Taking vitamin tablets is fashionable now. Doctors, therefore, need to know the features of both deficiency and overdosage of major vitamins.
Vitamins are organic substances in food which are required in small amounts but cann’t be synthesised in adequate quantity.
Vitamin A (Retinol)
Vitamin-A deficiency is one of the most common causes of blindness.
It has a place in the function of retina and of epithelial cells.
Dietary Sources :
- Retinol is found only in animal food e.g. milk, liver (richest source), Butter, Egg yolk, Cheese.
- In many parts of the world, most of the requirement is obtained from carotenoids (precursors of retinol) in vegetable foods. In small intestine, beta carotene is converted into retinol.
Night Blindness :
Retinol is an essential component of the pigment rhodopsin present in rod cells (responsible for dim light and night vision).
Causes of Vitamin-A deficiency :
- Malabsorption syndrome
- Poor people
Xerophthalmia :
- Xerosis conjunctivae (dry, thickened & pigmented bulbur conjunctiva)
- Bitot’s spots (white plaques of thickened conjunctival epithelium)
- Recognition of xerophthalmia is very important in young children because once the cornea is involved, the process can rapidly progress to keratomalacia.
Keratomalacia : involvement of cornea.
- Night blindness
- Xerophthalmia
- Later cornea undergoes necrosis & ulceration
Management :
60 mg retinol as acetate should be given orally.
Prevention :
Pregnant women should be advised to eat dark green leafy vegetables (contains carotenoids).
Vitamin-B Complex
A. Thiamine (Vit. B1) :
Thiamine pyrophosphate (TPP) is an essential co-enzyme for decarboxylation of pyruvate to acetyl coenzyme A.
Thiamine deficiency can produce –
- High output of cardiac failure
- Peripheral neuropathy
- Encephalopathy
These occur in various combination in wet and dry beri-beri.
- Wet beri-beri : A high output of cardiac failure with few ECG changes.
- Dry beri-beri : A type of peripheral neuropathy.
Dietary Sources :
- Whole wheat flour, bread
- White bread if flour enriched
- Oatmeal
- Legumes & nuts
- Yeast
Wet beri-beri : Wet beriberi is caused by eating diets having good calories, but are polished i.e. polished rice.
Clinical features :
- Oedema – not only in legs, but also on face.
- Palpitations
- Tachycardia
- Heart is enlarged
- Jugular venous pressure rises.
Management :
- 50 mg thiamine (intra muscular)
- After that 10 mg/T.D.S. by mouth.
Dry beri-beri :
This is essentially a peripheral neuropathy. Nutritional background is similar to wet beriberi.
In chronic cases, there is degeneration and demyelination of both sensory and motor nerves, resulting in severe muscle wasting.
Management :
If treated early, polyneuropathy responds will to a mixed diet and generous doses of Vitamin-B complex.
Niacin (nicotinic acid & nicotinamide) :
Nicotinamide is an essential part of the two important pyridine nucleotides. NAD and NADP which are hydrogen accepting coenzymes.
It is water soluble & resistant to heat.
Dietary Sources :
- Whole wheat
- Legumes, bran
- Peanuts
- Coffee
- Yeast
- Liver, Kidney
- Meat, Fish
Dose : 18 mg/day
Pellagra : It is due to niacin deficiency.
Clinical features :
It is called the disease of three Ds.
- Dermatitis
- Diarrhoea
- Dementia (Loss of memory)
Others are :
- Casal’s collar (collar shaped skin lesion on neck)
- Anorexia
- Nausea
- Mental disturbance
Management : 100 mg/T.D.S. by mouth
Riboflavin :
Riboflavin is a constituent of the flavoproteins which are concerned with tissue oxidation. It is water soluble vitamin.
Dietary Sources :
- Wheat Brain
- Fortified white flour
- Cereals
- Milk, cheese, yoghurt
- Liver, Kidney
- Eggs
Clinical features of riboflavin deficiency :
i. Angular Stomatitis : This is not specific for lack of riboflavin. Deficiencies of niacin, pyridoxine and iron all can produce it.
ii. Chelilosis : This is a zone of red, denuded epithelium at the line of closure of lips.
iii. Nasolabial dyssebacia : Enlarged follicles around the sides of nose with dry sebaceous material.