Canadian researchers conducted the study, funded by The Almond Board of California and the Canadian government, to determine whether almonds can help reduce heart disease risk by Lowering high cholesterol and at what consumption level.
Some previous research has suggested that nut consumption reduces the risk of coronary heart disease. Because previous research has suggested that eating more nuts increases calories, nuts generally are not recommended for people who need to restrict calories. Twenty-seven high cholesterol patients (15 men and 12 postmenopausal women, average age 64) completed the three-phase study. Their average total cholesterol level was 260 milligrams per deciliter (mg/dL) at baseline.
Three one-month diets were undertaken. For one month each participant ate a full dose of almonds (average 74 grams), which represented a little less that one quarter of their total daily caloric intake. For one month they took a half dose of almonds (average 37 grams) – described as a "handful" of almonds. In the last month, they ate a low-saturated fat, whole-wheat muffin as a daily snack.
The muffin snack served as the control diet because it had about the same amount of calories, protein and saturated and polyunsaturated fats, explains lead author David J.A. Jenkins, M.D., director at the Clinical Nutrition and Risk Factor Modification Center, St. Michael's Hospital, Toronto. The only difference was that the monounsaturated fat was swapped for the starch in the muffin, he says. Jenkins is also Canada Research Chair in Nutrition and Metabolism at the University of Toronto.
Researchers measured cholesterol levels, blood pressure and weight in the subjects. They found that patients reduced low-density lipoprotein (LDL – bad cholesterol) an average 4.4 percent with the half portion of almonds and 9.4 percent with the full portion.
"We were quite impressed," says Jenkins. "If you look at the ratio of LDL to HDL (high-density lipoprotein, the good cholesterol), the reduction was 7.8 percent for the half dose and 12 percent for the full dose by the fourth week. That ratio is very important in assessing cardiovascular risk."
The patients' cholesterol levels did not significantly drop after the muffin phase.
Jenkins says that practitioners should encourage patients to eat almonds as part of a healthy balanced diet as long as they are natural or "dry roasted" without added oils or salts.
Nuts do not have cholesterol and are a good source of protein, according to the American Heart Association. However, the association stresses that the potential benefits of nuts may be negated if they are added rather than substituted for other foods in the diet. While nuts and seeds tend to be very high in fat and calories, most of the fat is polyunsaturated or monounsaturated (e.g. almonds, pecans, walnuts).
Participants in this study were carefully counseled on how to use nuts in place of other foods in the diet.
Nuts, including almonds, walnuts, pecans, peanuts, macadamia and pistachios, have been shown to lower blood cholesterol, Jenkins says. The combination of monounsaturates with some polyunsaturates in nuts is an ideal combination of fats, he says. Although, there is not enough research to say that all nuts are equal in their health value, almonds have particularly well researched profiles, he says. "This study suggests that replacing carbohydrates with monounsaturated fat –
within the context of a diet that is low in saturated, trans fat and cholesterol – favorably affects cholesterol levels and cardiovascular risk," says Alice Lichtenstein, D.Sc., vice-chair of the aociation's nutrition committee.
Almonds are a good source of monounsaturated fat and potentially other beneficial compounds. The American Heart Association recommends eating an overall balanced diet that is high in fruits, vegetables and whole grains, and includes low-fat dairy products, fish and lean meats. Whenever any dietary change is made, care must be taken to avoid increasing total caloric intake, Lichtenstein says.
Co-authors of the study include: Cyril W.C. Kendall, Ph.D.; Augustine Marchie, B.Sc.; Tina L. Parker, R.D.; Philip W. Connelly, Ph.D.; Wei Qian, Ph.D.; James S. Haight, M.D.; Dorothea Faulkner, R.D.; Edward Vidgen, B.Sc.; Karen G. Lapsley, D.Sc.; and Gene A. Spiller, Ph.D.
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