https://goo.gl/oa9E5M
An enormous prospective study of food intake in adults, reported here, challenges several staunchly held beliefs about dietary components and their association with health risks: finding, for example that diets rich in fats, including saturated fats, don't increase mortality risk, but high-carbohydrate diets do.
And the study, called PURE (Prospective Urban Rural Epidemiology), also found that the benefits of fruits, vegetables, and legumes top out at just three to four total servings per day.
In sum, the results suggest that nutritional guidelines and conventional wisdom regarding these basic dietary elements may be seriously mistaken.
PURE investigators recorded food intake using questionnaires in 135,000 people in 18 countries, including high-, medium- and low-income nations. The latest findings from the ongoing study, with median follow-up of 7.4 years, were outlined in two separate presentations at the European Society of Cardiology meeting here, which were accompanied by simultaneous publications in The Lancet and in Lancet: Diabetes & Endocrinology.
Defying expectations, PURE found that high carbohydrate intake was associated with a significant increase in the risk of death, while both total fat and saturated and unsaturated fats were associated with a decreased risk of death. However, fat consumption was not associated with cardiovascular disease or cardiovascular mortality, though saturated fat had an inverse association with stroke.
The authors found that high intake of carbohydrates had "the most adverse impact on cardiovascular risk factors" while monounsaturated fats had a beneficial effect and saturated fat had a neutral effect.
The second presentation and Lancet paper, by Andrew Mente, PhD, also of McMaster University, challenges the widely held and nearly religious belief that more is always better when it comes to fruits, vegetables, and legumes.
The study did confirm that fruits and veggies (and legumes) in moderation are good for you, but it did not show that the benefits keep growing with increased consumption. Instead, the PURE researchers found that the maximum benefit was achieved with three to four serving per day. Current guidelines recommend that people consume five servings a day. The authors note that many people in lower income countries are unable to afford this high level of consumption.