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Relatively little is known about the role of specific saturated fatty acids in the development of high fat diet induced obesity and insulin resistance. Here, we have studied the effect of stearate in high fat diets (45% energy as fat) on whole body energy metabolism and tissue specific insulin sensitivity. C57Bl/6 mice were fed a low stearate diet based on palm oil or one of two stearate rich diets, one diet based on lard and one diet based on palm oil supplemented with tristearin (to the stearate level of the lard based diet), for a period of 5 weeks. Ad libitum fed Oxidative metabolism was assessed by indirect calorimetry at week 5. Changes in body mass and composition was assessed by DEXA scan analysis. Tissue specific insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamp analysis and Western blot at the end of week 5. Indirect calorimetry analysis revealed that high levels of dietary stearate resulted in lower caloric energy expenditure characterized by lower oxidation of fatty acids. In agreement with this metabolic phenotype, mice on the stearate rich diets gained more adipose tissue mass. Whole body and tissue specific insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamp and analysis of insulin induced PKBser473 phosphorylation. Whole body insulin sensitivity was decreased by all high fat diets. However, while insulin-stimulated glucose uptake by peripheral tissues was impaired by all high fat diets, hepatic insulin sensitivity was affected only by the stearate rich diets. This tissue-specific pattern of reduced insulin sensitivity was confirmed by similar impairment in insulin-induced phosphorylation of PKBser473 in both liver and skeletal muscle. In C57Bl/6 mice, 5 weeks of a high fat diet rich in stearate induces a metabolic state favoring low oxidative metabolism, increased adiposity and whole body insulin resistance characterized by severe hepatic insulin resistance. These results indicate that dietary fatty acid composition per sé rather than dietary fat content determines insulin sensitivity in liver of high fat fed C57Bl/6 mice.
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... For example, palmitic acid (C16:0) and C18:0 are the most common and abundant long chain SFAs in food and the human body, and C16:0 can be converted to C18:0 in the body [8]. A high fat diet with an increase in C18:0 has been found to induce a metabolic state favoring lower oxidative metabolism and severe hepatic insulin resistance in mice compared with an isocaloric high fat diet [9]. In mice deficient for Elovl6, a gene encoding the elongase that catalyzes the conversion of C16:0 to C18:0, the level of C18:0 decreased while the level of C16:0 increased in serum and liver, and the mice became obese and developed hepatosteatosis but were protected from insulin resistance when fed a high fat diet [10]. ...
... Respiratory exchange rate (RER) was calculated as VCO 2 /VO 2 . Fat and carbohydrate oxidation rates were calculated according to the following equation [9]: ...
Preprint
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Background: Differential effects of individual saturated fatty acids (SFAs), particularly stearic acid (C18:0), relative to the shorter-chain SFAs have drawn interest for more accurate nutritional guidelines. However, specific biologic and pathologic functions that can be assigned to particular SFAs are very limited. The present study was designed to compare changes in metabolic and transcriptomic profiles in mice caused by a high C18:0 diet and high palmitic acid (C16:0) diet. Methods: Male C57BL/6 mice were assigned to a normal fat diet (NFD), a high fat diet with high C18:0/C16:0 ratio (HSF) or an isocaloric high fat diet with a low C18:0/C16:0 ratio (LSF) for 10 weeks. An oral glucose tolerance test, 72-h energy expenditure measurement and CT scan of body fat were done before sacrifice. Fasting glucose and lipids were determined by an autobiochemical analyzer. Blood insulin, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) levels were measured by enzyme-linked immunosorbent assay methods. Free fatty acids (FFAs) profiles in blood and liver were determined by using gas chromatography-mass spectrometry. Microarray analysis was applied to investigate changes in transcriptomic profiles in the liver. Pathway analysis and Gene Ontology analysis were applied to describe the roles of differentially expressed mRNAs. Results: Compared with the NFD group, body weight, body fat ratio, fasting blood glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), triglyceride, IL-6, serum and liver FFAs including total FFAs, C16:0 and C18:0 were increased in both high fat diet groups and were much higher in the HSF group than in the LSF group. Both HSF and LSF mice exhibited distinguishable long non-coding RNA (lncRNA), microRNA and mRNA expression profiles when compared with those of NFD mice. Additionally, more differentially expressed lncRNAs and mRNAs were observed in the HSF group than in the LSF group. Some biological functions and pathways, other than energy metabolism regulation, were identified as differentially expressed mRNAs between the HSF group and LSF group. Conclusion: The high fat diet with a high C18:0/C16:0 ratio induced more severe glucose and lipid metabolic disorders and inflammation and affected expression of more lncRNAs and mRNAs than an isocaloric low C18:0/C16:0 ratio diet in mice. These results provide new insights into the differences in biological functions and related mechanisms, other than glucose and lipid metabolism, between C16:0 and C18:0.
... For example, palmitic acid (C16:0) and C18:0 are the most common and abundant long chain SFAs in food and the human body, and C16:0 can be converted to C18:0 in the body [8]. A high fat diet with an increase in C18:0 has been found to induce a metabolic state favoring lower oxidative metabolism and severe hepatic insulin resistance in mice compared with an isocaloric high fat diet [9]. In mice deficient for Elovl6, a gene encoding the elongase that catalyzes the conversion of C16:0 to C18:0, the level of C18:0 decreased while the level of C16:0 increased in serum and liver, and the mice became obese and developed hepatosteatosis but were protected from insulin resistance when fed a high fat diet [10]. ...
... Respiratory exchange rate (RER) was calculated as VCO 2 /VO 2 . Fat and carbohydrate oxidation rates were calculated according to the following equation [9]: ...
Preprint
Full-text available
Background: Differential effects of individual saturated fatty acids (SFAs), particularly stearic acid (C18:0), relative to the shorter-chain SFAs have drawn interest for more accurate nutritional guidelines. However, specific biologic and pathologic functions that can be assigned to particular SFAs are very limited. The present study was designed to compare changes in metabolic and transcriptomic profiles in mice caused by a high C18:0 diet and high palmitic acid (C16:0) diet. Methods: Male C57BL/6 mice were assigned to a normal fat diet (NFD), a high fat diet with high C18:0/C16:0 ratio (HSF) or an isocaloric high fat diet with a low C18:0/C16:0 ratio (LSF) for 10 weeks. An oral glucose tolerance test, 72-h energy expenditure measurement and CT scan of body fat were done before sacrifice. Fasting glucose and lipids were determined by an autobiochemical analyzer. Blood insulin, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) levels were measured by enzyme-linked immunosorbent assay methods. Free fatty acids (FFAs) profiles in blood and liver were determined by using gas chromatography-mass spectrometry. Microarray analysis was applied to investigate changes in transcriptomic profiles in the liver. Pathway analysis and Gene Ontology analysis were applied to describe the roles of differentially expressed mRNAs. Results: Compared with the NFD group, body weight, body fat ratio, fasting blood glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), triglyceride, IL-6, serum and liver FFAs including total FFAs, C16:0 and C18:0 were increased in both high fat diet groups and were much higher in the HSF group than in the LSF group. Both HSF and LSF mice exhibited distinguishable lncRNA, microRNA and mRNA expression profiles when compared with those of NFD mice. Additionally, more differentially expressed lncRNAs and mRNAs were observed in the HSF group than in the LSF group. Some biological functions and pathways, other than energy metabolism regulation, were identified as differentially expressed mRNAs between the HSF group and LSF group. Conclusion: The high fat diet with a high C18:0/C16:0 ratio induced more severe glucose and lipid metabolic disorders and inflammation and affected expression of more lncRNAs and mRNAs than an isocaloric low C18:0/C16:0 ratio diet in mice. These results provide new insights into the differences in biological functions and related mechanisms, other than glucose and lipid metabolism, between C16:0 and C18:0.
... For example, palmitic acid (C16:0) and C18:0 are the most common and abundant long chain SFAs in food and human body, and C16:0 can be conversed to C18:0 in the body [8]. A high fat diet with an increase in C18:0 has been found to induce a metabolic state favoring lower oxidative metabolism and severe hepatic insulin resistance in mice, compared with an isocaloric high fat diet [9]. In mice deficient for Elovl6, a gene encoding the elongase that catalyzes the conversion of C16:0 to C18:0, the level of C18:0 decreased while the level of C16:0 increased in serum and liver, and the mice became obese and developed hepatosteatosis, but were protected from insulin resistance when fed a high-fat diet [10]. ...
... Respiratory exchange rate (RER) was calculated as VCO 2 /VO 2 . Fat and carbohydrate oxidation rates were calculated according to the following equation [9]: ...
Preprint
Full-text available
Background: Differential effects of individual saturated fatty acids (SFAs), particularly stearic acid (C18:0) relative to the shorter-chain SFAs have drawn an interest for more accurate nutritional guidelines. But specific biologic and pathologic functions that can be assigned to particular SFAs are very limited. The present study was designed to compare changes in metabolic and transcriptomic profiles in mice caused by high C18:0 diet and high palmitic acid (C16:0) diet. Methods: Male C57BL/6 mice were assigned to a normal fat diet (NFD), a high fat diet with high C18:0 / C16:0 ratio (HSF) or an isocaloric high fat diet with a low C18:0 / C16:0 ratio (LSF) for 10 weeks. Oral glucose tolerance test, 72h-energy expenditure measurement and CT scan of body fat were done before sacrifice. Fasting glucose and lipids were determined by an auto-biochemical analyzer. Blood insulin, tumor necrosis factor-α (TNF-α),and interleukin-6 (IL-6) were measured by enzyme linked immunosorbent assay methods. Free fatty acids (FFAs) profiles in blood and liver were determined by using Gas Chromatography-Mass Spectrometry. Microarray analysis was applied to investigate changes in transcriptomic profiles in liver. Pathway analysis and Gene Ontology analysis were applied to describe the roles of differentially expressed mRNAs. Results: Compared with NFD group, body weight, body fat ratio, fasting blood glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), triglyceride, IL-6, serum and liver FFAs including total FFAs, C16:0 and C18:0 were increased in both high fat diet groups, which were much higher in HSF group than those in LSF group. Both HSF and LSF mice exhibited distinguishable lncRNA, microRNA and mRNA expression profiles, compared with NFD mice. And more differentially expressed lncRNAs and mRNAs were observed in HSF group than those in LSF group. Some biological functions and pathways, other than energy metabolism regulation, were identified that differentially expressed mRNAs between HSF group and LSF group probably involved in. Conclusion: The high fat diet with a high C18:0/C16:0 ratio induced much severe glucose and lipid metabolic disorders and inflammation, and affected more lncRNAs and mRNAs expression than an isocaloric low C18:0/C16:0 ratio diet in mice. These results provide new insights into the different biological functions and related mechanisms, other than glucose and lipid metabolism, between C16:0 and C18:0. Take home message: A high fat diet with a high C18:0/C16:0 ratio probably leads to more changes in multiple biological processes or signaling pathways at transcriptional level than an isocaloric low C18:0/C16:0 ratio diet. The ratio of C18:0/C16:0 in diets should be taken into account for accurate nutrition and health in future.
... The increase we observed in the proportion of VLDL palmitic (16:0) and stearic (18:0) acids, both saturated fatty acids, on the LFD likely reflects an increase in de novo lipogenesis [43]. There is evidence that stearic acid (18:0) in the diet or as free fatty acid induces insulin resistance [44]. Moreover, in a recent cohort study, palmitic (16:0) and stearic (18:0) acids, measured in plasma phospholipids, were positively associated with incident type 2 diabetes [45]. ...
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Purpose We sought to determine the effects of dietary fat on insulin sensitivity and whether changes in insulin sensitivity were explained by changes in abdominal fat distribution or very low-density lipoprotein (VLDL) fatty acid composition. Methods Overweight/obese adults with normal glucose tolerance consumed a control diet (35 % fat/12 % saturated fat/47 % carbohydrate) for 10 days, followed by a 4-week low-fat diet (LFD, n = 10: 20 % fat/8 % saturated fat/62 % carbohydrate) or high-fat diet (HFD, n = 10: 55 % fat/25 % saturated fat/27 % carbohydrate). All foods and their eucaloric energy content were provided. Insulin sensitivity was measured by labeled hyperinsulinemic-euglycemic clamps, abdominal fat distribution by MRI, and fasting VLDL fatty acids by gas chromatography. Results The rate of glucose disposal (Rd) during low- and high-dose insulin decreased on the HFD but remained unchanged on the LFD (Rd-low: LFD: 0.12 ± 0.11 vs. HFD: −0.37 ± 0.15 mmol/min, mean ± SE, p < 0.01; Rd-high: LFD: 0.11 ± 0.37 vs. HFD: −0.71 ± 0.26 mmol/min, p = 0.08). Hepatic insulin sensitivity did not change. Changes in subcutaneous fat were positively associated with changes in insulin sensitivity on the LFD (r = 0.78, p < 0.01) with a trend on the HFD (r = 0.60, p = 0.07), whereas there was no association with intra-abdominal fat. The LFD led to an increase in VLDL palmitic (16:0), stearic (18:0), and palmitoleic (16:1n7c) acids, while no changes were observed on the HFD. Changes in VLDL n-6 docosapentaenoic acid (22:5n6) were strongly associated with changes in insulin sensitivity on both diets (LFD: r = −0.77; p < 0.01; HFD: r = −0.71; p = 0.02). Conclusions A diet very high in fat and saturated fat adversely affects insulin sensitivity and thereby might contribute to the development of type 2 diabetes. ClinicalTrials.gov Identifier NCT00930371.
... Respiratory exchange rate (RER) was calculated as VCO 2 /VO 2 . Fat and carbohydrate oxidation rates were calculated according to the following equation [9]: ...
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Background: Differential effects of individual saturated fatty acids (SFAs), particularly stearic acid (C18:0), relative to the shorter-chain SFAs have drawn interest for more accurate nutritional guidelines. However, specific biologic and pathologic functions that can be assigned to particular SFAs are very limited. The present study was designed to compare changes in metabolic and transcriptomic profiles in mice caused by a high C18:0 diet and high palmitic acid (C16:0) diet. Methods: Male C57BL/6 mice were assigned to a normal fat diet (NFD), a high fat diet with high C18:0/C16:0 ratio (HSF) or an isocaloric high fat diet with a low C18:0/C16:0 ratio (LSF) for 10 weeks. An oral glucose tolerance test, 72-h energy expenditure measurement and CT scan of body fat were done before sacrifice. Fasting glucose and lipids were determined by an autobiochemical analyzer. Blood insulin, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) levels were measured by enzyme-linked immunosorbent assay methods. Free fatty acids (FFAs) profiles in blood and liver were determined by using gas chromatography-mass spectrometry. Microarray analysis was applied to investigate changes in transcriptomic profiles in the liver. Pathway analysis and gene ontology analysis were applied to describe the roles of differentially expressed mRNAs. Results: Compared with the NFD group, body weight, body fat ratio, fasting blood glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), triglyceride, IL-6, serum and liver FFAs including total FFAs, C16:0 and C18:0 were increased in both high fat diet groups and were much higher in the HSF group than those in the LSF group. Both HSF and LSF mice exhibited distinguishable long non-coding RNA (lncRNA), microRNA and mRNA expression profiles when compared with those of NFD mice. Additionally, more differentially expressed lncRNAs and mRNAs were observed in the HSF group than in the LSF group. Some biological functions and pathways, other than energy metabolism regulation, were identified as differentially expressed mRNAs between the HSF group and the LSF group. Conclusion: The high fat diet with a high C18:0/C16:0 ratio induced more severe glucose and lipid metabolic disorders and inflammation and affected expression of more lncRNAs and mRNAs than an isocaloric low C18:0/C16:0 ratio diet in mice. These results provide new insights into the differences in biological functions and related mechanisms, other than glucose and lipid metabolism, between C16:0 and C18:0.
... These fatty acids are responsible for insulin resistance, as well as impairing the uptake of glucose by the liver. Furthermore, diets with high levels of stearic acid reduce energy expenditure and consequently increase adiposity (Van den Berg et al., 2010). Therefore, the composition of fatty acids in the diet is more important for checking out metabolic parameters than their overall amount. ...
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Background: Differential effects of individual saturated fatty acids (SFAs), particularly stearic acid (C18:0), relative to the shorter-chain SFAs have drawn interest for more accurate nutritional guidelines. However, specific biologic and pathologic functions that can be assigned to particular SFAs are very limited. The present study was designed to compare changes in metabolic and transcriptomic profiles in mice caused by a high C18:0 diet and high palmitic acid (C16:0) diet. Methods: Male C57BL/6 mice were assigned to a normal fat diet (NFD), a high fat diet with high C18:0/C16:0 ratio (HSF) or an isocaloric high fat diet with a low C18:0/C16:0 ratio (LSF) for 10 weeks. An oral glucose tolerance test, 72-h energy expenditure measurement and CT scan of body fat were done before sacrifice. Fasting glucose and lipids were determined by an autobiochemical analyzer. Blood insulin, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) levels were measured by enzyme-linked immunosorbent assay methods. Free fatty acids (FFAs) profiles in blood and liver were determined by using gas chromatography-mass spectrometry. Microarray analysis was applied to investigate changes in transcriptomic profiles in the liver. Pathway analysis and gene ontology analysis were applied to describe the roles of differentially expressed mRNAs. Results: Compared with the NFD group, body weight, body fat ratio, fasting blood glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), triglyceride, IL-6, serum and liver FFAs including total FFAs, C16:0 and C18:0 were increased in both high fat diet groups and were much higher in the HSF group than those in the LSF group. Both HSF and LSF mice exhibited distinguishable long non-coding RNA (lncRNA), microRNA and mRNA expression profiles when compared with those of NFD mice. Additionally, more differentially expressed lncRNAs and mRNAs were observed in the HSF group than in the LSF group. Some biological functions and pathways, other than energy metabolism regulation, were identified as differentially expressed mRNAs between the HSF group and the LSF group. Conclusion: The high fat diet with a high C18:0/C16:0 ratio induced more severe glucose and lipid metabolic disorders and inflammation and affected expression of more lncRNAs and mRNAs than an isocaloric low C18:0/C16:0 ratio diet in mice. These results provide new insights into the differences in biological functions and related mechanisms, other than glucose and lipid metabolism, between C16:0 and C18:0.
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1. The oxidation rates of lauric, myristic, palmitic, stearic, oleic, α-linolenic, linoleic, γ-linolenic, dihomo- γ-linolenic and arachidonic acids were studied by use of a radioisotope tracer technique in weanling rats at rest in a metabolism chamber over 24 h. 2. Of the saturated fatty acids, lauric acid (12:O) was the most efficient energy substrate: the longer the chain length of the saturated fatty acids, the slower the rate of oxidation. 3. Oleic acid (18:1) was oxidized at a remarkably fast rate, similar to that of lauric acid. 4. Of the ω6 essential fatty acids studied, linoleic acid (18:2ω6) was oxidized at a faster rate than any of its metabolites, with arachidonic acid (20:4ω6) being oxidized at the slowest rate. 5. The rate of oxidation of γ-linolenic acid (18:3ω3) was almost as fast as that of lauric and oleic acids.
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Utilization of stearate as compared to various saturated fatty acids for cholesterol and lipid synthesis and beta-oxidation was determined in primary culture of rat hepatocytes. At 0.5 mmol/L in the medium, stearate (18:0) adequately solubilized by albumin was less inhibitory to cholesterol synthesis from [2-14C] acetate than myristate (14:0) and palmitate (16:0) (68% vs. 91 and 88% inhibition, respectively). The rate of incorporation into cholesterol from [1-14C] stearate (3.0 +/- 0.6 nmol/mg protein/4 h) was 37-, 1.8-, and 7.8-fold of that from myristate, palmitate, and oleate, respectively. Conversely, the rate of [1-14C] stearate incorporation into total glycerolipids was 88-90% lower than that of labeled palmitate, myristate, and oleate. The rate of [1-14C] stearate incorporation into triacylglycerol (3.6 +/- 0.4 nmol/mg protein/4 h) was 6-8% of that from myristate, palmitate, oleate, and linoleate. The rate of stearate incorporation into phospholipids was the lowest among tested fatty acids, whereas the rate of mono- and diacylglycerol synthesis was the highest with stearate treatment. The rate of beta-oxidation as measured by CO2 and acid soluble metabolite production was also the lowest with [1-14C] stearate treatment at 22.7 nmol/mg protein/4 h, which was 35-40% of those from other [1-14C] labeled fatty acids. A greater proportion of stearate than other fatty acids taken up by the hepatocytes remained free and was not metabolized. Clearly, stearate as compared to shorter-chain saturated fatty acids was less efficiently oxidized and esterified to triacylglycerol in cultured rat hepatocytes.
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Stearic acid as compared to myristate, palmitate, or oleate is poorly incorporated into triacylglycerol, a major lipid component of very low density lipoprotein (VLDL). The present study investigated the effects of these fatty acids on VLDL metabolism in cultured rat hepatocytes. All fatty acids stimulated [2-3H] glycerol incorporation into VLDL lipids and secretion of [3H]-labeled VLDL by hepatocytes. However, the rate of [3H]-labeled VLDL secretion in the presence of nonlabeled stearate (12.8 +/- 0.7 pmol/mg protein/4 h) was 46, 59, and 22% of that observed for those treated with myristate, palmitate, and oleate, respectively. [1-14C]Stearate as a substrate was also less effective than other labeled fatty acids to be incorporated into VLDL lipids. Of total VLDL lipids synthesized from [1-14C] stearate, triacylglycerol accounted for 78% as compared to 88-97% of that derived from palmitate, myristate, and oleate. The amounts of apoB100 and apoB48 were the same in hepatocytes treated with or without exogenous fatty acids. Similarly, the rate of apoB synthesis from [35S] methionine was not affected by exogenous fatty acids. The treatment of cells with various saturated fatty acids increased the particle size of VLDL to different extents. The largest particles of VLDL, with a mean diameter of 79.3 +/- 11.9 nm, were seen in the cells treated with stearate, followed by those treated with palmitate and myristate (45.5 +/- 9.8 and 38.6 +/- 6.8 nm, diameter, respectively). Clearly, hepatocytes treated with stearate secrete less VLDL and produce larger VLDL particles than those treated with shorter-chain saturated fatty acids.
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Dietary fatty acids that are more prone to oxidation than to storage may be less likely to lead to obesity. The aim of this study was to determine the effect of chain length, degree of unsaturation, and stereoisomeric effects of unsaturation on the oxidation of individual fatty acids in normal-weight men. Fatty acid oxidation was examined in men consuming a weight-maintenance diet containing 40% of energy as fat. After consuming the diet for 1 wk, subjects were fed fatty acids labeled with (13)C in the methyl or carboxyl position (10 mg/kg body wt). The fatty acids fed in random order were laurate, palmitate, stearate, oleate, elaidate (the trans isomer of oleate), linoleate, and linolenate blended in a hot liquid meal. Breath samples were collected for the next 9 h and the oxidation of each fatty acid was assessed by examining liberated (13)CO(2) in breath. Cumulative oxidation over the 9-h test ranged from a high of 41% of the dose for laurate to a low of 13% of the dose for stearate. Of the 18-carbon fatty acids, linolenate was the most highly oxidized and linoleate appeared to be somewhat conserved. (13)C recovery in breath from the methyl-labeled fatty acids was approximately 30% less than that from the carboxyl-labeled fatty acids. In summary, lauric acid is highly oxidized, whereas the polyunsaturated and monounsaturated fatty acids are fairly well oxidized. Oxidation of the long-chain, saturated fatty acids decreases with increasing carbon number.