25 November 2022

Multivitamin Trials

Welcome back. Several years ago, in a blog post, Canned Fish for Lunch, I wrote that although my diet is nutritionally impressive, I still take a multivitamin. I acknowledged that research has shown little or no benefit and that if one’s diet is well balanced, there’s probably no need for any dietary supplement. Nevertheless, I figured it can’t hurt.

Warren’s dietary supplements: multivitamin, vitamin C and calcium-vitamin D (from
Canned Fish for Lunch).
Oh, it’s not just me. Preceding my blog post by a few years, a national survey found that half of U.S. adults took at least one dietary supplement during a 30-day period. Multivitamins topped the list. The most commonly cited reason was for overall health and wellness and to fill nutrient gaps in the diet.

Bringing it up to date, a systematic review of 84 studies of dietary supplements found not much has changed regarding cardiovascular disease or cancer prevention. But surprise, surprise, there may be other benefits. Another recent study found that a daily multivitamin might improve cognition in older adults or protect cognitive health with age.

I’ll begin with the systemic review then move on to the cognitive health study.

The Systematic Review
The U.S. Preventive Services Task Force (USPSTF) is an independent (i.e., non-governmental), volunteer panel of national experts in disease prevention and evidence-based medicine. The Task Force works to improve the health of people nationwide by making evidence-based recommendations about clinical preventive services.

U.S. Preventive Services Task Force logo (from www.uspreventiveservicestaskforce.org/uspstf/).

Among a wide variety of subjects addressed over the years, the USPSTF provided the recent recommendations on dietary supplements to prevent cardiovascular disease and cancer as well as recommendations in 2003 and 2014.

For the 2022 recommendations, the USPSTF commissioned a team of researchers affiliated with Kaiser Permanente and Oregon Health & Science University to complete an evidence report and systematic review.

The USPSTF’s Recommendation Statement as well as the researchers’ evidence report and systematic review were both published in the 21 June issue of the Journal of the American Medical Association (JAMA).

As regards multivitamins for community-dwelling, nonpregnant, generally healthy adults, the USPSTF concluded: [T]he evidence is insufficient to determine the balance of benefits and harms of supplementation with multivitamins for the prevention of cardiovascular disease or cancer. Evidence is lacking and the balance of benefits and harms cannot be determined. The conclusion was consistent with the 2014 Recommendation Statement.

Multivitamin for Cognition
The study, COSMOS-Mind, was conducted by researchers affiliated with Wake Forest University School of Medicine, Brigham and Women's Hospital, Harvard Medical School and Harvard T.H. Chan School of Public Health.

COSMOS-Mind (COcoa Supplement and Multivitamin Outcomes Study of the Mind) was an ancillary study to a much larger, longer term study (graphic from www.whi.org/md/news/cosmos-mind-results).

Their study design was based on two findings:
(1) Normal brain function requires various vitamins, minerals and other nutrients, yet clinical trials of the effects of individual nutrients on cognition have yielded mixed results.
(2) Earlier research, mostly observational, has suggested that flavanols--compounds found in high levels in unprocessed cocoa--might benefit cognition (e.g., see 2014 and 2012 blog posts Chocolate for Health and Sleep and Memory).

For the study, participants were given a daily cocoa extract and/or multivitamin-mineral supplement, or a placebo, for three years. They completed a battery of cognitive tests over the phone at the beginning of the study and once a year afterward. Of the 2,262 participants initially enrolled (mean age 73 yr, 60% female), 92% completed the baseline and at least one annual assessment.

The study found no difference in global cognition between those who took cocoa extract and those who did not. Participants who took the multivitamin, however, had higher global cognition scores. Significant improvements in memory and executive function were also observed with daily multivitamin but not with the cocoa extract.

While the results suggest that a daily multivitamin-mineral supplement might improve cognition in older adults or protect cognitive health with age, the researchers caution that the results are still preliminary.

Wrap Up
So, should you take a multivitamin if your diet is well balanced? Your call. As for other vitamin and mineral supplements, you might take a look at the Evidence Report and Systematic Review or USPSTF’s Recommendation Statement. For most, there was little evidence of serious harms with recommended doses.

Stay safe, be well and thanks for stopping by.

National survey of dietary supplement use in Nutrients journal: www.mdpi.com/2072-6643/10/8/1114/htm
USPSTF: www.uspreventiveservicestaskforce.org/uspstf/
USPSTF Final Recommendation Statement: www.uspreventiveservicestaskforce.org/uspstf/recommendation/vitamin-supplementation-to-prevent-cvd-and-cancer-preventive-medication#bootstrap-panel--14--content
USPSTF Recommendation Statement in JAMA: jamanetwork.com/journals/jama/fullarticle/2793446
Updated Evidence Report and Systematic Review in JAMA:
USPSTF Recommendation in 2014 in Annals of Internal Medicine journal:
COSMOS-Mind study of cocoa and daily multivitamin for cognition in Alzheimers & Dementia journal: alz-journals.onlinelibrary.wiley.com/doi/full/10.1002/alz.12767

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