Written by Jessica Patella, ND. A study of 27 participants demonstrated that those who consumed a diet with 20% of calories derived from pistachios had higher antioxidant levels and lower oxidized LDL levels compared to control. Also the LDL:HDL ratio decreased as the amount of pistachios consumed increased.
Pistachios, compared to other nuts, contain high amounts of antioxidants, including lutein, beta carotene, and gamma-tocopherol (vitamin E). In addition, pistachios are a source of selenium, a nutrient that is necessary for the production of glutathione, a major cellular antioxidant.(1) Oxidized LDL cholesterol (“bad cholesterol”) and lipid peroxidation (oxidized fats) are found in the fatty plaques that lead to atherosclerosis, the thickening and hardening of arteries (2). The purpose of this study was to determine if the antioxidants in pistachios could decrease the oxidation of the cholesterol, thereby decreasing the risk of atherosclerosis and cardiovascular disease (2).
The study involved 27 study participants, ages 35-61 with moderately elevated LDL cholesterol (greater than 2.7mmol/L) who were randomized to three different diets over a 4-week period. The baseline and control diets did not contain pistachios. The first pistachio diet was calculated as 10% of calories from pistachios (about ¼ to ½ cup) and the second pistachio diet was calculated as 20% of calories from pistachios (about ½ to 1 cup) depending on the individual’s energy needs (2, 1). All food was prepared and consumed by the participants at the Metabolic Diet Study Center at Pennsylvania State University. They ate one meal per day at the center and all their other meals and snacks were packed for offsite consumption (2).
Blood levels of the antioxidants lutein, alpha-carotene, beta-carotene, gamma-tocopherol (vitamin E), and lycopene were all greater after consumption of the diet of 20% calories from pistachios (2). Participants also had lower oxidized LDL levels (43.43 ± 3.02 U/L) compared to baseline (48.57 ± 3.02 U/L), after the diet of 20% calories from pistachios. The ratio of LDL:HDL also decreased as the amount of pistachios in the diet increased (2).
The estimated cost of cardiovascular disease and stroke in the United States in 2009 was $475.3 billion, so prevention is key (1). This research demonstrates the beneficial effects of pistachios on multiple antioxidant levels and on decreasing LDL levels. This suggests that pistachios may be critically important in reducing oxidative stress of chronic diseases, especially cardiovascular disease (2).
This study was a randomized, crossover with controlled meals and calculated amounts of pistachios to decrease the number of variables. A similar study should be conducted with more study participants in the future.
Source: Kay, Colin D., et al. “Pistachios increase serum antioxidants and lower serum oxidized-LDL in hypercholesterolemic adults.” The Journal of nutrition 140.6 (2010): 1093-1098.
© 2010 American Society for Nutrition.
Posted April 22, 2010.
References:
- U.S. Department of Agriculture, Agricultural Research Service. 2009. USDA National Nutrient Database for Standard Reference, Release 22. Nutrient Data Laboratory Home Page.
- Colin, et al. Pistachios Increase Serum Antioxidants and Lower Serum Oxidized-LDL in Hypercholesterolemic Adults. J Nutr. 2010.
- American Heart Association.
