In certain target populations with poorer diets, taking a daily multivitamin over the long term may help to lower blood pressure and reduce hypertension risk, according to new findings from the Cocoa Supplement and Multivitamin Outcomes Study (COSMOS). The secondary analysis of the study, conducted by researchers at the Mass General Brigham Department of Medicine, was published in Hypertension.

While multivitamin supplementation didn’t meaningfully reduce hypertension risk or blood pressure compared to placebo, they noticed a small but statistically significant improvement among a subgroup that had a lower diet quality and normal blood pressure at the start of the study.

“Nutrition is one of the cornerstones for controlling blood pressure and hypertension,” said corresponding author Rikuta Hamaya, MD, PhD.

“Our findings suggest that a daily multivitamin may not be a one-size-fits-all solution for controlling blood pressure, but could be beneficial for important subsets of older adults,” said Howard Sesso, ScD, MPH, corresponding and senior author.  

COSMOS was a large-scale, randomized, placebo-controlled trial examining cocoa extract and multivitamin supplementation in older adults. For this analysis, researchers focused on 8,905 older adults who didn’t have hypertension at baseline and were randomly assigned to take a multivitamin or a placebo, with a median follow-up period of 3.4 years.

Across the full study population, the investigators didn’t find differences in self-reported and new-onset hypertension between multivitamin and placebo groups. However, in those with poorer diets as estimated by the Alternative Healthy Eating Index and Alternate Mediterranean Diet, hypertension risk was significantly reduced.

The authors noted that further studies are needed on older populations, as well as on those in younger and middle-aged people, to confirm results.