Genetic Testing For Vitamin D3: Why We Need It

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Why do a vitamin D3 test?

Vitamin D deficiency is prevalent throughout the Indian subcontinent, with reports suggesting a prevalence of 70%. Such reports have piqued interest about vitamin D3 tests and costs but many people continue to associate vitamin D deficiency with people who shy away from the sun or are vegan.

Seldom do people realize that, even if you are neither, eat fish like your roommate but, unlike her, experience fatigue or pain in the bones, it could signal vitamin D deficiency too. Most people rarely suspect a vitamin D deficiency, since it is a ‘sunshine vitamin’ that is produced naturally by the body. What they fail to realize is that everyone responds differently.

Picture this, your roommate and you step out for a walk every day at 7, spending the same amount of time under the sun. One of you may tan faster than the other, tire faster or even develop sun spots. Similarly, the amount of vitamin D synthesized by the body, the amount converted to its active form and the amount  taken up by the cells in the body are intrinsic to each person. An understanding about the unique needs of an individual will help in tailoring a suitable diet and lifestyle.


Which genes are analyzed in a Vitamin D3 genetic test?

The cholesterol in the skin and the sun’s UV rays synthesize a type of vitamin D that is the biologically inactive form, cholecalciferol or Vitamin D3. This inactive form has to then be converted into its active form in order to be utilised by the body.  

Conversion of inactive vitamin- vitamin D3: The liver is the primary site of conversion, where the inactive cholecalciferol is hydroxylated into calcifediol (25(OH)D) in the presence of an enzyme coded by CYP27A1 gene.

The next step is the conversion of 25(OH)D in the kidneys or macrophages into calcitriol, 1,25(OH)2D, which is the biologically active form of vitamin D. This step is mediated by the enzyme coded by CYP27B1 gene.  

Transportation of Vitamin D: Active vitamin D is then transported to the nucleus with the help of a binding protein coded by GC gene, binding to the vitamin D receptor coded by the VDR gene. Calcitriol, which is the active form of vitamin D, is utilised by cells via vitamin D receptor (VDR). VDR is also a  transcription factor associated with switching on genes or off. Apart from mediating the uptake of vitamin D, these receptors are associated with the activity of the immune system, bones, pancreas and skin.

Variations in these genes can affect the level of vitamin D levels in the body.

Do you need to take up a Vitamin D3 test?

One of the most important steps is to identify if you have any of the following symptoms.

  • Pain in bones and muscle without much strenuous activity
  • Fatigue and feeling tired often
  • Falling sick often
  • Signs of depression have also been associated with low blood levels of vitamin D


Why is a genetic test for Vitamin D3 important?

  • A genetic test is a one time test that provides an insight into the needs of the body, irrespective of the time of collection, age or dietary patterns at the time of testing.
  • Even if sufficient amount of vitamin D3 is produced by the body, variations in the VDR gene can affect the amount of vitamin D uptake. Therefore, testing for vitamin D3 levels alone may not provide the complete picture of vitamin D utilisation by the body.
  • Only about a quarter of the inter-individual variability in vitamin D3 levels is attributable to geographic location, dietary intake and season of measurement. Twin and family studies have shown that genetic variants contribute to variability in vitamin D levels, with certain studies estimating heritability to be as high as 53%.
  • A routine blood test for vitamin D3 levels may be skewered by a recent overt exposure to sun’s UV rays or a recent increased intake of vitamin D3 rich foods. Such an increased exposure may not be the norm for the individual, resulting in biased results.
  • The level of vitamin D3 is more in summer than in winter, therefore a routine blood test taken in summer may not indicate if there would be an increased need in winter. However, a genetic test will help in identifying probable insufficiency, which will encourage the individual to increase intake.


How to use the genetic test results to identify vitamin D3 needs

The genetic test results for vitamin D can be used to identify the need for vitamin D. The genetic test results should be correlated with a blood test for vitamin D3 levels.

  • If the genetic test results show that the need for Vitamin D is high and the blood test shows low serum vitamin  D levels, then increasing exposure to sun’s rays or intake of vitamin D rich foods will help in improving levels of vitamin D.
  • If the genetic test results show that the need for vitamin D is high but the blood test results show there is sufficient amount of vitamin D levels in the blood, then there may not be a need to increase intake of vitamin D rich foods as the individual is supplementing for the genetic insufficiency with optimal dietary intake or exposure to sunlight.


What is the normal blood levels of 25(OH)D?

The following information has been extracted from the NIH website.

Level (nmol/L)Effect
Less than 30Vitamin D deficiency
Between 30 to 50Inadequate for bone and overall health in healthy individuals
More than 50Adequate for bone and overall health in healthy individuals
More than 120Could lead to adverse effects


Is Vitamin D only about bone health?

The importance of vitamin D levels on musculoskeletal health is well documented, and is associated with the risk of childhood rickets, osteomalacia, and fractures. However, vitamin D is very important for many other functions in the body and its deficiency is also associated with

    1. Type 1 and 2 diabetes: A large meta- analysis has shown that supplementation of vitamin D during childhood could lower risk of development of type 1 diabetes. In a study published in 2018, low vitamin D levels have been associated with high blood glucose levels in Asian Indian Women with pre-diabetes.
    2. Cardiovascular disease: In a study conducted on Framingham Offspring study participants, low vitamin D levels were associated with incident cardiovascular disease.
    3. Breast cancer: The National Health and Nutrition Examination Survey Epidemiologic Follow-up Study showed that sufficient vitamin D levels lowered the risk for breast cancer.
    4. Prostate Cancer:  A study conducted on 89448 registered nurses, low levels of vitamin D was found to be associated with an increased risk for colorectal cancer.
    5. Colon Cancer: Studies have shown that sufficient supplementation with vitamin D could lower risk of colon cancer


A large meta-analysis has also found that supplementation with vitamin D could reduce mortality risk. Therefore, identifying the body’s need for vitamin D and supplementing with optimum amounts of vitamin D is essential for good health and lowered risk of diseases.

Is it sufficient to test for vitamin D levels alone?

Vitamin D is necessary for helping the body absorb calcium and low levels of vitamin D could also affect calcium levels. An understanding of the calcium needs of the body, therefore, will help in supplementing the right amount of calcium, necessary for bone health.

Our nutrition report tests for many vitamins and minerals important for health, including vitamin D and Calcium needs.  

Vitamin D3 Test Cost

Find the lowest genetic Vitamin D3 test cost with free return shipping anywhere within India here . This test not only includes information on vitamin D needs but it also includes the need for many vitamins and minerals as well as response to various micronutrients and macronutrients. It is included as a part of our nutrition package and is not a stand alone product,

  • Vitamin D3 test cost (nutrition report) is 9900 (inclusive of DNA testing)
  • Vitamin D3 test cost (nutrition report) is 2500  (if you have DNA raw data)




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