Time for a New Approach to Reducing Cardiovascular Disease: Is Limitation on Saturated Fat and Meat Consumption Still Justified?

It was 50 years ago that Ancel Keys published the Seven Countries Study (Italy, Greece, Yugoslavia, Finland, the Netherlands, Japan, and the United States), which showed that increasing dietary saturated fat intake influenced total cholesterol, and the increase in total cholesterol was associated with an increased 10-year coronary heart disease mortality. However, data were available for 22, rather than 7, countries and, in the analysis of all the data, a poor relationship between total fat intake and heart disease can be seen. As a result of Keys’ 7 country study, in February 1977, sweeping changes to nutritional guidance was recommended in the first edition of The Dietary Goals for the United States. People were encouraged to increase carbohydrate consumption to 55%-65% of their total calories; reduce overall fat consumption from 40%-30%; reduce saturated fat to around 10%; and to reduce their cholesterol, sugar, and salt consumption. The Honorable Senator George McGovern, in a statement, said, “Too much fat, too much sugar or salt, can be and are linked directly to heart disease, cancer, obesity, and stroke, among other killer diseases.” Dr. Mark Hegsted, professor of nutrition from Harvard, helped draft the forerunner to the federal government's dietary guidelines. He did not disclose that the Sugar Association paid him and two other Harvard scientists to publish a 1967 review of research on sugar, fat, and heart disease. The article minimized the link between sugar and heart health and cast aspersions on the role of saturated fat.

In 1980, the Dietary Guidelines Advisory Committee (DGAC) endorsed these recommendations. and these findings were carried further in the 2010 DGAC report despite concerns that were raised with the first dietary recommendations that had yet to be adequately addressed. The 2010 DGAC report demonstrated several critical weaknesses, including use of an incomplete body of relevant science, inaccurately representing, interpreting, or summarizing the literature, and drawing conclusions and making recommendations that did not reflect the limitations or controversies in the science. A 2010 meta-analysis of prospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of cardiovascular disease cardiovascular disease. Another systematic review and meta-analysis in 2014 showed people with higher saturated fat intake were not at an increased risk of heart disease or sudden death. On February 10-11, 2020, in Washington, DC, a workshop, "Saturated Fats: A Food or Nutrient Approach?" convened. The participants in the workshop found no significant evidence for effects of dietary saturated fat intake on cardiovascular or total mortality. Moreover, recent evidence indicates that saturated fat intake may be inversely related to stroke risk. In some individuals, an increase in total low-density lipoprotein cholesterol may occur, but this increase is predominantly in the larger particles less strongly associated with cardiovascular disease. Hence, there is no evidence that current population-wide arbitrary upper limits on commonly consumed saturated fats in the United States will prevent cardiovascular disease or reduce mortality. Consuming a variety of natural foods without restricting saturated fat intake would also be beneficial in helping to ensure a nutritionally adequate diet and maintain health. On February 20, 2020, a letter was sent to the Honorable Sonny Perdue, Secretary, and the Honorable Alex Azar, Secretary. In that letter, the participants conclude that there is no strong scientific evidence that the current population-wide upper limits on commonly consumed saturated fats in the United States will prevent cardiovascular disease or reduce mortality. A continued limit on these fats is therefore not justified.

Meat is a common source of protein and fat in many diets worldwide. Evidence from observational studies suggest that higher consumption of red meat and processed meat is associated with a higher risk of diabetes mellitus, cardiovascular disease, and certain cancers. Just like with saturated fat intake, it has been the dogma to reduce cardiovascular disease one must decrease the consumption of “red meat.” For many years, the mantra in the American Heart Association's dietary guidelines was “eat less meat.” However randomized controlled trials assessing the effect of red meat intake on cardiovascular risk factors are inconsistent. Two recent publications from investigators at McMaster University in Ontario, Canada, reported that in observational studies and randomized clinical trials, the evidence connecting red and processed meat products to cardiovascular disease and cancer was extremely weak.^, No surprise that the response to these studies from nutritional experts was voluminous. Some even insisted the papers be retracted and others claim obvious industry conflict of interest. Similar to saturated fat issues, many renowned nutritional experts remained divided.

It is important to note that nutritional studies are very difficult to perform and cannot for practical reasons be undertaken as long-term, double-blind, randomized clinical trials given the impossible task of completely controlling the dietary intake of large numbers of individuals. Most nutrition studies rely on observational methods, which can often be inherently flawed. The overwhelming majority of observational studies fail to be replicated by randomized controlled trials. Therefore, it is incumbent upon health professionals, the media, and others who utilize nutritional research to be aware of the shortcomings of different study designs in nutrition research, to read studies carefully, and to temper hyperbolic headlines based on weak or preliminary data.

In the meantime, obesity, cardiovascular disease, and diabetes remain serious health concerns and burdens on the healthcare system. The time has come to call it what it is and to tell patients that they weigh too much because they consume too many calories. Health and weight are the individual's responsibility. The focus should be placed on healthy food-based diet patterns that include more vegetables, fruits, whole grains, seafood, legumes, dairy products, and less consumption of sugary snacks and drinks and refined grains. Meat can be part of the diet, and there is no justification to restricting saturated fat intake. Limit portion size at mealtimes. Control weight by avoiding excess food and snack consumption. There is no “best diet.” All diets that lower calories will work equally well. The better the patient can adhere to the diet, the better they will do and the more weight they will lose. Also, to reduce the risk of cardiovascular disease cease using all tobacco products; control blood pressure and lipids. Diabetes patients should work diligently to get to an A1c as close to normal but not at the expense of hypoglycemia. Exercise 30 minutes each day. Develop and enjoy satisfying relationships with others and allow time for relaxation and contemplation.