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Vitamin D

The association is established; acting on it is not advised

Genotype explains part of why two people in the same sunlight end up with different blood levels. It does not tell either of them what to take.

What this supplement connects to

Vitamin D Variant: rs2282679 · GC rs2282679 · GC Variant Topic: Vitamins and nutrient levels Vitamins and nutrient levels Topic Topic: Bones and fractures Bones and fractures Topic Topic: Blood sugar and insulin Blood sugar and insulin Topic Vitamin D Vitamin D Fat-soluble …

Solid lines are connections this site curates. Dashed lines mean the two ends share a research paper — worth knowing, and not a claim that one explains the other.

A genome-wide study of 33,996 people found common variants that affect circulating 25-hydroxyvitamin D, the strongest of them in GC, the gene for the vitamin D binding protein. The association is solid and it has been replicated.

What it is not is a dosing instruction. Vitamin D status is measured directly by a blood test that is cheap and widely available, and a measurement beats a prediction every time. No guideline sets a dose from a genotype.

The useful thing the genetics does say is that low levels are not always a behaviour: some of the difference between two people is in the binding protein, not in how much time either of them spent outside.

Sources

Papers, with their authors
Common genetic determinants of vitamin D insufficiency: a genome-wide association study
Wang TJ, Zhang F, Richards JB, Kestenbaum B, van Meurs JB, Berry D, Kiel DP, Streeten EA, Ohlsson C, Koller DL, Peltonen L, Cooper JD
and 64 more — show all
O'Reilly PF, Houston DK, Glazer NL, Vandenput L, Peacock M, Shi J, Rivadeneira F, McCarthy MI, Anneli P, de Boer IH, Mangino M, Kato B, Smyth DJ, Booth SL, Jacques PF, Burke GL, Goodarzi M, Cheung CL, Wolf M, Rice K, Goltzman D, Hidiroglou N, Ladouceur M, Wareham NJ, Hocking LJ, Hart D, Arden NK, Cooper C, Malik S, Fraser WD, Hartikainen AL, Zhai G, Macdonald HM, Forouhi NG, Loos RJ, Reid DM, Hakim A, Dennison E, Liu Y, Power C, Stevens HE, Jaana L, Vasan RS, Soranzo N, Bojunga J, Psaty BM, Lorentzon M, Foroud T, Harris TB, Hofman A, Jansson JO, Cauley JA, Uitterlinden AG, Gibson Q, Järvelin MR, Karasik D, Siscovick DS, Econs MJ, Kritchevsky SB, Florez JC, Todd JA, Dupuis J, Hyppönen E, Spector TD
Lancet (London, England) · 2010 · PMID 20541252

Questions about Vitamin D

What is Vitamin D?

Vitamin D is a nutrient the body makes from sunlight exposure and also gets from food and supplements, needed for calcium absorption and bone health. Genotype explains part of why blood levels vary between people.

Does knowing my GC genotype tell me my vitamin D level?

No — it explains part of why two people in the same sunlight end up with different levels, not what any one person's level actually is. A blood test measures that directly.

Should a vitamin D dose be set from genotype?

No guideline does that. Vitamin D status is measured directly by a cheap, widely available blood test, and a measurement beats a prediction every time.

If my vitamin D is low, does that mean I have not spent enough time outside?

Not necessarily. Some of the difference between two people sits in the vitamin D binding protein itself, not in behaviour.

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Vitamin D. MyGeneLog™. https://www.mygenelog.com/supplements/vitamin-d

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