Obesity and vitamin D deficiency are associated with inflammation and activation of adipokine-related pathways thus increasing risk for several cancers. According to Paulette D. Chandler, MD, MPH, from Brigham and Women's Hospital and Harvard Medical School in Boston, "Observational studies highlight vitamin D sufficiency associated with a reduced risk of diseases that cluster with obesity, such as cardiovascular disease, diabetes, and certain cancers. Possible antiobesity mechanisms of calcium and vitamin D include the control of adipocyte death, adipogenesis, and lipid metabolism."

Evidence suggests that vitamin D is sequestered and stored in the fat cells leading to vitamin D deficiency in overweight individuals. It is believed that vitamin D is liberated when fat cells are lost as a result of weight loss thus increasing vitamin D level in the body. According to Catherine Duggan, PhD, from Fred Hutchinson Cancer Research Center in Seattle, "weight loss reduces levels of inflammation, so this effect, plus the added benefit of vitamin D3 supplements and the increased bioavailability of vitamin D3, reduces IL-6 levels by a measurable level."

Results from previous studies examining the effects of vitamin D and weight loss alone on inflammatory biomarkers reported inflammation reduction. However, it was not clear whether the effects are due to vitamin D itself or are related to dietary changes that occur as part of participating in a weight-loss program. Dr. Duggan and her team conducted a randomized controlled trial to further investigate the effect of both vitamin D and weight loss on bio-inflammatory markers.

The study consisted of 218 postmenopausal women with BMI > 25 kg/m2 and low serum 25-hydroxyvitamin D (25(OH) D; ≥10-<32 ng/mL). These women were randomized to receive 12 months of either weight-loss intervention + 2000 IU/day oral vitamin D3 or weight-loss intervention + daily placebo. Serum adiponectin, leptin, TNFα, IL6, IL1β, IL8, and IL10, were measured by immunoassay and calculated for a composite inflammatory biomarker score.

According to the results, participants in the vitamin D group who lost 5% to 10% of their baseline weight had a significantly lower level of IL6 as compared to participants in the placebo group (37.3% vs 17.2%; P = 0.004). Similar results were also seen in participants who lost ≥10% of baseline weight with (17.3% vs 13.6%; P = 0.02). Furthermore, the intervention has no effects on IL10, TNFα, IL8, the composite score, adiponectin, or leptin, when stratified by weight-loss.

This study confirms the benefits of vitamin D supplementation in addition to weight-loss in lowering inflammatory biomarkers thus potentially reducing cancer and other chronic disease risks.

Conclusions:

• Obesity and vitamin D deficiency are associated with inflammation and activation of adipokine-related pathway thus increase risk for several cancers.
• Evidence suggests that vitamin D is sequestered and stored in the fat cells leading to vitamin D deficiency in overweight individuals.
• Vitamin D3 supplementation in combination with weight-loss of at least 5% of baseline weight was associated with significant reductions in levels of IL6.

Duggan C, de Dieu Tapsoba J, Mason C, Imayama I, Korde L, Wang CY, McTiernan A. Effect of Vitamin D3 Supplementation in Combination with Weight Loss on Inflammatory Biomarkers in Postmenopausal Women: A Randomized Controlled Trial. Cancer Prevention Research (Phila). 2015 July; 8(7):628-35. doi:10.1158/1940-6207.CAPR-14-0449