Energy from different food components :
- Excess of the carbohydrates are stored in liver and muscles in the form of glycogen.
- Proteins are the macromolecules formed by bonding together many amino acids.
- Proteins of animal origin are called as ‘first class’ proteins.
- We get 4 Kcal of energy per gram of proteins.
- Amino acids are obtained after digestion of proteins.
- Those amino acids are absorbed in the body and transported up to each organ and cell via blood.
- From these amino acids, organs and cells produce various proteins necessary for themselves and the whole body.
- Excess of amino acids obtained from proteins are not stored in the body.
- They are broken down and the ammonia formed is eliminated out of the body.
- If necessary, excess of proteins are converted into other useful substances like glucose through the process of gluconeogenesis.
- Plants produce the necessary amino acids from minerals denovo and thereby produce different proteins.
- An enzyme RUBISCO present in the plant chloroplasts is most abundant protein found in nature.
Lipids:
- The substances formed by specific chemical bond between fatty acids and alcohol are called as lipids.
- Digestion of lipids consumed by us is nothing but their conversion into fatty acids and alcohol.
- Fatty acids are absorbed up and distributed everywhere within the body.
- From those fatty acids, different cells produce various substances necessary to themselves.
- Ex. the molecules called as phospholipids which are essential for producing plasma membrane are formed from fatty acids.
- Besides, fatty acids are used for
- producing hormones like progesterone, estrogen, testosterone, aldosterone, etc.
- the covering around the axons of nerve cells.
- We get 9 KCal of energy per gram of lipids.
- Excess of lipids are stored in adipose connective tissue in the body.
Vitamins :
- A group of heterogeneous compounds of which, each is essential for proper operation of various processes in the body.
- There are main six types of vitamins,
- e.g. A, B, C, D, E and K.
- A, D, E and K are fat-soluble.
- B and C are water-soluble.
- Vitamins like riboflavin (Vitamin B2) and nicotinamide (Vitamin B3) respectively are necessary for production of FADH2 and NADH2.
Water :
- There is about 65 – 70% water in our body.
- Each cell contains 70% water weight by weight.
- Blood-plasma also contains 90% of water.
- water is an essential nutrient.
Fiber :
- fibers are also essential nutrients.
- In fact, we cannot digest the fibers.
- However, they help in the
- digestion of other substances and
- egestion of undigested substances.
- We obtain the fibers from leafy vegetables, fruits, cereals, etc.