The Importance of Nutrition and Health: What You Need to Know

Nutrition and Health

Nutrition & health


  • Nutrition may be defined as the sciences of food & its relationship to is concerned primarily with the part played by nutrients in body growth development & maintenance
  • The word nutrient or food factor is used for specific dietary constituents such as proteins, vitamins & minerals. dietetics is the practical application of the principle of nutrition. it includes the planning of meals for the well & the sick good nutrition means maintaining a nutritional status that enables us to grow well & enjoy good health
  • Protein, carbohydrate & fat had been recognized early in the 19th century as energy-yielding food & mush, attention was paid to their metabolism & contribution to energy requirements.

Classification of foods

Classification by origin

Classification by origin

  1. Foods of animal origin
  2. Foods of vegetable origin

Classification by chemical compositions

  1. Proteins
  2. Fats
  3. Carbohydrates
  4. Vitamins
  5. Minerals

Classification by predominant function

Bodybuilding foods- meal, milk, poultry, fish, eggs, pulses, etc.

Energy giving foods – sugars, fats, oil, etc

Protective foods – Vegetables, fruits, milk, etc


Definition – Organic & inorganic complexes contained in food are called nutrients.

They are broadly divided into

  • Macronutrients
  1. Proteins
  2. Fats
  3. Carbohydrates
  • Micronutrients
  1. Vitamins
  2. Minerals


  1. Proteins are complex organic nitrogenous compounds.
  2. They also contain sulphur & in some cases phosphorous & iron
  3. Proteins are made up of monomers called amino acids.
  4. There are about 20 different amino acids that are found in the human body.
  5. Of this 8AA are termed essential as they are not synthesized in the human body and must be obtained from dietary proteins.

Functions of proteins

  1. Bodybuilding
  2. Repair & maintenance of body tissue
  3. Maintenance of osmotic pressure
  4. Synthesis of bioactive substance & other vital molecules


  1. Vitamins are a class of organic compounds categorized as essential nutrients that are required by the body in very small amounts. they fall in the category of micronutrients.
  2. Vitamins are divided into two groups
  • Fat-soluble – A, D, E, K
  • Water-soluble vitamins- Vitamins of the B-group & vitamin- C.

Vitamin A

  1. Vitamin A – covers both a preformed vitamin A, retinol & provitamin, beta carotene some of which is converted to retinol in the intestinal mucosa.
  2. The international unit (IU) of vitamin A is equivalent to 0.2 micrograms of retinol (or 0.55) microgram of retinol palmitate.

Deficiency of vitamin A

The signs of vitamin A deficiency are predominantly ocular, they are

  1. Night blindness
  2. Conjunctival xerosis
  3. Bigot’s spots
  4. Corneal xerosis
  5. Keratomalacia

Vitamin D

  1. The nutritionally important forms of vitamin D in man are calciferol ( Vitamin D2) & (Vitamin D3)


  1. Pyridoxine (vitamin B6) exists in three forms pyridoxine, pyridoxal & pyridoxamine.
  2. It plays an important role in the metabolism of amino acids, fats & carbohydrates
  3. The requirements of adults vary directly with protein intake. adults may need 2 mg/day during pregnancy & lactation 2.5mg/day. balanced diets usually contain pyridoxine therefore deficiency is rare.


  1. Thiamine (vitamin B1) is a water-soluble vitamin
  2. It  is essential for the utilization of carbohydrate
  3. Thiamine pyrophosphate (TPP) the coenzymes of cocarboxylase plays a part in activating transketolase an enzyme involved in the direct oxidative pathway for glucose.

Functions of vitamin D & its metabolites

  1. Intestine – promotes intestinal absorption of calcium & phosphorous.
  2. Bone- stimulates normal mineralization enhances bone reabsorption affects collagen maturation.
  3. Kidney- increase tubular reabsorption of phosphate

Vitamin B12

  1. Vitamin B12 is a complex organometallic compound with a cobalt atom. the preparation which is therapeutically used is cyanocobalamin
  2. Vitamin B12 cooperates with foliate in the synthesis of DNA
  3. Vitamin B12 has a separate biochemical role, unrelated to folate in the synthesis of fatty acids in myelin.

Vitamin B12 deficiency

  1. Vitamin B12 deficiency is associated with megaloblastic anaemia (per nitrous anaemia) demyelinating neurological lesions in the spinal cord & infertility (in animal) species. dietary deficiency of B12 may arise. the subjects who are strict vegetarians & eat animal products at the present time there is little evidence the vitamin B12 deficiency anaemia represents an important public health problem.

Vitamin C

  1. Vitamin c (Ascorbic acid) is a water-soluble vitamin. it is the most sensitive of all vitamins to heat. man, monkey & guinea pig are perhaps the only species known to required vitamin c in their diet.
  2. Vitamin C has an important role to play in tissue oxidation it is needed for the formulation of collagen, which accounts for 25 percent of total body protein.


  1. Carbohydrate is the main source of energy, providing 4 Kcals per one gram carbohydrate is also essential for the oxidation of fats & for the synthesis of certain non-essential amino acids.

Dietary fiber

  1. Dietary fiber which is mainly non-starch poly-saccharide is a physiological important component of the diet.
  2. It is found in vegetables, fruits & grains. it may be divided broadly into cellulose & non-cellulose polysaccharides which include hemicellulose, pectin, storage polysaccharides like insulin & the plant gums & mucilage
  3. These are all degraded to a greater or lesser extent by the microflora in the human colon.

Nutritional profiles of principal foods

  • The principal food includes
  1. Cereals
  2. Millets
  3. Pulses
  • Cereals
  1. Cereals (eg. rice, wheat) constitute the bulk of the daily. rice is the staple food of more than half the human race. next to rice-wheat is the most important cereal.

That’s all for nutrition & health

Next Chapter                –                                       Demography & family planning

Previous Chapter         –                     Introduction To Concept Of Disease Notes