In a first-of-its-kind study with nuts, randomised controlled-feeding research conducted by the Agricultural Research Service (ARS) of the United States Department of Agriculture (USDA) found that fat in pistachios may not be completely absorbed by the body. The findings indicate that pistachios may actually contain fewer kilojoules per serving than originally thought – further validating pistachios as one of the lowest-kilojoule nuts with 672 kilojoules per 30g serving. The study was presented at the Experimental Biology conference in Washington DC in the US.
The research measured the energy value of pistachios by feeding 16 healthy adults the nuts as part of a controlled diet and calculating the energy value from differences in energy excretion during the dietary treatment timeframe. The resulting energy value of one 30g serving of pistachios was 5.9% less than previous calculations.
Fat from nuts poorly absorbed
"Existing scientific research indicates that fat from nuts is poorly absorbed through the gastrointestinal tract," said lead ARS researcher David J. Baer, Ph.D., Supervisory Research Physiologist with the Beltsville Human Nutrition Research Centre. "This study confirms that the fat from pistachio nuts, specifically, is not completely digested or absorbed, resulting in a lower energy value."
Additional data from this study presented at Experimental Biology reinforced the heart-health benefits of pistachios. The ARS researchers found that when healthy individuals included 42.5g and 85g of pistachios into their typical American diet, cardio-supportive results were shown.
Pistachios deliver weight management support benefits
The new data demonstrating the potential kilojoule savings of pistachios builds on previous research showing that pistachios are a weight-wise snack. According to researchers at the University of California, US, choosing to snack on pistachios rather than pretzels not only supports body mass index (BMI) goals, but can support heart health, too.
In a 12-week randomised study, 52 overweight and obese subjects were placed on a 2,100-kilojoule deficit diet and assigned to either a pistachio snack (about 75 pistachios providing 1,000 kilojoules) or a pretzel snack group (57g of pretzels providing 924 kilojoules). The results showed that the pistachio group had better success with supporting their BMI goals compared to the pretzel group, showing pistachios can be included in a healthy diet, even for those managing their weight.
Additionally, pistachios – also known as the "Skinny Nut" – are shown to be a "mindful snack" in terms of taking longer to eat and requiring the snacker to slow down and be more conscious of what has been consumed. According to behavioural eating expert, James Painter, Ph.D., Chair of the School of Family and Consumer Sciences at Eastern Illinois University (US), "Our research shows in-shell snackers eat 41% fewer kilojoules than those who snack on shelled nuts. We also found that in-shell pistachios offer a visual cue to help reduce intake. When leftover shells are cleared immediately, snackers eat up to 22% more compared to leaving left over shells as a reminder of consumption."
Pistachios are also a good source of fiber and protein. Providing about 49 kernels per 30g serving, pistachios offer the most nuts per serving when compared to other popular snack nuts – comparatively, almonds have 23 in a serving, walnuts 14 halves and cashews, 18.