top of page

dnaMD- The Genes Behind Your Vitamin D Deficiency

Updated: Aug 9, 2021

Are you deficient in Vitamin D? Unfortunately, the answer is probably yes. But you’re not alone. According to a 2011 study, 41.6% of all American adults have a deficiency in Vitamin D. This number only gets higher for American adults with high levels of melanin.

Vitamin D deficiencies can lead to very serious health consequences like cardiovascular disease, cancer, and severe COVID-19 reactions. Moreover, some people have genetic variations that hinder their ability to produce and absorb the essential vitamin. So, we’ve compiled some tips on how to boost your vitamin D levels.

sun, sun damage, vitamin D,

Vitamin D 101:

Also known as the “Sunshine Vitamin”, Vitamin D is a staple nutrient for optimal health. But vitamin D is technically not a vitamin, it breaks many of the rules for vitamins because it requires conversion within the body. Vitamin D is also absent from all natural foods except egg yolks and fish. In order to use the vitamin D obtained from food, your body must first transform it.

Your body can also absorb vitamin D from UV-B rays from the sun. When you walk into a sunny patch, the sun’s energy transforms a chemical in your skin into vitamin D, which is then carried to your liver and kidneys to convert it into a usable form of the vitamin. The graphic below depicts the process from UV-B to usable vitamin D in the body.

The vitamin D your body gets from the sun is actually more potent and beneficial than vitamin D you obtain from food. Sun-derived vitamin D can circulate in your body twice as long as food-derived vitamin D. This is why it is so critical to spend time outside and absorb those UV-B rays whenever you can.

Just how essential is vitamin D?

Vitamin D is an essential vitamin for many different functions throughout your entire body. Some of its purposes include:

  • Essential for a healthy functioning immune system.

  • Supporting healthy bones and teethPromoting the nervous system, brain, and nervous system

  • Supporting cardiovascular health and lung function

  • Regulating insulin levels

  • Influencing the expression of genes involved in the development of cancer

Especially topical right now, vitamin D has been found to be an important factor in the severity of COVID-19 infection. Vitamin D deficiencies have been linked to an increase in the likelihood of a severe COVID-19 case. This is because vitamin D plays an important role in supporting the immune system. Several studies have found that higher levels of vitamin D have protective effects against respiratory viral infections and suppress the overexpression of pro-inflammatory cytokines. An over-expression of cytokines is what causes a cytokine storm, which can lead to tissue damage, organ failure, and is thought to be one of the factors behind chronic COVID-19.

Poor levels of Vitamin D are also linked to other serious health consequences. Vitamin D deficiency increases the risk of osteoporosis, cardiovascular disease, cancer, diabetes, and other serious chronic conditions. Low vitamin D is also associated with inflammation and an increased risk of developing cognitive impairment and several other neurological conditions.

How much vitamin D do you need?

The Recommended Dietary Allowance (RDA) for vitamin D is 600 IU daily for men and women over 19 and 800 IU for adults over the age of 70. But as described in our previous blog on micronutrients, the RDA only recommends enough of a certain nutrient to prevent disease, not sufficiently supply the body with enough micronutrients to fulfill all its functions. In the case of vitamin D, the RDA only recommends enough to maintain healthy bones and significant calcium metabolism. This often leaves the body without enough vitamin D to carry out other important functions like promoting the immune system and supporting cardiovascular health.

Recent studies suggest that your Vitamin D consumption should be much higher than the RDA. Especially given how much time modern humans spend inside.

Moreover, vitamin D absorption can be affected by several factors like your age, current vitamin D levels, and location. Those who live further from the equator are often deficient in vitamin D. One study in Norway found that vitamin D levels dropped during the dark winter months from October to March. Further, for older adults, as skin thins in the aging process, the body becomes less efficient in absorbing vitamin D.

Another factor impacting vitamin D absorption is the color of your skin. Evolutionarily, it was beneficial for people in hot, sunny climates near the equator to have more melanin to protect them from the sun’s harmful ultraviolet radiation. But more melanin also limits vitamin D absorption. Dark-skinned people require a six-time longer exposure to sunlight than fair-skinned people to achieve the same levels of Vitamin D. This dilemma is evident when looking at rates of vitamin D deficiencies across ethnicities. African Americans have nearly double the rate of vitamin D deficiencies as white Americans. Hispanic Americans also have a much higher rate of Vitamin D deficiency when compared to white people.

Vitamin D absorption can also be impacted by certain genetic variations.

Genetic components:

There are several different genes that impact how well your body absorbs vitamin D and converts it into a usable form. These genes are:

  • CPY2R1 gene- This gene provides instructions for making an enzyme that creates a vitamin D binding protein that links to vitamin D and transports it to the kidneys for further conversion. Mutations of this gene are related to several vitamin D-dependent types of rickets. If you have one of these mutations, CPY2R1 will not sufficiently code for the enzyme that binds to vitamin D, causing your body to become deficient in vitamin D and several other minerals like calcium and phosphate. This can lead to weak, soft bones and further muscle weakness.

  • VDR gene- This gene instructs the body on how to make a protein called a vitamin D receptor (VDR). The VDR protein binds to the active form of vitamin D, which then binds to other proteins and regions of DNA to regulate the activity of vitamin D-responsive genes. These genes have important effects in regulating growth, immunity, and many more signaling pathways. Mutations in this gene can prevent the VDR protein from properly binding to vitamin D, which will impact the absorption of vitamin D and other nutrients like calcium and phosphate.

  • DHCR7 gene- This gene is a regulatory switch that controls the conversion of the enzyme "7DHC" to either cholesterol or vitamin D. Individuals with certain variants of this gene have a higher conversion of 7DHC to cholesterol rather than vitamin D, and are therefore prone to lower vitamin D levels. Note this SNP is not associated with higher blood levels of cholesterol.

If you have a mutation or variant in one of these genes that will limit your vitamin D absorption, it is critical that you have your Vitamin D level checked and supplement accordingly.

Optimal vitamin D levels?

As stated earlier, researchers think for optimal health, your vitamin D intake must be higher than the RDA. Several studies examining those with higher than recommended vitamin D intake have found significant health benefits.

  • An analysis of five studies examining the link between vitamin D and colorectal cancer found that people who had the highest levels of the vitamin (over 33 ng/ml) had a 50% lower risk of colorectal cancer than those with lower levels (under 12 ng/ml).

    • Research has found that to achieve 33 ng/ml, you must take from 1,000-2,000 IU per day.

  • Another study examining over 300,000 people found that high levels of vitamin D can reduce the risk of heart disease. In this study, participants who took 1,000 IU of vitamin D per day saw a 10% reduction in heart disease.

Reaching optimal vitamin D levels:

There are several steps you can take to raise your levels of vitamin D:

  • Take a vitamin D supplement- There are many different kinds of vitamin D supplements on the market, but it’s critical that you obtain your supplement through a medical professional. Only medical professionals can prescribe medical-grade supplements that guarantee you are receiving 100% vitamin D and no fillers or additives. It is also important to note the vitamin A is necessary to sensitize the vitamin D receptor to promote proper absorption. Therefore, it is best to take vitamin D with vitamin A and K.

  • Eat a diet high in vitamin D- While vitamin D is more effectively absorbed directly in the sun, there are still several types of food you should add to your diet to ensure sufficient levels of the vitamin. Such foods include:

    • Cod liver oil

    • Egg yolk

    • Salmon

    • Swordfish

    • Tuna fish

    • Sardines

    • Beef liver

  • Spend time outside without sunscreen- We only approve of going sunscreen-free when in pursuit of vitamin D absorption. Some sunscreens can completely block your vitamin D production. Most research on vitamin D absorption has suggested that only 8-15 minutes of sunscreen-free sunshine time in midday sun can provide between 1000-2000 IU of vitamin D. However, for those who are older, darker-skinned, or live further from the equator, more time may be necessary.

At the Johnson Center, we specify our vitamin D recommendation to ensure that you are reaching an optimal level based on factors like your age and genetic variations.

If you are interested in checking your levels of Vitamin D or starting supplementation, email us at or call 276-235-3205.

The Johnson Center for Health services patients in-person in our Blacksburg and Virginia Beach / Norfolk locations. We also offer telemedicine for residents of Virginia and North Carolina!