Lipid response to a low-fat diet with or without soy is modified by C-reactive protein status in moderately hypercholesterolemic adults.
Recent evidence suggests that individuals with high concentrations of C-reactive protein (CRP), a marker of inflammation, are less responsive to cholesterol-lowering diets. CRP concentrations are increased by oral estrogen; however, the effect of soy phytoestrogens on inflammation has not been studied comprehensively, especially in women receiving hormone replacement therapy (HRT). This study was conducted to determine whether adding soy to a low-fat, high-fiber diet affects CRP and interleukin (IL)-6, and to examine the association between CRP levels and lipid response in moderately hypercholesterolemic adults (men = 18, postmenopausal women = 14; 6 receiving HRT). After a 3-wk run-in period with consumption of a Step I diet (27% total fat, 7% saturated fat, 275 mg cholesterol), participants were randomly assigned to diets containing 25 g/d soy protein (+ 90 mg/d isoflavones) or 25 g/d milk protein for 6 wk in a crossover design. Lipids and lipoproteins, CRP, and IL-6 were measured at the end of each diet and participants were categorized into high (>3.5 mg/L) or low CRP groups based on a median split. The addition of soy or milk protein to the Step I diet did not affect lipids or inflammatory markers. Regardless of protein source, those with low CRP exhibited significant decreases in LDL cholesterol (-3.5%) and the LDL:HDL cholesterol ratio (-4.8%), whereas those with high CRP had significant increases in LDL cholesterol (+4.8%), the LDL:HDL cholesterol ratio (+5.2%), apolipoprotein B (+3.8%), and lipoprotein(a) (+13.5%) compared with the run-in diet. These results suggest that inflammation may not only attenuate lipid responses, but also aggravate dyslipidemia in hypercholesterolemic subjects consuming a cholesterol-lowering diet.
Hilpert
Kirsten F
KF
Department of Nutritional Sciences, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, USA. kfc107@psu.edu
Kris-Etherton
Penny M
PM
West
Sheila G
SG
D000328:Adult; D001053:Apolipoproteins / Q000097:blood; D002097:C-Reactive Protein / Q000378:metabolism; D018752:Diet, Fat-Restricted; D004043:Dietary Fiber; D005260:Female; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood / Q000178:diet therapy*; D007249:Inflammation; D015850:Interleukin-6 / Q000097:blood; D008055:Lipids / Q000097:blood*; D008074:Lipoproteins / Q000097:blood; D008297:Male; D008875:Middle Aged; D008517:Phytotherapy; D030262:Soybean Proteins
D001053:Apolipoproteins; D004043:Dietary Fiber; D015850:Interleukin-6; D008055:Lipids; D008074:Lipoproteins; D030262:Soybean Proteins; D002097:C-Reactive Protein