Recent research presented at the 2014 Experimental Biology conference found that eating up to 20% of daily calories from pistachios in the diet does not contribute to weight gain or body fat changes, and may even potentially improve blood lipids and blood pressure.
In an effort to learn the effects of regular pistachio consumption on body composition and blood lipids in healthy subjects (an area with historically limited research), scientists asked a group of healthy women in their 20s to add a couple servings of pistachios to their daily diets, accounting for up to one-fifth of their daily calorie needs. After 10 weeks, they found that the women experienced no changes in their weight, waist circumference or body mass index.
"The results show us that nuts can be included in a healthy diet and not cause weight gain," Kathleen Kissee, marketing project manager for the American Pistachio Growers, told NutraIngredients-USA. "The health benefits of pistachios – a good source of fiber and protein, and containing the 'good' fats, poly- and mono- unsaturated fats, prove pistachios to be a healthy and filling snack option. In addition, scientific evidence suggests, but does not prove, that eating 1.5 ounces per day of most nuts, such as pistachios, as a part of a diet low in saturated fat and cholesterol may reduce the risk of heart disease.
Kissee wasn't surprised by the results, noting that past research has produced similar data. "In June 2013, Dr. Flores-Mateo et al., reported in the American Journal of Clinical Nutrition the results of a meta-analysis of 33 clinical nut-feeding studies that compared a control diet to a diet containing nuts and weight outcomes. The researchers found that nuts, including pistachios, did not increase body weight, waist circumference or body mass index," she said.
For this study, the researchers recruited 48 healthy women with a mean age of 21 for a free-living crossover design that involved two 10-week treatment periods with pistachios added (20% of calories), a no pistachio control treatment and a 15-week washout period. Pistachios were provided weekly in pre-measured sealed snack bags to the participants, and empty bags and diet data were collected at that time. Blood lipids, waist circumference (WC), weight, body composition (bioelectrical impedance analysis), and blood pressure (BP) measurements were taken at the beginning and end of each treatment after a 12-hour fast. A mixed effects model determined the effect of the treatments.
The researchers found that neither treatment had a significant effect on blood lipids, body weight, WC, percent body fat, or BP; however, LDL (80.8±1.21 vs. 81.5±1.18), cholesterol (160±1.41 vs. 162±1.36), triglycerides (80.8±2.52 vs.84.0±2.46), WC (28.3±0.10 vs. 28.4±0.10), and systolic/diastolic BP (106±1.24/66.6±0.64 vs. 106±1.26/67.2±0.65) were slightly lower in the pistachio groups versus the habitual groups.
These results have only been published in abstract form to date. Constance J Geiger, PhD, RD, LD, Nutrition Consultant for the American Pistachio Growers, also noted that more research is needed to support health claims related to weight management.
"More research in the area of weight management would be needed to apply for a Qualified Health Claim from the FDA," Dr. Geiger said. "Specifically, a few more randomized controlled trials need to be conducted on a larger number of subjects. Additionally, an organization or company would need to submit a health claim petition with all the evidence (research) to the FDA to request a health claim for weight management be considered for nuts such as pistachios."
Source: The Journal of the Federation of American Societies for Experimental Biology
DOI: vol. 28 no. 1 Supplement 640.6
“Effects of pistachio consumption on body composition and blood lipids in healthy young women”
Authors: Bonny Burns-Whitmore, Laura Hall, Alison Bushnell, Amy Towne and Soma Roy