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Natural abundance stable carbon isotope evidence for the routing and de novo synthesis of bone FA and cholesterol
Author(s) -
Jim Susan,
Ambrose Stanley H.,
Evershed Richard P.
Publication year - 2003
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-003-1049-1
Subject(s) - lipidology , clinical chemistry , cholesterol , medicine , oleic acid , endocrinology , linoleic acid , chemistry , stearic acid , biology , biochemistry , food science , fatty acid , organic chemistry
This research reported in this paper investigated the relationship between diet and bone FA and cholesterol in rats raised on a variety of isotopically controlled diets comprising 20% C 3 or C 4 protein (casein) and C 3 and/or C 4 nonprotein or energy (sucrose, starch, and oil) macronutrients. Compoundspecific stable carbon isotope analysis (δ 13 C) was performed on the FA (16∶0, 18∶0, 18∶1, and 18∶2) and cholesterol isolated from the diet ( n =4) and bone ( n =8) of these animals. The dietary signals reflected by the bone lipids were investigated using linear regression analysis. δ 13 C values of bone cholesterol and stearic (18∶0) acid were shown to reflect whole‐diet δ 13 C values. whereas the δ 13 C values of bone palmitic (16∶0), oleic (18∶1), and linoleic (18∶2) acids reflected dietary FA δ 13 C values. Dietary signal differences are a result of the balance between direct incorporation (or routing) and de novo synthesis of each of these bone lipids. Estimates of the degree of routing of these bone lipids gleaned from correlations between Δ 13 C d lipid‐wdiet (δ 13 C diet lipid ‐δ 13 C whole diet ) spacings and Δ 13 C b lipid‐ w diet (δ 13 C bone lipid ‐δ 13 C whole diet fractionations demonstrated that the extent of routing, where 18∶2>16∶0>18∶1>18∶0>cholesterol, reflected the relative abundances of these lipids in the diet. These findings provide the basis for more accurate insights into diet when the δ 13 C analysis of bone fatty FA or cholesterol is employed.