Britons urged to take vitamin D while sheltering inside during the pandemic

Vitamin D is made in the skin by the action of sunlight.

The health organization stressed there is no evidence to suggest the vitamin can reduce the risk of catching Covid-19, the disease caused by the novel coronavirus.

The guidance in the United States, however, has not changed: the National Institutes of Health recommends an average daily amount of vitamin D that varies from 10 micrograms to 20 micrograms, depending on one's age. It says that people should get most of their nutrients from food and beverages.

Good food sources of vitamin D include fatty fish, including canned fish like salmon and sardines; eggs, fortified milk and plant milk products; cheese, fortified juice, tofu and mushrooms.

A nation with less sunshine

Dr. Alison Tedstone, chief nutritionist at Public Health England, said that Britons may not be getting all the vitamin D they need from sunlight during lockdown.

"To protect their bone and muscle health, they should consider taking a daily supplement containing 10 micrograms of vitamin D," she said in an emailed statement.

"With the nation staying in to save lives and protect the NHS, many people are spending more time indoors and may not get all the vitamin D they need from sunlight," she added.

Previously the health body had advised people to take vitamin D supplements during fall and winter.

Vitamin D helps regulate the amount of calcium and phosphate in the body, keeping bones, teeth and muscles healthy. A lack of vitamin D can lead to bone deformities such as rickets in children, and bone pain caused by a condition called osteomalacia in adults.

Some research suggests that vitamin D supplements may help to protect against acute respiratory tract infections.

Dr. Michael Holick, an expert on vitamin D research from Boston University, told CNN last month the vitamin regulates the production of a protein that "selectively kills infectious agents, including bacteria and viruses."

Vitamin D also alters the activity and number of white blood cells, known as T 2 killer lymphocytes, which can reduce the spread of bacteria and viruses, Holick added.

However, a systematic review of clinical trials found mixed, conflicting results about the vitamin's use in virus control, calling for more research to be done before recommendations could be made.