Massive meta-study finds most vitamin supplements have no effect on lifespan or heart health
A massive umbrella study, encompassing 277 clinical trials, into the effects of nutritional supplements and dietary interventions has concluded almost all vitamin and mineral supplements play no role in protecting from cardiovascular disease, or extending one's lifespan.
The new study gathered data from a large number of randomized clinical trials examining 16 vitamin supplements and their associations with general mortality and cardiovascular conditions such as heart attack or stroke. Almost all the supplements reviewed, including multivitamins, selenium, vitamin A, vitamin B6, and vitamin D, showed no association with either increased or decreased risk of death or heart disease.
Only three specific interventions displayed associations of any statistical significance. Unsurprisingly, the most relevant result was the finding that low-salt diets reduced heart disease and death by around 10 percent in healthy subjects. Both omega-3 and folic acid supplements showed small beneficial effects, but the researchers ranked these interventions as of a low impact.
"Our analysis carries a simple message that although there may be some evidence that a few interventions have an impact on death and cardiovascular health, the vast majority of multivitamins, minerals and different types of diets had no measurable effect on survival or cardiovascular disease risk reduction," explains Safi Khan, lead author on the new research.
The only supplement intervention that actually increased mortality or cardiovascular risk was calcium and vitamin D supplements. When taken alone these two supplements showed no health risks or benefits, but taken together they showed a 17 percent increased risk of stroke. This conclusion was generated from 20 trials looking at the effects of the combined supplements.
This is not the first large-scale meta-review to conclude vitamin supplements are essentially useless in healthy adults. Two 2018 studies using similar umbrella review strategies, came to much the same conclusions. Both of those studies concluded that if you are a healthy adult, with no specific diagnosed deficiency, then vitamin and mineral supplements will not confer any extra health boost, or longevity bonus.
The researchers behind this new study point out over half of all Americans take some kind of dietary vitamin supplement every day, making the industry more than US$30 billion a year. Senior author on the research, Erin Michos, suggests if you are eating a good diet and are otherwise generally healthy then you simply do not need to be taking vitamin supplements.
"The panacea or magic bullet that people keep searching for in dietary supplements isn't there," says Michos. "People should focus on getting their nutrients from a heart-healthy diet, because the data increasingly show that the majority of healthy adults don't need to take supplements."
It is important to note that these broad meta-studies do not encompass patients with identified deficiencies that may need vitamin supplementation. It is also important to note these types of umbrella reviews are only looking at ultimate mortality or general cardiovascular outcomes, so there certainly could be more specific health benefits to be gained from some supplements that these kinds of studies are not set up to identify. Having said that, mortality is a decent metric to review general efficacy from, because it is reasonable to assume any specific benefit from a supplement should ultimately reflect in better health, and subsequently a longer life.
In the end, the main takeaway from this growing body of convincing research is that if you exercise, eat well, and are living an otherwise healthy life, then you probably won't get any additional benefit from vitamin supplements. For most people, all these costly vitamin and mineral supplements result in is expensive urine.
The new research was published in the journal Annals of Internal Medicine.
Source: Johns Hopkins Medicine