Antioxidants are molecules that prevent oxidation damage to other molecules, which can lead to serious illness and disease. Low levels of antioxidants in the blood may cause "oxidative stress". Oxidative stress, particularly oxidized low-density lipoproteins (LDL) are implicated in inflammation and plaque buildup inside blood vessels. Antioxidants prevent LDLs from oxidizing, migrating into the blood vessel walls and causing inflammation.
Pistachios are not only an antioxidant-laden food, they are also high in other nutrients such as lutein, beta carotene, and Vitamin E, which are all oil-soluble vitamins. Oil soluble vitamins are important to health because they are stored in tissues longer and released at a slower rate than water soluble vitamins.
Pistachios are also excellent sources of bone-building copper, manganese, and phosphorous along with heart healthy potassium and magnesium. Pistachios are the only nut to contain the two carotenoids, lutein and zeaxanthin.
The researchers of the study said:
"This new study shows an additional effect of pistachios so now there are multiple health benefits of eating pistachios."
The researchers conducted a randomized, controlled feeding experiment to test the effects of pistachios on antioxidant levels when added to a heart healthy moderate-fat diet. Controlled feeding experiments provide all the food eaten by study subjects for the duration of the study period.
The participants first ate a typical American diet consisting of 35 percent total fat and 11 percent saturated fat for two weeks. They then tested three diets for four weeks each with about a two-week break between each diet. All three diets were variations on a common heart-healthy diet in general use.
The diets included, as a control, a Step I diet with no pistachios and about 25 percent total fat and 8 percent saturated fat. The pistachio-enhanced diets were Step I Diets with 10 and 20 percent of the energy supplied by pistachio nuts, respectively.
The actual amounts of pistachios included in each diet were 1.5 ounces and 3 ounces for the 10 and 20 percent diets, respectively.
Both pistachio diets produced higher blood serum levels of Beta-carotene, lutein and gamma-tocopherol than the typical American diet. Compared to the pistachio-free diet, the pistachio-enhanced diets produced greater blood plasma levels of lutein and gamma-tocopherol. After eating both pistachio-enriched diets, the participants had lower oxidized-LDL concentrations in their blood than after the control diet.
"Our results suggest that a heart-healthy diet including pistachios contributes to a decrease in serum oxidized-LDL levels, in part through cholesterol lowering, and also due to an added benefit of the antioxidants in the pistachios," said one of the researchers.
Pistachios make a tasty snack by themselves or add them to salads, smoothies and desserts.
Research Paper Details:
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