Does vitamin D deter diabetes?
The answer may be “yes”, in light of the growing body of research that links the two.
We cannot yet be certain, because most of the evidence is epidemiological, which cannot prove a cause-and-effect relationship between intakes or body levels of a given food or nutrient and rates of a given disease.
The authors of a recent evidence review detailed the current state of the evidence, from epidemiological and clinical studies (Pittas AG et al. 2010):
Vitamin D supplementation in pregnancy or early childhood is associated with a reduced risk of type 1 diabetes.
Most but not all studies link low vitamin D levels to a higher risk of type 2 diabetes.
Clinical trials testing vitamin D supplementation suggest that it may delay the progression to diabetes among adults diagnosed with insulin resistance.
The available clinical trials found that vitamin D supplements have no effect on blood sugar levels in healthy adults … which seems both unsurprising and desirable.
We should note that people with higher intakes and/or blood levels of vitamin D are generally healthier than their peers, so the positive results reported in some studies might be misleading.
For some of our past coverage, see:
Fish fit the vitamin D bill; Sockeye salmon stand out
In addition to getting vitamin D from supplements, certain fish rank among the very few substantial food sources of vitamin D, far outranking milk and other D-fortified foods.
Among fish, wild Sockeye Salmon may be the richest source of all, with a single 3.5 ounce serving surpassing the US RDA of 400 IU by about 70 percent. Why? See “Why Does Sockeye Offer a Surfeit of Vitamin D?”:
Vitamin D per 3.5 ounce serving*
Sockeye Salmon 687 IU
Albacore Tuna 544 IU
Silver Salmon 430 IU
King Salmon 236 IU
Sardines 222 IU
Sablefish 169 IU
Halibut 162 IU
*For our full test results, click here.
Kilpeläinen TO, Zillikens MC, Stančákova A, et al. Genetic variation near IRS1 associates with reduced adiposity and an impaired metabolic profile. Nat Genet. 2011 Jun 26. doi: 10.1038/ng.866. [Epub ahead of print]
Mitri J, Muraru MD, Pittas AG. Vitamin D and type 2 diabetes: a systematic review. Eur J Clin Nutr. 2011 Jul 6. doi: 10.1038/ejcn.2011.118. [Epub ahead of print]
Pittas AG, Dawson-Hughes B. Vitamin D and diabetes. J Steroid Biochem Mol Biol. 2010 Jul;121(1-2):425-9. Epub 2010 Mar 18. Review.