Vitamin D deficiency is one of the most prevalent micronutrient deficiencies in the world. It has emerged as a public health problem in many developing countries of the world including Bangladesh. Over a billion people worldwide are vitamin D deficient. The worldwide prevalence of vitamin D deficiency is 30-50% among children and even higher in tropical countries.
A recent study conducted in Bangladesh revealed that 75% of Bangladeshi children have suboptimum vitamin D status. The study results found that urban children are 76% more likely to have low vitamin status compared to rural children. In humans, the main source of vitamin D is obtained from sunlight. Small amounts of vitamin D can be obtained from oily fish like tuna, salmon, cod, hilsha, egg yolk, margarine and vitamin D fortified cereals.
In Bangladesh, the high prevalence of vitamin D deficiency is frequently underestimated considering the presence of abundant sunlight. In the presence of easily available sunlight, most of us do not avail it. Our sedentary lifestyle with poor exposure to sunlight results in vitamin D deficiency. Due to the COVID-19 pandemic with prolonged school closure, children are staying most of the time at home are deprived of sunlight and becoming vulnerable to vitamin D deficiency.
Air pollution is also another cause of vitamin D deficiency in urban children and adults. Dhaka city is one of the most polluted cities in the world which not only greatly contribute to children developing pneumonia and other respiratory illnesses but also hampers the bioavailability of optimum sunlight to manufacture adequate vitamin D. During winter, vitamin D is usually less available from sunlight due to dust, fog and smog in the environment and people tend to stay at home.
Vitamin D is essential for bone health of children and adults which helps the deposition of calcium in bones to make them strong. Vitamin D deficiency is traditionally thought to be analogous to rickets (skeletal deformity in children) and bony defects (osteomalacia and osteoporosis) in adults. Healthy-looking children and adults presenting with non-specific symptoms like limb pain, fatigue, unexplained weakness and lethargy may have vitamin D deficiency with its potential health problems. Vitamin D deficiency increases the risk of developing many chronic non-communicable diseases in adults like diabetes, coronary heart diseases, cancer etc.
Public health initiative is required to prevent the condition. An outdoor-based lifestyle with sufficient exposure of exposed skin to sunlight should be encouraged in children as well as adults. Sunlight exposure of at least 10% exposed skin for 30-45 minutes should be advised. School children should be allowed to spend an hour under the sun. During the COVID-19 pandemic, children can sunbathe at the roof top or in the open non-crowded field with a face mask. Fortification of milk and food grains with vitamin D should be done. Screening for vitamin D should be considered in risk groups like infants having exclusive breastfeeding and the elderly. Air pollution in the urban area needs to be addressed properly.
Vitamin D deficiency can easily be prevented. The medical and economic burden of untreated vitamin D deficiency is huge and preventive strategies are cost-effective. Better targeting of health resources to antenatal care, pregnant mothers and at-risk children, adolescents and adults regarding supplementation is required. Until such strategies are in place, children, as well as adults, will continue to present with vitamin D deficiency with its health consequences.
The writer is a Senior Consultant at the Department of Paediatrics, United Hospital, Dhaka.