Tree nut consumption is associated with higher sex hormone-binding globulin levels in premenopausal US women

Abstract

Low levels of sex hormone-binding globulin (SHBG) are associated with many diseases including hypertension, diabetes, and polycystic ovarian syndrome. Walnuts increased circulating SHBG in 31 women complicated with polycystic ovarian syndrome. However, whether tree nuts increase SHBG in women in a general population is unknown. It was hypothesized in this study that consumption of tree nuts was positively associated with SHBG levels in women in a general population. This cohort study included 2699 adult women from the 2013- to 2016 US National Health and Nutrition Examination Survey. Tree nut consumers were defined as those who consumed tree nuts on either of the 2 24-hours recall days. Associations of tree nut consumption with SHBG were assessed using least squares regression. Among the 2699 women, 234 were consuming tree nuts. The median SHBG concentrations were 67.1 and 59.3 nmol/L among tree nut consumers and non-consumers, respectively. Tree nut consumption was positively associated with circulating SHBG (β=0.041, P=.018) but not testosterone nor estradiol after adjustment for all tested confounders. Sub-analyses showed that the positive association of tree nuts with SHBG presented in premenopausal women but not in postmenopausal women. Tree nut consumption remained independently associated with higher circulating levels of SHBG in premenopausal women when tree nut consumption was expressed as percentage of energy derived from tree nuts or when tree nut consumption was defined as a tree nut intake of ≥0.25 ounce per day. Future research will verify the effectiveness of using tree nuts to treat low SHBG in premenopausal women in the general population.