PURE multinational nutrition research supports what we already know – despite the headlines
When the results of the massive “PURE” nutrition study were published, the headlines reported:
“A huge new study casts doubt on the conventional wisdom of fat and carbohydrates” (PBS).
“Large-scale food research puts current nutrition standards in question” (Mother Nature Network).
But not so fast. A close examination of the findings supports what we already know.
To do so, scientists collected 135,335 self-reported food frequency questionnaires from 18 countries on five continents (representing low income, middle income and high-income countries). They tracked participants for an average of 7.4 years and discussed the relationship between reported nutrition intake and health outcomes.
The researchers then published three studies in the lancet in August 2017:
First look at the relationship between cardiovascular disease and eating fruits, vegetables and beans. They concluded that “consumption of higher fruits, vegetables and beans was associated with lower non-cardiovascular and total mortality. The benefits of non-cardiovascular mortality and the total mortality of 3-4 per day seem to be the greatest. ”
The second looked at the relationship between fat and carbohydrate intake and cardiovascular disease and mortality. The study concluded: “high carbohydrate intake is associated with higher overall mortality, while total fat and individual type fat are associated with total mortality… [and] were unrelated to cardiovascular disease, myocardial infarction or cardiovascular mortality, while saturated fat was negatively correlated with stroke.
Third, the relationship between nutrient intake and blood lipids. It concluded: “reducing the intake of saturated fat and replacing it with carbohydrates has a negative effect on blood fat. Substituting saturated fatty acids for unsaturated fatty acids may improve some risk markers, but may worsen others.
It is difficult to draw global conclusions from these studies, at least in part because of the accuracy of the dietary data collected. David Katz, director of the Yale university prevention research center, MD, MPH, FACP, FACPM, FACLM pointed out in his review of the study, all participants completed the food frequency questionnaire and questionnaire in 24 hours for an hour dietary recall completed by a team of participants (HuffPost 2017). Harvard school of public health response to point out that the researchers from China accounts for nearly a third of the total number of participants, the report of the fat in approximately 18% of total calories from fat, while other survey found that a typical Chinese consumption 30% of calories from fat.
In addition, there are big differences in food types around the world, especially in low – and high-income countries. The researchers did not distinguish between types of carbohydrates, although clear fruit, vegetables and legumes (mostly carbohydrate) and white rice has a great deal of nutritional differences, the study of many low-income countries, rice is a staple food of low nutrition. The health benefits of fruits, vegetables and legumes have been widely recognized, but they are still adversely affected in the United States
The researchers did break down fat ingredient (though not trans fats, they are the most deadly), and found consistent with what we already know the data – use carbohydrates instead of saturated fat does not make people healthier. However, randomized trials showed that replacing saturated fat with polyunsaturated fats did improve health, but PURE researchers did not. In addition, the people who ate the most saturated fats were still eating less saturated fats than americans, and denying that americans should eat more of these fats to improve their health.
All in all, according to PURE research, American nutrition recommendations should not be changed. In fact, the standard advice still echoes Michael Pollan’s simple three-sentence mantra: “eat food. Not too much. Mainly plants. “