Abstract
CONTEXT: Growth hormone (GH) is known to be nutritionally regulated, but the effect of dietary composition on detailed GH secretion parameters has not previously been comprehensively evaluated. OBJECTIVE: The objective of the study was to determine whether specific macro- and micronutrients are associated with discrete parameters of GH secretion among subjects with wide ranges of body mass index. DESIGN: Detailed macro- and micronutrient intake was assessed by 4-day food records while GH secretion was assessed by standard stimulation testing in 108 men and women in one study (Study 1), and by overnight frequent blood sampling in 12 men in another study (Study 2). RESULTS: Peak stimulated GH was positively associated with vitamin C (r=+0.29; P=0.003), dietary fiber (r=+0.27; P=0.004), arachidic acid (r=+0.25; P=0.008), and behenic acid (r=+0.30; P=0.002) intake in univariate analysis. Controlling for age, gender, race/ethnicity, visceral fat, HOMA-IR, total caloric intake and these four dietary factors in step-wise multivariate modeling, peak GH remained significantly associated with vitamin C and visceral fat (both P<0.05). In addition, vitamin C intake was associated with various parameters of endogenous GH secretion including basal GH secretion (r=+0.95; P<0.0001), GH half-life (r=+.75; P=0.005), total GH production (r=+0.76; P=0.004), GH area-under-the-curve (r=+0.89; P=0.0001), mean log(10) GH pulse area (r=+0.67; P=0.02), and overnight maximum (r=+0.62; P=0.03), nadir (r=+0.97; P<0.0001), and mean GH secretion (r=+0.89; P=0.0001). CONCLUSIONS: These results suggest that certain micronutrients such as vitamin C intake are strongly and uniquely associated with stimulated and endogenous spontaneous GH secretion.