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NEW YORK (Reuters Health) - Eating plenty of nuts can lead to healthier cholesterol levels, but the benefits seem to be greatest for thinner people, those eating less healthy diets, and people with higher levels of "bad" LDL cholesterol and triglycerides, according to a new analysis of published studies of nut consumption and blood fats.
Studies in men and women from different countries have shown that "nuts do lower cholesterol, so it's pretty much universal," Dr. Joan Sabate of Loma Linda University in California, told Reuters Health.
Nuts contain a number of healthful substances, including "good" fats, fiber, and antioxidants. In 2003, the US Food and Drug Administration stated that eating 1.5 ounces a day of certain nuts might help reduce heart disease risk.
To further examine the cholesterol-lowering effects of nuts and whether this effect might be strengthened or weakened by a person's overall diet, body size or other factors, Sabate and colleagues pooled data from 25 studies from seven countries including 583 men and women, some with high cholesterol, some with normal cholesterol.
They found that eating an average of 67 grams (about 2.4 ounces) of nuts daily brought people's total cholesterol levels down by 11 points (a 5 percent reduction); reduced their harmful LDL cholesterol levels by 10 points (a 7 percent drop); and shifted the ratio of total cholesterol or LDL cholesterol to "good" HDL cholesterol in a favorable direction. The benefits were seen both in people with normal cholesterol levels and those with high cholesterol.
But while nuts reduced triglyceride levels by 21 points in people whose triglycerides were too high (150 milligrams per deciliter or higher), they didn't affect triglycerides in people with normal levels.
The researchers also found a "dose-response" relationship, meaning the more nuts people ate, the greater the changes in their cholesterol levels. Different types of nuts had similarly healthful effects on blood fats.
Eating nuts had the biggest effect on people who started out with LDL cholesterol levels above 160 milligrams per deciliter, people with lower body weight, and those who were eating more "Western" diets (meaning more saturated fats and refined carbohydrates), the researchers found.
This makes sense, Sabate noted, because people who were already eating a more Mediterranean diet rich in olive oil, fish, whole grains and other healthy foods wouldn't show as much benefit from adding nuts to their diet.
"Eating one to two servings of nuts a day benefits most of the people by improving their lipid profile," Sabate added. In turn, the researcher said, this leads to a "drastically decreased" heart attack risk.
Sabate and one co-author on the study have received funding from several different trade groups for nut producers, and the International Tree Nut Council Nutrition Research and Education Foundation helped fund the new analysis.
SOURCE: Archives of Internal Medicine, May 2010.