The relationship between the diet and the cardiovascular disease and mortality has been an issue of long debate. Pure study was presented by the researchers at ESC Congress 2017 in BARCELONA. Separate findings from the PURE study suggesting an association between cardiovascular disease and mortality and fruit, vegetables and legume intake, as well as intake of fats and carbohydrates, could have an impact on global dietary guidelines.
All three studies, which were published in The Lancet, are based on the large, epidemiological PURE study involving 135,335 individuals aged 35-70 years across 18 countries and five continents between January 2003 and March 2013. Researchers used country-specific food frequency questionnaires at baseline and collected demographic, socioeconomic, lifestyle, family history and individual health history and medication information. The primary clinical outcomes were major cardiovascular disease, fatal and non-fatal MI, fatal and non-fatal stroke, cardiovascular mortality, non-cardiovascular mortality and total mortality. During a median 7.4 years (5.5-9.3), there were 4,784 major cardiovascular disease events, 1,649 cardiovascular deaths and 5,796 total deaths.
In an analysis of fruit, vegetable and legume intake, researchers found a higher consumption was associated with a lower risk of non-cardiovascular and total mortality. Three to four servings per day (equivalent to 375-500 g/day) appeared to provide the maximum benefits for both non-cardiovascular mortality and total mortality. When looked at separately, researchers noted fruit intake was associated with lower risk of cardiovascular, non-cardiovascular and total mortality, while legume intake was inversely associated with non-cardiovascular death and total mortality. Raw vegetable intake was strongly associated with a lower risk of total mortality, while cooked vegetables were associated with a modest benefit against mortality.
A separate analysis of nutrient intake (carbohydrate, fats and protein) found high carbohydrate intake was associated with higher risk of total mortality, but not with the risk of cardiovascular disease or cardiovascular disease mortality. Total fat and individual types of fat were associated with lower risk of total mortality but were not significantly associated with risk of myocardial infarction or cardiovascular disease mortality. Higher saturated fat intake was associated with lower risk of stroke.
In a third analysis, not presented at ESC, multilevel modeling was used to assess the effect of dietary nutrients on blood lipids and blood pressure in 125,287 PURE participants. Intake of total fat and each type of fat was associated with higher concentrations of total cholesterol and LDL cholesterol (LDL-C), and with higher HDL cholesterol (HDL-C) and apolipoprotein A1 (ApoA1), and lower triglycerides, ratio of total cholesterol to HDL-C, ratio of triglycerides to HDL-C, and ratio of apolipoprotein B (ApoB) to ApoA1. Higher carbohydrate intake was associated with lower total cholesterol, LDL-C and ApoB, but also with lower HDL-C and ApoA1, and higher triglycerides, ratio of total cholesterol to HDL-C, ratio of triglycerides to HDL-C, and ApoB-to-ApoA1.
Higher intakes of total fat, saturated fatty acids and carbohydrates were also associated with higher blood pressure, whereas higher protein intake was associated with lower blood pressure. Replacement of saturated fatty acids with carbohydrates was associated with the most adverse effects on lipids, according to researchers. While replacement of saturated fatty acids with unsaturated fats improved some risk markers (LDL-C and blood pressure), it seemed to worsen others (HDL-C and triglycerides).
“The PURE study was an incredibly large, international effort with robust follow-up over seven years focusing on the relationship between dietary habits and cardiovascular outcomes. The authors conclude that a diet rich in carbohydrates, not fat, was associated with elevated risk of total mortality,” says Jeffrey T. Kuvin, MD, FACC.
“This furthers confirms the author’s suspicion that a diet heavy in carbohydrates can have long-term negative effects on cardiovascular health. While the findings of this study are provocative and add to our understanding of the relationship between diet and disease, deriving firm conclusions for all populations from these types of cohort studies should be taken with a grain of salt (pun intended),” Kuvin adds. “Importantly, we need to continue to examine the impact of a diet in controlled settings to tease out the specific role that certain foods have on health. While these outcomes studies are difficult to perform, the PURE study certainly helps to further our understanding. Until we get more definitive data, my take away from this study, and other similar studies, is everything in moderation, including diet.”