Long-term multivitamin use linked to fewer heart problems: Harvard study

Multivitamin use for over 20 years was associated with a 44% lower risk of major CVD events, report scientists from Brigham and Women’s Hospital (Boston), Karolinska Institutet (Stockholm), and Harvard T.H. Chan School of Public Health.

However, data from the 18,530 male physicians participating in the Physicians’ Health Study I cohort indicated that no heart health benefits were observed for multivitamin use over a shorter time period (about 12 years).

“Although our results suggest that continuous multivitamin use over a longer duration may be significantly associated with a lower risk of major CVD, the low number of cases supporting these results indicates that they should be interpreted with caution,” ​wrote the researchers in The Journal of Nutrition​​, but they noted that some other observational studies have also reported cardiovascular benefits among long-term multivitamin users.

Painting a complicated picture​

Dr Howard Sesso from Brigham and Women’s Hospital and Harvard T.H. Chan School of Public Health, and co-author on the paper, told NutraIngredients-USA that the duration issue is intriguing. “There was a relatively weak association for multivitamin use over 13 years and major cardiovascular events, a suggestion, but this was not clear cut. This was encouraging but I wouldn’t make any strong statements about it. But for long term use over a 20 year time period we saw a 44% reduction. That’s an interesting result but we did not have many men who were taking multivitamins for that long. ​

“It paints a complicated picture but there does seem to be something going on for long-term use and major CVD events.”​

Importantly, Dr Sesso added that there was no evidence of any safety concerns from long-term multivitamin use. 

PHS I & II​

Regular readers of NutraIngredients-USA may remember that findings from the Physicians’ Health Study (PHS) II​ study (published in 2012) did not indicate any cardiovascular benefits.

PHS II  is the only large-scale, randomized, double-blind, placebo-controlled trial investigating the long-term effects of a common multivitamin in the prevention of chronic disease.

The men were randomly assigned to receive a daily multivitamin or equivalent placebo for more than 10 years of intervention and follow-up. While no significant reductions were observed for major cardiovascular events, heart attack, stroke, or death from cardiovascular disease, multivitamin users who had cardiovascular disease at the start of the study were significantly less likely to die of a heart attack (44% risk reduction).

The PHS II study also found that a daily multivitamin may reduce the risk of cancer by 8%​.

The new paper deals with data from the original Physicians’ Health Study, which started in 1982.

Study details​

The PHS I included over 18,000 healthy male physicians aged 40 or over. The researchers documented 1697 incident cases of major cardiovascular disease over a mean follow-up period of 12.2 years. While there were no significant differences between multivitamin users and nonusers for major CVD risk, longer term use was found to reduce the risk. Indeed, the researchers found a 44% reduction in major CVD event risk in men who were multivitamin users for at least 20 years.

“The precise mechanisms through which long-term multivitamin use may be more strongly associated with CVD are unclear from observational studies and may reflect residual confounding by healthy behaviors. Alternatively, a longer period of time may be necessary for multivitamins to affect the long-term development of CVD,” ​wrote the researchers.

However, hypothetically vitamins and minerals may be impacting on a number of potential mechanisms that protect heart health, said the researchers, including protecting low-density lipoproteins from oxidative damage, boosting homocysteine metabolism, and reducing endothelial dysfunction.

Commenting on the paper and its findings, Dr Duffy MacKay, Sr VP of scientific and regulatory affairs for the Council for Responsible Nutrition, told us: “Multivitamins are clearly one component of a healthy lifestyle, and we would expect subtle effects over time. ​

“When you look at the mechanisms proposed, it’s clear that nutrients would play an important role. These vitamins and minerals are not treating any of these issues, but if you’re insufficient or deficient then you’re challenging the body on maintaining the systems.​

“It’s exciting to see these Harvard researchers continuously exploring the data in both of these studies [PHS I and II], and I really enjoy how these authors put their studies in context with the other studies out there. Multivitamins are the flagship product for dietary supplements, but there is a limited number of good rigorous studies about them, and they do an excellent job in reviewing those key studies.” ​

Source: The Journal of Nutrition​​
Published online ahead of print, doi: 10.3945/​jn.115.227884
“Multivitamin Use and the Risk of Cardiovascular Disease in Men”​
Authors: S. Rautiainen, et al.