Vitamin D has been proven to have an effect on pancreatic insulin secretion, and by extension diabetes; calcium also has an indirect role in the development of type 2 diabetes. Given the high prevalence of diabetes, this study was designed to look at the effects of a vitamin D- and calcium-supplemented yogurt on the blood sugar level in type-2 diabetics. In this study, 90 diabetics were randomized into three groups, each receiving either plain yogurt, yogurt with vitamin D, or yogurt with both vitamin D and calcium. It was seen that the blood sugar level improved in both the groups receiving vitamin D, irrespective of the calcium supplementation.
Diabetes is the most common endocrine disorder globally, and the prevalence is affected by vitamin D deficiency. Convincing evidence has established a link between vitamin D and insulin secretion and/or insulin sensitivity. Since calcium affects vitamin D levels indirectly, both vitamin D and calcium could improve blood sugar levels. This study was undertaken due to the high prevalence of vitamin D deficiency among individuals with diabetes and in overweight patients. Most results on this relationship are limited and most previous studies did not measure blood vitamin D concentration. Thus, this study was designed to be a comparison study with effective supplementation of vitamin D and calcium.
* The study examined 90 diabetics in the age group between 30 and 60 years, randomly separated into three groups. One group received plain yogurt without vitamin D or calcium supplements, the second had only vitamin D-fortified yogurt and the last group received yogurt fortified with both.
* The subjects were put on a diabetic weight maintenance diet for two weeks prior to the study. They were also asked to record the time they spent exposed to sunlight.
* After 12 weeks, the tests were repeated on all subjects. Fasting blood glucose (blood sugar) and vitamin D levels in the blood were assessed.
* The blood glucose levels of the patients receiving vitamin D improved significantly. These changes were independent of calcium supplementation. Fasting blood glucose, and other markers of insulin resistance, increased significantly in the plain yogurt group after 12 weeks.
* Levels of the active vitamin D metabolite were significantly more in those receiving yogurt fortified with vitamin D.
* Those who had yogurt fortified with vitamin D, as well as those who had yogurt with both vitamin D and calcium, had a lower weight, BMI and waist circumference than the baseline values by the end of 12 weeks.
* The lipid levels of all participants had no significant change. Vitamin D metabolite levels in the blood were found to have a contrary relationship with waist circumference or body fat mass.
Earlier studies have reported contradictory results on weight issues with vitamin D fortification. These are opposite to the results from this study. The 12-week intervention in this study is not sufficient to comment on the long-term status of the effect of vitamin D. There was no approach to assess the total intake of yogurt.
Vitamin D has a regulatory role in diabetes, along with insulin and diet control. This study has shown the significant effects of vitamin D, even in an intervention of just three months. This study has also shown that the quantity of vitamin D required to alter blood sugar levels in diabetics was more than the current recommended daily allowance of vitamin D. Vitamin D affected the blood sugar levels in diabetics both directly in terms of reducing insulin levels and indirectly, by weight reduction. Thus, assessment of vitamin D levels in diabetics is crucial; and replenishment for deficient levels could be adopted in current nutritional policies.
For More Information:
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
Publication Journal: The American Journal of Clinical Nutrition, February 2011
By Bahareh Nikooyeh; Tirang Neyestani; Shahid Beheshti University of Medical Sciences, Tehran, Iran
*FYI Living Lab Reports Are Summaries of the Original Research.