A recent review by Dakshinamurti has examined the therapeutic potential of vitamin A, vitamin D, biotin and other B vitamins in the treatment of metabolic syndrome – a condition known to be a major risk factor for the onset of type 2 diabetes.
Metabolic syndrome has become a major public health concern and is reported as having a prevalence of 15–35% of the global population depending on location. Metabolic syndrome is actually a cluster of various conditions including high blood pressure, centralized obesity and impaired glucose regulation, which together become a serious risk factor for the onset of cardiovascular disease and T2D.
Vitamins A and D are essential for insulin secretion and insulin sensitivity. Both can reduce insulin resistancethrough their effects on cell immunity and cell inflammatory systems. Vitamin A (retinol) is metabolized in the body into the oxidation products 9-cis-retinoic acid (9CRA) and all-trans retinoic acid (ATRA), both of which are known to increase insulin secretion. Metabolic syndrome can be thought of as an inflammatory condition. 1,25(OH)2D3, the active form of vitamin D, is able to reduce the production of pro-inflammatory cytokines and chemokines through suppression of the nutrient factor kappa-B signaling pathway. However, it is to be noted that the required intake levels of these vitamins necessary to have this physiological effect are much higher than recommended daily allowances (RDA) found in most nutritional advice.
Biotin influences the production of insulin from the cells of the islets of Langerhans by encouraging the production of hepatic glucokinase.
The increased onset of Advanced Glycation End-Products (AGE) is a characteristic of the onset of metabolic syndrome, atherosclerosis and the ageing process. AGE cause damage to structures in the extracellular matrix. The presence of AGE appears to be directly related to an increase in reactive oxygen species (ROS) and hence nutrients with antioxidant properties could be beneficial. Vitamin B1 (thiamine) and pyridoxamine (a metabolite of vitamin B6) are thought to have a role in the suppression of the production of AGE.