Soy protein and isoflavones: their effects on blood lipids and bone density in postmenopausal women.
The effects of soy protein (40 g/d) containing moderate and higher concentrations of isoflavones on blood lipid profiles, mononuclear cell LDL receptor messenger RNA, and bone mineral density and content were investigated in 66 free-living, hypercholesterolemic, postmenopausal women during a 6-mo, parallel-group, double-blind trial with 3 interventions. After a control period of 14 d, during which subjects followed a National Cholesterol Education Program Step I low-fat, low-cholesterol diet, all subjects were randomly assigned to 1 of 3 dietary groups: Step I diet with 40 g protein/d obtained from casein and nonfat dry milk (CNFDM), Step I diet with 40 g protein/d from isolated soy protein containing 1.39 mg isoflavones/g protein (ISP56), or Step I diet with 40 g protein/d from isolated soy protein containing 2.25 mg isoflavones/g protein (ISP90). Total and regional bone mineral content and density were assessed. Non-HDL cholesterol for both ISP56 and ISP90 groups was reduced compared with the CNFDM group (P < 0.05). HDL cholesterol increased in both ISP56 and ISP90 groups (P < 0.05). Mononuclear cell LDL receptor mRNA was increased in subjects consuming ISP56 or ISP90 compared with those consuming CNFDM (P < 0.05). Significant increases occurred in both bone mineral content and density in the lumbar spine but not elsewhere for the ISP90 group compared with the control group (P < 0.05). Intake of soy protein at both isoflavone concentrations for 6 mo may decrease the risk factors associated with cardiovascular disease in postmenopausal women. However, only the higher isoflavone-containing product protected against spinal bone loss.
Potter
S M
SM
Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, USA. spotter@protein.com
Baum
J A
JA
Teng
H
H
Stillman
R J
RJ
Shay
N F
NF
Erdman
J W
JW
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D015519:Bone Density / Q000187:drug effects*; D002784:Cholesterol / Q000097:blood; D004044:Dietary Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007529:Isoflavones / Q000008:administration & dosage / Q000494:pharmacology*; D008055:Lipids / Q000097:blood*; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood / Q000187:drug effects; D012333:RNA, Messenger / Q000302:isolation & purification; D011973:Receptors, LDL / Q000235:genetics; D030262:Soybean Proteins / Q000008:administration & dosage / Q000494:pharmacology*
D004044:Dietary Proteins; D007529:Isoflavones; D008055:Lipids; D012333:RNA, Messenger; D011973:Receptors, LDL; D030262:Soybean Proteins; D002784:Cholesterol