Previously in this blog I have covered some of the evidence linking vitamin D with positive health outcomes, including a reduced risk of cardiovascular disease and several forms of cancer. Vitamin D has also been linked with diabetes, in that some studies have found those with higher levels of vitamin D to be a reduced risk of this condition. There has also been a little evidence that supplementation with vitamin D and/or calcium may have some benefit in terms of blood sugar control. There’s a hint, therefore, that higher intakes of these nutrients might reduce the risk of type 2 diabetes.
Recently, a study was published which assessed the impact of giving nutrient fortified yoghurt to individuals with type 2 diabetes. 90 individuals were treated with one of the following each day:
- 500 mls of plain yoghurt
- 500 mls of plain yoghurt containing 1000 IU of vitamin D and 300 mg of calcium
- 500 mls plain yoghurt containing 1000 IU of vitamin D and 500 mg of calcium
A range of body and biochemical measurements were assessed at the beginning and end of the study.
At the beginning of the study, about three-quarters of the study participants were deemed to be ‘insufficient’ in vitamin D (vitamin D3 level 27.5 – >50.0 nmol/l = 11.0-20.0 ng/ml). About 40 per cent were deemed to have severe deficiency (<27.5 nmol/l = 11.0 ng/ml). At the end of the study, vitamin D levels had risen significantly in groups 2. and 3. Relative rise was about 75 per cent in both groups, which corresponded to an absolute rise of 30-35 nmol/l (12.0-14.0 ng/ml).
Those in groups 2. and 3. saw significant reductions in:
- Body mass index
- Waist circumference
- Fasting blood sugar (glucose) level
- HbA1c level (gives a guide to blood sugar levels over the preceding 2-3 months)
As well as improvement in markers of insulin sensitivity (to an extent comparable to treatment with the diabetes drug metformin).
The authors of this study conclude that vitamin D fortified yoghurt (with or without additional calcium) helped blood sugar control in type 2 diabetics probably through direct effects on insulin sensitivity and indirectly also through improvements in weight.
One interest thing to note about this study was just how effective vitamin D-supplemented yoghurt was in raising vitamin D levels. Vitamin D is fat-soluble, and it’s just possible, I suppose, that the fat in the yoghurt enhanced the absorption and ‘bioavailability’ of the vitamin D.
1. Nikooyeh B, Daily consumption of vitamin D- or vitamin D + calcium-fortified yogurt drink improved glycemic control in patients with type 2 diabetes: a randomized clinical trial.
Neyestani TR, Farvid M, Alavi-Majd H, Houshiarrad A, Kalayi A, Shariatzadeh N, Gharavi A, Heravifard S, Tayebinejad N, Salekzamani S, Zahedirad M. Am J Clin Nutr. 2011 Feb 2. [Epub ahead of print]