Macronutrient absorption from pistachio nuts: the measured energy value of pistachios in the human diet

Abstract

Epidemiological studies have demonstrated an inverse association between frequent nut consumption and body mass index. Clinical studies have shown that lipid from nuts may be more poorly absorbed than that from other food sources, which suggests that the metabolizable energy (ME) contained in nuts may be less than that predicted by the Atwater general factors. However, data from human feeding studies are lacking. We conducted a randomized controlled-feeding study in healthy adults (n = 16) and fed pistachio nuts (roasted, salted) in 3 doses as part of a controlled diet: 0 g/day (control), 42 g/day (1.5 oz/d), and 84 g/day (3 oz/d). Urine and fecal samples were collected for 7 to 10 day periods during each 3-week diet period. Urine, feces, and diet were analyzed for nitrogen, fat, total dietary fiber, ash, and combustible energy. The energy value of pistachio nuts was calculated from differences in energy excretion during the dietary treatments. The measured energy density of pistachio nuts was found to be 5.49 kcal/g, which is less than the currently accepted energy value of 5.67 kcal/g, as calculated using the Atwater general factors. In conclusion, pistachio nuts contain less ME than that calculated from the Atwater general factors. Accurate information about ME content of foods is important for reliable food labeling so consumers can make informed dietary choices. Support: USDA and Paramount Farms.