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Latest studies fine-tune ACC/AHA dietary guidelines


 

EXPERT ANALYSIS FROM THE CARDIOVASCULAR CONFERENCE AT SNOWMASS

SNOWMASS, COLO. – Recent large studies validate and fine-tune the 2013 American Heart Association/American College of Cardiology guidelines on diet and lifestyle management to reduce cardiovascular risk.

The guidelines recommend a dietary pattern that emphasizes fruits and vegetables, whole grains, legumes, fish, poultry, nuts and vegetable oils for fat, and restricted consumption of saturated and trans fats, sugar, sodium, and red meat. It’s a dietary pattern evocative of the Mediterranean or DASH-type diet (J. Am. Coll. Cardiol. 2014 Jan. 28 [doi:10.1016/j.jacc.2013.11.003]).

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The guidelines recommend a dietary pattern that emphasizes fruits and vegetables, whole grains, legumes, fish, poultry, nuts and vegetable oils for fat, and restricted consumption of saturated and trans fats, sugar, sodium, and red meat.

"There’s nothing particularly controversial here. I support all these recommendations," Dr. Robert A. Vogel commented at the Annual Cardiovascular Conference at Snowmass.

A fair number of important studies bearing on the topic of diet and longevity have appeared since the AHA/ACC guidelines were developed. Dr. Vogel shared highlights of these randomized and cohort studies, some of which were published in journals most physicians don’t read regularly.

Fruits and veggies: Conventional dietary guidance has emphasized the importance of eating a wide range of fruits and vegetables.

"You’ve been told to eat vegetables and fruits of every different color. Variety is the cornerstone of dietary advice, right? Wrong!" said Dr. Vogel, a cardiologist at the University of Colorado, Denver.

He cited a prospective study of the independent roles of quantity and variety in vegetable and fruit consumption in association with incident coronary heart disease in 71,141 women and 42,135 men participating in the Nurses’ Health Study and the Health Professionals Follow-Up Study. During follow-up there were 2,582 documented cases of CHD in women and 3,607 in men. In a multivariate analysis, subjects in the highest quintile of daily fruit and vegetable consumption had a 17% lower risk of CHD. The absolute quantity of fruit and vegetable intake, but not the variety, was associated with a significantly lower risk of CHD. (Am. J. Clin. Nutr. 2013;98:1514-23).

Nuts: In a separate analysis of more than 3 million person-years of prospective follow-up data from the Nurses’ Health Study and the Health Professionals Follow-Up Study, increasing consumption of nuts was associated with a stepwise reduction in all-cause mortality. People who consumed nuts less than once a week had a statistically significant 7% reduction in the risk of total mortality, compared with those who didn’t eat nuts. Subjects who ate nuts once per week had an 11% reduction in risk; those who ate nuts 2-4 times per week had a 13% reduction; nut eaters 5 or 6 times per week had a 15% reduction in risk; and subjects who ate nuts 7 or more times per week had a 20% reduction in the risk of total mortality. Also, significant inverse relationships were seen between nut intake and specific common causes of death, including cancer, heart disease, and pulmonary disease.

Investigators reanalyzed the data separately for consumption of tree nuts and peanuts, which are actually legumes. The mortality risk reduction was the same for both (N. Engl. J. Med. 2013;369:2001-11).

"Peanuts are not nuts, but they work like nuts," Dr. Vogel observed.

Meat: An analysis of 448,568 participants in the EPIC (European Prospective Investigation into Cancer and Nutrition) trial, 26,344 of whom have died, showed what investigators termed "a moderate positive association" between processed meat consumption and mortality, especially deaths from cardiovascular disease and cancer. In a multivariate analysis, daily consumption of red meat at an average of 160 g or more – that’s 5.6 oz. – was independently associated with 14% higher all-cause mortality than in individuals who consumed an average of 10-19.9/day.

The association was more striking for processed meat, such as salami: Subjects who ate an average of 5.6 oz/day had 44% greater all-cause mortality. The investigators estimated that if all study participants limited their processed meat consumption to less than 20 g/day, 3.3% of deaths could be prevented (BMC Med. 2013;11:63 [doi:10.1186/1741-7015-11-63]).

Dr. Robert A. Vogel

The EPIC findings call to mind an earlier study by investigators at Loma Linda (Calif.) University, who reviewed six prospective cohort studies and concluded that very low meat consumption – less than once weekly – was associated with increased longevity, but that how long subjects had been on such a diet was a key factor. Individuals who had at least a 20-year history of very low meat intake lived an average of 3.6 years longer than those who had adopted the dietary practice more recently (Am. J. Clin. Nutr. 2003;78:526S-532S).

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