What is the headline saying or claiming?
Link to article: There’s even more evidence to suggest popular vitamin supplements are essentially useless
What is the article saying?
Popular vitamin supplements such as vitamin C and calcium don’t have any major health benefits…
Folic acid and B vitamins with folic acid could reduce the risk of cardiovascular disease and stroke…
Niacin and antioxidants could actually cause harm…
Multivitamin use has increased although there is little to no evidence to show that this prevents disease and mortality and the U.S. Dietary Guidelines Advisory Committee recommends that people meet nutritional requirements by eating a healthy diet that is largely plant-based.
What are the implications of this headline?
Everyone should stop taking multivitamins because they are useless.
Are there similar and/or opposing headlines from other news outlets?
Do the news outlets only link back to other news outlets?
Similar article that looks at the same study:
New Evidence Your Daily Multivitamin Doesn’t Help Heart Health or Help You Live Longer
What are the data sources (i.e. memo, official statement, official document, research study, validated surveillance system, official report, etc.) supporting the article?
Supplemental Vitamins and Minerals for CVD Prevention and Treatment
Are these data sources credible when applied to the article? Why or why not.
Yes. The sources review multiple studies as well as previous recommendations made by the U.S. Dietary Guidelines Advisory Committee.
What are the data sources saying?
A systematic review of data and trials published over the past 5 years (Jan 2012 – Oct 2017) shows that even if multivitamins do not harm people, they do not benefit them either (particularly, when evaluating whether they can reduce the risk of cardiovascular disease, heart attack, stroke, or early death). However, folic acid and B vitamins may actually reduce the risk of cardiovascular disease and stroke, according to the 2013 U.S. Preventive Services Task Force.
Are the data sources being interpreted correctly?
Results from the systematic reviews and meta-analyses revealed generally moderate- or low-quality evidence for preventive benefits (folic acid for total cardiovascular disease, folic acid and B-vitamins for stroke), no effect (multivitamins, vitamins C, D, β-carotene, calcium, and selenium), or increased risk (antioxidant mixtures and niacin [with a statin] for all-cause mortality). Conclusive evidence for the benefit of any supplement across all dietary backgrounds (including deficiency and sufficiency) was not demonstrated; therefore, any benefits seen must be balanced against possible risks.
What is the study design?
Researchers conducted a review and meta-analysis of existing systematic reviews and meta-analyses and randomized controlled trials published in English (using Cochrane Library, MEDLINE, and PubMed). They also conducted searches for individual supplements of the vitamins and minerals in the USPSTF report of 2013 for CVD outcomes and total mortality.
- Researchers used forest plots to identify relevant articles as well as 2 independent investigators to review full papers and perform data abstraction. The information gathered included the number of cases and participants in the intervention and control groups.
Where both supplements and dietary intakes of nutrients in foods were combined as total intakes, data were not used unless supplement data were also presented separately
- Assessed multivitamins that include the majority of vitamins and minerals as well as B-complex vitamins and antioxidant mixtures as (composite entities with >10 RCTS, all-cause mortality data available for both types of supplements).
- Summary plots were also undertaken as summaries of pooled effect estimates to include all cardiovascularoutcomes, and cumulative plots were undertaken to illustrate what was already significant or had becomesignificant since the USPSTF 2013 assessment.
- Using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation (GRADE) tool), evidence was graded as high-quality, moderate quality, low-quality, or very low-quality evidence. By default, RCTs were graded as high-quality evidence. Criteria used to downgrade evidence included: study limitations (as assessed by the Cochrane Risk of Bias Tool), inconsistency (substantial) unexplained by interstudy heterogeneity, I2 > 50%, and p < 0.10; indirectness (presence of factors that limited the generalizability of the results); imprecision (the 95% confidence interval [CI] for effect estimates crossed a minimally important difference of 5% [risk ratio (RR): 0.95 to 1.05] from the line of unity); and publication bias (significant evidence of small study effects).
- Attention was drawn to outcomes of meta-analyses that showed significance with moderate- to high-quality evidence (with >1 RCT). In this way, [they] reduced the risk of type 1 errors in the multiple comparison undertaken and avoided the use of corrections, such as the Bonferroni correction, which might have been too conservative.
- Review Manager (RevMan)
- Stata (publication bias analysis)
- Mantel-Haenszel method (used to obtain summary statistics, data presented for random effect models only)
- Cochran Q Statistic: p < 0.1 (assess heterogeneity), I2 statistic (used to quantify the Q statistic, greater than or equal to 50% = high heterogeneity
- Funnel plots and quantitative assessment using Begg’s and Egger’s tests (p < .05 = small study effects, publication bias, only conducted when >10 trials available in meta-analysis)
- Number needed to treat (NNT), Number needed to harm (NNH) (inverse of Absolute Risk Reduction)
What does this mean for the public?
Otherwise healthy individuals should meet nutritional requirements by eating a healthy diet that is largely plant-based in order to prevent cardiovascular disease, heart attack, stroke, or early death- instead of depending on supplements and multivitamins.