What does the best possible evidence actually tell us?
A new meta-analysis has just been published (June 2018) within JACC (The Journal of the American College of Cardiology). Titled “Supplemental Vitamins and Minerals for CVD Prevention and Treatment“, it looks into the impact that supplements have had on cardiovascular disease outcomes and also all-cause mortality.
What data did they review?
They looked at all the available evidence that has been published since 2012. That includes not only existing systematic reviews, but also randomized controlled trials available via both PubMed, MEDLINE, and also the Cochrane Library.
We assessed those supplements previously reported on by the USPSTF: vitamins A, B1, B2, B3 (niacin), B6, B9 (folic acid), C, D, and E, as well as β-carotene, calcium, iron, zinc, magnesium, and selenium
All in all, they reviewed 179 individual studies, hence this new meta-analysis is a good summary of all of the latest available evidence.
What did they find?
Moderate- or low-quality evidence for preventive benefits …
- folic acid for total cardiovascular disease
- folic acid and B-vitamins for stroke.
No effect at all …
- multivitamins, vitamins C, D, β-carotene, calcium, and selenium
Increased risk of dying …
- antioxidant mixtures and niacin [with a statin].
In other words, conclusive evidence for the benefit of any supplement across all dietary backgrounds (including deficiency and sufficiency) was not demonstrated. For the instances where benefits are seen, this must be balanced against possible risks.
Reactions
Dr Steven Novella writes about this within his posting on Science Based Medicine. He sums it up for the average consumer as follows ..
There is essentially no benefit to routine supplementation, and there may be some risks. You are far better off saving your money, and spending it on fresh produce. Have a varied diet with plenty of fruits and vegetables and you are overwhelmingly likely to get all the nutrition you need.
For those with special needs or if you have any questions, simply consult your physician. Targeted supplementation based on specific needs and measured blood levels is the way to go. You probably should be taking prenatal vitamins if you are trying to get pregnant, and should be under the care of an OB. If you are trying to reduce your stroke and vascular risk, again you should be doing this under the supervision of an appropriate physician. This may include folic acid supplementation.
Also, while we are at it – do not believe supplement hype (antioxidant or otherwise), do not believe nutrition gurus, do not take megadoses, and there is no such thing as a “superfood.”
Shock Item
There has been a thriving belief that antioxidants are good for you and that taking a supplement that contains them will be greatly beneficial. The available evidence is that if you are taking these then you should stop doing so because you are increasing your risk of death, and not decreasing it.
This is not new information. If you go to the Wikipedia page that describes antioxidants, it very clearly tells you this and cites references …
Antioxidant dietary supplements do not improve health nor are they effective in preventing diseases. This includes supplements of beta-carotene, vitamin A, and vitamin E having no effect on mortality rate[1][2] or cancer risk.[3][4] Supplementation with selenium or vitamin E does not reduce the risk of cardiovascular disease.[5][6]
Conclusions
If you believe your diet is poor and you are trying to fix that with supplements, then your strategy is most probably flawed. You are better off skipping the supplements (unless of course you are taking them under medical guidance for a specific reason), and investing in fresh fruit and vegetables.