Scientists discover three genes linked to skin color and risks for severe vitamin D deficiency

Genes linked to skin color have may be the strongest indicator of whether or not a person is deficient in vitamin D, a new study suggests.

Researchers found that African American participants with a specific mutation had vitamin D levels up to three times lower than what is considered the normal range for a healthy person.

Scientists have found that having low levels of Vitamin D are linked to several cancers including breast, colon, rectal and prostate, as well as COVID-19.

The team, from City of Hope – an independent biomedical research and treatment center based in Duarte, California – says the findings suggest that, in the future, doctors could better prescribe the correct dose of vitamin D supplements and help decrease black Americans’ risk of these illnesses.

Researchers from City of Hope looked at three genes – SLC24A5, SLC45A2 and OCA2 – with strong links to skin color among African Americans (file image)

The team hopes doctors can use the findings in the future to better prescribe vitamin D supplements and help decrease the risk of certain cancers (above)

The team hopes doctors can use the findings in the future to better prescribe vitamin D supplements and help decrease the risk of certain cancers (above)

‘We should not shy from this new study looking at the genetics of skin color and its effects on vitamin D deficiency because being “colorblind” is what has led to the widespread health disparities that we as a society are now trying to address,’ said Dr Rick Kittles, director of the Division of Health Equities at Beckman Research Institute of City of Hope. 

Vitamin D is sometimes called the ‘sunshine vitamin’ because the skin naturally creates it when exposed to sunlight.

It is found in foods such as milk, cheese, egg yolks, tuna and salmon, although often in low amounts, which is why supplements are sometimes needed.

Epidemiological research has suggested that incidence and death rates for certain types of cancer are lower among people living at southern latitudes, with high levels of sunlight exposure, compared to those living at northern latitudes.

In addition, previous studies have found that having ‘adequate’ levels of vitamin D reduces the risk of severe complications and death from COVID-19

What’s more, race is one of the biggest predictors of low vitamin D levels. 

‘Skin color has strong social and biological significance – social because of race and racism and biological because over 70 percent of African Americans are vitamin D deficient, resulting in increased risk for cancer and cardiovascular disease,’ Kittles added. 

For the study, published in the journal PLOS Genetics, the team looked at the data of 1,076 people who self-identified as African American.

Researchers collected blood samples, which they used to analyze DNA and vitamin D levels. 

They also measured the skin covering the area of the inner upper arm using a digital reflectometer.

Normal levels of the 'sunshine vitamin' range between 20 and 40 ng/mL for a healthy person

Normal levels of the ‘sunshine vitamin’ range between 20 and 40 ng/mL for a healthy person 

They looked at three genes with strong links to skin color: SLC24A5, SLC45A2 and OCA2

All three provide instructions for making a protein that is located in melanocytes, which are specialized cells that produce melanin, the pigment that determines skin color.

Black participants with a genetic variant in the gene called SLC24A5 were more likely to have vitamin D levels of 12 nanograms per milliliter (ng/mL) or less.

Normal levels range between 20 and 40 ng/mL for a healthy person.

The team hopes to use their findings to create a risk score assessment that can be used in doctors’ offices one day. 

For example, in the future, a doctor could assess a person’s skin tone and lifestyle and use the tool to prescribe the proper dosage of vitamin D supplements.

‘This study is an example of the interplay of race and skin color on health and how if we ignore things such as the color of a person’s skin, we may be ignoring potential medical issues, thus contributing to health care disparities,’ Kittles said. 

‘Our study provides new knowledge about an easily modifiable factor such as vitamin D supplementation and inherited genetic factors affecting vitamin D deficiency in African Americans. 

‘With more research, in the future doctors could offer patients of color with an inexpensive way to reduce their risk of vitamin deficiency, which ultimately could help protect against certain cancers.’