Saturated Fats and Heart Disease: Corrections Highlight Study Flaws
Addressing potential study errors
The original scientific paper was a meta-analysis of 72 individual studies, including a mix of clinical trials and observational (epidemiological) research. The media widely portrayed the meta-analysis results as an invitation to step up saturated fats in the diet, but the study showed no such thing: it originally found that saturated and polyunsaturated omega-6 fats appeared neutral for heart health, while omega-3 fats provided some heart health benefits.
Some of the studies considered dietary fat intake alone, and others included blood measures of fatty acids. Given the range in type and quality of study included in the meta-analysis, the results depend upon how carefully and properly the data are combined.
Many health experts who took exception with the paper raised questions about the validity of some assumptions made when the pooled data were analyzed, hence the subsequent corrections issued on the paper:
- The authors originally assumed one study included in the meta-analysis found a negative effect of omega-3 fats on heart disease risk. Most experts agree that study showed a heart-health benefit from omega-3s. This error alone calls into question the conclusion that polyunsaturated fats offer no protection against heart disease.
- The authors didn’t address how total diet may change for people who eat less saturated fat. If saturated fat calories are replaced with an abundance of simple carbohydrates (sugar) and processed foods, this isn’t likely to minimize heart disease risk. Replacing saturated fat with the omega-3, omega-6, and omega-9 fats in nuts, seeds, olive oil, and fish is supported by decades of research in a variety of adult populations.
Clarifying the confusion
Dr. Emanuele Di Angelantonio of the University of Cambridge, one of the authors of the meta-analysis, believes the paper’s conclusions remain valid. He believes the main problem is how the results were “wrongly interpreted by the media.” While media misrepresentation of scientific papers is a valid concern for many researchers, Dr. Walter Willett, Chair of the Harvard School of Public Health Nutrition Department believes the paper has done damage. Dr. Willett noted, “A retraction [of the original paper] with similar press promotion should be considered.”
Back to basics
This brings us back to the basics: a heart-healthy diet means eating real food, and limiting the amount of processed and packaged foods in the diet. Many health experts feel small amounts of high-fat animal products are okay, but only in the context of a totally healthy diet.
In terms of heart disease, and just about any other chronic disease one can name, the best nutritional insurance comes from eating unprocessed, whole foods, including nuts, legumes (beans and peas), vegetables and fruit, whole grains, vegetable and olive oils, and small portions of animal products, if desired.
(Ann Intern Med. 2014;160:398–406)