CBSE Class 10 Biology Food and Nutrition Notes Set 10

Vitamins

Vitamins are organic substances needed in tiny amounts. They give no energy but work with enzymes and keep the body healthy. Vitamins B complex and C dissolve in water; vitamins A, D, E and K dissolve in fat. A shortage causes a deficiency disease that is cured by giving the missing vitamin.

Minerals

Minerals regulate body processes and build bones, teeth and blood. They are needed in small but regular amounts.

Balanced Diet

A balanced diet has all food components in the right proportion for the person's age and work: carbohydrates and fats for energy, proteins for growth, vitamins and minerals for regulation, water as the solvent and fibre as roughage. Cheap foods such as seasonal fruits, greens, groundnut, pulses, jaggery, banana and moringa leaves can supply what costlier foods do.

Special Needs and Colostrum

Growing children need extra protein and calcium. Pregnant and nursing women need extra protein, calcium and iron. People doing heavy work or suffering from wasting diseases need more food. The first milk after childbirth is called colostrum; it is rich in antibodies that protect the baby from infections.

Deficiency Diseases

1. Protein-calorie malnutrition (PCM) and protein-energy malnutrition (PEM) affect young children and slow down growth.
2. Kwashiorkor: caused by too little protein, mostly after weaning. The child has swollen belly and legs (oedema), dry scaly skin and discoloured hair.
3. Marasmus: seen in infants under one year when breast milk is replaced by a diet low in both protein and calories. The child is thin with a wasted body and prominent ribs, without oedema.
4. Iron deficiency causes anaemia; iodine deficiency causes goitre, which is common in hilly areas because the soil and water there are poor in iodine, and rare on the coast where sea food is eaten.
Poverty is the main cause, but food habits matter too. Polishing rice removes vitamin B and protein; cutting fruits and vegetables and leaving them open oxidises vitamin C; washing cut vegetables and throwing away cooking water removes water-soluble vitamins and minerals. Parboiled rice, sprouted seeds and short cooking keep more nutrients.

Excess Intake

Too much carbohydrate and fat is stored under the skin as fat and causes obesity, with a risk of high cholesterol, high blood pressure and heart attack. Too much calcium may form stones in kidney and gall bladder; too much fluorine damages enamel and bones. Excess of fat-soluble vitamins (hypervitaminosis) is harmful because they are stored, mainly in the liver; excess water-soluble vitamins are passed out in urine.

Food Adulteration

Adulteration is mixing harmless or harmful cheap substances with food for profit. It is a punishable offence under the Prevention of Food Adulteration law. Buy products with the ISI or Agmark mark and read the manufacture and expiry dates.

Simple tests: a lactometer measures the density of milk (pure milk reads not less than 1.026). Warm ghee with concentrated hydrochloric acid and a pinch of sugar gives a crimson lower layer if vanaspati is present. Concentrated nitric acid turns oil with argemone oil red to reddish brown. A drop of hydrochloric acid on dal shaken with water turns pink if metanil yellow is present.