Science Update

Recent Randomized, Placebo-Controlled Trial Explores the Role of Vitamin D and Aerobic Training in Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) is an endocrine disorder that is increasingly common among adults. T2DM has been associated with chronic inflammation and oxidative stress. Certain lifestyle interventions have been shown to help support metabolic health, a healthy response to inflammation, and antioxidative status. Deficiencies in vitamin D status have also been linked to T2DM. Hypovitaminosis D is believed to influence intracellular calcium levels and the function of glucose transporter type 4 (GLUT4), which can impact insulin secretion. 

A recent randomized, placebo-controlled trial published by Hoseini and colleagues explored the potential supportive role of aerobic training and supplementation with vitamin D in individuals with T2DM. The study lasted for 8 weeks and involved 48 men between 35 and 50 years of age. There were four groups: (1) aerobic training (AT) plus vitamin D, (2) AT plus the placebo, (3) vitamin D only, and (4) controls plus the placebo. AT consisted of aerobic exercise for 20 to 40 minutes at 60% to 75% heart rate maximum at a frequency of three sessions per week. Vitamin D supplementation involved 50,000 IU once per week for 8 weeks. Biomarkers assessed included inflammatory cytokines in peripheral blood mononuclear cells (PBMCs) and markers related to antioxidative status, glucose metabolism, and vitamin D status. 

Excluding the group receiving the control plus the placebo, all groups receiving an intervention (either AT, vitamin D, or combined) showed improvements in biomarkers related to antioxidative status, including total glutathione, superoxide dismutase, glutathione peroxidase, and total antioxidant capacity. All treatment arms also showed improvements in inflammatory markers, including high sensitivity C-reactive protein (hs-CRP), interleukin (IL)-1β, and nuclear factor kappa-B (NF-κB). Improvements in markers related to glucose metabolism were also observed, including fasting blood glucose and Homeostasis Model Assessment of Insulin Resistance (HOMA-IR).  

The treatment arm involving the combination of both AT and vitamin D reflected the largest improvements in inflammatory cytokines, including IL-1β, tumor necrosis factor-alph, and NF-κB. The authors postulated that both AT and vitamin D may act on the body through different physiologic mechanisms and influence multiple downstream targets.  

Drawbacks to the study include a relatively small sample size, demographic homogeneity among participants, and treatment period length. Study strengths, as reported by the authors, included a low dropout rate and involved randomization and a control.  

Although more research is needed, the study by Hoseini and colleagues suggests that supplementation with vitamin D and aerobic training may support metabolic health. Certain lifestyle changes and support of healthy nutrient levels may promote healthy glucose metabolism and antioxidative status.  

By Colleen Ambrose, ND, MAT