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Disease Prevention

Nutritional Pearls: Mediterranean Diet vs Low-Fat Diet: Which is Better for Prevention?

11/01/2022

  • In a 2011 column on low-fat diets, I wrote: "One of the great benefits of our understanding of the Mediterranean diet is that it put to rest the myth that a low-fat diet is beneficial."1

    Unfortunately, I was wrong. But not about a low-fat diet.

    The Research

    For the last decade, health professionals have been promoting the myth that low-fat diets will prevent or reverse heart disease. But as I said in my column more than a decade ago (and what the research still shows), it's the quality of fats—and the ratio of saturated to unsaturated fats in the diet—that are beneficial to heart health, with a healthy target being 35% to 40% of calories from fat.

    In 2007, we reported on an early study that focused on the effects of a Mediterranean diet on heart disease.2 The study assessed the risk of a second coronary event within 30 days in those who had already been hospitalized for either a heart attack or unstable angina. The researchers found that a higher Mediterranean diet score meant a 15% lower risk of heart attack, a 23% lower risk of dying during that initial hospitalization, and a 19% lower risk of any other cardiac event during those first 30 days.3

    Additionally, in 2013, I wrote about an analysis of participants in the Nurses' Health Study and the Health Professionals Follow-Up Study.4 The researchers examined those who had experienced a heart attack and concluded that individuals who improved their diet the most—measured by the Alternative Healthy Eating Index 2010, which is similar to a Mediterranean diet—after their heart attack were 27% less likely to die of any cause and 19% less likely to die from a heat-related illness compared with those who did not improve their diet.5

    Today, research is being conducted on individuals who are at a greater risk of a coronary event: patients who experience a coronary event a second time.6

    The Results

    This study, performed in Cordoba, Spain, recruited about 1,000 men and women who had been hospitalized in the Reina Sofia University Hospital for a major cardiovascular event such as stroke, heart attack, or peripheral artery disease. They were randomly assigned to follow either a low-fat or Mediterranean diet.

    Both groups received intense coaching and support from dietitians. Those following a low-fat diet were assigned a goal of less than 30% total calories from fat (less than 10% saturated fat) and 55% of calories from carbohydrates. Those following a Mediterranean diet consumed about 35% of their calories from fat (less than 10% saturated fat) and a maximum of 50% of calories from carbohydrates. Both diets aimed for about 15% of calories from protein.

    The study lasted for 7 years, during which 132 patients abandoned their diets, although some allowed the authors to continue monitoring their health records until the end of the study. (Interestingly, nearly twice as many assigned to the low-fat diet quit the study as those who had been assigned to the Mediterranean diet: 86 vs 46.)

    After taking into account the participants' age, family history of coronary disease, smoking status, and other variables, the authors found that for participants whose diets matched their assigned diets at least 80% of the time, those who followed a Mediterranean diet were 26% less likely to experience another coronary event than those who followed a low-fat diet. When the authors limited their analysis to only men, this climbed to 33%, although the authors note that there may not have been enough women in the study to be able to draw strong conclusions.

    What’s The Take Home?

    What's particularly interesting about this study is that the researchers found no significant difference between the 2 diets in their effects on cholesterol or glucose scores, which means the effects of the diet were not due to better metabolic scores alone. Still, given the results of this recent study, I would recommend a Mediterranean-type diet to a patient interested in dieting as a way to prevent potential heart disease.

     

    References:

    1. Harlan TS. Forget you ever heard the words “low” and “fat” and “diet” together. Dr Gourmet. Accessed October 6, 2022. https://www.drgourmet.com/column/dr/2011/062011.shtml
    2. Harlan TS. The Mediterranean diet and heart attack survival. Dr Gourmet. Accessed October 6, 2022. https://www.drgourmet.com/bites/2007/051507.shtml
    3. Panagiottakos DB, Arapi S, Pitavos C, et al. The relationship between adherence to the Mediterranean diet and the severity and short-term prognosis of acute coronary syndromes (ACS): the Greek study of ACS (the GREECS). Nutrition. 2006;22(7-8):722-730. doi: 10.1016/j.nut.2006.04.005
    4. Harlan TS. Improve your diet, live longer – even after a heart attack. Dr Gourmet. Accessed October 6, 2022. https://www.drgourmet.com/bites/2013/103013.shtml
    5. Li S, Chiuve SE, Flint A, et al. Better diet quality and decreased mortality among myocardial infarction survivors. JAMA Intern Med. 2013;173(19):1808-1819. doi: 10.1001/jamainternmed.2013.9768.
    6. Delgado-Lista J, Alcala-Diaz JF, Torres-Peña JD, et al. Long-term secondary prevention of cardiovascular disease with a Mediterranean diet and a low-fat diet (CORDIOPREV: a randomised controlled trial. Lancet. 2022;399(10338):1876-1885. doi:10.1016/S0140-6736(22)00122-2

    Dr. Gourmet is the definitive health and nutrition web resource for both physicians and patients with evidence-based resources including special diets for coumadin users, patients with GERD/acid reflux, celiac disease, type 2 diabetes, low sodium diets (1500 mg/d), and lactose intolerance. 

    Timothy S. Harlan, MD, FACP, CCMS, is a practicing, board-certified Internist. He is currently an Associate Professor of Medicine at George Washington University and Director of the GW Culinary Medicine Program.

    Health meets Food: the Culinary Medicine Curriculum, is an innovative program teaching medical students about diet and lifestyle that bridges the gap between the basic sciences, clinical medicine, the community, and culinary education. Medical students work side-by-side in the kitchen with culinary students to teach each other, and most importantly, teach the community and patients how to return to their kitchens and transform their health. 

    He served as Associate Dean for Clinical Services at Tulane University School of Medicine and is the founder and Senior Advisor of the Goldring Center for Culinary Medicine, the first-of-its-kind teaching kitchen operated by a medical school.

    Dr Harlan attended medical school at Emory University School of Medicine in Atlanta, Georgia, and pursued his residency at Emory University School of Medicine Affiliated Hospitals in Atlanta, GA.