Pistachios increase levels of antioxidants in the blood

Pistachios increase levels of antioxidants in the blood


A diet high in pistachios can increase the level of disease-fighting antioxidants in your blood, according to a study conducted by an international researcher team and published in the Journal of Nutrition.

"Our previous study showed the benefits of pistachios in lowering lipids and lipoproteins, which are a risk factor for heart disease," said researcher Penny Kris-Etherton of Penn State University. "This new study shows an additional effect of pistachios so now there are multiple health benefits of eating pistachios."

Researchers assigned study participants to eat four different diets for two weeks each, with a two-week break between each diet. Levels of the antioxidants beta-carotene, gamma-tocopherol and lutein were measured after each step of the process, along with levels of oxidized LDL ("bad") cholesterol.

Because oxidation can transform LDL cholesterol into a form more likely to lead to inflammation and to plaque buildup inside the body's blood vessels, antioxidants are expected to reduce levels of oxidized LDLs and thereby reduce the risk of heart disease.

Participants began the study by eating a typical U.S. diet, getting 11 percent of their total calories from saturated fat and 24 percent from unsaturated fats. This was followed by a cholesterol-lowering Step I Diet, then by a modified Step I Diet in which 10 percent of its calories from pistachios, and finally by a modified Step I Diet in which 20 percent of total calories came from pistachios.

Pistachio consumption was roughly 1.5 ounces per day in the 10 percent diet and 3 ounces per day in the 20 percent diet. While on the 10 percent diet, participants got 8 percent of their calories from fat and 22 percent from unsaturated fats; on the 20 percent diet they got 8 percent from saturated fat and 26 percent from unsaturated fats.

While participants were on the pistachio diets, blood levels of all three antioxidants increased significantly compared to the initial diet. Levels of oxidized LDLs decreased relative to the unmodified Step I Diet.

"Our results suggest that a heart-healthy diet including pistachios contributes to a decrease in serum oxidized-LDL levels," Kris-Etherton said.

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