September 2019

NM Effectiveness Ratings for CVD Differ from New Meta-Analysis: Why the Discrepancy?

A new large meta-analysis shows that, with the exception of fish oil and folic acid, most supplements don’t help reduce the risk of cardiovascular disease (CVD) or reduce the risk of death. But we rate other natural medicines as being POSSIBLY EFFECTIVE for CVD. So, why is there a discrepancy?

When evaluating the potential benefit of any ingredient, we review potential benefits from both DIETARY intake and SUPPLEMENTS. We make these distinctions clear in our effectiveness summaries when there is supportive evidence for supplements but not dietary intake, and vice versa. This new study on CVD reviewed intake from supplements only.

When it comes to fish oil, this new study linked fish oil supplements to a lower risk for CVD, but the researchers noted that the level of evidence was low. In our monograph for fish oil, we consider there to be insufficient reliable scientific evidence to provide an Effectiveness Rating for fish oil for CVD. This is because results from clinical research are conflicting and controversial. Most research shows that fish oil SUPPLEMENTS, typically taken in doses of 1 gram daily, aren’t beneficial for CVD. Taking higher doses, 3-4 grams daily, might offer some benefits in certain people, but this still needs to be confirmed. Similarly, DIETARY intake of fish oil might offer some benefit, but results are somewhat conflicting and any benefit is probably modest at best. Still, we recommend that people continue to eat fish and other foods that provide omega-3 fatty acids, as these foods make up part of a healthy diet.

Folic acid was another ingredient identified as potentially beneficial in this new study. Similar to fish oil, the level of evidence was not high. We currently rate folic acid as possibly INEFFECTIVE for CVD. If you take a closer look at what this new study actually says, they concluded that folic acid might reduce the risk for STROKE, not CVD in general. We agree with this conclusion – folic acid currently has a POSSIBLY EFFECTIVE rating for stroke in Natural Medicines, but only when it relates to people who live in countries where grains aren’t fortified with folic acid. The authors in this new study also pointed out that the data was most supportive in these countries.

One conclusion in this new study that we fully agree with is the potential benefits of a low-salt diet, like the DASH diet. Research shows that sticking to a DASH-style diet for 7-24 years is linked to a 20% reduced risk of CVD.

For more details on these and other natural medicines studied for CVD, check out our comparative effectiveness chart. Make sure to review our rating system and always read our effectiveness summaries to fully understand why we rate the ingredients or dietary interventions the way we do.

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