Link Between Skin Pigmentation and Vitamin D Absorption

Deficiency in vitamin D affects roughly 50% of the global population, and it often leads to skeletal deformities, difficulty moving, and even death.

Despite being considered a vitamin, you aren't likely to consume much of this critical compound through your skin pigment controlled by at least six genes. Melanin is present in the outer skin layers called the epidermis, and specialized cells called melanocytes produce it.

There are two main types of melanin: pheomelanin and eumelanin. Pheomelaninproduces red and yellow coloring, while eumelanin ranges from dark brown to black. Light and dark-toned skin both contain melanin, but each one has more of one type than the other.

Like your eyes, melanin cells have photosensitive receptors that detect ultraviolet radiation from the sun. By design, the compound acts as a biological shield for your skin that reduces your risk of sunburns and consequential DNA damage.

Likewise, the number and size of melanin particles in the skin also vary. The more melanin is within your skin, the darker it will appear. Too much sun exposure can trigger melanin production to increase the number and size of melanin granules in your skin, darkening it within hours.

Links Between Vitamin D and Skin Pigmentation

Different populations have varying melanin levels, and communities closest to the equator tend to have the darkest skin. Is there a biological reason for this?

The answer lies in the fact that not all sunlight is equal when it comes to vitamin D absorption. Geographic and seasonal variations on earth affect the strength of the sun's rays, which impacts how easily they are absorbed into the skin.

This has led to the vitamin D hypothesis, which states that skin pigment regulates vitamin D production by either absorbing or blocking it, depending on what the needs are for specific populations. The theory goes that once early humans migrated out of the tropics of Africa and into higher and lower latitudes, the reduced sunlight caused their skin to lose melanin and improve its efficiency at converting it into vitamin D.

For this reason, populations around the equator tend to have the darkest skin tones, and global distributions show that skin tones tend to progressively lighten until peaking in Northern Europe.

Does Skin Pigmentation Level Affect Vitamin D Levels?

Will the color of your skin determines whether you are deficient in vitamin D? The research says it will certainly be a factor.

Though not directly associated with vitamin D deficiency, pigmentation levels in the skin can affect your vitamin D levels. This is because melanocytes (the cells that produce melanin) are also the body's vitamin D production site.

Put simply, the higher your skin's eumelanin concentration, the longer it takes to absorb adequate amounts of vitamin D from the sun. Light skinned individuals (those with more pheomelanin) require less sunlight, while those with darker skin need longer or more intense exposure to get the same levels of vitamin D.

Research shows that fair-skinned Europeans are roughly six times as efficient at converting sunlight to vitamin D than populations at the equator, as eumelanin acts as a natural sunscreen in these populations.

A study from the University of Pennsylvania determined that light-skinned participants experienced a 50-fold increase in the vitamin D in their blood within 8 hours of UVB exposure, while it took darker-skinned participants over 40 hours to experience just a 30-fold increase in vitamin D.

In the same way, eumelanin is linked with providing sun protection for skin, while too much sun exposure on pheomelanin is likely to lead to DNA damage and skin cancer.

Dangers of Skin Pigmentation and Vitamin D Absorption

The consequences of too little skin pigmentation can be deadly. The CDC states that approximately 76,000 Americans are diagnosed with skin cancer each year, and over 9,000 die from it. Light-skinned European Americans have a ten times greater risk of developing skin cancer than African Americans, and too much ultraviolet radiation penetrating through the skin can trigger the breakdown of folate, leading to anemia.

Likewise, people with darker skin have a limited capacity to obtain vitamin D from sun exposure, putting them at a higher risk for vitamin D deficiency than are lighter-skinned individuals. For this reason, those with darker skin are significantly more likely to experience vitamin D deficiency than the general population.

A 2008 report by Public Radio International found that African Americans are twice as likely to develop vitamin D deficiency than European Americans, and the condition can lead to rickets, osteoporosis, and even diabetes.

For these reasons, it's hypothesized that the significant levels of hypertensive disease in African American populations might be caused partly by low serum vitamin D.

Vitamin D for Treating Vitiligo (Hypopigmentation)

Sometimes melanin production doesn't work as it should, which can lead to skin conditions like vitiligo. This is a skin pigmentation disorder known for leaving vitiligo remedy when psoriasis patients who also had vitiligo were treated with topical analogs of vitamin D called calcipotriol and tacalcitol. For these patients, the vitamin D treatment led to hyperpigmentation of their skin (the opposite of hypopigmentation), which successfully worked to re-pigment their white patches.

Calcipotriol is the vitamin D analog most studied for treating vitiligo. Also called calcipotriene, the synthetic compound can be found in creams and ointments for treating skin conditions. Concentrations of up to 6% calcipotriol applied topically to the skin works well to treat skin disorders without side effects, though hypercalcemia (excessive calcium) is a rare side effect at higher concentrations.

How to Maintain Skin Health and Vitamin D Levels

Knowing that your skin tone affects your vitamin D levels, what should you do to best stay healthy? That depends on what your specific skin concerns are.

Most adults require about 5000 IU of daily vitamin D when sun exposure is not direct (usually fall, winter, and spring), but your level may differ depending on your age, skin tone, and where you live in relation to the equator.

The Office of Dietary Supplements' recommendation is that adults get between five to thirty minutes of sun exposure each day to generate enough vitamin D to stay healthy.

While spending more time in the sun will raise your vitamin D levels, it isn't necessarily safe for lighter-skinned populations. If you fall into this category, it'soften best to control your sun exposure by wearing protective clothing after you have exposed your skin to sunlight but BEFORE you start burning.

If you aren't sure what amount of sunlight is beneficial for your skin tone without being dangerous, it's best to get an opinion from your doctor. A health professional will help you determine whether you are at risk for skin cancer or vitamin D deficiency and give you advice for adjusting your lifestyle accordingly.