How Genes Influence Your Vitamin D Requirements

The sun has always been the most important source of energy for all living beings in the world. The sun makes life possible.

Your body needs sunlight to stay healthy. Sunlight is the major source of vitamin D for human beings. 

Vitamin D is a kind of fat-soluble vitamin needed by all living beings. This vitamin is also known as calciferol. Though it is present in a few food sources like fatty fish (salmon, tuna, sardines), mushrooms, and egg yolks, a majority of vitamin D is obtained from sunlight naturally. 

What are the significant functions of vitamin D?

  • Helps absorb calcium
  • Prevents the risk of bone diseases like rickets
  • Prevents the development of osteoporosis (weakening of bones) and osteomalacia (softening of bones) 
  • Protects against respiratory diseases
  • Can lower the risk of developing type II diabetes
  • Strengthens your defense against recurring infections

Depending on their chemical composition, there are 5 different types of vitamin D available.

  • Vitamin D1 (ergocalciferol + lumisterol)
  • Vitamin D2 (ergocalciferol)
  • Vitamin D3 (cholecalciferol)
  • Vitamin D4 (22-dihydroergocalciferol)
  • Vitamin D5 (sitocalciferol)

Out of these, Vitamin D2 and D3 are the major ones usually discussed. 

The Story Behind Vitamin D

Rickets is a condition that causes soft bones in children. The telltale signs of rickets are bowed legs, an abnormally large forehead, a curved spine, and stunted growth. 

There are mentions of children born with deformed bones as early as in the first and second centuries AD. Though rickets was not identified as a specific medical condition until 1645, instances of children born with bone deformities were quite common. 

Until the early 20th century, the reason and cure for rickets remained a mystery. Parents with newborns had no idea whether their child would grow up healthy or end up with bone deformities and stunted growth.

In 1914, Elmer McCollum, an American biochemist, identified that a certain additive in cod liver oil helped prevent rickets. He assumed it was vitamin A.

In 1922, he realized that cod liver oil without vitamin A, also prevented rickets. This led to the identification of a new 4th vitamin in history and this was named vitamin D. At that time, people did not realize sunlight could produce vitamin D.

That knowledge was brought forth by another American physician Alfred Hess who concluded “Light equals vitamin D”

Molecular Role Of Vitamin D- Getting Technical

The skin consists of two layers – the outermost layer, epidermis and the inner layer, dermis. The epidermis is made up of 5 layers. Vitamin D is produced using sunlight by the two innermost layers of the epidermis.

7-Dehydrocholesterol, also known as 7-DHC, is a chemical compound that is made in the skin in large quantities. 7-DHC reacts with the ultraviolet (UV) rays from the sun and is converted into vitamin D.

This process happens in the arms, legs, and face. The produced vitamin D is then carried in the blood to the liver. Here it is converted into a pre-hormone (a chemical substance produced by glands that is later converted into hormones) known as calcifediol. 

Calcifediol is then converted into calcitriol in the kidneys, which is the vitamin D form actually used by the body. From here, calcitriol is sent out for circulation. 

Did You Know?

More and more doctors and scientists globally are encouraging people to increase their vitamin D intake to prevent the severity of the COVID-19 infection.

With the vaccine for coronavirus still not approved or available, people are looking towards alternate solutions to boost their immunity. Vitamin D has emerged as a powerful nutrient to keep away infections.

There are a few notable studies conducted around the world that link vitamin D deficiency to an increased risk of developing COVID-19. Some studies say people living in areas that receive lesser amounts of sunlight see higher coronavirus deaths. 

Few other studies point to the fact that people with vitamin D deficiency seem to have worse symptoms when they test positive for the infection.

While there could be links between vitamin D consumption and the effects of the coronavirus, as of now, there is no solid proof that the vitamin can completely prevent or cure the infection.

The National Institutes of Health has also given out a statement stating that there is no evidence vitamin D can treat COVID-19.

However, making sure you get your recommended dose of vitamin D will definitely keep your immune system healthy during this pandemic.

Recommended Values

According to the Food and Nutrition Board, here are the daily recommended intake values of vitamin D.

What Happens When You Take Excess Of Vitamin D?

Excess quantities of vitamin D are unsafe. When you consume excess vitamin D, the calcium levels in the body increase too. This condition is called hypercalcemia. Hypercalcemia can result in the below conditions:

  • Weak bones
  • Kidney stones
  • Nausea and vomiting
  • Loss of appetite
  • Dehydration
  • Polyuria (frequent urination)
  • Abnormal thirst
  • Muscle weakness

Vitamin D toxicity can also cause hypercalciuria (excess calcium in the urine). Extreme cases of vitamin D toxicity can lead to renal failure, irregular heartbeat, and even death.

Overexposure to the sun does not usually cause vitamin D toxicity because the skin learns to regulate the amount of vitamin D it produces. However, excessive use of tanning beds and excess consumption of vitamin D supplements can both cause vitamin D toxicity. 

What Happens When You Have Vitamin D Deficiency

When your vitamin D levels are low because of unhealthy eating habits and less/no exposure to sunlight, you can get vitamin D deficient with time. 

In children, vitamin D deficiency is reflected as rickets disease. Children can also suffer from developmental delays and dental problems early on. In adults, this can cause a condition called osteomalacia. Osteomalacia causes soft and weak bones. Adults also develop dental issues because of vitamin D deficiency. 

Non-genetic factors affecting Vitamin D levels

  • Limited exposure to sunlight – Limited exposure to sunlight is one of the common non-genetic factors that can cause vitamin D deficiency with time. Experts suggest up to 30 minutes of sun exposure between 10.00 AM and 4.00 PM for at least 2 days a week to help your skin produce vitamin D.
  • Food choices – Since fish, red meat, and dairy products have the maximum amounts of vitamin D, if you are a vegan, then your food choices may put you at the risk of developing vitamin D deficiency. In such cases, vitamin D supplements and fortified foods are important.
  • Lactose intolerance – People who are lactose intolerant do not consume dairy and this can also lead to a deficiency in vitamin D. Again, supplements and fortified foods help.
  • Breastfed infants – One liter of breastmilk contains only 0.6 to 2.0 mcg of vitamin D. Hence children aged 0-6 months who are exclusively breastfed can develop vitamin D deficiency quickly. It is necessary to supplement the nutrition until the child is ready for other kinds of food.
  • Age – As people age, their skin is unable to produce as much vitamin D as it used to. This can lead to deficiency. Older adults also spend more time indoors that can intensify the condition. Starting vitamin D supplements after 60 will help prevent bone-related disorders.
  • Skin color – People with darker skin color have excess melanin pigments in the epidermal layer which is said to interfere with producing the right amounts of vitamin D. However, some experts point to the fact that Black Americans have lower instances of bone-related abnormalities than White Americans. There are still studies trying to understand the effects of darker skin color on vitamin D absorption rates. 
  • Medical conditions – Some conditions like liver disease, Crohn’s disease, and ulcerative colitis prevent the gut from absorbing fat from foods. Since vitamin D is a fat-soluble nutrient, these conditions can also lead to poor absorption of the vitamin. Individuals with these health conditions are likely to require more vitamin D than others.

Genetic Association

There are two genes that seem to affect vitamin D concentrations in the body. Variations in these genes can cause increased/decreased needs for vitamin D.

GC gene – The GC gene is responsible for making the Vitamin D binding protein (VDBP) that helps in transporting vitamin D. One particular variant (type) of the GC gene is known to cause vitamin D deficiency.

CYP27B1 gene – The CYP27B1 gene is responsible for making vitamin D active and available for use by the cells in the body. One particular type of this gene can cause lowered vitamin D levels in the body.

Recommendations For Healthy Vitamin D Levels

  • Enjoy a variety of vitamin-D rich foods including fatty fishes, eggs, beef, and all kinds of dairy products. Just one teaspoon of cod liver oil gives you 34 mcg vitamin D. You can include cod liver oil as a part of your everyday dietary supplement.
  • Ensure you have healthy exposure to sunlight- at least 30 minutes to one hour in a week. This will help your skin produce needed vitamin D.
  • If you have a breastfeeding infant at home, definitely talk to your pediatrician about including vitamin D supplements.
  • About 53 million adults in the United States have osteoporosis or will develop it in the near future. Checking your vitamin D levels and compensating for its deficiency can bring down your risk.
  • Get your genetic testing in place and if you find you are likely to require more vitamin D than the recommended values, consider opting for supplements and choose fortified foods over regular foods.
  • As you grow older, the limited production of vitamin D by the skin will not be enough to match your body’s needs. Supplements will help you stay healthy.


  1. Vitamin D is a fat-soluble essential vitamin that is majorly got from sunlight. Vitamin D is also called calciferol. 
  2. There are five types of vitamin D found and D2 and D3 are the major ones. 
  3. Excess consumption of vitamin D is harmful and leads to hypercalcemia and hypercalciuria. Vitamin D deficiency leads to rickets in children and causes soft bones (osteomalacia) in adults
  4. Lesser exposure to sunlight and imbalanced food choices can all result in vitamin D deficiencies. 
  5. As people age, their vitamin D needs are not met sufficiently. People with health conditions like renal diseases or ulcerative colitis also are at risk of developing vitamin D deficiency.
  6. Genetically, you may be designed to require more vitamin D than regular recommended doses. In that case, you should compensate with fortified foods and supplements.


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