An analysis of the landmark VITAL trial is reigniting the debate about the benefits, or lack thereof, seen with vitamin D supplementation, suggesting that the determinant of whether or not a patient will see benefit depends on their body mass index. body (BMI).
The results of the analysis, which stratified patients based on baseline BMI, suggest that a robust response was seen for those who were overweight or obese among patients in the Vitamin D and Omega-3 Trial (VITAL).
“This study sheds light on why we are seeing 30 to 40 percent reductions in deaths from cancer, autoimmune disease, and other outcomes with vitamin D supplementation among people with lower BMIs, but minimal benefit in people with a higher BMI, suggesting that population-wide benefits may be possible with more personalized doses of vitamin D,” said lead investigator JoAnn E. Manson, MD, DrPH, chief of the Division of Preventive Medicine at Brigham and Women’s Hospital and principal investigator for VITAL, in a statement from Brigham and Women’s Hospital for Women “These nuances make it clear that there is more to the vitamin D story.”
With regard to their impact on general health, few items other than coffee and caffeine have gained the level of public interest or been studied as extensively as vitamin D. Most of these studies are riddled with design flaws. , confusion or other problems. , the VITAL trial was born to provide a more definitive answer to questions related to vitamin D supplementation. Designed with the specific intention of evaluating the effects of high daily doses of vitamin D for the prevention of cancer and cardiovascular disease, the trial enrolled 25,871 adults who were randomized and followed for a median of 5.3 years.
The trial results demonstrated that daily vitamin D supplementation did not provide a significant reduction in the risk of cancer, cardiovascular disease, or stroke among the study cohort. However, the researchers did observe a statistical correlation between BMI and cancer incidence, cancer mortality, and the incidence of autoimmune diseases. The current study was designed as a post hoc analysis of the VITAL trial to test the investigators’ hypothesis that obesity would modify vitamin D metabolism and response to supplementation. By limiting their analyzes to those with a baseline vitamin D assay, the researchers identified a cohort of 16,155 patients to include in their analysis.
The study cohort had a mean age of 67.7 (SD, 7.0) years, 50.7% were female, and 76.9% were non-Hispanic white. Of note, 2,742 of the 16,155 patients included in the investigators’ analyzes had a follow-up blood sample taken after 2 years. The researchers noted that those initially overweight or overweight (40.5%) or obese (27.0%) were typically younger and more likely to self-report black race and ethnicity, had lower annual household income, and a lower attained educational level than their normal body weight counterparts.
Before randomization, serum total 25-OHD levels were progressively lower in the higher BMI categories. The adjusted means for each BMI category are highlighted below (P <.001 for linear trend).
- Underweight: 32.3 (SE, 0.7) ng/mL
- Normal weight: 32.3 (SE, 0.1) ng/mL
- Overweight: 30.5 (SE, 0.1) ng/mL
- Class I obesity: 29.0 (SE, 0.2) ng/mL
- Class II obesity: 28.0 (SE, 0.2) ng/mL
Further analysis indicated that baseline levels of 25-OHD3, FVD, BioD, VDBP, albumin, and calcium were lower with higher BMI categories. Conversely, the PTH level appeared to increase as BMI categories increased (all P <.001 for linear trend).
Assessing the effects of randomization, the results demonstrated that randomization to daily vitamin D supplementation was associated with increases in 25-OHD, 25-OHD3, FVD, and BioD levels compared with placebo at 2 years. However, the researchers noted that the increases were significantly greater in the higher BMI categories. Furthermore, no substantial changes in VDBP, albumin, PTH, or calcium levels were observed as a result of vitamin D supplementation.
“Analysis of the original VITAL data found that vitamin D supplementation was correlated with positive effects on several health outcomes, but only among people with a BMI less than 25,” said lead investigator Deirdre K. Tobias, ScD, an epidemiologist. associate in the Division of Preventive Medicine, in the aforementioned statement. “It appears that something different happens with vitamin D metabolism at higher body weights, and this study may help explain the diminished results of supplementation for people with high BMIs.”
This study, “Association of Body Weight with Response to Vitamin D Supplementation and Metabolism,” was published in JAMA Open Network.
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