Weight loss, when combined with vitamin D supplements, has more effect on reducing chronic inflammation than weight loss alone, researchers at Fred Hutchinson Cancer Research Center have found.
It is known that chronic inflammation contributes to the development and progression of multiple diseases, including some cancers.
Lead author Catherine Duggan, Ph.D., of the Public Health Sciences Division at Fred Hutch, said:
“We know from our previous studies that by losing weight, people can reduce their overall levels of inflammation, and there is some evidence suggesting that taking vitamin D supplements can have a similar effect if one has insufficient levels of the nutrient.
It’s the first study to test whether adding vitamin D augments the considerable effect of weight loss on inflammatory biomarkers.”
The randomized, controlled clinical trial involved more than 200 overweight, postmenopausal women who had insufficient levels of vitamin D at the beginning of the study.
Half the participants in the study were selected randomly and received 2,000 IU of vitamin D daily for the year-long trial. The other half got an identical-looking placebo vitamin.
Inflammation biomarkers were measured at the beginning and end of the study. The researchers then compared changes in these levels between the two groups.
All participants were found to have reduced levels of inflammation, regardless of whether they took vitamin D, Duggan said, which highlights the importance of weight loss in reducing inflammation.
But those who saw the largest decline in inflammation markers were those who took vitamin D and lost 5 to 10 percent of their baseline weight.
Those participants had a 37 percent reduction in a pro-inflammatory cytokine called interleukin-6, or IL-6, versus those in the placebo group, who saw a 17.2 percent reduction in IL-6.
Similar results were seen among women in the vitamin D group who lost more than 10 percent of their starting weight. While IL-6 has normal functions in the body, elevated levels are associated with an increased risk of developing certain cancers and diabetes and may be implicated as a cause of depression, Duggan said.
“We were quite surprised to see that vitamin D had an effect on an inflammation biomarker only among women who lost at least 5 percent of their baseline weight,” Duggan said. “That suggests vitamin D can augment the effect of weight loss on inflammation.”
A steroid hormone, vitamin D has numerous functions beyond regulation of calcium levels and bone metabolism.
Vitamin D receptors are found in more than 30 cell types. The research focus around this nutrient recently has shifted from bone health to vitamin D’s effect on cancer, cardiovascular health and weight loss, among other health issues.
“Weight loss reduces inflammation, and thus represents another mechanism for reducing cancer risk,” Duggan said. “If ensuring that vitamin D levels are replete, or at an optimum level, can decrease inflammation over and above that of weight loss alone, that can be an important addition to the tools people can use to reduce their cancer risk.”
Duggan says women should talk with their health care providers about measuring their levels of vitamin D to find the best dosage.