Personalising Vitamin D supplementation according to Genetics

Vitamin D is a fat-soluble vitamin which functions as a steroid hormone in the body where its primary role is in the maintenance of bone health to reduce risk of osteoporosis and bone fractures [26681795] [28612338].

Vitamin D deficiency is of growing global concern. Emerging research suggests that low serum 25-hydroxyvitamin D ( 25(OH)D ) the most useful biomarker of vitamin D status - has also been associated with many chronic diseases including cardiovascular disease, diabetes, cancers, autoimmune diseases, infections and total mortality [26681795] [27649525] [24622671] [28207791].

The majority of vitamin D is synthesised in the skin upon exposure to sunlight, however this method of production is hugely influenced by various factors including latitude, time of day, season, air pollution, skin pigmentation, aging, skin exposure, sunscreen, and air pollution. Thus, dietary supplements are a much more manageable way to ensure sufficient serum 25(OH)D and help protect against adverse health effects.

Now this is the interesting part.. the daily dosage of vitamin D required to keep serum 25(OH)D in the optimum range (>50nmol/L) depends on which combination of genetic variants you carry, known as your genetic risk score (GRS).

Such genetic factors modify serum 25(OH)D levels [11204437] [18030310] [17236760] [20943799] [31365099] and affect response to vitamin D intake [27683185] [23190755] [24934498] [24694335] [31841498] [20541252] thus some individuals require a higher vitamin D supplement to reap the same results.

Many genetic variants have been associated with low serum 25(HO)D, however the two variants most correlated to personalized supplementation research are the rs4588 (A allele) in the GC gene and the rs10741657 (G allele) in the CYP2R1 gene [20418485] [25208829] [26704534] [29343764] [29545823] [28757204] [29325163] [32059762] [32242144].

Your GRS is a range from 0-4 and is the sum of the number of risk copies you carry from each of these gene variants - either 0, 1, or 2 from each variant [33382404].

Daily Vitamin D supplementation for those with serum 25(OH)D < 50nmol/L according to your GRS are as follows:

GRS 0: 10-20 micrograms (400-800 IU)
GRS 1-2: 20-30 micrograms (800-1200 IU)
GRS 3-4: 50 micrograms (2000 IU)

These recommendations are given in conjunction with dietary recommendations to eat 2-3 serves of fish per week along with daily consumption of vitamin D fortified dairy/soy milk products and fat spreads. Mushrooms are the only natural plant based source of vitamin D so for those following a vegetarian or vegan diet, fortified foods such as cereals and dairy or plant milks should be regularly included in the diet.

It is very important to check your vitamin D levels with a blood test. Currently, it is estimated that 50% of Australians are deficient in Vitamin D, so chances are you could be deficient without even knowing it. Symptoms can include fatigue, mood changes, muscle weakness or cramps, and bone pain.

From supplements alone, most adults can benefit from a dose of 2000-4000IU Vitamin D per day [33520645] however always consult your healthcare professional before making any supplemental changes.

Written by
Alannah Mezzatesta, BSc
Nutrition Scientist (ANutr)
 last updated  27th July 2022