Circulating vitamin D concentrations differ by skin color: Individuals with darker skin produce less vitamin D with the same amount of sunlight exposure than individuals with lighter skin color [10,12].
Skin pigmentation, i.e., melanin, absorbs the UVR that initiates vitamin D synthesis, and hence decreases the vitamin D that is made for a given exposure compared to less pigmented skin. This has been observed in UVR intervention studies [7] and more generally.
Just like sunscreen, melanin can reduce a person's ability to make vitamin D from sun exposure by up to 99%! This means that it takes a person of color 3-6 times longer to make the same amount of vitamin D from sun exposure as a person with lighter skin tones.
Vitamin D synthesis is highly dependent on the concentration of melanin in the skin as melanin absorbs and scatters UVR-B, resulting in a less efficient conversion of 7-dehydrocholesterol to previtamin D3[3]. Therefore, dark-skinned individuals will experience slower vitamin D synthesis than light-skinned ones.
Studies have shown that individuals with darker skin pigmentation require longer or more intense ultraviolet radiation exposure to synthesize sufficient levels of vitamin D. In other words, if you have darker skin, you tend to make less vitamin D in the sun than people with lighter skin.
Do lighter skin tones need less vitamin D? People with lighter skin don't need less vitamin D, but because their skin can generate vitamin D more quickly, they need less sun exposure. This means that light-skinned people should find it easier to get vitamin D from sunlight between April and September.
Vitamin D insufficiency 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.
And indeed, fair-skinned people of European descent are nearly six times more efficient at making Vitamin D from UVB rays than those living near the equator. Different types of melanin pigments in skin trigger these variations.
The pigment melanin, which is more prevalent in people with darker skin, reduces your body's ability to make vitamin D in response to sunlight exposure. Essentially, this means that people who have pale skin produce vitamin D more quickly than people with darker skin.
Vitamin D production depends on exposure to sunlight. Humans living at latitudes far from the equator developed light skin in order to help absorb more vitamin D. People with light (type II) skin can produce previtamin D3 in their skin at rates 5–10 times faster than dark-skinned (type V) people.
One estimate is that a dark-skinned black person may need 2.5 times the amount of sun a light-skinned white person would need. That means 20 minutes for one person, and 50 minutes for another to produce the same amount of vitamin D. Read more here about how to get vitamin D from the sun.
Spending even a short time in the sun can provide the body with all of the vitamin D it needs for the day. According to the Vitamin D Council, this could be: 15 minutes for a person with light skin. a couple of hours for a person with dark skin.
Therefore, conditions that affect the gut and digestion, like celiac disease, chronic pancreatitis, Crohn's disease, and cystic fibrosis, can reduce vitamin D absorption.
If you're lacking in vitamin D, your skin may tell on you. For example, if you're not getting enough vitamin D, your complexion might be dull, lacking that desired glow and you might also experience dry, flaky skin on your face and other areas of your body.
Medical conditions that can cause vitamin D deficiency include: Cystic fibrosis, Crohn's disease and celiac disease: These conditions can prevent your intestines from adequately absorbing enough vitamin D through supplements, especially if the condition is untreated.
The highest prevalence of vitamin D deficiency was found in Pakistan (73%;95% CI: 63 to 83%) followed by Bangladesh (67%; 95% CI: 50 to 83%), India (67%; 95% CI: 61 to 73%), Nepal (57%; 95% CI: 53 to 60%) and Sri Lanka (48%; 95% CI: 41 to 55%), respectively.
Prevalence of vitamin D deficiency worldwide
Worldwide, many countries report very high prevalences of low vitamin D status. 25(OH)D levels <30 nmol/L (or 12 ng/ml) in >20% of the population are common in India, Tunisia, Pakistan, and Afghanistan.
There are three main reasons for Vitamin D deficiency: diet, sun exposure and a darker skin pigmentation. South Asian cuisine is wonderfully varied with each region having its own take on traditional recipes. Unfortunately, diets in South Asian countries aren't particularly high in Vitamin D.
Circulating vitamin D concentrations differ by skin color: Individuals with darker skin produce less vitamin D with the same amount of sunlight exposure than individuals with lighter skin color [10,12].
Benefits of vitamin D for your skin
If your skin doesn't get enough vitamin D, it can cause wrinkles and fine lines to appear on your face. The antioxidants in this vitamin help fight these signs of premature ageing and protect your skin.
In summer and spring, with 22% of uncovered skin, 1000 IU vitamin D doses are synthesized in 10-15 min of sun exposure for adults.
What About If I'm Wearing Clothes? A common misconception is that you can get vitamin D from the sun through clothing. This is not true, as the only way to trigger the chemical reaction that results in vitamin D production is for sunlight to reach your skin directly.
Many people can produce enough vitamin D by spending roughly 30 minutes in the sun a few times a week, but that isn't true for everyone. The amount of vitamin D the body produces in the sun varies from person to person and depends on your physical environment.