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Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies

BMJ 2015; 351 doi: https://doi.org/10.1136/bmj.h3978 (Published 12 August 2015) Cite this as: BMJ 2015;351:h3978

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Re: Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies

The data in this article do not support the conclusion in the abstract: “saturated fats are not associated with all-cause mortality, mortality from cardiovascular disease, prevalence of coronary heart disease, ischemic stroke or type 2 diabetes.”

These data showed just the opposite: intake of saturated fats was significantly correlated with each of these measures.

The article looked at data in two ways: most adjusted for covariates and least adjusted. In the abstract, only the most adjusted data were reported, yet the least unadjusted data showed a statistically significant relationship between intake of saturated fats and increased all-cause mortality, mortality from cardiovascular disease, prevalence of coronary heart disease, risk of stroke, and risk of type 2 diabetes.

At a minimum, both types of analyses in the abstract should have been included, especially since adjusting for covariates such as LDL-cholesterol may obscure statistically significant differences since, for example, saturated fats affect LDL-cholesterol. One wonders why this was not done.

The least adjusted data showed a statistically significant relationship between intake of saturated fats and increased all-cause mortality, mortality from cardiovascular disease, prevalence of coronary heart disease, risk of stroke, and risk of type 2 diabetes. This was not reported in the abstract or the conclusion.

1. In the first paragraph, second column, page 4 of the article, the authors wrote, “a 5% increase in energy from saturated fats was associated with a 4.7% increase in age-adjusted all-cause mortality rate.”

2. In the next paragraph on page 4, for saturated fats and coronary heart disease (CHD) mortality, there was a highly statistically significant relationship (P= 0.02) using the least adjusted method.

3. Similarly, in the next paragraph on page 4, there was a statistically significant relationship (P<0.05) between intake of saturated fats and total coronary heart disease prevalence using the least adjusted method.

4. In the next paragraph, there was a statistically significant relationship between intake of saturated fats and the risk of ischemic stroke (P<0.001).

5. In the next paragraph on page 4, continuing onto page 5, there was a borderline statistically significant relationship between consumption of saturated fats and type 2 diabetes using the least adjusted method (P= 0.07).

6. At the bottom of page 11, replacing dietary saturated fats with “good carbs” such as fruits, vegetables, and whole grains reduced the risk of cardiovascular disease. At the top of page 12, replacing dietary saturated fats with “good fats” (polyunsaturated fats) decreased the risk of cardiovascular disease. If saturated fats were harmless, then neither of these would be true. However, replacing saturated fats with sugar and refined carbohydrates increased the risk of cardiovascular disease.

Also, the authors did not distinguish between saturated fats that may not be harmful such as stearic acid from saturated fats from animal products that are clearly harmful.

I am very concerned that the erroneous conclusion of this article that saturated fats are not harmful is making international headlines, causing many people to make dietary changes that may be very detrimental to their health.

Dean Ornish, M.D.
Founder & President, Preventive Medicine Research Institute (nonprofit)
Clinical Professor of Medicine, University of California, San Francisco
www.ornish.com
dean.ornish@pmri.org

Competing interests: I conduct research, write books, and lecture about the benefits of lifestyle changes including a whole foods plant-based diet, moderate exercise, stress management, and social support, and consult with Healthways to train health care professionals.

12 August 2015
Dean Ornish
Clinical Professor of Medicine
University of California, San Francisco School of Medicine
900 Bridgeway, Sausalito, CA 94965 USA