CHS 214 Introduction to the Science of Nutrition and Related Definitions Lecture 1.

CHS 214

Introduction to the Introduction to the Science of Nutrition and Science of Nutrition and

Related DefinitionsRelated Definitions

Lecture 1

Objectives Introduction Definitions Energy from food Functions of food nutrients Composition of human body Nutrition assessment of individual Sign of good nutrition The relationship of nutrition with other

sciences Nutrient intake limits

Introduction Most of the organized studies of nutrition have

been confined to the 20th century. Although there was evidence of long-standing

curiosity about nutrition. Hippocrates, the father of medicine(400 BC)

considered food as one universal nutrient. Antonie Lauret Lavoisier(18th century, a French

chemist) is known as father of nutrition. In Islam there are many verses of the Quran

and Hadeeths in food and nutrition. Some of these fact has just been proved by the

modern science and some not.

Nutrition has played a significant role in our life, even from before our birth.

Many people are concerned only with food that relives their hunger or satisfies their appetite .

But in many times, these foods don't supply their bodies with all the component of good nutrition.

Definitions

Food:Foods are products derived from plants or animals .that can be taken into the body to yield energy and nutrients for maintenance of life ,for growth and repair tissues.Food is that nourishes the body.Food is a prerequisite of nutrition.

DietDiet is the foods and beverages a person eats and drinks.

Food composition

Nutrients:

Chemical substances obtained from foods used in the body to provide energy, structure materials,

regulating agents to support growth, maintenance, repair of body's tissues and may

also reduce the risks of some diseases.

•

Nutrients divided into two categories:

Macronutrients

Are the nutrients which the body needed in large amount such as carbohydrate, protein and fats.

Carbohydrates, protein and fats are the main source of energy for human body.

Are the energy yielding nutrients. Micronutrients Are nutrients needed in lesser amounts such

as: Vitamins & minerals.

Chemical composition of the nutrients

Organic nutrients: substance that contain carbon atom.Inorganic: substances that do not contain carbon atoms.

Essential nutrients:

Are nutrients a person must obtain from food because the body cannot make them for itself insufficient quantity to meet physiological needs. Also called indispensable nutrients.

Nutrition:

• Nutrition is the science of foods, nutrients and other substances they contain their actions within the body (including ingestion, digestion, absorption, transport, metabolism and excretion).

• A broader definition includes the social, economic, cultural, and psychological implications of food and eating.

Nutritional requirements

The amounts of nutrient which are needed for covering the human needs to be healthy depend on sex, age and few other factors.

Nutritional status

An individual condition of health in relation to digestion and absorption of nutrients.

Nutritional care:Application of the science of nutrition in nourishing the body regardless of health problems or potential problems.

Adequate diet: is a diet providing all the needed nutrients in the right total amounts.

Junk food: Refers to foods that are harmful.

Calories• The energy released from carbohydrates,

proteins and fats can be measured in calories. • A calorie is the amount of heat necessary to

raise temperature of 1 gm of water by 1 C.• 1000-calorie metric units are known as

kilocalories (kcal).

Empty-kcalorie foods a popular term used to denote foods contribute

energy (from sugars, fat or both) but lack in protein, vitamins and minerals

Example:(potato chips and candies).

Dieteticsthe health profession responsible for the

application of nutrition science to promote human health and treat disease

MetabolismThe sum of all chemical reactions that take

place in the body which it maintains itself produces energy for its functioning.

Nutrition science

Nutrition science: 1-The study of nutrients and other substances in foods

and the body's handling of them.2-Its foundation depends on several other sciences

including biology, biochemistry, and physiology.3- Comprises the body of knowledge governing the food

requirement growth, activity, reproduction and lactation.

Nutritional genomics: the science of how nutrients affect the activities of genes and how genes affect the interactions between diet and disease.

Malnutrition: Malnutrition has two types:

Undernutrition: deficient energy or nutrients.

•Symptoms of under nutrition (extremely thin, losing muscle tissues, prone to infection and disease, skin rashes, hair loss, bleeding gum and night blindness).

Overnutrition: excess energy or nutrient.

•Symptoms of overnutrition (heart disease, diabetes, yellow skin, rapid heart rate and low blood pressure).

Nitrogen balance

The proteins in the body undergo constant turnover (degraded to amino acids and resynthesized).

Nitrogen balance is the difference between the amount of nitrogen taken into the body each day and the amount of nitrogen in compounds lost.

if: 1- More nitrogen is ingested than excreted, a person is said to be in positive nitrogen balance (growing individual such as children and pregnant).

2- Less nitrogen is ingested than is excreted (negative nitrogen balance, person eating either too little protein or protein is deficient in one or more of the essential amino acids, new protein cannot be synthesized and the unused amino acids will be degraded, body function will be impaired by the net loss of critical proteins.

3- In contrast, healthy adults are in nitrogen balance and the amount of nitrogen consumed in the diet equals its loss in urine.

Nutritive value

The amounts of nutrient which the food consist of, determined by using:

Food analysis. Food analysis tables.

Energy from food The amount of energy a food provide depends

on how much CHO, fat, and protein contains. When completely broken down in the body,1 gm CHO 4 kcal of energy1 gm protein 4 kcal of energy1 gm of fat 9 kcal of energytherefore fat has the greater energy density

than either CHO or protein. Alcohol is not considered a nutrient because it

interferes with health but it yields energy1 gm of alcohol 7 kcal of energy

Functions of food nutrients

1-Provide energy sources2-Build tissues3-Regulate metabolic process

1-Provide energy sources The major carbohydrates in the human diet

are starch, sucrose, fructose and glucose.

Dietary carbohydrate (starches and sugars) provided the body's primary source of fuel for energy.

Oxidation of carbohydrates to CO2 and H2O in the body produces approximately 4 kcal/g.

They also maintain the back-up store of quick energy as glycogen (animal starch).

Fats are lipids composed of triacylglycerols.

A triacylglycerol molecule contains three fatty acids esterified to one glycerol molecule.

Dietary fats, from both animal and plant sources, provided the body's secondary or storage

form of energy.

It is a more concentrated, yielding 9 kcal for each gram consumed.

In a well-balanced diet, protein provided about 15 % of the total kcalories.

Each gram of protein can yield 4 kcal.

How to calculate the energy available from 1 slice of bread with 1slice of bread with 1 tablespoon of peanut

butter on it contains 16 grams carbohydrate, 7 grams protein and

9 grams fat?

2-Build tissues• Proteins are composed of amino acids that are joined

to form linear chains. • The digestive process breaks down proteins to their

constituent to amino acids, which enter the blood.

• The primary function of protein is tissue building and repairing body tissues.

• Dietary protein provides amino acids, amino acids are the building unit necessary for construction and repairing body tissues.

• Muscle protein is essential for body movement. • Other proteins serve as enzymes.

• Other nutrients such as minerals and vitamins used in tissue building and maintaining tissue.

• Minerals are also found in the fluids of the body and influence their properties.

• There are 13 different vitamins, one vitamin enables the eyes to see in dim light,

protect the lungs from air pollution make the sex hormones, stop the bleeding, helps repair the skin, replace old blood cells and lining of the digestive

tract.

3-Regulate metabolic process• Many vitamins and minerals function as

coenzymes factors in cell metabolism.

• Other nutrients (water and fibers), water provides the environment in which nearly all the body's activities. Also, in many metabolic reactions and supplies

the medium for transporting vital materials to cells and waste products away from them.

• Dietary fibers help regulate the passage of food material through the gastrointestinal tract and influences absorption of various nutrients.

Composition of human body

61%17%

14%

6% 2%

water (61%)

Protein (17%)

Fats(13.8)

Minerals(6.1%)

Carbohydrates(1.5)

Nutrition assessment of individual

Evaluation of person's nutrition1- Historical information (socioeconomic status,

drug use, diet and person's family history).2-A=Anthropometric data (height and weight).3- B= biochemical data (Laboratory tests).4-C=clinical assessment(Physical examinations)5-D=Dietary assessment

Sign of good nutrition1. Well-developed body.2. Ideal weight.3. Good muscle development.4. The skin is smooth and clear5. The hair glossy and the eyes clear and

bright.6. Appetite, digestion and elimination are

normal.7. Have good resistance to infection.

The relationship of nutrition with other sciences

There are three main areas of overlapping between nutrition and medicine:1-dietary control of disease.2-the relationship between diet as a possible causative factor in disease ex: cancer, heart diseases etc.3-the toxicology of natural and processed foods.

Nutrient intake limits

Safety

RDA

Danger

Danger of toxicity

marginal

Safety

RDA

Safety

marginal

Danger of deficiency

Naive View

Accurate View

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