The study goes on to highlight that very few food products – “dairy products, eggs, fish, and cod liver oil” – contain natural vitamin D, and while much of the industrialised world has access to foods that have been fortified with vitamin D, the majority of the world living in low to middle-income countries depends on the sun for the vitamin. Other foods such as beef liver and mushrooms also contain smaller amounts of the vitamin.

What vitamin D does for the body and the risks posed by a deficiency

An up-to-date fact sheet published by the US’s National Institute of Health lists numerous bodily functions of vitamin D, including calcium absorption and bone health, as well as working with the parathyroid glands, which “work minute to minute to balance the calcium in the blood by communicating with the kidneys, gut and skeleton.”

Regarding bone health, vitamin D protects children from conditions such as rickets. The above-mentioned report backs this claim: “Rickets is a disorder that causes children to have bones that are weak and soft. It is caused by a lack of vitamin D in the body,” adding further, “you need vitamin D so that calcium and phosphorus can be used to build bones. In adults, having soft bones is a condition called osteomalacia.” While much is known about the vitamin, there is still a lot of ongoing research into its potential to prevent inflammation, as well as slow the growth of cancer cells.

However, the vitamin is not a panacea for all kinds of conditions as excessive intake can be toxic. According to the fact sheet, “in extreme cases, vitamin D toxicity causes renal failure, calcification of soft tissues throughout the body (including in coronary vessels and heart valves), cardiac arrhythmias, and even death”. It is key to only consider taking vitamin D supplements in consultation with a physician.

How does sunscreen application affect Vitamin D intake from the sun?

King’s College researchers in London conducted a study about the impact of sunscreen on Vitamin D intake. The research featured participants that were split into four different groups, three of which were sent to Tenerife in Spain, a place with plenty of sunlight.

“Sunlight is the main source of vitamin D. Sunscreens can prevent sunburn and skin cancer, but there has been a lot of uncertainty about the effects of sunscreens on vitamin D,” says Andrew Young, the lead author of the research. The professor also acknowledged in an article by Kings College published in May last year, “Our study, during a week of perfect weather in Tenerife, showed that sunscreens, even when used optimally to prevent sunburn, allowed excellent vitamin D synthesis.”

Who is affected the most by a vitamin D deficiency

The above-mentioned ODS fact sheet pointed out the various groups of people that are at a high risk of having a vitamin D deficiency. They are breastfed infants, older adults, people with limited sun exposure, those with dark skin, and people with conditions that limit fat absorption, as well as people who are obese and those that have had gastric bypass surgery.

Specifically, with regards to dark skin, the report stated that “greater amounts of the pigment melanin in the epidermal layer of the skin result in darker skin and reduce the skin’s ability to produce vitamin D from sunlight. Black Americans, for example, typically have lower serum 25(OH)D levels than white Americans”. However, whether these lower levels in persons with dark skin have significant health consequences is not clear.

And with regards to bone health, “those of Africa- American ancestry, for example, have lower rates of bone fracture and osteoporosis than do Whites (see the section below on bone health and osteoporosis),” says the report. DM/ ML