The methodology of the study includes a population-based observational study of nonfrail women aged 60 and above from 11 states across the US, from the Nurses' Health Study. The outcome focused on incidence of frailty, defined through the FRAIL components such as fatigue, lower strength, reduced aerobic capacity, multiple chronic conditions, and significant weight loss. These were assessed every four years from 1992 to 2016. Food Frequency Questionnaires were used to examine the intake of peanuts, peanut butter, walnuts, and other nuts every four years from 1990 to 2014. Total nut consumption was calculated and categorized into varying serving sizes, and the relation of intake of each type of nut with frailty was examined separately using Cox proportional hazard models, adjusted for various factors such as age, smoking, BMI, diet quality, and medication use.

In discussing the results, out of 71,704 participants, 14,195 frailty cases arose over a million person-years. Notably, regular consumption of nuts, particularly peanuts and walnuts, showed a significant inverse relation with frailty. That is, a higher intake of these types of nuts were associated with lower cases of frailty. However, the same didn't apply to peanut butter. This affirms the potential benefits of regular nut consumption in aging female population's health and well-being.