Nutrition & health
- Nutrition may be defined as the sciences of food & its relationship to health.it 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
- Foods of animal origin
- Foods of vegetable origin
Classification by chemical compositions
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
- Proteins are complex organic nitrogenous compounds.
- They also contain sulphur & in some cases phosphorous & iron
- Proteins are made up of monomers called amino acids.
- There are about 20 different amino acids that are found in the human body.
- 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
- Repair & maintenance of body tissue
- Maintenance of osmotic pressure
- Synthesis of bioactive substance & other vital molecules
- 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.
- Vitamins are divided into two groups
- Fat-soluble – A, D, E, K
- Water-soluble vitamins- Vitamins of the B-group & vitamin- C.
- Vitamin A – covers both a preformed vitamin A, retinol & provitamin, beta carotene some of which is converted to retinol in the intestinal mucosa.
- 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
- Night blindness
- Conjunctival xerosis
- Bigot’s spots
- Corneal xerosis
- The nutritionally important forms of vitamin D in man are calciferol ( Vitamin D2) & (Vitamin D3)
- Pyridoxine (vitamin B6) exists in three forms pyridoxine, pyridoxal & pyridoxamine.
- It plays an important role in the metabolism of amino acids, fats & carbohydrates
- 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.
- Thiamine (vitamin B1) is a water-soluble vitamin
- It is essential for the utilization of carbohydrate
- 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
- Intestine – promotes intestinal absorption of calcium & phosphorous.
- Bone- stimulates normal mineralization enhances bone reabsorption affects collagen maturation.
- Kidney- increase tubular reabsorption of phosphate
- Vitamin B12 is a complex organometallic compound with a cobalt atom. the preparation which is therapeutically used is cyanocobalamin
- Vitamin B12 cooperates with foliate in the synthesis of DNA
- Vitamin B12 has a separate biochemical role, unrelated to folate in the synthesis of fatty acids in myelin.
Vitamin B12 deficiency
- 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 (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.
- 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.
- 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 which is mainly non-starch poly-saccharide is a physiological important component of the diet.
- 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
- 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
- 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