Vitamin D is an important element not only for bone health but also for functioning of several important organs such as heart, brain, lungs and the immune system. It is one of the few vitamins that can be produced within the body, apart from being available through dietary sources. A majority of Vitamin D is produced under the skin by the ultraviolet light (UV-B) from sun. However its deficiency is purported to be very rampant in all parts of ourcountry (70-90% of population is either deficient or insufficient), despite plentiful sunshine that is available through most part of the year.
There are several reasons attributed to this deficiency. Melanin is the dark pigment present in the skin of every individual. This is present in increased concentration in the Indian race and acts as a natural sunscreen reducing the effect of UV rays on the skin. Thus production of Vitamin D is reduced.
Use of excessive sunscreens and socio-cultural practices dictate that people here tend to keep their skin covered, which again reduces sun exposure. Children tend to spend more time indoors with the advent of video games consoles and cartoon channels on televisions rather than being active outdoors.
One study has even reported that high levels of pollution in urban areas coupled with increased density of poorly planned houses, decreases the amount of sun’s ultraviolet rays from reaching the ground level.
In temperate climates, exposing the face, arms and legs to morning sunlight for 15 minutes is sufficient for adequate production of Vitamin D. However in the tropical climates, the time required has to be increased to 45 minutes, which may be difficult in the hectic lifestyle of children.
The alternative way to obtain Vitamin D is from diet. There is however a catch here. Rich dietary sources of Vitamin D include oily fish such as tuna and salmon, fish oils and eggs. Fortified milk, cereals, and butter can also provide Vitamin D but this is very arbitrary as none of these products are fortified on a mass scale and therefore not widely available. Hence diet for vegetarians is grossly lacking in Vitamin D.
Pregnant and lactating women are most at risk of getting Vitamin D deficient. Because mothers are deficient, infants born to them are also deficient, and the deficiency continues after birth, especially since breast milk is equally deplete. Prolonged exclusive breast feeding may add to vitamin D deficiency beyond the infancy.
The only way to judge Vitamin D deficiency is by doing a simple blood test to look for 25 hydroxy Vitamin D level. This can be performed by any standard pathology laboratory in the country. The level of Vitamin D above 30 ng/mL is considered adequate and normal. Levels between 20 and 30 are considered insufficient, those between 10 and 20 are considered deficient and levels of less than 10 are severely deficient.
Vitamin D deficiency has been linked to all kinds of problems. In children it produces a bone disease called Rickets after prolonged deficiency. In adults, it affects bones by causing Osteomalacia, and has been linked to stroke, heart disease, diabetes, cancer (notably colon cancer), Alzheimer’s disease, asthma and tuberculosis.
Apart from its skeletal ill-effects, the other associations have not been conclusively proven. Not all who are Vitamin D deficient manifest bone problems either. Vitamin D deficiency over a long period of time can alter bone metabolism and cause symptoms.
It is therefore important to do additional blood tests in patients who are suspected to have Vitamin D deficiency. These include Calcium and phosphorus levels in blood, an enzyme which is specifically produced by bone called alkaline phosphatase (which is increased in Vitamin D deficiency) and a hormone called parathyroid hormone which is again increased in Vitamin D deficiency. These patients definitely need treatment in consultation with the doctor.
Vitamin D deficiency can cause symptoms of vague bone pain in children, particularly during growth spurts. If left untreated, it can manifest signs of rickets such as swelling around the wrist or ankle, deformity in the leg, or swelling around the rib cage. These children also grow at a much slower pace and are usually the shortest in the class. In severe cases, Vitamin D deficiency can cause deficiency of calcium in the blood and cause symptoms of weakness, lethargy, and rarely convulsions. In the long term, it can cause stunted growth.
Most of these problems are completely reversible once the deficiency is identified and treated with adequate dose of Vitamin D. Even after the treatment is complete, it is important to educate parents regarding the long term needs of continuing Vitamin D supplementation in order to prevent future deficiency. Very rarely if the deformity of the leg does not correct with vitamin D supplementation, surgical correction may be needed. The recommended dietary allowance for Vitamin D is 400 IU for all age groups which can be obtained from diet, sunlight and supplements. This is increased to 600 IU for pregnant and lactating women.
It is also important to keep in mind that an occasional child may not respond to standard Vitamin D treatment. This may be due to a genetic deficiency and will need further investigating.
Vitamin D deficiency is widespread in our country and affects all regions, all age groups and both genders. It particularly affects children and can manifest as rickets. Replenishing the Vitamin D levels with sunlight is ideal but unfortunately an untenable solution. Vitamin D supplementation in diet is essential for good bone health and should be started at an early age to optimise peak bone mass in adults.