by Dr. Joel Kahn, MD
The observation that diet and health are related can be traced back at least to Hippocrates over 2,000 years ago with the statement credited to him that “food is medicine”. The average lifespan in the last century has been been extended greatly, but many of those additional years are burdened with chronic diseases and disabilities. Trying to determine what dietary pattern is most likely to facilitate a long life without disease can be confusing. Nutrition science is difficult and conflicting at times. No topic generates more debate than the role of reducing dietary saturated fat for heart health.
In the last few months this situation has again grabbed headlines. Can you trust the new announcements that saturated fat was never a risk?
Research on the contribution of diets rich in saturated fats like cheese, butter, meats, eggs, and pastries to heart disease has been ongoing since the 1950’s. Recently, a systematic review and meta-analysis of the relationship between saturated fat and heart disease was published by the Cochrane Database of Systematic Reviews (CDSR) on May 19, 2020. The CDSR is widely regarded as the leading and most respected of sources for evaluating topics in health care. The authors analyzed 15 controlled trials involving over 59,000 subjects and concluded that “The findings of this updated review suggest that reducing saturated fat intake for at least two years causes a potentially important reduction in combined cardiovascular events (21%). Replacing the energy from saturated fat with polyunsaturated fat or carbohydrate appear to be useful strategies.” It would seem clear that reducing or eliminating meats, cheeses, egg yolks, lard, butter, ghee and baked goods would favor better odds of avoiding heart disease. You may have missed this important research paper as major media outlets did not report on this publication.
The CDSR lasted was buried by a publication that followed it by 4 weeks. A “State of the Art Review” by 12 authors on the topic of saturated fat and health was published in a major cardiology journal on June 16, 2020. They did not do original research, but rather analyzed previously published studies. The 12 authors concluded that “Whole-fat dairy, unprocessed meat, eggs and dark chocolate are SFA-rich foods with a complex matrix that are not associated with increased risk of CVD. The totality of available evidence does not support further limiting the intake of such foods.” Unlike the esteemed CDSR paper, this review created 100’s of headlines worldwide that implied enjoy your meats, cheeses, pastries and egg yolks again without concern.
How can we reconcile such conflicting conclusions? The media failed to report that the 2nd paper was written by authors with important funding conflicts of interest. Indeed, 9 of the 12 authors of the 2nd paper disclosed funding by dairy or beef foundations. At least 75% of the authors promoting saturated fat were funded by industry organizations that promote foods rich in saturated fat!
In a second challenge to the findings of the CDSR to reduced foods rich in saturated fats, 10 different authors published a “hypothesis” that those suffering from a relatively rare genetic disorder causing a high cholesterol would benefit more from a low-carbohydrate diet than a low-fat diet. The media, again, went wild reporting on this paper, but they left out that 5 of the 10 authors revealed financial ties that they benefit from relating to low-carb diets. The other 5 are well known low-carb advocates routinely advocating for dietary approaches in conflict with major medical societies and research findings.
When I am faced with conflicting data like these reports I rely on a structure for analyzing nutrition research proposed by Valter Longo, Ph.D, author of The Longevity Diet and creator of the plant-based Fasting Mimicking Diet. In his book, Longo favors the use of the “Five Pillars of Longevity” as a format to evaluate nutrition research.
These 5 pillars are:
- Biochemical research
- Randomized trials
- Epidemiology
- Study of centenarians
- Analysis of complex systems (like the environmental impact of a diet)
Dr. Longo teaches a plant-based diet low in foods rich in saturated fat (e.g. no red meat or poultry) in his book as it encompasses all 5 pillars of science. Using the 5 Pillars of Longevity, there is ample data from biochemical studies, randomized trials, epidemiology, and centenarian data that indicate that diets lower in saturated fats improve health and reduce the risk of heart disease. Simply put, 1-2 studies with severe funding conflicts cannot upend 70 years of high-quality research.