Sidika E Kasim-Karakas1, Wendy M Cunningham1 and Alex Tsodikov1
1 From the Department of Internal Medicine, Division of Endocrinology, Clinical Nutrition and Vascular Medicine, University of California, Davis, Davis, CA (SEK-K); the Department of Biostatistics, School of Public Health, University of Michigan at Ann Arbor, Ann Arbor, MI (AT); and the Department of Nutrition, Family and Consumer Sciences, California State University, Sacramento, CA (WMC)
Background: Insulin resistance, infertility, and hirsutism,>common characteristics of polycystic ovary syndrome (PCOS),>improve with even modest weight loss. Optimal dietary treatment>for PCOS is not known.>
Objective: We compared the effects of acute protein administration>with those of glucose challenges on hormones related to obesity>and insulin resistance (ie, cortisol and insulin), hirsutism>[ie, dehydroepiandosterone (DHEA) and androstenedione], and>hunger (ie, ghrelin).>
Design: Patients with PCOS (n = 28; aged 26 ± 2 y) were>tested with a 5-h oral-glucose-tolerance test (OGTT) and a euvolemic,>euenergetic protein challenge.>
Results: Glucose ingestion caused larger fluctuations in blood>glucose and more hyperinsulinemia than did protein (P < 0.01,>overall treatment-by-time interaction). During the protein challenge,>cortisol and DHEA declined over 5 h. During OGTT, cortisol and>DHEA increased after the third hour and began to show significant>divergence from protein from the fourth hour (P 0.01). During>OGTT, 18 patients who had a blood glucose nadir of <69 mg/dL>had elevated cortisol (baseline: 10.4 ± 0.4; nadir: 5.9>± 0.1; peak: 12.7 ± 0.9 µg/dL) and DHEA>(baseline: 15.6 ± 1.3; nadir: 11.2 ± 1.0; peak:>24.6 ± 1.6 ng/mL) (P < 0.01), whereas the remaining>10 patients with a glucose nadir of 76 ± 2 mg/dL had>no increase in adrenal steroids. Both glucose and protein suppressed>ghrelin (from 935 ± 57 to 777 ± 51 pg/mL and from>948 ± 60 to 816 ± 61 pg/mL, respectively). After>glucose ingestion, ghrelin returned to baseline by 4 h and increased>to 1094 ± 135 pg/mL at 5 h. After the protein challenge,>ghrelin remained below the baseline (872 ± 60 pg/mL)>even at 5 h. The overall treatment effect was highly significant>(P < 0.0001).>
Conclusions: Glucose ingestion caused significantly more hyperinsulinemia>than did protein, and it stimulated cortisol and DHEA. Protein>intake suppressed ghrelin significantly longer than did glucose,>which suggested a prolonged satietogenic effect. These findings>provide mechanistic support for increasing protein intake and>restricting the simple sugar intake in a PCOS diet.