PURE: Guideline-based diets may not improve risk for mortality, CV outcomes

Diets based on global guidelines, which typically limit carbohydrate and total fat intake while increasing the intake of fruits, vegetables and legumes, did not have an impact on CVD and total mortality, according to analyses from the PURE trial published in The Lancet and The Lancet Diabetes and Endocrinology.

The researchers found elevated carbohydrate intake was associated with adverse outcomes, three or four servings per day of fruits and vegetables was associated with positive outcomes and elevated fat intake was associated with reduced mortality risk.

Vegetable, fruit, legume intake

A diet high in vegetables, fruits and legumes reduced the risk for non-CV and total mortality, according to a study published in The Lancet.

“Our findings suggest an approach that is likely to be more affordable in lower- and middle-income countries — that three to four servings of fruit, vegetables and legumes per day show a similar benefit against reducing the risk of death to ‘five-a-day’ guidance,” Victoria Miller, doctoral candidate at McMaster University in Hamilton, Ontario, Canada, said in a press release. “For people in higher-income countries already eating five servings per day, this is not a suggestion to eat less.”

Researchers in this prospective cohort study analyzed data from 135,335 participants aged 35 years to 70 years without CVD from 18 countries of varying incomes. Dietary assessments were performed using country-specific food frequency questionnaires. Standardized questionnaires were used to gather information such as health history, lifestyle and family history of CVD. Participants were followed up at least every 3 years for a median of 7.4 years.

The outcomes of interest were fatal and nonfatal MI, CV mortality, fatal and nonfatal strokes, non-CV mortality, total mortality and major CVD, which was defined as nonfatal MI, stroke, HF and CV-related death.

The combined mean vegetable, fruit and legume intake was 3.91 servings per day.

During follow-up, 1,649 CV death events, 5,796 mortality events and 4,784 major CVD events occurred. An increase in vegetable, fruit and legume intake was inversely associated with MI, CVD, non-CV mortality, CV mortality and total mortality when adjusted for sex, age and center.

The event estimates were attenuated in multivariable-adjusted models for MI (HR = 0.99; 95% CI, 0.74-1.31), CVD (HR = 0.9; 95% CI, 0.74-1.1), CV mortality (HR = 0.73; 95% CI, 0.53-1.02), stroke (HR = 0.95; 95% CI, 0.67-1.25), non-CV mortality (HR = 0.84; 95% CI, 0.68-1.04) and total mortality (HR = 0.81; 95% CI, 0.68-0.96).

PAGE BREAK

Participants who consumed three to four servings per day had a lower HR for total mortality (HR = 0.78; 95% CI, 0.69-0.88) vs. the reference group. HR did not decrease with a higher consumption of fruits, vegetables and legumes.

Fruit intake was linked to a reduced risk for CV, non-CV and total mortality. An inverse association was seen between legume intake and both non-CV death and total mortality. Raw and cooked vegetable intake was associated with a lower risk for total mortality, although the association was stronger for raw vegetables.

“Our findings indicate that even relatively moderate intakes of fruits, vegetables and legumes might lower the risk of death,” Miller and colleagues wrote.

“A healthy diet rich in fruits and vegetables needs to be considered as part of a high-quality overall eating pattern, and this pattern should be based on country-specific dietary traditions to be fostered as an effective tool for prevention of [CVD] and premature mortality,” Estefania Toledo, a professor in the department of preventive medicine and public health at the University of Navarra in Pamplona, Spain, and Miguel A. Martínez-González, professor at the Navarra Institute for Health Research and adjunct professor at the Harvard T. H. Chan School of Public Health, wrote in a related editorial.

Fats, carbohydrate intake

A higher risk for total mortality was more common in participants who had elevated carbohydrate intake, according to an analysis of data from the PURE study published in The Lancet.

“For the first time, our study provides a global look at the realities of people’s diets in many countries and gives a clearer picture of people’s fat and carbohydrate intake,” Mahshid Dehghan, MD, an investigator in the nutrition epidemiology program at the Population Health Research Institute in Hamilton and a senior research associated in the department of medicine at McMaster University in Hamilton, said in a press release. “The current focus on promoting low-fat diets ignores the fact that most people’s diets in low- and middle-income countries are very high in carbohydrates, which seem to be linked to worse health outcomes. “

The primary outcomes in this analysis were total mortality and major CV events, defined as non-fatal MI, fatal CVD, HF and stroke. Secondary outcomes included all MIs, CVD mortality, stroke and non-CVD mortality.

Participants who consumed more carbohydrates had a higher risk for total mortality (HR for quintile 5 vs. quintile 1 = 1.25; 95% CI, 1.12-1.46). The risk for MI, major CVD, stroke and CVD mortality was not affected by an increased carbohydrate intake.

PAGE BREAK

Total fat (HR = 0.77; 95% CI, 0.67-0.87), saturated fatty acids (HR = 0.86; 95% CI, 0.76-0.99), monounsaturated fat (HR = 0.81; 95% CI, 0.71-0.92) and polyunsaturated fat consumption (HR = 0.8; 95% CI, 0.71-0.89) were linked to a lower risk for total mortality. An increased saturated fat intake was associated with a reduced risk for stroke (HR = 0.79; 95% CI, 0.64-0.98).

The risk for MI or CVD mortality were not affected by a higher intake of total fat, saturated fats or unsaturated fats.

“Our findings do not support the current recommendation to limit total fat intake to less than 30% of energy and saturated fat intake to less than 10% of energy,” Dehghan and colleagues wrote. “Individuals with high carbohydrate intake might benefit from a reduction in carbohydrate intake and increase in the consumption of fats.”

“Dehghan and colleagues report that high intake of total carbohydrates was associated with increased mortality,” Christopher E. Ramsden, MD, of the laboratory of clinical investigation at the National Institute on Aging of the NIH, and Anthony F. Domenichiello, a postdoctoral fellow at NIH, wrote in a related editorial. “In a concurrent Lancet article, the PURE group reports that intakes of fruits, legumes and raw vegetables (three major carbohydrate sources) were associated with lower mortality. This discrepancy suggests that processed carbohydrates, including added sugars and refined grains, are likely driving this association.”

Total fat and BP, blood lipids

Replacing saturated fatty acid intake with carbohydrates had an adverse effect on blood lipids, according to a separate analysis of data from the PURE study published in The Lancet Diabetes and Endocrinology.

Andrew Mente, PhD, MA, associate professor in the department of health research methods, evidence and impact at McMaster University, and colleagues analyzed data from 125,287 participants from the PURE study who had baseline BP measurements.

The primary outcomes were BP and blood lipids concentrations such as LDL, HDL, total cholesterol, triglycerides, apolipoprotein B and apolipoprotein A1.

Consumption of total fat and each type of fat, including monounsaturated, polyunsaturated saturated fatty acids, were linked to higher LDL, HDL, total cholesterol and apolipoprotein A1 and lower triglycerides, ratio of total cholesterol to HDL, apoB-to-apoA1 ratio and triglycerides-to-HDL ratio (P for trend for all < .0001).

An increased carbohydrate consumption was associated with lower LDL, HDL, total cholesterol, apoB and apoA1 and higher triglycerides, ratio of triglycerides to HDL, ratio of total cholesterol to HDL and apoB-to-apoA1 ratio (P for trend for all except apoB < .0001; (P for trend for apoB = .0014).

PAGE BREAK

Total fat and carbohydrate consumption was linked to higher systolic BP (P for trend < .0001), and a higher intake of dietary cholesterol and saturated fatty acids were associated with higher systolic and diastolic BPs (P for trend < .0001). Increased protein consumption was linked to lower systolic and diastolic BP (P for trend < .0001).

Replacing saturated fatty acids with carbohydrates decreased LDL, HDL, total cholesterol, apoA1 and apoB and increased triglycerides, the ratio of triglycerides to HDL (P for all < .0001) and the ratio of total cholesterol to HDL (P = .0354).

The link between saturated fatty acids and CVD events were estimated by the effects of the apoB-to-apoA1 ratio.

“Determining the net clinical effects of nutrients on [CVD] risk requires information from large studies on clinical outcomes,” Mente and colleagues wrote. “Current recommendations to reduce total fat and saturated fatty acids in all populations, which de facto increases carbohydrate intake, are not supported by our data.”

“The PURE study offers a global perspective that fills an important research gap, for which the study investigators should be applauded,” Nita G. Forouhi, of the MRC Epidemiology Unit at the University of Cambridge, and colleagues wrote in a related editorial. “However, their cross-sectional evidence should be considered hypothesis-generating and their prospective findings need to be replicated.”

The results were also presented at the European Society of Cardiology Congress. – by Darlene Dobkowski

References:

Dehghan M, et al. Lancet. 2017;doi:10.1016/S0140-6736(17)32252-3.

Forouhi NG, et al. Lancet Diabetes Endocrinol. 2017;doi:10.1016/S2213-8587(17)30285-1.

Mente A, et al. Lancet Diabetes Endocrinol. 2017;doi:10.1016/S2213-8587(17)30283-8.

Miller V, et al. Lancet. 2017;doi:10.1016/S0140-6736(17)32253-5.

Ramsden CE, et al. Lancet. 2017;doi:10.1016/S0140-6736(17)32241-9.

Toledo E, et al. Lancet. 2017;doi:10.1016/S0140-6736(17)32251-1.

Disclosure : The authors and editorialists report they have no relevant financial disclosures.