Take a stroll through the isles of a health food shop or even a pharmacy, and you’ll find that there’s a supplement for just about everything. Want more energy? Sorted. Bad knees? There’s a formula for that. Want to stay on top of your health as a whole? That multivitamin combination could be the answer, and if not, there’s a diet that promises to rid you of all your woes. But just how much of an impact do any of these things have on our health? Well, not a lot, according to the results of a review done by Johns Hopkins Medicine researchers on 277 studies, published earlier this month in the Annals of Internal Medicine journal.

The study

The 277 studies analysed for this research involved randomised control trials studying the effects of 16 vitamins or other types of supplements as well as eight diets and their relationship with the risk of mortality and heart conditions. The heart conditions looked at in this research included heart attacks, strokes and coronary heart disease. In total, the data of 992,129 research participants across the globe was used in this analysis.

The vitamins and supplements looked at in this study included: vitamins A, C and D (on its own), vitamin B-complex, vitamin B3 (niacin), B6, folic acid, vitamin D and Calcium together, antioxidants, beta-carotene, selenium, iron, omega-3 fatty acid (fish oil), and multivitamins.

The diets explored included:

– Lower saturated fat (i.e. reduced intake of fats from meat and dairy);
– The Mediterranean diet;
– “Modified dietary fat intake” diet (fewer saturated fats or replacing calories with more unsaturated fats or carbohydrates);
– Lower fat;
– Lower salt, for both healthy people and those with high blood pressure;
– Higher alpha linolenic acid (ALA) (found in nuts, seeds and vegetable oils);
– Higher omega-6 fatty acid (also found in nuts, seeds and vegetable oils).

The impact of every supplement or diet was ranked according to the evidence supporting their effectiveness and were classed as either high, moderate, low or very low-risk impact.


Most supplements were not linked to an increased or decreased risk of death or changes in heart health. These included vitamins A, C, E, selenium, vitamin B6, iron, vitamin D alone, and calcium alone.

In terms of low salt diets, researchers looked at three studies involving 3518 people with healthy blood pressure. Among that group, 79 deaths were recorded, which researchers said means that there was a 10% decreased risk of death associated with that diet. They rated the impact of this association as moderate.

They also looked at the effects of these diets on people with healthy blood pressure and used five studies involving 3,680 people for their analysis. The risk of death from heart disease fell by 33% for these participants, as the total number of heart disease deaths throughout the study periods was 674. The evidence of the diet’s impact on this group was also classed as moderate.

To assess the effects of omega-3 fatty acid supplements, researchers evaluated 41 studies involving 134,034 participants. Ten thousand seven hundred seven individuals from this group suffered an event like a heart attack or stroke, both signs of heart disease. As a whole, the studies suggested that supplementing with omega-3 was linked to decreases in the risk of cardiovascular disease. The risk of coronary heart disease and heart attacks dropped by seven and eight per cent respectively when compared with not taking anything. Still, researchers ranked the evidence for its effectiveness of as low.

For folic acid, 25 studies involving 25,580 healthy individuals were analysed and, like omega-3, folic acid supplementation was also linked to a reduced risk of stroke, by around 20 per cent. About 877 of the people had strokes during the study period. The evidence of a positive impact of the supplement was also rated low.

The study’s authors also pointed out that the impact of folic acid supplementation was most evident in places like China, where cereals and grains are not fortified with the nutrient. Because of this, they say that those results may not apply to countries like the US and others (like Qatar!) where grains and cereals tend to be fortified.

The study also included 20 studies looking at the effects of vitamin D and calcium combo supplements. Of the 42,072 people enrolled in these studies, 3,690 had strokes during the trial periods, which the researchers say suggests a 17% higher risk for stroke. The evidence of this risk was categorised as moderate. But, there was no evidence to show that taking vitamin D or calcium on their own came with any risks or benefits.

Researcher’s take

The lead author of the study, Safi U. Khan, M.D., assistant professor of Medicine at West Virginia University, described the message of this study as “simple”. He said that the overwhelming majority of these interventions had no significant effect on mortality or heart health, even though some were shown to have an impact.

Writer’s thoughts

Maybe the elixir for eternal health can’t be found in a bottle. But, we can still do all of the old-fashioned things that we know keep us well, like eating a variety of foods, sleeping enough and staying active. And lastly, don’t forget to take what your doctor has prescribed you, even if it includes a supplement. If you’re concerned about their advice, talk to them about it, because it’s their job to help you.

Written by Tesneem Ayoub

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