Vitamins Vital amines

Vitamins

Vital amines – “vital to life” (1900s)Their deficiency attests to their importance

Three new columns added to the Vitamins table on the web

http://www.iom.edu/Object.File/Master/7/296/0.pdfhttp://arbl.cvmbs.colostate.edu/hbooks/pathphys/

misc_topics/vitamins.html

The Vitamins• They are organic non-energy yielding,

micronutrients.• They are necessary for normal metabolism

in animals. • They either are not synthesized in the

body or are synthesized in inadequate quantities. Hence they are essential nutrients (Vitamin D is an exception).

• Most vitamins function as coenzymes or cofactors.

• Deficiency states are recognized for all vitamins, and in many cases, excessive intake also leads to disease.

Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning

The Vitamins• Vitamins vs carbohydrates, fats, and

proteins– Structure (organic)

• They are not macromolecules made by linking individual units

– Function (non-energy yielding)• Do not provide usable energy • They are required to help the various

enzymes in the body some of which help to release the energy from food

– Food contents (micronutrients)• Amounts in food and amounts required are

measured in micrograms (as opposed to grams and milligrams for other nutrients)


The Vitamins• Bioavailability

– Amount of vitamin available in foods:• Amount in food• Amount absorbed and used by the body

– Determined by• Efficiency of digestion • Time to go through GI tract• Previous nutrient intake and nutrition status• Other foods consumed at the same time

– E.g. alcohol inhibits thiamin absorption• Method of food preparation (raw, cooked or processed)

– Some vitamins may get leached out if cooked into too much water

– Some vitamins are inactivated by high heat• Source of nutrient

– Synthetic– Fortified– Naturally occurring


The Vitamins• Precursors

– Some vitamins are available in foods as precursors– Necessary to measure amount of active vitamin

plus potential amount available from precursors• E.g. tryptophan is a precursor for Niacin• 1 mg of Niacin required 60mg of dietary tryptophan• So recommended intakes are in Niacin equivalents (NE)

• Organic nature– Can be destroyed by heating, UV rays (sun) or

fluorescent light (Riboflavin)– Can be destroyed by oxidation (Vitamin C) cut fruits,

fruit juices– Table 10-1 “ Minimizing nutrient losses”

• Refrigerate, wash before cutting, use microwave oven or steam in small amount of water, cook for short time, low temperature


The Vitamins• Solubility

– Hydrophilic (water soluble)• B Vitamins and Vitamin C

– Hydrophobic (fat soluble)• Vitamins A, D, E and K

• Toxicity– More is not necessarily better


The Vitamins


The Vitamins


The Water-Soluble Vitamins

B Vitamins and

Vitamin C



Metabolic Pathways Involving B Vitamins

NiacinB6

ThiaminRiboflavin

Pantothenic acid

Folate

Riboflavin

The B Vitamins• Coenzymes


Thiamin


• Other names: Vitamin B1

• 1998 RDA – men: 1.2 mg/day– women: 1.1 mg/day

• Chief functions in the body– Part of coenzyme TPP (thiamin pyrophosphate)

used in energy metabolism– Required for the breakdown of glucose to release

energy– Required for the functioning of the nervous

system, especially the peripheral nerves, like those found in your hands and feet

– Vital for adequate muscle coordination

Thiamin

• Significant sources– Whole grain, fortified, or

enriched grain products– Moderate amounts in all

nutritious food– Pork

• Easily destroyed by heat



Thiamin


• Deficiency disease– Beriberi

• Wet, with edema• Dry, with muscle wasting

• Deficiency symptoms– Enlarged heart, cardiac failure– Muscular weakness – Apathy, poor short-term memory,

confusion, irritability – Anorexia, weight loss

• Toxicity symptoms: none reported

Riboflavin


Riboflavin• Other names: Vitamin B2

• 1998 RDA– Men: 1.3 mg/day– Women: 1.1 mg/day

• Chief functions in the body– Part of coenzymes FMN (flavin mononucleotide)

and FAD (flavin adenine dinucleotide) – These coenzymes are used in energy-yielding

metabolic pathways from both glucose and fatty acids

– Metabolism of certain vitamins and minerals also requires Riboflavin


Riboflavin

• Significant sources– Milk products (yogurt,

cheese)– Enriched or whole grains– Liver

• Easily destroyed by ultraviolet light and irradiation



Riboflavin


• Deficiency disease: ariboflavinosis• Deficiency symptoms

– Inflamed eyelids and sensitivity to light, reddening of cornea

– Sore throat– Cracks and redness at corners of

mouth– Painful, smooth, purplish red tongue– Inflammation characterized by skin

lesions covered with greasy scales


Niacin


• Other names– Nicotinic acid– Nicotinamide– Niacinamide

– Vitamin B3

• Precursor: dietary tryptophan• 1998 RDA

– Men: 16 mg NE/day– Women: 14 mg NE/day

• Upper level for adults: 35 mg/day

Niacin

• Chief functions in the body– Part of coenzymes NAD

(nicotinamide adenine dinucleotide) and NADP (its phosphate form) used in energy metabolism

• Significant sources– Milk, eggs, meat, poultry, fish– Whole-grain and enriched breads

and cereals– Nuts– All protein-containing foods



Niacin


• Deficiency disease: pellagra• Deficiency symptoms

– Diarrhea, abdominal pain, vomiting– Inflamed, swollen, smooth, bright red tongue– Depression, apathy, fatigue, loss of memory,

headache– Bilateral symmetrical rash on areas exposed to

sunlight

• Toxicity Symptoms– Painful flush, hives, and rash (“niacin flush”)– Excessive sweating– Blurred vision– Liver damage, impaired glucose tolerance

Biotin• 1998 adequate intake (AI)

– Adults: 30 g/day

• Chief functions in the body– Part of a coenzyme used in energy

metabolism, fat synthesis, amino acid metabolism, and glycogen synthesis

• Significant sources– Widespread in foods– Organ meats, egg yolks, soybeans, fish, whole

grains– Raw egg yolks have avidin which binds up

biotin making it unavailable– Also produced by GI bacteria


http://www.chowbaby.com/img/articlepics/soybeans.jpg

Biotin


• Deficiency – Rare– Seen in adults that are fed artificially by vein

without biotin supplementation – Caused by long term alcohol abuse– Can be induced by feeding people raw eggs

(avidin)

• Deficiency symptoms– Depression, lethargy, hallucinations, numb or

tingling sensation in the arms and legs– Red, scaly rash around the eyes, nose, and mouth– Hair loss


Pantothenic Acid


• 1998 adequate intake (AI)– Adults: 5 mg/day

• Chief functions in the body– Part of coenzyme A, used in energy

metabolism

• Significant sources– Widespread in foods– Organ meats, mushrooms, avocados,

broccoli, whole grains

• Easily destroyed by food processing

Pantothenic Acid


• Deficiency symptoms– Vomiting, nausea, stomach cramps– Insomnia, fatigue, depression,

irritability, restlessness, apathy– Hypoglycemia, increased sensitivity to

insulin


Vitamin B6


• Other names– Pyridoxine– Pyridoxal– Pyridoxamine

• 1998 RDA– Adults (19-50 years): 1.3 mg/day

• Upper level for adults: 100 mg/day• Stored extensively in muscle tissue

(unlike other water soluble vitamins)

Vitamin B6


• Chief functions in the body– Part of coenzymes PLP (pyridoxal

phosphate) and PMP (pyridoxamine phosphate) used in amino acid and fatty acid metabolism

– Helps to convert tryptophan to niacin and to serotonin

– Helps to make red blood cells– Influences cognitive performance,

immune function and steroid hormone activity

Vitamin B6

• Significant sources– Meats, fish, poultry– Potatoes, legumes,

noncitrus fruits– Fortified cereals– Liver– Soy products

• Deficiency symptoms– Scaly dermatitis– Anemia (small-cell type)– Depression, confusion,

abnormal brain wave pattern, convulsions

– One cause is INH (TB drug)


Vitamin B6


• Toxicity symptoms– Depression, fatigue, irritability,

headaches– Nerve damage causing numbness and

muscle weakness leading to an inability to walk and convulsions

– Skin lesions


Folate

• Absorption

• Folate is absorbed efficiently from fortified products

• Too much folate Copyright 2005 Wadsworth Group, a division of Thomson Learning

Copyright 2005 Wadsworth Group, a division of Thomson Learning

Folate

• Absorption– Folate is absorbed efficiently from

fortified products– Neural tube defects (spina bifida) in

babies born to women with folate deficiency

– Deficiency takes effect early on in pregnancy

– So all women of child bearing age are advised to take folate supplements


Folate• Activation

– Vitamin B12


Folate• Recommendations

– Dietary folate equivalents (DFE)


Folate• Neural tube defects

– Spina bifida


Folate• Heart disease

– High levels of homocysteine and low levels of folate

• Cancer


Folate: In Summary


• Other names– Folic acid– Folacin– Pteroylglutamic acid (PGA)

• 1998 RDA– Adults: 400 g/day

• Upper level for adults: 1000 g/day

Folate: In Summary


• Chief functions in the body– Part of coenzymes THF

(tetrahydrofolate) and DHF (dihydrofolate) used in DNA synthesis and therefore important in new cell formation

• Significant sources– Fortified grains– Leafy green vegetables, legumes,

seeds– Liver

Folate: In Summary


• Deficiency symptoms– Anemia (large-cell type)– Smooth, red tongue– Mental confusion, weakness, fatigue,

irritability, headache

• Toxicity symptoms– Masks vitamin B12-deficiency

symptoms

FolateSources


Vitamin B12

• Activation– Folate


Vitamin B12

• Absorption– HCl– Pepsin– Intrinsic factor


Vitamin B12• Deficiency of folate or B12 produces

pernicious anemia


Vitamin B12: In Summary


• Other names: cobalamin (and related forms)

• 1998 RDA– Adults: 2.4 g/day

• Chief functions in the body– Part of coenzymes methylcobalamin

and deoxyadenosylcobalamin used in new cell synthesis

– Helps to maintain nerve cells– Reforms folate coenzyme– Helps to break down some fatty acids

and amino acids



• Significant sources– Animal products (meat, fish, poultry,

shellfish, milk, cheese, eggs)– Fortified cereals

• Easily destroyed by microwave cooking

• Deficiency disease: pernicious anemia



• Deficiency symptoms– Anemia (large-cell type)– Fatigue, degeneration of peripheral

nerves progressing to paralysis


Non-B Vitamins• Choline


Non-B Vitamins• Inositol

– Cell membrane structure• Carnitine

– Transports long chain to the mitochondria for oxidation

• Vitamin imposters– Many of these are included in Vitamin

supplements– Unnecessary since they are available

in foods



Metabolic Pathways Involving B Vitamins

The B Vitamins• B vitamin deficiencies

– Glossitis– Cheilosis

• B vitamin toxicities

• B vitamin food sources


Vitamin C


Vitamin C


• Other name: ascorbic acid• 2000 RDA

– Men: 90 mg/day– Women: 75 mg/day– Smokers: + 35 mg/day

• Upper level for adults: 2000 mg/day

Vitamin C


• Chief functions in the body– Collagen synthesis

• Strengthens blood vessel walls, forms scar tissue, provides matrix for bone growth

– Antioxidant– Thyroxin synthesis– Amino acid metabolism– Strengthens resistance to infection– Helps in absorption of iron

Vitamin C


• Significant sources– Citrus fruits– Cabbage-type vegetables, dark green

vegetables (such as bell peppers and broccoli)

– Cantaloupe, strawberries– Lettuce, tomatoes, potatoes– Papayas, mangoes

• Easily destroyed by heat and oxygen

Vitamin C

Sources



Vitamin C


• Deficiency disease: scurvy• Deficiency symptoms

– Anemia (small-cell type)– Atherosclerotic plaques– Pinpoint hemorrhages, bone fragility,

joint pain– Poor wound healing, frequent

infections, bleeding gums, loosened teeth

– Muscle degeneration and pain, hysteria, depression, rough skin, blotchy bruises

Vitamin C


• Toxicity symptoms– Nausea, abdominal cramps, diarrhea– Headache, fatigue, insomnia– Hot flashes, rashes– Interference with medical tests,

aggravation of gout symptoms, urinary tract problems, kidney stones

Vitamin And Mineral Supplements

• Arguments for supplements– Correct overt deficiencies– Improve nutrition status– Reduce disease risks– Support increased nutrient needs– Improve the body’s defenses



• Who needs supplements?



• Arguments against supplements– Toxicity– Life-threatening misinformation– Unknown needs– False sense of security– Other invalid reasons



• Bioavailability

• Antagonistic actions



• Selection of supplements– Form– Contents– Misleading claims– Cost



• Regulation of supplements


An Example of a Supplement Label


Vitamins Vital amines – “vital to life” (1900s) Their deficiency attests to their importance Three new columns added to the Vitamins table on the web.

Documents

vitamins copyright

vitamins precursors

vitamins table

vitamins function

vitamins bioavailability

wadsworth group

vitamin c copyright