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What do genes tell us about vitamin D requirements?

Vitamin D and health


Vitamin D is a hot topic these days. We get it from the sun, fortified milk, butter, ghee, soybeans, soy milk, cheese, eggs and certain types of fish and mushrooms. It’s usually credited with promoting bone strength and overall health. And vitamin D deficiency has been linked to many chronic diseases, including, but not limited to, infectious diseases, autoimmune diseases, cardiovascular diseases, diabetes and cancer.

 

A recent study revealed that a whopping 70% of the Indians suffer from vitamin D deficiency. This study further adds that sunlight exposure is not a tenable solution to obtain vitamin D sufficiency among Indians, as darker skin has high melanin content and produces a significantly lesser amount of vitamin D when compared with individuals with fairer skin. Indian skin tone requires daily sunlight exposure of at least 45 minutes to produce sufficient amounts of vitamin D.

Vitamin D and genes


You may also need more vitamin D depending on the genes that you carry. Variations in two genes, GC and VDR, are responsible for lower vitamin D levels. The GC gene produces the main transporter of vitamin D in circulation while VDR  gene produces vitamin D receptor which allows the body to respond appropriately to vitamin D. Compared to others, people carrying one type of GC and one type of  VDR  need to ensure they have adequate sun exposure or dietary intake of vitamin D to avoid deficiency.

Diet and vitamin D


Various nutritional factors attributing to high prevalence of vitamin D deficiency in India are:

    1. Most Indians are vegetarians and most of the foods rich in vitamin D are of animal origin.
    2. Indian diets are low in calcium and high in phytate.
    3. High prevalence of lactose intolerance is a major factor for reduced intake of calcium and vitamin D.
    4. Intake of caffeine from coffee and tea is high in India.

Factors such as age (old age), body weight (people with a body mass index of 30 or greater), problems of the digestive tract like Crohn’s disease and cystic fibrosis, kidney problems results in low blood levels of vitamin D.

The National Institute of Nutrition recommends 200 units, 5 mcg of vitamin D everyday. The following are the recommendations from the vitamin D council:

    1. It is essential to maintain healthy levels by including fatty fish such as salmon, mackerel, herring, tuna, fish oils, egg yolks, fortified milk and other fortified foods such as cereals etc.
    2. Vitamin D supplements could be a good alternative. Many forms of vitamin D exist, with vitamin D3 the most effectively used in the body.
    3. Get adequate sunlight exposure: The amount of vitamin D you get from exposing your bare skin to the sun depends on the time of the day, where you live, the color of your skin and the amount of skin you expose.

 

Want to know what type of VDR and GC gene you have, Xcode’s nutrigenetics test can tell you what versions of the VDR & GC gene you have in your DNA. You can also learn about how your genes may influence other traits, including your risk for certain diseases.  You can write to us at info@xcode.in.

Janani Thiru
Janani Thiru
Janani is a Nutrigenetic Counselor at Xcode, Freelance Writer, Food Scientist and Nutritionist by academics. She received the prestigious Erasmus Mundus Award by the European Commission for her post graduate program in Food Science and Technology in 2010. She worked with Food & Agriculture Organisation of the United Nations in Rome and Cambodia previously. Her latest project is an e-book of nutrigenetics she is compiling that will be published next year.