Vitamins and Minerals; Nutrient Inter-relationships

What to remember

• Vitamins are organic micronutrients needed in tiny amounts: A, D, E, K are fat-soluble; the B-complex and C are water-soluble.
• Key deficiency diseases: vitamin A (night blindness, xerophthalmia), D (rickets), B1 (beriberi), B2 (cheilosis), niacin (pellagra), B12 (pernicious anaemia), C (scurvy), iron (anaemia), iodine (goitre), calcium (osteoporosis).
• Nutrients work together: vitamin D with calcium, vitamin C with iron, folate with B12, tryptophan with niacin, vitamin E with PUFA.

Vitamins: basics

Fat-soluble vitamins

Vitamin A (retinol)

• Functions: vision (rhodopsin in the retina, dim light vision), healthy skin and mucous membranes, growth, immunity.
• Sources: liver, egg yolk, milk, butter, ghee, fish liver oil (preformed); beta-carotene (provitamin A) in green leafy vegetables, carrot, yellow and orange fruits, ripe mango, papaya. Beta-carotene is converted to retinol in the body (6 µg beta-carotene = about 1 µg retinol).
• Deficiency: night blindness (nyctalopia) is the first sign; conjunctival xerosis, Bitot's spots (foamy patches on the white of the eye), corneal xerosis and keratomalacia (softening of the cornea, can cause permanent blindness); dry rough skin (follicular hyperkeratosis); frequent infections.
• Excess: hypervitaminosis A (headache, vomiting, bone pain).
• National programme: vitamin A solution is given to children in a schedule from nine months to five years (with the first dose given along with measles vaccine); check the latest official schedule.

Vitamin D (calciferol)

• Made in skin from 7-dehydrocholesterol by sunlight (UV-B); activated in liver and kidney to calcitriol.
• Functions: calcium and phosphorus absorption and bone mineralisation.
• Sources: sunlight, fish liver oils, egg yolk, fortified milk; very little in plant foods.
• Deficiency: rickets in children (bow legs, knock knees, delayed fontanelle closure, pigeon chest, rachitic rosary); osteomalacia in adults (especially pregnant and lactating women); excess causes hypercalcaemia.

Vitamin E (tocopherol)

• Natural antioxidant that protects cell membranes and PUFA from oxidation.
• Sources: vegetable oils (sunflower, safflower, wheat germ oil), nuts, whole grains.
• Deficiency is rare: haemolysis of red cells in premature babies, nerve problems. The need rises with intake of PUFA.

Vitamin K (phylloquinone, K1; menaquinone, K2)

• Needed for the synthesis of prothrombin and other clotting factors in the liver.
• Sources: green leafy vegetables, also made by intestinal bacteria.
• Deficiency: bleeding, delayed clotting; haemorrhagic disease of the newborn, so a dose is given to newborns; long antibiotic use or fat malabsorption can cause deficiency.

Water-soluble vitamins

Points: tryptophan to niacin conversion: about 60 mg tryptophan gives 1 mg niacin. Maize- and jowar-based diets are linked to pellagra (maize niacin is bound and its protein is poor in tryptophan; jowar has excess leucine). Vitamin B12 needs the intrinsic factor from the stomach for absorption. Vitamin C is the most easily destroyed vitamin in cooking and storage. Thiamine need is related to calorie (carbohydrate) intake. Folic acid is given to women before and in early pregnancy to prevent neural tube defects.

Minerals: major and trace

Minerals are inorganic elements. Macrominerals (needed over about 100 mg/day): calcium, phosphorus, magnesium, sodium, potassium, chloride, sulphur. Trace elements: iron, iodine, zinc, copper, fluorine, selenium, chromium, manganese, cobalt.

Calcium

• About 99% of body calcium is in bones and teeth. Functions: bone and teeth, clotting, muscle contraction, nerve impulse.
• Sources: milk and milk products, ragi, green leafy vegetables, small fish eaten with bones, sesame.
• Absorption is helped by vitamin D, lactose and acid medium; reduced by phytates, oxalates, excess fibre and a lot of phosphorus.
• Deficiency: rickets, osteomalacia, osteoporosis, tetany. Needs are higher in childhood, adolescence, pregnancy, lactation and old age.

Phosphorus: bones, ATP, nucleic acids; present in nearly all foods. The calcium:phosphorus ratio of about 1:1 is good for adults.

Iron

• Component of haemoglobin, myoglobin and many enzymes.
• Sources: liver, meat (haem iron), green leafy vegetables, jaggery, pulses, bajra, dates, beetroot (non-haem iron).
• Absorption: haem iron is absorbed better than non-haem iron. Vitamin C, meat factor and an acid medium increase absorption; phytates, oxalates, tea and coffee tannins, and calcium reduce it.
• Deficiency: iron-deficiency (nutritional) anaemia with pallor, tiredness, breathlessness, spoon-shaped nails (koilonychia), poor learning and work capacity. It is the most common nutritional deficiency in India, mainly affecting women, adolescent girls and young children. Iron and folic acid supplementation and deworming are used in national programmes.
• Excess iron (haemochromatosis) is harmful.

Iodine

• Part of the thyroid hormones thyroxine (T4) and triiodothyronine (T3).
• Sources: iodised salt, seafood, sea fish; water and soil in the area.
• Deficiency: goitre, cretinism (mental and physical retardation in babies), hypothyroidism, stillbirths and miscarriages. The group of disorders is called iodine deficiency disorders (IDD). The National Iodine Deficiency Disorders Control Programme promotes iodised salt (standard: not less than 30 ppm at manufacture and 15 ppm at the consumer level, as laid down by FSSAI).
• Goitrogens in cabbage, cassava and some millets worsen the problem when iodine is low.

Fluorine: small amounts protect against dental caries; excess in drinking water causes fluorosis (mottled teeth, bone deformity). The safe upper limit in drinking water is about 1.0-1.5 mg per litre.

Zinc: needed for growth, wound healing, immunity, taste and sperm production; deficiency leads to growth retardation, delayed sexual maturity and skin changes. Zinc is given with ORS in diarrhoea in children. Copper: needed with iron for haemoglobin; selenium works with vitamin E as part of an antioxidant enzyme; magnesium for bone and enzymes; sodium and potassium for fluid and acid-base balance, nerve and muscle (excess sodium raises blood pressure).

Nutrient inter-relationships

Comparison table: major deficiency diseases

Exam traps

• Night blindness is the earliest sign of vitamin A deficiency, but keratomalacia is the most severe.
• Beriberi is thiamine; pellagra is niacin; scurvy is vitamin C; do not mix them.
• Vitamin B12 is found only in animal foods and contains cobalt; folate is in green leafy vegetables.
• Vitamin D deficiency gives rickets in children and osteomalacia in adults.
• Haem iron (animal) is absorbed better than non-haem iron (plant).
• Tea and coffee reduce, and vitamin C increases, iron absorption.
• Excess fluoride in water causes fluorosis; deficiency favours dental caries.
• Ragi is rich in calcium; spinach calcium and iron are poorly absorbed because of oxalates.

One-liners

• 1. Vitamins A, D, E and K are fat-soluble.
• 2. Night blindness is caused by lack of vitamin A.
• 3. Vitamin D is made in the skin by sunlight.
• 4. Vitamin K is needed for blood clotting.
• 5. Beriberi is due to thiamine deficiency.
• 6. Pellagra has three Ds: dermatitis, diarrhoea, dementia.
• 7. Vitamin B12 contains cobalt.
• 8. Folic acid prevents neural tube defects.
• 9. Scurvy is due to vitamin C deficiency.
• 10. Amla is the richest source of vitamin C.
• 11. Iodine is needed to make thyroxine.
• 12. About 99% of body calcium is in bones and teeth.

Practice questions

1. Which group contains only fat-soluble vitamins?

   1. A, D, E and K
   2. B and C
   3. B1, B2 and C
   4. C, D and K only
   Answer

   A. A, D, E and K

   B-complex and C are water soluble.

2. The earliest sign of vitamin A deficiency is

   1. Keratomalacia
   2. Bitot's spots
   3. Rickets
   4. Night blindness
   Answer

   D. Night blindness

   Poor dim-light vision appears first.

3. Foamy white patches on the conjunctiva are called

   1. Pigeon chest
   2. Cheilosis
   3. Koilonychia
   4. Bitot's spots
   Answer

   D. Bitot's spots

   They are a sign of vitamin A deficiency.

4. Softening of the cornea that can lead to blindness is

   1. Goitre
   2. Osteomalacia
   3. Cheilosis
   4. Keratomalacia
   Answer

   D. Keratomalacia

   It is the most severe eye sign of vitamin A deficiency.

5. Rickets in children is caused by deficiency of

   1. Vitamin C
   2. Vitamin A
   3. Vitamin D
   4. Vitamin K
   Answer

   C. Vitamin D

   Vitamin D is needed for calcium absorption and bone growth.

6. Osteomalacia in adults is due to deficiency of

   1. Iodine
   2. Vitamin E
   3. Thiamine
   4. Vitamin D
   Answer

   D. Vitamin D

   It is the adult form of rickets.

7. Vitamin D is made in the skin from

   1. Tryptophan
   2. Ascorbic acid
   3. 7-dehydrocholesterol
   4. Beta-carotene
   Answer

   C. 7-dehydrocholesterol

   Sunlight (UV-B) converts it to cholecalciferol.

8. The vitamin needed for the formation of prothrombin is

   1. Vitamin E
   2. Vitamin A
   3. Vitamin K
   4. Vitamin C
   Answer

   C. Vitamin K

   Needed for blood clotting.

9. A natural antioxidant that protects PUFA is

   1. Niacin
   2. Vitamin B12
   3. Vitamin D
   4. Vitamin E
   Answer

   D. Vitamin E

   Tocopherol protects cell membranes from oxidation.

10. Beriberi results from lack of

    1. Niacin
    2. Thiamine
    3. Riboflavin
    4. Vitamin B12
    Answer

    B. Thiamine

    Thiamine (B1) deficiency causes beriberi.

11. Cheilosis and angular stomatitis are signs of lack of

    1. Thiamine
    2. Vitamin C
    3. Vitamin D
    4. Riboflavin
    Answer

    D. Riboflavin

    Riboflavin (B2) deficiency.

12. The three Ds of pellagra are

    1. Dwarfism, deafness, dermatitis
    2. Diabetes, dysentery, dehydration
    3. Dermatitis, diarrhoea, dementia
    4. Dysphagia, diarrhoea, dropsy
    Answer

    C. Dermatitis, diarrhoea, dementia

    Death is sometimes called the fourth D.

13. Pellagra is related to diets based on

    1. Parboiled rice
    2. Wheat with milk
    3. Maize and jowar
    4. Ragi
    Answer

    C. Maize and jowar

    Poor niacin availability and tryptophan in such diets.

14. The vitamin containing cobalt is

    1. Folic acid
    2. Vitamin B12
    3. Vitamin B6
    4. Riboflavin
    Answer

    B. Vitamin B12

    Cobalamin contains cobalt.

15. Neural tube defects in the baby are prevented by adequate

    1. Folic acid
    2. Vitamin K
    3. Vitamin D
    4. Iodine
    Answer

    A. Folic acid

    Women should have enough folate before and in early pregnancy.

16. Pernicious anaemia is due to lack of

    1. Iron only
    2. Vitamin C
    3. Zinc
    4. Vitamin B12 or intrinsic factor
    Answer

    D. Vitamin B12 or intrinsic factor

    Intrinsic factor is needed to absorb B12.

17. Scurvy is caused by lack of

    1. Vitamin C
    2. Vitamin B1
    3. Vitamin A
    4. Vitamin K
    Answer

    A. Vitamin C

    Bleeding gums and poor wound healing are signs.

18. Vitamin C helps in the absorption of

    1. Calcium only
    2. Non-haem iron
    3. Vitamin K
    4. Sodium
    Answer

    B. Non-haem iron

    It reduces ferric iron to the ferrous form.

19. About 99% of the body's calcium is found in

    1. Blood
    2. Muscles
    3. Liver
    4. Bones and teeth
    Answer

    D. Bones and teeth

    The rest is in blood and soft tissues.

20. Which factor reduces calcium absorption?

    1. Acid medium
    2. Vitamin D
    3. Oxalates and phytates
    4. Lactose
    Answer

    C. Oxalates and phytates

    They form insoluble salts with calcium.

21. Which beverage reduces iron absorption when taken with meals?

    1. Tea
    2. Orange juice
    3. Lemon juice
    4. Amla juice
    Answer

    A. Tea

    Tannins bind iron.

22. Haem iron compared with non-haem iron is

    1. Absorbed less
    2. Absorbed better
    3. Found only in plants
    4. Not absorbed at all
    Answer

    B. Absorbed better

    Haem iron comes from meat and is well absorbed.

23. Spoon-shaped nails (koilonychia) suggest

    1. Vitamin A deficiency
    2. Zinc excess
    3. Iron deficiency
    4. Iodine deficiency
    Answer

    C. Iron deficiency

    Iron-deficiency anaemia.

24. Goitre and cretinism result from lack of

    1. Fluorine
    2. Calcium
    3. Zinc
    4. Iodine
    Answer

    D. Iodine

    Iodine is needed for thyroxine.

25. Excess fluoride in drinking water causes

    1. Goitre
    2. Fluorosis
    3. Rickets
    4. Scurvy
    Answer

    B. Fluorosis

    It mottles teeth and may deform bones.

26. Which mineral is given along with ORS in childhood diarrhoea?

    1. Zinc
    2. Fluorine
    3. Iron
    4. Iodine
    Answer

    A. Zinc

    Zinc shortens diarrhoea and prevents recurrence.

27. The mineral working with vitamin E as an antioxidant is

    1. Fluorine
    2. Iodine
    3. Selenium
    4. Sodium
    Answer

    C. Selenium

    Selenium is part of glutathione peroxidase.

28. The conversion of tryptophan to niacin requires about

    1. 600 mg tryptophan for 1 mg niacin
    2. 1 mg tryptophan for 1 mg niacin
    3. 6 mg tryptophan for 1 mg niacin
    4. 60 mg tryptophan for 1 mg niacin
    Answer

    D. 60 mg tryptophan for 1 mg niacin

    This is the standard conversion ratio.

29. A diet gives 180 mg tryptophan. The niacin that the body can make from it is

    1. 3 mg
    2. 30 mg
    3. 18 mg
    4. 0.3 mg
    Answer

    A. 3 mg

    180 ÷ 60 = 3 mg.

30. The retinol equivalent of 120 µg beta-carotene (6 µg = 1 µg retinol) is

    1. 720 µg
    2. 20 µg
    3. 6 µg
    4. 60 µg
    Answer

    B. 20 µg

    120 ÷ 6 = 20 µg.

31. A diet has 12 mg preformed niacin and 120 mg tryptophan. The niacin equivalents are

    1. 24 mg
    2. 13 mg
    3. 14 mg
    4. 12 mg
    Answer

    C. 14 mg

    120 ÷ 60 = 2 mg; 12 + 2 = 14 mg.

32. A diet gives 20 mg iron, of which 10% is absorbed. Iron absorbed is

    1. 0.2 mg
    2. 10 mg
    3. 20 mg
    4. 2 mg
    Answer

    D. 2 mg

    10% of 20 mg = 2 mg.

33. Milk has 120 mg calcium per 100 mL. Calcium in 250 mL is

    1. 300 mg
    2. 480 mg
    3. 120 mg
    4. 240 mg
    Answer

    A. 300 mg

    1.2 mg per mL × 250 = 300 mg.

34. Salt iodised at 15 ppm contains iodine per kg of

    1. 15 g
    2. 15 mg
    3. 150 mg
    4. 1.5 mg
    Answer

    B. 15 mg

    15 ppm = 15 mg per kg.

35. The need for vitamin E rises when the diet has more

    1. Protein
    2. Sodium
    3. PUFA
    4. Fibre
    Answer

    C. PUFA

    Vitamin E protects PUFA from oxidation.

36. Which of the following statements is/are correct? 1. Vitamin B12 is found only in animal foods. 2. Folic acid is found in green leafy vegetables.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both are correct.

37. Which of the following statements is/are correct? 1. Vitamin A is a water-soluble vitamin. 2. Vitamin A deficiency can cause night blindness.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    B. 2 only

    Vitamin A is fat soluble.

38. Which of the following statements is/are correct? 1. Thiamine need rises with higher carbohydrate intake. 2. Riboflavin is easily destroyed by sunlight.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both are correct.

39. Which of the following statements is/are correct? 1. Vitamin C reduces iron absorption. 2. High calcium intake can reduce iron absorption.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    B. 2 only

    Vitamin C increases it.

40. Which of the following statements is/are correct? 1. Ragi is a rich source of calcium. 2. Spinach calcium is well absorbed because of its oxalates.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    Oxalates reduce absorption.

41. Which of the following statements is/are correct? 1. Iodine is part of thyroxine. 2. Iodine deficiency can cause cretinism.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both are correct.

42. Which of the following statements is/are correct? 1. Vitamin K can be synthesised by intestinal bacteria. 2. Haemorrhagic disease of the newborn is due to lack of vitamin C.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    It is vitamin K related.

43. Which of the following statements is/are correct? 1. Vitamin C is the most stable vitamin to cooking. 2. Amla is the richest natural source of vitamin C.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    B. 2 only

    Vitamin C is easily destroyed.

44. Which of the following statements is/are correct? 1. Iron deficiency anaemia is the commonest nutritional deficiency in India. 2. Haemoglobin contains iodine.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    Haemoglobin contains iron.

45. Which of the following statements is/are correct? 1. Excess water-soluble vitamins are mostly stored in the liver. 2. Excess vitamin A can be toxic.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    B. 2 only

    They are largely excreted.