To examine the effect of diet fat type on rates of cholesterol
synthesis and esterification during feeding and fasting, nine healthy
male subjects were fed solid-food diets of 40% fat as predominantly
either olive oil (MONO), safflower-oil margarine (POLY), or butter
(SAT). At the end of each two-week diet trial, subjects were given
deuterium (D) oxide orally and de novo synthesis was measured from D
incorporation into cholesterol and interpreted as rates of fractional
synthesis (FSR) (pools/day) into the rapidly exchangeable free
cholesterol (FC) pool. Absolute synthesis rates (ASR) were calculated
as the product of FSR and the FC pool. Pool size for each subject was
obtained from analysis of the specific activity decay curve of an
intravenous injection of 4-14C-cholesterol over nine months. Synthesis
was measured over two consecutive 12-h fed periods followed by two
consecutive 12-h fasted periods. Serum samples were also assayed for
lathosterol concentration, an index of cholesterol synthesis. Serum
cholesterol and non-HDL cholesterol concentrations were highest on the
SAT diet, lowest (P<0.001) on the POLY diet and intermediate on the MONO
diet, triglyceride levels were greater (P<0.03) on the SAT diet than on
the POLY diet, and HDL levels were lowest (P<0.05) on the SAT diet and
highest on the MONO diet. Cholesterol D enrichment and FSR during each
12-h period were greater (P<0.014) on the POLY diet than on the SAT
diet; MONO enrichment and FSR were not significantly different from
those on the other two diets. Similar results were obtained for rates of
cholesterol esterification (P<0.001). Deuterium enrichment data
suggested, and lathosterol data confirmed, that free cholesterol
synthesis was greater during the fed period than during the fasted
period (P<0.01); however, this could not be confirmed for rates of
cholesterol esterification. Results suggest that POLY fat feeding
augments de novo cholesterol synthesis without adverse effects on total
serum cholesterol concentrations, and that the deleterious effects of
SAT fat on serum cholesterol are not brought about by augmented de novo
synthesis. Finally, the combination of deuterium incorporation and
mathematical modelling produces estimates of daily cholesterol synthesis
which are compatible with those invoked by more laborious techniques. / Land and Food Systems, Faculty of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/8877 |
| Date | 05 1900 |
| Creators | Mazier, Marie Jeanne Patricia |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Format | 13498376 bytes, application/pdf |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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