3rd Part
Q What do you understand by the terms "Recommended Daily Intake of Nutrients" and "Balanced Diet"? Explain their significance in maintaining good health. 2+2+6
A Recommended Daily Intake of Nutrients - The Recommended Dietary Intake (RDI) is the amount of a nutrient to be actually consumed in order to meet the requirements of the body. The requirement for a particular nutrient is the minimum amount that needs to be consumed to prevent symptoms of deficiency and to maintain satisfactory levels of the nutrient in the body. An important aspect of RDI is -
# RDIs are set high enough to meet the needs of almost all healthy people.
# RDIs do not apply to people who are suffering from diseases as it can influence nutrient needs.
# Recommended dietary intakes for adults are based on sex, age, body size, and activity level
Balanced Diet - A balanced diet is the one that contains different types of foods in such quantities and proportions that it meets all the requirements of calories, minerals, vitamins, and other nutrients. Moreover, a small provision is also made for extra nutrients to withstand the short duration of leanness.
Some important aspects of the planned diet are-
# Different food items: A balanced diet includes a variety of food items. The main objective is to ensure that all nutrients are supplied. This can be achieved by first classifying food into groups. Each group provide certain specific nutrients and then items from each food group are selected to plan a balanced meal or diet. Including items from each food, the group would ensure that all the nutrients will be supplied.
# Nutrient needs to be fulfilled: A balanced diet meets nutrient needs because of the quantity and proportion of various foods selected. This would be based on the recommended dietary intakes (RDIs) laid down for an individual for whom the diet is planned.
# Periods of leanness: Balanced diets also provide for the period of leanness. This implies that there is a "safety margin" or a "little extra" for those times when we do not meet our nutrient needs adequately. A normal individual consumes a variety of foods. It is possible that on a given day he may not consume foods that supply all the nutrients in the right quantity.
Q Enumerate the food sources and functions of the following nutrients in our body: 5+5
(b) Iron
(c) Calcium
(d) Vitamin A
A b) Iron - Iron is a trace element present in the body to the extent of 3-5 g.
Food sources: Organ meats like liver, kidney, the spleen contains substantial amounts of iron. Among the plant foods, the list includes green leafy vegetables (like amaranth leaves, mustard leaves, colocasia leaves, mint leaves), cereals (like whole wheat flour, rice flakes, bajra, ragi, jowar) and pulses (especially the whole ones). Soybean is an example of a pulse containing good amounts of iron. Jaggery is another food that contains fair amounts of iron.
Functions - Oxygen transport: Iron is a major constituent of a red-colored compound called haemoglobin present in the blood. Iron is present in the haem part of haemoglobin.
Haemoglobin is necessary for the transport of oxygen to various parts of the body. Haemoglobin carries oxygen from the lungs to the tissues and in turn, helps in carrying carbon dioxide from the tissues to the lungs.
# For muscle contraction: Iron is also present in the muscle in the form of myoglobin. Myoglobin has the capacity to store oxygen. This oxygen is used for muscle contraction and for other immediate needs of the muscle cells.
# Promotion of oxidation: Iron helps in the complete oxidation of carbohydrates, fats, and proteins within the cell. This results in the release of energy due to oxidation.
# Brain - Iron plays an important role in the maintenance of specific brain functions like immediate memory, capacity to learn, and attention span.
# Metabolism - Iron forms an important part of certain enzymes and chemical substances that helps in metabolism.
# Preventive - Iron helps in preventing infections.
c) Calcium -
Food Sources - Milk and milk products like curd, khoa, cheese are excellent sources of calcium. Foods like fish especially dried fish and other seafood e.g. crab, shrimp provide substantial quantities of calcium. Among the plant sources, ragi (a millet grown in South India) is particularly rich in calcium. Pulses like Bengal gram, black gram, green gram, rajma, soybean contribute substantial amounts of calcium. Green leafy vegetables (like amaranth leaves, colocasia leaves, mustard leaves also contain good amounts. Among nuts and oilseeds, gingelly (til) seed is particularly rich in calcium. Others like coconut, almonds, walnuts have a fairly good amount of calcium.
Functions -
# Development of bones and teeth: Calcium and phosphorus are mainly present in bones and teeth. The ratio of calcium and phosphorus in the bones is roughly 2:l. Calcium combines with phosphorus, some other minerals, and water to form a compound. It is this compound that provides rigidity and firmness to the bones. Like bones, teeth also require calcium for their proper development. It is for this reason that the need for calcium is the most during the growing years.
# Regulatory functions: Apart from building bones and teeth, calcium, and phosphorus perform regulatory functions as well.
Calcium helps in:
a) regulating the contraction and relaxation of muscles especially that of the heart
b) regulating the passage of substances into and out of the cells
c) conveying messages from one nerve cell to another and
d) the clotting of blood.
d) Vitamin A -
Food Sources - Vitamin A or Retinol is found only in the foods of animal origin. Animal foods like milk, ghee, egg, fish, and liver are rich sources of vitamin A. Liver oils of fish like halibut, cod, and shark are the richest sources. Plant foods do not contain retinol. They contain certain orange or yellow-colored pigments called carotenoids which can be converted to retinol in the body.
Beta carotene is the most widely distributed carotenoid in plant foods. Most of the yellow and orange color of vegetables and fruits is due to these carotenoid pigments. Ripe fruits such as mango, papaya, and yellow/orange vegetables like carrot and pumpkin are rich in beta carotene. Green leafy vegetables also contain carotenoid pigments. Green leafy vegetables such as spinach, mustard leaves, and fenugreek leaves are very rich sources of beta carotene.
Functions -
# Maintaining normal vision: Vitamin A plays an important role in maintaining normal vision.
# Supporting growth: Vitamin A helps in the growth of the skeleton and soft tissues. Due to deficiency of vitamin A in the body, bones do not grow to their full length and the overall growth of the body is affected.
# Protecting against disease: Vitamin A plays an important role in keeping epithelial tissues moist and healthy. Some examples of epithelial tissues are the skin, the lining of our eyes, and the lining of organs like the intestine and lungs. Without vitamin A the epithelial tissue will become dry and cracks will appear in the skin or inner walls of the digestive tract or lungs. This makes it easy for the germs to enter and cause diseases like diarrhea, respiratory infections, and eye infections.
Q What are trace elements? Name any two trace elements required by the body. 2
A Trace elements are the minerals that are required in a tiny amount in our body. Some examples of trade elements are - iron, iodine, zinc, copper. They constitute a very small proportion of the body's inorganic material.
Q Vitamin A plays an important role in maintaining vision 5 (Explain briefly)
A Xerophthalmia
Vitamin A plays an important role in maintaining normal vision. The retina has two kinds of cells - rods and cones. Both rods and cones are sensitive to changes in light but they react differently and perform different functions. While rods are sensitive to dim light, the cones respond to bright light.
The rods contain a pigment called rhodopsin. Rhodopsin is formed by the combination of a specific form of vitamin A with a protein. However, rhodopsin breaks down into its components when exposed to bright light. In the dark these components - vitamin A and protein - again combine to regenerate rhodopsin. Rhodopsin helps us to see in dim light. Thus, in bright light, Rhodopsin breaks down into components while Rhodopsin is regenerated once again in the dark. This is called the visual cycle and Vitamin A plays an important role in it.
Q Give one example for each of the following: 10
(i) Pigment contained in the rod cells of the eye
(ii) Vitamin which prevents destruction of unsaturated fatty acids
(iii) Antibleeding vitamin
(iv) Nutrient lost when the outer layer of rice is removed during processing
(v) Nutrient which plays an important role in blood formation
A a Rhodopsin
b Vitamin E
c Vitamin K
d thiamine
e Folic acid and Vitamin B12
Q Role of Vitamin B 12 and folic acid 5
A Vitamin B12 - Vitamin B12 is necessary for the proper functioning of the digestive tract, nervous system, and bone marrow. In the bone marrow, vitamin B12 (like folic acid) is involved in the formation of normal red blood cells.
Folic Acid - Folic acid plays an important role in blood formation. It is required for the formation of normal red blood cells in the bone marrow.
Q What is required for the synthesis of Vitamin D in our body? Where is it synthesized ? 4
A Vitamin D is also called the "sunshine vitamin". This is because it is manufactured from a substance present in our skin when exposed to sunlight.
Q Justify the following statements giving examples: 5+5+5+5
(b) The extent of iron absorption from different foodstuffs varies.
(c) Balanced diets are income specific.
(d) Milk can help us to meet niacin needs.
A
b) Iron absorption from different foodstuffs varies -----
In general, iron absorption from animal foods is high. However, the amount of iron absorbed from many of the plant sources is very low. This is because certain substances present in plant foods bind the iron and hinders its absorption. These substances are called inhibitors. Some plant foods such as green leafy vegetables and cereals contain fairly substantial amounts of iron. Unfortunately, they also contain inhibitors that prevent much of the iron from being absorbed. On the other hand, there are substances like protein and vitamin C present in foods that aid in the absorption of iron. These substances are called enhancers. It is, therefore, suggested that protein-rich foods like milk and vitamin C-rich foods like oranges, lime, amla, and guava should be taken to increase absorption of iron.
c) Balanced diets are income specific -
Balanced diets are income-specific. Balanced diets for an individual of a given age, body type, sex, and activity level varies according to income. A balanced diet would imply the use of all food groups- energy-giving, bodybuilding and protective/regulatory - in each and every meal. However, the selection of foods and the amounts in which they are consumed would vary depending on income. As the income increases, consumption of cereals reduces, and consumption of milk and other animal foods, vegetables, and fruits, fat and sugar tend to increase. Having more money enables a person to add more variety to the diet. Unusual foods or foods not locally available can be purchased or ordered from elsewhere. The judicious selection of food is, however, as important for the rich as for the poor. The ultimate aim is to provide a balanced diet. Cheap cereals for the poor.
d) Milk can help us to meet niacin needs ---
Niacin is another member of the Vitamin B-complex family. The good sources of niacin include meat, fish, poultry, cereals, pulses, nuts, and oilseeds. However, niacin can also be formed in the body from an amino acid called tryptophan. Milk is rich in tryptophan but not in niacin. The tryptophan present in milk protein can be converted to niacin in the body. Thus milk provides appreciable amounts of niacin.
Q Extracellular fluid (Explain the following in 2-3 sentences) 2
A Extracellular fluid refers to the fluid outside the cell. Sodium is the principal mineral present in the extracellular fluid and is responsible for maintaining the fluid balance. Examples are blood plasma and the fluid surrounding the cell.
Q Fluid balance 2 (Explain the following in 2 — 3 sentences)
A Fluid balance is a process of maintaining a balance between the fluid present within the cells (intracellular) and that circulating outside the cells (extracellular). Sodium is the principal mineral in the extracellular fluid. Sodium along with potassium helps to maintain this balance.
Q Fat-soluble and Water-soluble vitamins (Differentiate between the following) 2
A Fat Soluble Vitamins -These vitamins are soluble in fats and are present in food in close association with fats. The fat-soluble vitamins after being used for specific functions, the excess amount of these vitamins gets stored in the body. Vitamins A, D, E, and K are known as fat-soluble vitamins.
Water Soluble Vitamins - Vitamin C and vitamins of the B-complex group are known as
water-soluble vitamin as they are soluble in water. Unlike the fat-soluble vitamins, these vitamins cannot be stored in our bodies in considerable amounts. The excess amount of these vitamins is excreted from the body through urine.
No comments:
Post a Comment