06 Jul Large Harvard Study Confirms Health Benefits of Unsaturated Fats
MedicalResearch.com Interview with:
Daniel (Dong) Wang, MD, ScD, Research Fellow
Department of Nutrition | Harvard T.H. Chan School of Public Health
Boston, MA 02115
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: There has been widespread confusion in the biomedical community and the general public about the health effects of specific types of fat in the diet. In particular, the role of unsaturated fats vs. saturated fat in cardiovascular disease prevention remains controversial. Our study is by far the most detailed and powerful examination of this very important research topic, i.e., health effects of specific types of dietary fats, because of very large sample size (more than 120,000 men and women), repeated and validated measurements of diet and lifestyle over an extended follow-up (up to 32 years). In addition, our study is able to examine a much broader range of outcomes, including total mortality and mortality due to cardiovascular disease, cancer, neurodegenerative disease and respiratory disease.
We found that different types of dietary fat had different associations with mortality. Consuming higher amounts of unsaturated fats- mainly from plant-based foods like olive oil, canola oil, soybean oil and nuts – was associated with lower mortality, while higher consumption of saturated-found in red meat, butter, cheese, and ice cream- and trans fats- predominantly from hydrogenated oils- was linked with higher mortality compared with the same number of calories from carbohydrates. Most importantly, replacing saturated fats with unsaturated fats conferred substantial health benefits, including lowering risk of all-cause premature death and premature death due to cardiovascular disease, cancer, neurodegenerative disease and respiratory disease.
MedicalResearch.com: What should readers take away from your report?
Response: When preparing foods or at the table, consumers should feel confident that choosing many plant-based oils, such as olive oil, canola oil and soybean oil instead of foods or ingredients loaded with large amount of saturated fats, such as butter, will be better for their health. A healthy overall diet should include sources of both omega-6 polyunsaturated fats– the main polyunsaturated fat found in vegetable oils, nuts, and seeds – and n-3 polyunsaturated fats from both plant sources and seafood.
Our findings also support the elimination of partially hydrogenated of vegetable oils, the primary source of trans fatty acids. This study provides further support for the 2015-2020 Dietary Guidelines for Americans that emphasize the types of fat rather than total amount of fat in the diet.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: As we have done in this current study, studies on nutritional factors should be very specific about the comparison or replacement macronutrient or food. For example, if one replaces saturated fat with carbohydrates especially refined carbohydrates, there is no or only minimal benefits in reducing mortality. However, if one replaces saturated fat with healthy sources of fats such as plant oils, nuts/seeds, and seafood, then there is a substantial benefit in reducing mortality and improving overall health.
MedicalResearch.com: Is there anything else you would like to add?
Response: Our study has the following findings regarding neurodegenerative disease and respiratory disease mortality, which have not been reported before:
- Higher intakes of polyunsaturated and monounsaturated fats were associated with lower risk of neurodegenerative and respiratory disease mortality.
- Higher trans fat intake was associated with significantly higher risk of neurodegenerative and respiratory disease mortality.
- Higher saturated fat intake was associated with a substantial increase of mortality due to respiratory disease.
- Omega-3 PUFA intake, primarily α-linolenic acid (found in soybean and canola oils, walnuts, flax seeds and flaxseed oil, and green leafy vegetables) was associated with lower risk of death due to neurodegenerative disease.
- Marine omega-3 PUFA intake (mainly from fish) was associated with lower respiratory disease mortality.
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Association of Specific Dietary Fats With Total and Cause-Specific Mortality
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