30 minutes of sunbath a week can make infants vitamin-D sufficient: study

A study from Delhi has suggested an estimate for the minimum duration for which infants need to be exposed to sunlight every day to achieve sufficient levels of vitamin-D in their body

By Bhavya Khullar

New Delhi: It used to be a routine practice in India to massage infants and give them a sunbath. But changing lifestyles in recent decades have confined kids to indoors. This has led to emergence of Vitamin D deficiency as a major problem among infants.

A study from Delhi has suggested an estimate for the minimum duration for which infants need to be exposed to sunlight every day to achieve sufficient levels of vitamin-D in their body.

Doctors at the University College of Medical Sciences, New Delhi enrolled 100 infants and asked their mothers to record the time, duration, and the body area exposed during sunbath every day starting 6 weeks of age.

The study found that an exposure of as low as about 30 minutes of sunlight per week with about 40% of the child’s body exposed to the sunlight can help achieve adequate vitamin-D status at 6 months of age. The researchers also found that the ideal time to give the sunbath is between10 AM and 3 PM.

“This small intervention can help improve levels of vitamin D in infants without the need for supplements or formula feed, and can possibly benefit more than 16 million babies born in the country every year,” mentuioned Dheeraj Shah, professor of pediatrics at the University College of Medicine Sciences, New Delhi, who is a co-author of the studyIndia Science Wire.

The study took into account factors like skin colour of infants and season of sunbath. About 90% of the mothers in the study were themselves vitamin D deficient. Mothers who were on vitamin D supplements were excluded so that the study results remained unaffected, researchers explained. The study has been published in journal Indian Pediatrics.

“We are planning further studies with a larger group of infants to test it as an intervention therapy”, said Piyush Gupta, corresponding author of the paper. Vitamin D is synthesized in the skin when ultraviolet rays from the sun convert a molecule, 7-dehydrocholesterol, on the skin into an inactive form of the vitamin. This enters the blood circulation and is converted to its active form in the liver and kidney.

Several studies over the years have shown that more than 50% of the Indian population is vitamin D deficient. This is a matter of concern especially for infants because Vitamin D is important for calcium absorption, normal growth and development, and maintenance of bone health and hair follicles. Insufficient vitamin D levels cause lethargy, irritability, and a predisposition to infections. Extreme Deficiency of vitamin D can causes ricket which results in malformation of leg bones.

Umesh Kapil, professor of Gastroenterology at the All India Institute of Medical Sciences (AIIMS), New Delhi, who is not connected to the study, felt that the proposed strategy may not be feasible in winters when the temperature remains low. While agreeing with Kapil, Shah said “we have reported that for the winter months if the child is fully clothed with only face and hands are exposed, the required sunbath is calculated to be two hours per week or approximately 17 minutes per day.”

Ramesh Agarwal, Professor of Pediatrics, AIIMS New Delhi, suggested that randomized control trials must be done to test this intervention as a therapy. He also highlights the need to evaluate the safety of sun exposure in relation to hyperthermia, burns and skin cancer in infants. (India Science Wire)