Eating a serving of nuts each day can lead to lower cholesterol levels. But, according to a new study published in the Archives of Internal Medicine, the cardio-protective effects of nuts seem to be greatest for leaner people, those eating less healthy diets and people with higher levels of "bad" LDL cholesterol.
Many studies conducted in men and women from different countries have shown that nuts do lower cholesterol. Nuts contain a number of protective compounds including vegetable protein, unsaturated fats, fibre, folate, vitamin E, magnesium and plant sterols.
To further examine the cholesterol-lowering effects of nuts and whether it might be strengthened or weakened by a person's overall diet, body size or other factors, researchers from Loma Linda University in California 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 5 percent; reduced their harmful LDL cholesterol levels 7 percent; and shifted the ratio of total cholesterol or LDL cholesterol to "good" HDL cholesterol in a favourable direction. The benefits were seen both in people with normal cholesterol levels and those with high cholesterol.
But while nuts reduced blood triglyceride levels in people whose triglycerides were too high (1.7 mmol/L 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 strongest effect on people who started out with LDL cholesterol levels above 4.1 mmol/L, people with lower body weight, and those who were eating more "Western" diets (meaning more saturated fats and refined carbohydrates).
According to the researchers, this makes sense since people who were already eating a more Mediterranean-style diet rich in olive oil, fish, whole grains and other healthy foods wouldn't show as much benefit from adding nuts to their diet.
The bottom line: eating one to two servings of nuts a day - any type - benefits most of the people by improving their lipid profile. This, in turn, can lead to a "drastically decreased" heart attack risk, the researchers concluded.
SOURCE: Archives of Internal Medicine, May 2010.
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