While most human beings consume foods almost every couple of hours, not all of it constitutes healthy eating. To live a healthy, wholesome life, you need to consciously eat foods that give your body the essential nutrients it needs to nourish, energise and rebuild itself on a constant basis.
To do this, the human body requires several nutrients that it obtains from the various foods and drinks that you consume on a daily basis. Scientifically speaking, nutrients are a wide range of chemical substances that play an important role in physical growth and development of an individual. These substances are needed to maintain normal body functions, physical activity and your overall health. Nutritious food is, thus, needed to sustain life and activity.
What is a nutritious diet?
The nutritional requirement of the body varies with age, gender, health status and physical activity. A nutritious diet is one which provides all the required essential nutrients in the right quantities. This will vary from person to person, and is best defined by a dietician.
Dietary intake lower or higher than the body requirements can lead to under-nutrition (deficiency diseases) or over-nutrition (eg. overweight, obesity) respectively.
The essential nutrients in your diet
An adequate diet, providing all nutrients, is typically obtained through a judicious choice and combination of a variety of foodstuffs from different food groups. The nutrients in your diet consist of carbohydrates, proteins, fats, vitamins and minerals.
Carbohydrates, fats and proteins are macronutrients, needed in large amounts by the body. They are energy-yielding nutrients. Vitamins and minerals constitute the micronutrients and are required in small amounts. These nutrients are necessary for several important bodily processes.
Carbohydrates are either simple or complex, and are major sources of energy in all human diets. They provide energy of 4 Kcal/g. The simple carbohydrates, glucose and fructose, are found in fruits, vegetables and honey, sucrose in sugar and lactose in milk, while the complex ones are in the form of starches in cereals, millets, pulses(whole grains)and root vegetables. In India, 70-80% of total dietary calories are derived from carbohydrates.
Dietary fibre delays and slows absorption of carbohydrates and fats and increases the satiety value. Diets rich in fibre reduce glucose and lipids in blood and increase the bulk of the stools. Diets rich in complex carbohydrates are healthier than low-fibre diets based on refined and processed foods. A few complex carbohydrates, which are not digested in the human body, are cellulose in vegetables and whole grains, cereals like oats, bajra,jowar, ragi etc. and gums and pectins in vegetables, fruits with peels which constitute the dietary fibre component.
Proteins are important macronutrients as they are the building blocks in the body. Almost half the protein in our body is in the form of muscle and the rest, is in bone, cartilage and skin. Proteins perform a wide range of functions and also provide energy (4 Kcal/g).
Protein requirements vary with age, health status and stress. More proteins are required by growing infants and children, pregnant women and individuals during infections and illness or stress. Animal foods like milk, meat, fish and eggs and plant foods such as pulses and legumes are rich sources of proteins.
Animal proteins are of high quality as they provide all the essential amino acids(units of protein) in right proportions, while plant or vegetable proteins are not of the same quality because of their low content of some of the essential amino acids. However, a combination of cereals, millets and pulses provides most of the amino acids, which complement each other to provide better quality proteins.
Fats are a concentrated source of energy providing 9 Kcal/g. Dietary fats are derived from two sources viz. the invisible fat present in plant and animal foods; and the visible or added fats and oils (cooking oil, butter, ghee).
Fats serve as a vehicle for fat-soluble vitamins like Vitamins A, D, E and K and promote their absorption. They are also sources of essential polyunsaturated fatty acids which have many benefits like brain development in infants, positive effects on serum cholesterol levels in adults etc.
The type and quantity of fat in the daily diet influences the level of cholesterol and triglycerides in the blood. Diets should include adequate amounts of fat, particularly in the case of infants and children, to provide concentrated source of energy, since their energy needs per kg body weight are nearly twice those of adults.
Adults need to be cautioned to restrict intake of saturated fat (butter, ghee and hydrogenated fats) and cholesterol (red meat, eggs, organ meat). Excess of these substances could lead to obesity, diabetes, cardiovascular disease and cancer.
Vitamins and minerals:
Vitamins are chemical compounds required by the body in small amounts. They are essential for numerous body processes and for maintenance of the structure of skin, bone, nerves, eye, brain, blood and mucous membrane. They are either water-soluble or fat-soluble. Vitamins A, D, E and K are fat-soluble, while vitamin C, and the B-complex vitamins such as thiamin, riboflavin, niacin, pyridoxine, folic acid and cyanocobalamin are water-soluble. Fat-soluble vitamins are stored in the body while water-soluble vitamins are not; they get easily excreted in urine.
Vitamins B-complex and C are heat labile vitamins and are easily destroyed by heat, air or during drying, cooking and food processing.
Minerals are inorganic elements found in body fluids and tissues. The important macro-minerals are sodium, potassium, calcium, phosphorus, magnesium and sulphur, while zinc, copper, selenium, molybdenum, fluorine, cobalt, chromium and iodine are micro-minerals. They are required for maintenance and integrity of skin, hair, nails, blood and soft tissues. They also govern hormone activity as well as the blood- clotting processes.
What are nutrient requirements and Recommended Dietary Allowances (RDA)?
Nutrient Requirements are the quantities of nutrients that healthy individuals must obtain from food to meet their body needs. The Recommended Dietary Allowances (RDAs) are estimates of nutrients to be consumed daily to ensure the requirements of all individuals in a given population. The RDAs are suggested for age groups such as infants, pre-schoolers, children, adolescents, pregnant women, lactating mothers, and adult men and women.
To ensure that your body is fit and healthy at all times, it is important to have all the essential nutrients in your regular diet in the amounts recommended for your age, gender and physical activity. In other words, eat healthy, live healthy!