Diabetics who consumed the vitamin D-enriched yogurt for 12 weeks had lower levels of certain markers of inflammation, including C-reactive protein (CRP), fibrinogen and interleukin-6 (IL-6), according to findings published in the Journal of Clinical Endocrinology and Metabolism.
Chronic inflammation is brought about by an over-expression or lack of control of the normal protective mechanisms. It is known to have a central role in the development of type-2 diabetes and its further complications like coronary heart disease and stroke.
“We showed for the first time that a daily intake of 1000 IU vitamin D either with or without extra calcium for 12 weeks resulted in a significant decrease of serum CRP and plasma fibrinogen concentrations and also in improved serum adipokines including adiponectin […] and decreased cellular secretion of the inflammatory cytokines IL-6 and IL-1beta in type 2 diabetic subjects,” report researchers from Shahid Beheshti University of Medical Sciences in Tehran, Iran.
Vitamin D-fortified yogurt
For the new study, the Tehran-based scientists recruited 90 type-2 diabetics and randomly assigned them to one of three groups: The first group received 500 mL per day of plain doogh, the second group received the same amount of vitamin D-fortified doogh (1,000 IU pr day), and the third group received calcium (500 mg per day) plus vitamin D (1,000 IU)-fortified doogh.
After 12 weeks of supplementation the researchers found that levels of CRP, IL-6, IL-1beta, and fibrinogen decreased in both fortified doogh groups, compared to levels at the start of the study.
Both fortified groups displayed significant increases in levels of adiponectin, a hormone released from fat cells that plays an important role in the regulation of insulin sensitivity and energy.
“Our study showed for the first time that adiponectin, a substance secreted by fat tissue that has an anti-inflammatory effect, increased when calcium and vitamin D-fortified doogh was consumed,” said Tirang Neyestani, PhD, lead author of the study.
“Our findings may offer interesting therapeutic options for diabetic patients.”
Commenting on the potential mechanisms, the researchers note that it is not known how vitamin D influences inflammatory biomarkers, but noted that some studies have reported a potential role for 1,25-dihydroxyvitamin D (1,25(OH)2D), the biologically active form of the vitamin, to down regulate the expression of pro-inflammatory compounds.
Sunshine vitamin
Vitamin D refers to two biologically inactive precursors - D3, also known as cholecalciferol, and D2, also known as ergocalciferol. Both D3 and D2 precursors are transformed in the liver and kidneys into 25- hydroxyvitamin D (25(OH)D), the non-active 'storage' form, and 1,25-dihydroxyvitamin D (1,25(OH)2D).
While our bodies do manufacture vitamin D on exposure to sunshine, the levels in some northern countries are so weak during the winter months that our body makes no vitamin D at all, meaning that dietary supplements and fortified foods are seen by many as the best way to boost intakes of vitamin D.
Vitamin D deficiency in adults is reported to precipitate or exacerbate osteopenia, osteoporosis, muscle weakness, fractures, common cancers, autoimmune diseases, infectious diseases and cardiovascular diseases. There is also some evidence that the vitamin may reduce the incidence of several types of cancer and type-1 and -2 diabetes.
Source: Journal of Clinical Endocrinology and Metabolism
June 2012, doi: 10.1210/jc.2011-3465
“Improvement of vitamin D status via daily intake of fortified yogurt drink either with or without extra calcium ameliorates systemic inflammatory biomarkers, including adipokines, in the subjects with type 2 diabetes”
Authors: T.R. Neyestani, B. Nikooyeh, H. Alavi-Majd, et al.