Updated: Jul 29, 2019
Last month, the results of the Prospective Urban and Rural Epidemiology (PURE) study were published in the Lancet. The major findings – that a low fat diet in which saturated fats are minimized and replaced with carbohydrates is actually associated with increased all-cause mortality – has caused quite a stir among conservative U.S. nutrition policy makers who have been advocating a low-fat diet for decades. The study included over 135,000 people in 18 countries. It examined the dietary habits, blood biomarkers (like lipids), and survival/disease outcomes over about a 10 year period and included a very sophisticated statistical analysis that accounted for confounders like socioeconomic status. The major findings may surprise you, but they reaffirm my approach to lifestyle and nutrition – real food, eaten in moderate balance, is best for longevity and heart disease. Here’s what they found:
Moderate vegetable intake – 3 to 4 servings per day – is associated with the lowest risk of mortality. More vegetables did not confer increased benefit. However, raw vegetables seem to be more beneficial than cooked veggies. How much veggies should we eat? 350-500grams per day
Total fat and types of fat were inversely associated with mortality. That is, people eating a higher fat diet, even a high saturated fat diet, survived longer than those consuming a low fat diet. The worst mortality and cardiovascular disease outcomes were observed among people with the lowest saturated fat intake. Yes, that is the opposite of what you’ve been previously told. Total fat and saturated and unsaturated fats were not significantly associated with risk of myocardial infarction or cardiovascular disease mortality.So how much fat should we eat? About 35% of our daily intake, primarily from polyunsaturated sources like nuts, seeds, and safflower oil. Monounsaturated fats like olive oil and saturated fats from foods such as avocado, macadamia, coconut, and animal products are also healthy.
High carbohydrate intake was associated with the worst mortality and cardiovascular outcomes. High carb diets, such as those with lots of sugars, breads, pastas, and processed flour products are the worst for us.
High carb diets appear particularly detrimental for low and moderate income populations. This may be because of the high proportion of packaged processed carbs (vs. whole grains) eaten among these populations.
Legumes (such as beans, lentils, chickpeas, soy) are associated with lower risk of mortality, and it only takes one serving per day.
Senior author of the PURE study, Dr Salim Yusuf (McMaster University, Hamilton, ON), commented to theheart.org / Medscape Cardiology: “My hope is that our results will stop the whole population from feeling guilty if they eat fat in moderation. While very high fat intake—when it accounts for 40% or more of your dietary intake—may be bad, the average fat intake is about 30% and that’s okay. We’re all afraid of saturated fat, but actually we shouldn’t be. Saturated fat in moderation actually appears good for you.
“Also, you don’t need to stress out trying to eat five or more portions of fruit and vegetables, when three or four will probably have the same benefits. We’ve had enough evangelism in dietary guidelines. We need more moderation.”
He added: “My advice to the general population to lead a healthy lifestyle is don’t smoke and take exercise—those two things are very clearly beneficial. And then I would say maintain a reasonable weight. You don’t want to be too overweight but you also don’t want to be too skinny. Eat a balanced diet—a bit of meat, fish, several portions of fruit and vegetables, but you don’t have to be vegan or eat an excessive amount of plants to be healthy.
“This is good old-fashioned advice. When I showed these results to my mother, she said, ‘Why did you bother doing this study? This is what our grandmothers and their grandmothers have been advocating for centuries.’ And actually she is right.”
Read more yourself – citations
1:Prospective Urban Rural Epidemiology (PURE) study investigators. Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study. Lancet. 2017 Aug 28. pii: S0140-6736(17)32252-3. doi: 10.1016/S0140-6736(17)32252-3. [Epub ahead of print] PubMed PMID: 28864332.
2: Prospective Urban Rural Epidemiology (PURE) study investigators. Fruit, vegetable, and legume intake, and cardiovascular disease and deaths in 18 countries (PURE): a prospective cohort study. Lancet. 2017 Aug 28. pii: S0140-6736(17)32253-5. doi: 10.1016/S0140-6736(17)32253-5. [Epub ahead of print] PubMed PMID: 28864331.
3:Prospective Urban Rural Epidemiology (PURE) study investigators. Association of dietary nutrients with blood lipids and blood pressure in 18 countries: a cross-sectional analysis from the PURE study. Lancet Diabetes Endocrinol. 2017 Oct;5(10):774-787. doi: 10.1016/S2213-8587(17)30283-8. Epub 2017 Aug 29. PubMed PMID: 28864143.