from dietary analysis

In this section, findings from dietary analysis are discussed and evaluated in the light of

existing literature on phytate and oxalate. The current study provides novel information on

intake of phytic acid and oxalic acid, two strong dietary factors potentially related to bone

health, from Bangladeshi foods recorded in the prospective weighed 24-hour records of

dietary intake in Dr. Ahmed’s study [9]. Ahmed et al. showed that the quality of the diet of

these study children was poor. The diet was low in calcium with a dominance of cereals,

vegetables and legumes which we know are rich sources of phytate and oxalate from

literature probably making the calcium less bioavailable to the body. Similar dietary intake

had been noted in earlier studies on rickets conducted in Chakaria, Nigeria, The Gambia and

India [27-30]. However, there was a lack of studies which had investigated the phytic acid

and oxalic acid content of various foods in Bangladesh, and specifically in Chakaria region.

Moreover, there was a dearth of information on the contribution of different food groups in

total phytate and oxalate intake in this region. In my study, dietary analysis showed that rice,

wheat products (flat breads, noodles, vermicelli etc), vegetables together were the major

contributors of phytic acid and oxalic acid in the diet. Vegetables included green leaves,

potato, radish etc. Red gram was the mostly reported pulse in the current study. Legumes,

pulses are very important nutrient sources for many population including Bangladeshis.

Chick pea/bengal gram, red gram, mung beans are very commonly consumed in

Bangladesh. However, presence of very high concentrations of antinutrients can decrease

the nutritional quality.

Dietary analysis showed that foods, grouped as the same type, did not provide same amount

of phytate and oxalate. Phytate and oxalate content varied due to a variation in the water or

moisture content. For example, roti (flat bread) and pitha (pancake) both were made of

wheat flour. However, phytate content of roti was higher compared to pitha which is moister

in type than roti. Phytate content of wheat flour is also affected by cooking temperature and

activation of phytase which is why phytate content of some wheat products are different than

raw wheat flour [31]. Composition of a meal was another important factor in determining

phytate and oxalate intake. For example, both fish curry with green bean seeds and only

green bean fried were reported in the dietary assessment. Recipe calculation showed that

phytate and oxalate content of 100 gram green bean fry was much higher than 100 grams of

fish curry with grean bean. As a result, a meal with rice and green bean fry provided more

phytate and oxalate compared to a meal with rice and fish curry with green bean. Another

notable thing was the increase in antinutrient content after adding specific food items. A very

popular wheat product in Bangladesh is vermicelli. Phytate content of wheat made vermicelli

34

was low when prepared with only water. However, the phytate content increased after

adding coconut, a very rich source of phytate.

In this part, I have presented finding of different studies in Table 4-2. There was a very few

studies on rickets from other parts of the world who included dietary assessment (Table 4.2).

None of the earlier studies on rickets conducted in Bangladesh collected any information

intake of phytic acid and oxalic acid.

Table 4-2 Dietary intake in studies of rickets children and controls (adapted from Dr. Ahmed’s thesis and revised,

updated)

Study and method Subjects Age Phytate mg/d Oxalate mg/d

Ahmed S, 2014,

Bangladesh[9]

Method: 24-h

weighed food intake

& FFQ

AR, n=24 1-6 y 318 15.6

AR-VC, n=24 1-6 y 319.5 18.6

BDNAR, n=38 1-10.6 y 339.5 9.0

BDNAR-VC, n=38 1-10.6 y 402.6 12.4

Thacher et al. 2000,

Bangladesh [28]

Method: Two 24-h

dietary recalls

Rickets, n=123 1-14 y - -

Control, n=123 - -

Graff et al.2004,

Nigeria [32]

Method: Two 24-h

dietary recalls

Rickets, n=15 2-8 y - -

Control, n=15 - -

Aggarwal et al,

2012, India [30]

Method: 24-h recall,

FFQ

Rickets, n=67 <1-<2 y 25 6.7

Control, n=68 <1-2 y 13 7.3

Braithwaite et al.

2012, The Gambia

[29] Method: 2 days

weighed food intake

and FFQ

Rickets follow-up,

n=33

6-10 y 720 -

Control, n=30 6-10 y 720 -

Arsenault et al.

2013,

Bangladesh[33]

Rural normal

children

2-4 y - -

35

There is no recommended daily intake or safe limits of intake of phytic acid and oxalic acid.

As a result, findings of my study could not be compared with a standard recommendation. A

recent study conducted in rural Bangladesh could be cited which used USDA food tables

and reported daily intake of phytic acid to be 286 mg in normal (non-rickets) children. In my

study, daily intake of phytic acid was found to be 318 mg in AR children, however, this intake

was less than half of that in less than 6 year old Gambian Children (Table 4.2). Moreover,

oxalate intake was higher in my study compared to an Indian study conducted on rickets and

their controls who included oxalate intake values collected by 24-h recall assessment [30].

Unlike this aforesaid Indian study which showed a significantly higher intake of phytate in

rickets children, differences in daily phytate and oxalate intake between AR and their

controls were not significant in my study. It should be noted that phytate intake was

significantly higher in Active Rickets children when presented intake per 1000 kcal of food

energy and per kg body weight of the subjects. It means, one of the main outcome of interest

phytate showed the higher intakes in AR than their controls. Dr. Ahmed showed a consistent

and noticeable lower intake of calcium in AR than their controls. It means that AR children

were not only having very low calcium intake, their phytate intake was very high at the same

time which was affecting their calcium absorption.

4.3 Limitations

A major limitation of food composition data is the lack of information on foods of Bangladeshi

origin. While working on Bangladeshi foods, I found a very limited number of sources which

were available electronically. Most of the foods were not analysed by following standard

methods. Organizations who had food composition tables did not necessarily carried out

food analysis and derived data. Some of them have taken data from other sources. In my

study, electronic version of a recently published food composition table of Bangladesh did

provide phytate and oxalate values [25]. The other important source was the ‘Nutritive Value

of Indian Foods’ which was not available electronically [20]. Another limitation of working on

the food composition was the non-availability of both phytate and oxalate values from the

same source. If I could have phytate and oxalate content from same source it would have

given more reliability on the origin of food, analysis method etc.

Losses of phytate and oxalate during domestic food processing and cooking could not be

studied in my project. Cooking method, duration of cooking, temperature could not be taken

into account because there was too little data available to attempt this.

No further analysis was done to see the phytate and oxalate intake in different age groups

and sex. Percentage contribution of different food groups in the total intake of phytate and

oxalate among different study groups has not been studied. This area of work with the data

36

which I have derived will be taken forward by Dr. Sonia Ahmed, Dr. Gail Goldberg and me in

the future.

37

4.4 Conclusion and Recommendations

The data suggests that the diet of young children in Chakaria, Bangladesh is cereal and

vegetables based which contributes to the higher phytate and oxalate intake of children

when compared with total food energy consumption. Dietary assessment through a single

prospective 24 hour weighed record is not sufficient to comment about overall quality of the

diet which is low in calcium and high in phytate and oxalate. Future research should focus on

designing intervention to provide nutrition education to the parents and care givers to modify

the dietary pattern of young children.

More research on food composition is required. Emphasis should be given on updating food

composition tables with revised values. There is a lack of studies on effect of domestic food

processing, traditional cooking methods on antinutrients present in Bangladeshi foods.

Research is required on the effect of household food processing to reduce antinutrients

which can influence mineral bioavailability.

38

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