Few of us can be in any doubt about the crucial role of vitamin D in our all-round health. This fat-soluble vitamin is naturally produced by the body in response to sunlight exposure – which helps explain why it is widely known as the “sunshine vitamin”. Furthermore, it is associated with various functions and positive outcomes for health, including regulating the amount of calcium and phosphate in our bodies, and supporting the immune system.

Speaking of the immune system, there is one subject in relation to vitamin D that has been attracting ever-greater attention during the COVID-19 pandemic: whether people with darker skin are at heightened risk of being deficient in vitamin D compared to lighter-skinned individuals.

And even more importantly, many people are asking, what implications could this have for such darker-skinned people’s health, and what actions should they take in response?

It’s a more complicated situation than first appears

COVID-19 has become relevant here, given the indications that Black people have been hit particularly hard by the coronavirus outbreak. A Centers for Disease Control and Prevention (CDC) study from last April, for instance, looked at 580 patients hospitalised with the condition, and found that one-third were Black, despite only making up 18% of the population examined, and 13% of the wider United States population.

This adds to Black people’s pre-existing higher risk of various health conditions. This is again as reported by the CDC, which has said that African Americans aged 18-49 are twice as likely as whites to die from heart disease, and – in the 35-64 age category – 50% likelier to have high blood pressure than whites.

What relevance does all of this have to vitamin D deficiency in darker-skinned people? Well, as observed in a 2006 abstract by Susan S. Harris of Tufts University: “Vitamin D deficiency is more prevalent among African Americans (Blacks) than other Americans and, in North America, most young, healthy Blacks do not achieve optimal 25-hydroxyvitamin D [25(OH)D] concentrations at any time of year.”

As for how being deficient in vitamin D may impact on COVID-19 outcomes, David O. Meltzer – Chief of the Section of Hospital Medicine at the University of Chicago – led a study last year that examined this relationship.

Scrutinising a cohort of 489 patients who had tested positive for the coronavirus at University of Chicago Medicine, the research found that patients whose medical records indicated probable vitamin D deficiency were at 1.77 times greater risk of testing positive than those who weren’t deficient. And as Meltzer noted, a majority of the patients in the cohort were Black.

So, what contributes to darker-skinned individuals’ vitamin D deficiency?

Commenting in 2006, Harris said that the higher rate of vitamin D insufficiency among Blacks was “primarily due to the fact that pigmentation reduces vitamin D production in the skin.”

Indeed, it has long been established that people with darker skin have more melanin – which is the pigment responsible for skin colour – than lighter-skinned individuals. Furthermore, the Office of Dietary Supplements (ODS) at the National Institutes of Health (NIH) has said that a higher level of melanin reduces a person’s ability to synthesize vitamin D from the sun, which leads to lower 25-hydroxyvitamin D levels.

However, the ODS pointed out that it wasn’t yet clear whether the lower serum 25(OH)D levels in Black Americans compared to White Americans actually translated into “significant health consequences”. It cited the example of those of African American ancestry being found to have lower rates of bone fracture and osteoporosis than their White counterparts.

Meltzer has also warned that the reasons behind darker-skinned people’s higher rates of vitamin D deficiency may be complex, possibly necessitating further study in order to gain greater clarity.

Such factors as age, sunscreen, clothing that covers up the skin, and exact levels of sunlight exposure varying with the seasons could all contribute to any one person not getting enough vitamin D. It is therefore important for all of us not to draw hasty conclusions about the causes of any darker-skinned individual’s vitamin D deficiency, or the steps they ought to take in response.

Nonetheless, if there’s one thing that should be beyond question, whatever your ancestry or ethnicity, it is the importance of vitamins to fight cold and flu and help support overall health. We are certainly great believers in this here at Tonic Health, as embodied by our own well-regarded high-dose vitamin drink.

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