Most dietary guidelines are based on studies begun decades ago in high-income, Western countries. The problem is that diets vary around the world, and it is not known how applicable guidelines based on studies done in wealthier countries are to the populations of less developed low- and middle-income countries.
Canadian researchers used information on the diets of almost 150,00 participants in the Population Health Research Institute’s global Prospective Urban and Rural Epidemiological (PURE) study to develop the PURE Healthy Diet Score. This score was applied to data from almost 245, 000 participants in five studies done in 80 countries in different regions of the world.
A diet that included a wide variety of unprocessed foods reduced the risk of cardiovascular disease and death. Increasing consumption of these foods in low- and middle-income countries can lead to important reductions in these risks. “Globally, the key to a healthy diet is probably one that includes diverse natural foods in moderation,” the researchers said, in a statement.
“When we think of elements in food that may be harmful, we can overlook protective elements in that food.”
Scores of four or above were associated with significant reduction in cardiovascular disease and mortality risk. About a 20 percent improvement in diet score, which is very achievable, reduced mortality risk by eight percent and cardiovascular disease risk by six percent, Andrew Mente, lead author on the study, told TheDoctor.
A daily serving of unrefined whole grains or unprocessed red meat or poultry can be substituted for any of these foods. For example, vegetarians or vegans can remove fish or dairy and have whole grains, Mente said. Substituting unrefined whole grains or poultry did not affect how well the PURE score predicted the risk of cardiovascular disease or death. “You could substitute those foods to fit the personal or cultural preferences of a population,” said Mente, a scientist at the Population Health Research Institute and an assistant professor at McMaster University in Ontario.
When included in a healthy diet, whole-fat dairy reduced the risk of cardiovascular disease and death. Mente pointed out that other studies have also shown this. Most dairy products people consumed in low- and middle-income countries are whole fat, he said, but in North America and Europe most of the dairy consumed is low fat.
More studies are needed to better understand why whole-fat dairy reduces cardiovascular disease and mortality risk. Most people are concerned that the saturated fats in whole-fat dairy may raise levels of lipids and increase cardiovascular disease risk, Mente pointed out, but it doesn’t quite work that way with nutrition.
Past studies have relied on self-reporting — participants filled out a survey about what they ate. Study findings based on self-reporting can show an association or relationship between diet and health outcomes, but because they are based on subjective, unverified information, they cannot prove cause-and-effect. Studies using new technologies that can show a stronger relationship between diet and health outcomes are needed, Mente said.
One of these technologies, called metabolomics, measures levels of the products from the breakdown and digestion of food called metabolites. The ability to measure metabolite levels gives researchers stronger evidence about the connection between diet and health. “If we can solidify this causal connection,” Mente said, “we can be more confident that we are making dietary recommendations that are correct.”