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Dietary conjugated linoleic acid (CLA) in the cis‐9, trans‐11 isoform reduces parathyroid hormone (PTH) in male, but not female rats
Author(s) -
Weiler Hope A,
Fitzpatrick Sandra,
FitzpatrickWong Shirley
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a561-c
Subject(s) - medicine , endocrinology , parathyroid hormone , conjugated linoleic acid , weanling , osteoporosis , chemistry , bone mineral , adipose tissue , linoleic acid , fatty acid , calcium , biochemistry
Previously a mixture of CLA isoforms reduced PTH in male rats over 8 wk. The objective herein was to determine: which isoform caused the reduction in PTH; if the affect was sex specific; and if CLA‐induced reductions in PTH were transient. Male and female weanling rats (n=48) were randomized to a control diet or one made with 0.5% of the diet as cis‐9, trans‐11 CLA, 0.5% of the diet as trans‐10, cis‐12 CLA or these CLA in a mixture. Measurements made after 4, 8 and 16 wk were: body weight, bioactive PTH, ionized Ca, whole body and regional (lumbar spine, femur and tibia) bone mineral content (BMC) and density (BMD) using dual energy x‐ray absorptiometry. Using a factorial design (CLA isomers, age and sex plus interactions), a sex by cis‐9, trans‐11 CLA interaction was observed in that reduced PTH (139.5 ± 63.9 vs 95.8 ± 42.4 pg/ml, P=0.02) and reduced femur BMC (0.63 ± 0.22 vs 0.58 ± 0.18 g, P=0.03) occurred in males only. No other effects of cis‐9, trans‐11 CLA were observed. Regarding trans‐10, cis‐12 CLA, no interaction effects were observed, but a main effect was observed to reduce lumbar spine BMC (0.56 ± 0.17 vs 0.53 ± 0.16 g, P<0.01) and BMD (0.265 ± 0.044 vs 0.255 ± 0.044 g/cm 2 , P<0.01). In summary, the cis‐9, trans‐11 CLA isoform is responsible for reduced PTH and this effect is sex‐specific; this was true whether fed as a pure isomer or mixed with an equal amount of trans‐10, cis‐12 CLA. These results require confirmation in other animal models such as ovariectomized rats and also in humans to expand the understanding of dietary CLA in health. Funding: Dairy Farmers of Canada & NSERC.