The PURE (Prospective Urban Rural Epidemiology) Study, reported at the European Society of Cardiology Congress in Munich on August 28, 2018, concludes that increasing intake of fruits, vegetables, nuts, legumes, fish, dairy and non-processed red meat is linked to reduced death rate and reduced incidence of heart attacks in three data sets (European Heart Journal, May 1, 2018;39(17):1503–1504). However, I hope that you do not use these results as a reason to increase your intake of meat. The population used in this study includes many very poor countries, and other studies on North American populations strongly associate red meat with increased risk for heart attacks, strokes and some cancers.
This is one of the largest dietary studies ever done. It includes 135,335 people, 35 to 70 years old, from 21 countries in North America, Europe, South America, the Middle East, South Asia, China, South East Asia and Africa. The authors are highly respected academics and report no conflicts of interest. The study reports that:
• The death rate world-wide increases with a high-carbohydrate intake (>60 percent),
• There is no association between total fat and death from heart attacks and heart failure, and
• A diet high in fat, particularly saturated fat, is associated with a reduced death rate from strokes (Lancet 2017;390:2050–2062).
My Criticism of the PURE Study
• A large percentage of the study population was from very poor countries where there is significant malnutrition, so adding any foods that provide vitamins, minerals and other nutrients to correct deficiencies may make these people more healthy. However, in North America we suffer from too much food, not too little, and deficiencies are seldom seen except in people who have diseases that prevent them from absorbing vital nutrients or increase their chance of losing nutrients. Thus the PURE Study's reason for recommending additional meat and dairy does not apply to the vast majority of North Americans.
• The authors did not compare dietary components in which the fat was reduced or removed from dairy and meat products.
• The authors did not report the ratios of potentially-harmful saturated fat with the amount of potentially healthful polyunsaturated and monounsaturated fats in foods.
• The authors did not report the amounts of carbohydrates eaten by the subjects.
The Authors Defend Their Recommendations to Eat more Meat and Diary
The authors agree that their conclusions that dairy and unprocessed meat be included in a healthy diet conflict with current North American guidelines, but strongly defend their conclusions in their study population that includes many poor countries.
• They state that dairy products and red meats both have many nutrients not found in fruits and vegetables.
• They do not recommend eating large amounts of dairy and meat; they recommend three servings of dairy and one and a half servings of unprocessed red meat per day.
• They cite the Women’s Health Initiative trial of 49,000 women that showed that a low fat diet does not reduce death rate from heart attacks or strokes (JAMA, 2006;295:655–666).
• Replacing calories from fats in meat with calories from carbohydrates in sugar, fruits and refined carbohydrates can increase triglyceride concentrations, reduce high density HDL cholesterol, and create smaller size cholesterol fractions, all of which are markers for diabetes and increased risk for heart attacks. However, the PURE study found that neither increasing fat nor increasing carbohydrates was associated with increased risk for, or deaths from, heart attacks.
• The PURE Study authors reported that diets that get 77 percent of their calories from carbohydrates are associated with a 28 percent higher risk of death compared with diets where carbohydrates made up 46 percent of calories, and that diets with the highest fat intake are associated with a 23 percent lower risk of death. This suggests that the most harmful diet component may be sugar added to foods, drinks with sugar in them, and refined carbohydrates in most processed foods and bakery products.
Saturated Fat May Not be the Harmful Component in Meat
At the 2017 European Society of Cardiology meeting, the same authors reported that a high-fat diet that includes lots of saturated fats was associated with a reduced death rate. There is accumulating evidence that saturated fats are not the harmful component in meat that is associated with increased heart attack risk. Several other studies show a lack of association between saturated fats and death rate, heart disease and diabetes (BMJ, 2015;351:h3978). However, other data show that red meat may increase risk for heart attacks and premature death because of other components, such as Neu5Gc, or the substances such as lecithin that can be converted to TMAO by colon bacteria.
I agree with the PURE Study's recommendation that you should eat more fruits, vegetables, nuts, whole grains and beans, and restrict refined carbohydrates such as sugar-added foods and all drinks with sugar in them. If you have a big belly, can pinch more than two inches of fat under the skin around your naval, have triglycerides >150, HDL<40, or LDL cholesterol >70, you should restrict all refined carbohydrates, which include foods made from flour and most dry breakfast cereals.
I still recommend that you restrict red meat and processed meats. The PURE study has not shown that North Americans will benefit from increasing their intake of meat or dairy products. If you live in a country where you have difficulty meeting your needs for food, then increasing your intake of nutrient-dense foods such as meat or dairy products may help to prolong your life.