Study: Saturated fat may not increase risk of heart attack, other cardiac events

The New York Times “Well” blog reports that research published in the Annals of Internal Medicine “found no evidence that eating saturated fat increased heart attacks and other cardiac events.” These “findings are part of a growing body of research that has challenged the accepted wisdom that saturated fat is inherently bad for you and will continue the debate about what foods are best to eat.”

Bloomberg News reports that the data also indicated that “food rich in fish oils such as omega-3 don’t reduce heart-disease risk.”

The CNN “The Chart” blog reports that the investigators came to these conclusions after reviewing “a large spectrum of studies on the subject: 32 observational studies looking at fatty acids from dietary intake, 17 observational studies of fatty acid biomarkers, and 27 randomized, controlled trials examining fatty acid supplementation.” Among the chief findings:

  • Omega-3 and omega-6 fatty acids: There were trends for modest benefits associated with dietary intake or supplements, but these did not achieve statistical significance. There was some evidence that people with high circulating levels of omega-3 fatty acids may have a reduced risk of coronary disease.
  • Saturated fatty acids: There was no discernible effect of total saturated fat as measured by either dietary intake or circulating biomarkers. There was a signal suggesting different effects for individual saturated fatty acids as measured by biomarkers, but the authors noted that circulating levels of these are often only poorly determined by dietary intake. There was a suggestion of benefit for saturated fats derived from milk or dairy consumption.
  • Monunsaturated fatty acids: No effect was found, either harmful or beneficial.
  • Trans dietary fats: A harmful effect was confirmed.

The authors stated that “the pattern of findings from this analysis did not yield clearly supportive evidence for current cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of saturated fats.” The conclusions are consistent with a recent editorial that urged revision of guidelines advocating low-fat diets, especially when saturated fats are replaced with carbohydrates or omega-6 fatty acids.

Forbes contributor Larry Husten writes that a “second study, published in JAMA Internal Medicine, reports the cardiovascular outcomes of patients who participated in AREDS2 (Age-Related Eye Disease Study 2).” Just over 4,200 “patients with age-related macular degeneration were randomized twice, to either omega-3 fatty acids (DHA 350 mg and EPA 650 mg) or placebo and also to lutein and zeaxanthin (carotenoids found in the eye) or placebo.”

Investigators found that “after 4.8 years of followup there was no significant reduction in cardiovascular outcomes in either of the treatment groups.”

In an invited commentary, Evangelos Rizos and Evangelia Ntzani write that after many years of investigation it is now clear that omega-3 supplements “with daily doses close to 1 g in patients with or without established CVD shows no clear, considerable benefit.” Future trials “should focus on the remaining gaps of knowledge such as high-dose omega-3 supplementation (definitely more than 1 g daily) with various EPA/DHA ratios” in patients with high triglyceride levels. For now, omega-3 supplements should only be prescribed for patients with severe hypertriglyceridemia, “an extreme minority of the general population.”

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