By Markian Hawryluk

WesCom News Service

A little more than a decade ago, the prevailing nutritional consensus was you’d have to be nuts to eat nuts. In the midst of the low-fat diet craze, the high fat content of nuts made them prime villains in the battle of the bulge. Of late, the low-carb trend has helped rehabilitate their image as dieters searched for high-protein snacks.

But nuts have made their comeback as much in the laboratory as on grocery shelves. A decade’s worth of clinical studies has subjected nuts to as much study as any pharmaceutical product. And scientists have found nuts have the potential to combat heart disease, cancer, diabetes, Alzheimer’s disease and even obesity. Not bad for a snack food.

If you think that’s mere hyperbole, consider the study published in the American Journal of Clinical Nutrition last month that pitted nuts, fiber, soy and other cholesterol-reducing foods in a head-to-head clinical trial with statins, the class of drugs doctors prescribe most often to reduce cholesterol.

It’s surprising that researchers would even consider comparing the impact of particular foods to medication. What’s more surprising, however, is that nuts and their dietary compatriots held their own.

n Portfolio power

Researchers from the University of Toronto wanted to test the recommendations of the National Cholesterol Education Program and the American Heart Association for people with high cholesterol to eat foods that have been shown to lower cholesterol.

Physicians generally recommend dietary changes for patients with high cholesterol, but those usually focus on reducing red meat and dairy products. Because patient compliance is often low, doctors then resort to medication.

This study, for the first time, created a diet from a portfolio of cholesterol-reducing products – oatmeal, beans, olive oil, soy products and almonds. All of the foods are permitted by the Food and Drug Administration to carry a health claim that they reduce the risk of cardiovascular disease.

The researchers tested the impact of this portfolio diet against a normal diet and a normal diet with statins. Both the statin and portfolio diet groups had significantly lower levels of LDL, the bad cholesterol, than the control group. Statins still did better than the portfolio diet in lowering cholesterol, but nine individuals (26 percent) showed a better response to the diet than to statin therapy.

While those results shouldn’t encourage anybody to stop taking prescribed medications, they do suggest an alternative or complementary approach, particularly for those with borderline high cholesterol and no heart troubles, the researchers said.

By combining the portfolio diet with statins, patients might also avoid the need for high doses of drugs, which come with an additional risk of side effects.

n Dietary option

The study has led to renewed faith among many physicians in the power of diet generally, and nuts specifically, to help control cholesterol and heart diseases.

“I am convinced that if people eat the proper diet, they will have more reduction in their heart risk than just taking a medication,” says Dr. Anderson Morris, a cardiovascular surgeon at HealthSouth Medical Center in Birmingham, Ala. “Walnuts are a very good source of antioxidants, vitamins, fiber and omega-3 fatty acids. That’s why I tell my patients that eating walnuts is like wearing a seat belt for your heart.”

While nuts may not be as effective as medication, they carry virtually no side effects, except in the case of allergic reactions.

It’s a “dietary intervention that can be applied with little risk,” says Dr. Christine Albert, a researcher at Brigham and Women’s Hospital in Boston, which looked at the role of nuts in protecting against cardiovascular disease in the landmark U.S. Physicians Health Study.

In fact, nuts were the first food approved by the Food and Drug Administration to carry a qualified health claim on packaging saying that “scientific evidence suggests but does not prove that eating 1.5 ounces per day of most nuts, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease.”

n Mountain of evidence

The FDA approved that claim on the basis of more than 30 studies that have shown that a variety of nuts can reduce the risk of heart disease. One of the first studies to identify the link was the Adventist Health Study.

Researchers at Loma Linda University tracked the dietary habits of Seventh-day Adventists living in California. Their diet differs from that of most Americans, consisting of more cereal products, fruits and vegetables, but little or no meat.

More than 30,000 Adventists agreed to fill out questionnaires 30 years ago and allow researchers to track their health over the years.

When researchers looked at nut consumption, they found significant heart benefits. Those eating nuts once or twice a month had a 22 percent lower risk of fatal coronary heart disease, while those eating nuts daily or more than once a day had a 59 percent lower risk.

The study data also showed that frequent nut consumption was linked to a lower incidence of colon cancer.

Another study conducted by the Harvard School of Public Health with nurses found that women who ate five ounces of nuts per week had one-third fewer heart attacks than those who rarely or never ate nuts. High nut and peanut butter consumption was also shown to reduce the risk of type 2 diabetes.

Nuts help protect the heart, in part, by improving the ratio of good cholesterol to bad cholesterol, as well as lowering total cholesterol. A variety of studies have looked at the impact of nut consumption on cholesterol. Although the studies took different approaches to measure the impact, they consistently report a 5 percent to 15 percent reduction in blood cholesterol levels and a similar effect on levels of LDL, the bad cholesterol. Levels of HDL, the good cholesterol, in most studies were unaffected.

But it appears that nuts do more for the heart than just reduce cholesterol. Dr. Penny Kris-Etherton and researchers from Pennsylvania State University found that the reduction in coronary heart disease risk attributable to the changes in fatty acid profiles by consuming nuts should only account for a portion of the overall reduction in risk. Other components in nuts probably contribute to the effect. And there’s no shortage of ideas on how.

Some argue that nuts are high in arginine, a basic amino acid that is a precursor to nitric oxide, which, in turn, is known to inhibit the formation of plaques that can cause heart attacks. Other experts have posited that it is the copper, magnesium, selenium, potassium or folic acid. And the explanations just get more complicated from there.

n Weight concerns

Still, there is concern that the high calorie and fat content of nuts could lead to weight gain.

“You can’t simply add nuts, nut butters or nut oils to your usual diet without making some adjustments,” Kris-Etherton says. “You have to replace some of the calories you usually consume with nuts and substitute the unsaturated fat in nuts for some of the saturated fat in your diet.”

About 90 percent of the fat in nuts is unsaturated, so it’s not the saturated and trans fats nutritionists warn against. Although nuts are considered energy-dense they carry twice as many calories per ounce as meat, poultry or fish studies that introduced nuts into diets have not seen significant weight gain among study subjects. Joan Sabate, a researcher with Loma Linda University, recently reviewed a number of studies that looked at nut consumption and measured body mass.

“So far, no well-controlled feeding study on nuts that has body weight as the main outcome has been conducted,” she says. But she found many studies that looked at other outcomes that also measured changes in body mass index (BMI).

The Adventist study found an inverse correlation between nut consumption and BMI, as did the Harvard nurses study. Sabate found that subjects on nut diets tended to be hungrier and require more energy intake to maintain body weight than while on the nut-free control diets. Most studies she reviewed found a nonsignificant trend toward lower weight while on nut diets.

That could be because nuts are not completely digested and some of the calories may be passing through the digestive system untouched. But according to Maureen Ternus, a registered dietitian and nutrition coordinator for the International Tree Nut Council Nutrition Research and Education Foundation, it may be because people can feel satiated with nuts and avoid less-nutritious, high-calorie foods.

“Nuts tend to be filling, which can actually help with weight control,” she says. “Since tree nuts have such rich and complex flavors, a single 1 1 1/2-ounce serving is quite satisfying and can easily be eaten as a snack.”

There may be some merit to that claim. Last year, a Loma Linda study looked at the impact of adding almonds to a regular diet. Despite adding a calorie-rich food to their diet, the people in the study did not gain additional weight.

“We found that those who ate almonds tend to naturally balance their calorie intake,” said Dr. Karen Jaceldo-Siegl, of Loma Linda University, the study’s lead researcher. “So even though they were introducing an additional food into their repertoire, they were making appropriate dietary substitutions, so there was not a significant change in body weight.”