Latest studies fine-tune ACC/AHA dietary guidelines

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

The guidelines recommend a dietary pattern that emphasizes fruits and vegetable, whole grains, legumes, fish, poultry, nuts and vegetable oil for fat, and restricted consumption of saturate and trans fats, sugar; sodium, and red meat. It’s a dietary pattern evocative of the Mediterranean of DASH-type diet.

A fair number of important studies bearing on the topic of diet and longevity have appeared since the AHA/ACC guidelines were developed. Highlights of these randomized and cohort studies, some of which were published in journals.

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

“You’ve been told to eat vegetable and fruit of every different color. Variety is the cornerstone of dietary advice, right? Wrong!” said cardiologist at the University of Colorado, Denver.

They cited a prospective study of the independent roles of quantity and variety in vegetable and fruit consumption in association with the 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 multi-variate analysis, subjects in the highest quintile of daily fruit and vegetable intake, but not the variety, was associated with a significantly lower risk of CHD.

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 one per week had an 11% reduction in risk; those who ate nuts two or four times per week had a 13% reduction; nut eaters five or six times per week had 15% reduction in risk; and subjects who ate nuts even or more times per week had a 20% reduction of risk of total mortality. Also, significant inverse relationship 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.

Peanuts are not nut, but they work like nuts.

Meat: An analysis of 448,568 participants in the EPIC (European Prospective Investigation Cancer and Nutrition) trial, 26,344 of who 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.

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 meat intake lived an average of 3.6 adopted the dietary practice more recently.

“When you make the changes to adopt a healthier lifestyle substantially matters in terms of longevity. It’s great to change your diet after your first non ST-elevation MI, but in fact you want to do it before.”

Which components of the Mediterranean diet are most beneficial? Greek investigators involved in the EPIC study addressed this question in 23,349 subjects followed for a mean of 8.5 years, during which 1,075 deaths occurred.

Greater adherence to the Mediterranean diet was associated with larger reductions in total mortality. By analyzing Mediterranean diet adherence scores, the investigators determined that 16% of the mortality benefits was attributed to high vegetable consumption, 11% to high fruit and nut intake, 10% to legume consumption, 17% to low intake of meats, and just 11% to fats and oils having a high, monounsaturated-to-saturated lipid ratio.

We think that the Mediterranean diet is olive oil, but probably olive oil is good because you put it on a salad; and fruits and vegetables are the best part of a diet.

How to maximize longevity: “If I had one recommendation based upon all the data reviewed, it would be to become a pesco-vegetarian. They in fact are the longest-living Americans. That’s a vegetarian diet with the addition of fish.”

Seventh-Day Adventist as a group have the longest life expectancy among all Americans. And analysis of 73,308 Seventh-Day Adventists participating in the Adventist Health Study 2 showed that during a mean follow-up of 5.8 years, the adjusted risk of all cause mortality was 12% lower among all vegetarians, and 19% lower in the subgroup composed of pesco-vegetarians.