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The main natural source of its availability is through the interaction of ultraviolet sun rays with the bare skin. Indians are fortunate to get sunshine throughout the year. But the presence of pigment melanin in higher proportion in the relatively dark complexion of our skin is an inhibitory factor for the vitamin D formation. Furthermore, the use of sun screens and the tendency to cover each part of our body (including hands and face) with clothes prevents the formation of vitamin D from the skin. The effect of vitamin D deficiency on bones leads to diseases called rickets in children and osteomalacia in adults; both the diseases are characterised by the presence of soft and weak bones. In the western world,
vitamin D deficiency was largely cured through the fortification of
various commercial foods. However, this deficiency never got much
attention in India because Indians were thought to be immune to this
disease due to abundance of sun. A research conducted at Sri
Venkateswara Institute of Medical Sciences in Tirupati, one of the
sunniest parts of India, documented the evidence of vitamin D
deficiency in India. The study was one of the earliest studies from
India which broke the myth of Indians being immune to vitamin D
deficiency.
Magnitude and impact Various studies have estimated that 50-90 per cent healthy Indians suffer from low vit4amin D levels in blood. A recent study conducted on healthy physicians in Kolkata showed that more than 92 per cent of physicians and diabetologists suffered from vitamin D deficiency. Thus this deficiency has no relation with the age, education status or socio-economic status. In a study conducted in Lucknow in pregnant women, the rate of deficiency was found to be 94 per cent. Supplementation of vitamin D to the pregnant women resulted in an increased size of the head of the baby, increased body weight and increased height. Another study from Hyderabad proved that vitamin D supplementation in 6-16-year-old children resulted in significant gain in height and weight of the children. It is assumed that vitamin D deficiency is a correctable cause of short stature in children. Vitamin D deficiency can also be a predisposing risk factor for many other diseases like heart disease, weakened immune system, diseases of muscles, infections like tuberculosis and osteoarthritis. Recently, vitamin D status is being strongly linked to Crohn's disease, multiple sclerosis, rheumatoid arthritis, type I diabetes mellitus and risk of developing cancers of the breast, colon, prostate and ovary. Deficiency effect on bones Vitamin D plays an important role of facilitating the absorption of calcium from the diet. The deficiency causes availability of inadequate calcium in the blood which plays an important role for mediation of many metabolic functions in the body. To supplement the levels of low calcium in the blood, the body triggers the parathyroid gland and makes it overactive which starts secreting more parathyroid hormone (parathormone). The increased levels of parathormone in the body initiate resorption of calcium from the bones and restores the calcium levels of the blood so that the metabolic functions of the body do not suffer. But this resorption of calcium from bones results in weak bones. The patient only come to know about its ill effects when clinical symptoms of weak bones appear which take years to develop. Probable factors of poor availability n
Food fads and food habits contribute to low dietary vitamin D
intake. Vegetarian food is not a good source of vitamin D.
Furthermore, vegetarian diet contains phosphates and phytates which
can deplete vitamin D stores and increase calcium requirement. So it
is advisable that the commercially available vegetarian foods like
milk and milk products, juices, cereals etc should be fortified with
vitamin D.
n It is estimated that the cloud-free sun is available in northern India for an average duration of 7-9 hours per day in summer and approximately 3-5 hours per day in winter, which is reasonably adequate to get sufficient amount of vitamin D from sunshine. Exposure of 10 per cent bare skin to sun for 30 minutes a day can prevent its deficiency. But long duration in the air-conditioned environments, use of dark glasses in vehicles, dwindling habits of playing outdoor games and increased hours before computer have acted as barriers for availability of vitamin D from sunshine. n Increased pollution levels in the air prevent the ultraviolet rays to adequately act with the skin to synthesise vitamin D. n Covering the face and limbs with clothes is another factor which does not allow the sun rays to act on the bare skin. n Frequent, unspaced pregnancies aggravate vitamin D deficiency in the mother and the newborn. n High temperatures in some regions during daytime and humid climate are the deterrents for adequate sun exposure.
The diagnosis of deficiency can be made by estimation of the blood levels of vitamin D. If found deficient, the deficiency should be treated by supplementation with weekly dose of 60,000 IU of vitamin D for 8-12 weeks followed by regular supplementation of at least 2000 IU/day to maintain normal vitamin D levels. Although this deficiency is emerging as a public health problem in our country, we must be careful not to over treat the vitamin D deficiency without monitoring the vitamin D levels. The hyperviaminosis D (the excess of vitamin D in body) can cause various other symptoms and ailments like hypercalcemia, constipation, decreased appetite, lethargy, dehydration, stunted growth in children, polyuria, polydipsia, nausea, vomiting, abdominal pain and kidney stones. Vitamin D deficiency is definitely preventable. The current recommendations of intake of calcium and vitamin D of 1 gram of dietary calcium and 400 - 800 IU of vitamin D per day in the diet, if adhered to, will not allow this disease to emerge in our population. — The writer is Professor, Orthopaedics, Government Medical College Hospital, Chandigarh Sources of vitamin D Vitamin D is available to human body either through diet or by the direct exposure of the uncovered skin to the sunlight (ultraviolet rays). Thus it is also known as sunshine vitamin. The normal daily requirement of vitamin D is estimated to be 400 - 600 international units (IUs) per day. n Cod liver oil. n Some varieties of fish: Atlantic herring, salmon, mackerel are rich sources. Other fish varieties that contain vitamin D include sardines and tuna. Raw fish and canned fish have more vitamin D than the cooked ones. Caviar (fish eggs) is another rich source of vitamin D. n Fortified foods: In the western countries, commercial cereals, canned juices, tofu and soya milk, dairy milk, cheese and butter are usually fortified with vitamin D. Before buying these products check for the fortification of vitamin D on the label. n Oysters: Besides vitamin D, oysters are rich in vitamin B12, zinc, iron, manganese, selenium and copper. Paradoxically, oysters are also high in cholesterol and should be eaten in moderation by people at risk of heart disease or stroke. n Other foods with mild amounts of vitamin D are salami, ham, sausages, eggs and button mushrooms. n
Sunshine: A very important source of natural vitamin D to our body is
through the direct exposure of the bare skin to sunlight. It is
thought that at least 10 per cent of the body should be exposed to
direct sunlight for at least half an hour every day for adequate
intake of vitamin D.
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A
Diagnosis and
treatment
London: Lack of a
good night's sleep may damage your brain in a similar way to
being hit on the head, a new study has warned.
A new study has
revealed that high blood pressure is potentially more dangerous
for women than men. Scientists at Wake Forest Baptist Medical
Centre, North Carolina, US, for the first time found significant
differences in the mechanisms that cause high blood pressure in
women as compared to men. "This is the first study to
consider sex as an element in the selection of antihypertensive
agents or base the choice of a specific drug on the various
factors accounting for the elevation in blood pressure,"
author of the study, Carlos Ferrario, said. Although there has
been a significant decline in cardiovascular disease mortality
in men during the last 20 to 30 years, the same has not held
true for women. Hundred men and women age 53 and older with
untreated high blood pressure and no other major diseases were
evaluated. The researchers found 30 to 40 per cent more vascular
disease in the women compared to the men for the same level of
elevated blood pressure. The study is published in
Therapeutic Advances in Cardiovascular Disease.
Teen eating
disorders may impact weight later