Human Anatomy and Physiology : III. Vitamins And Nutrition Part-IV

The cells of the human body can synthesize most of the fatty acids. However only essential fatty acids cannot be synthesized in the body. Thus, essential fatty acids should be a part of human diet. Deficiency diseases develop due to the absence of essential fatty acids. A normal diet of 2200-2400 calories should contain about 75 gm of fat per day.

Linseed is a food and fibre crop that is grown in cooler regions of the world. The oil is extracted from its seed, known as linseed oil, which is a very good source of omega-3 fatty acid, which is able to prevent the deposition of fat in blood vessels.

Alpha-linolenic acid is a kind of omega-3 fatty acid found in plants. It is found in flaxseed oil, canola, soyabean and walnut oil.

Vitamins and minerals are often called micronutrients because our body needs only tiny amounts of them. Cereals, green vegetables, milk, fruit, and meat are a good source of vitamins. White blood cells (not vitamins) help to keep the body healthy by destroying harmful bacteria.

Glycine, serine, and tyrosine are non-essential amino acids, which are synthesized inside our bodies. There are 20 biologically active amino acids found in human body. These are divided into two categories - 10 are essential amino acids and 10 are non-essential amino acids. Essential amino acids are those which can’t synthesize inside the human body.

Amino acids are the building blocks of protein. Foods that contain all essential amino acids are called complete protein foods. Complete proteins are supplied by meat, poultry, yogurt, eggs, fish, milk, quinoa and soyabean etc. Among the given options, except rice, all other food materials contain all essential amino acids.

Egg is the best source of all the essential amino acids for human nutrition because it has the highest Biological Value (BV). The Biological Value (BV) is a scale of measurement used to determine what percentage of a given nutrient source is utilized by the body. BV (for protein sources) is derived from providing a measure intake of protein, then determining the nitrogen uptake versus nitrogen excretion. When a protein source contains the essential amino acids in a proportion similar to that required by the body, it has a high BV, while when one or more of the essential amino acids are missing or present in low numbers, it has a low BV. The Biological Value of some protein sources is given in the following table:

Fat present below the skin surface of our body forms a complete barrier against the external environment. It is an energy store and also acts as a thermal insulating layer. It protects the underlying structure of the body from any physical trauma.

Fats have highest calorie value per unit. 4.0 Kcal energy is obtained by metabolic oxidation of 1 gm carbohydrate or protein whereas about 9.3 Kcal is received from fats of the same amount. Flora and fauna, both are a source of fats.

Fats have the highest energy value since 1g of fat contains 9.3 kcal of energy; one gram of proteins contains about 4.0 kcal and one gram of carbohydrates also contains about 4.0 kcal of energy.