MUFA Group Research Articles

High-fat diets containing different types of fatty acids modulate gut-brain axis in obese mice

BackgroundExcessive consumption of high-fat diets is associated with disordered metabolic responses, which may lead to chronic diseases. High-fat diets containing different types of fatty acids lead to distinct alterations in metabolic responses of gut-brain axis.MethodsIn our study, normal male C57BL/6J mice were fed to multiple high fatty acid diets (long-chain and medium-chain saturated fatty acid, LCSFA and MCSFA group; n-3 and n-6 polyunsaturated fatty acid, n-3 and n-6 PUFA group; monounsaturated fatty acid, MUFA group; trans fatty acid, TFA group) and a basic diet (control, CON group) for 19 weeks. To investigate the effects of high-fat diets on metabolic responses of gut-brain axis in obese mice, blood lipids were detected by fast gas chromatography, and related proteins in brain and intestine were detected using Western blotting, ELISA, and immunochemistry analysis.ResultsAll high-fat diets regardless of their fatty acid composition induced obesity, lipid disorders, intestinal barrier dysfunction, and changes in gut-brain axis related factors except basal diet in mice. For example, the protein expression of zonula occludens-1 (ZO-1) in ileum in the n-3 PUFA group was higher than that in the MCSFA group (P < 0.05). The expressions of insulin in hippocampus and leptin in ileum in the MCSFA group significantly increased, compared with other groups (all Ps < 0.05).ConclusionThe high MCSFA diet had the most effect on metabolic disorders in gut-brain axis, but the high n-3 PUFA diet had the least effect on changes in metabolism.

Differences in Fatty Acid Profile and Physical-Chemical Composition of Slavonska slanina-Dry Cured Smoked Bacon Produced from Black Slavonian Pig and Modern Pigs.

Simple SummaryResearch on the products of local pig breeds is quite challenging as the populations are small, breeders are less educated and it is often difficult to design systematic research in various and usually different breeding conditions, compared to commercial breeds. In this study, we have analysed dry cured bacons, produced from the local Black Slavonian and modern breeds on the small home-made scale, and compared their physico-chemical properties and fatty acid profiles. Results have showed significant differences in chemical composition and fatty acid profiles between analysed pig breeds.The objective of this study was to compare the psysico-chemical composition and fatty acid (FFA) profile of traditional dry cured bacon Slavonska slanina, produced from the authentic Black Slavonian Pig (BP) and modern pigs (MP), using traditional homemade principles. The samples of Slavonska slanina produced from BP had a significantly (p < 0.05) higher fat content (78.32%) than the samples produced from MP (46.47%), while the samples produced from MP showed significantly higher (p < 0.05) protein and moisture content. The samples produced from BP also showed lower aw and salt content but higher pH. Determination of fatty acid composition was performed at the end of the production process. The composition of fatty acids with respect to the groups of saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids was determined, as well as the ratios n-6/n-3 and PUFA/SFA. The results of fatty acid composition determination of Slavonska slanina produced from BP and MP show that oleic acid (C18: 1n9) is the most dominant fatty acid from the MUFA group (47.02 and 46.25%), the most common SFA acid was palmitic acid (C16: 0) (23.44 and 24.96%), and PUFA linoleic acid (C18: 2n-6c) (10.76 and 9.74%). The genotype had a significant (p < 0.05) effect on the SFA and USFA composition of Slavonska slanina. The ratios PUFA/SFA (0.34–0.28) and n-6/n-3 (31.84–27.34) for samples of Slavonska slanina produced from BP and MP are in concordance with previously published data for different dry cured meat products, and do not comply with the nutritionally recommended values of international health organizations (PUFA/SFA > 0.4 and n-6/n-3 < 4).

Dietary fatty acids affect learning and memory ability via regulating inflammatory factors in obese mice

High-fat diets are linked to obesity, contributing to the alterations in inflammatory signaling pathways, which is associated with cognitive function. We aim to investigate the mechanisms by which various different types of dietary fatty acids affecting cognitive function in obese mice through the gut/brain axis-inflammatory signaling pathway. 8-week-old male C57BL/6 mice were fed with basal diet (control group), lard high-fat diet (containing long-chain saturated fatty acid (LCSFA group)), coconut oil high-fat diet (containing medium-chain saturated fatty acid (MCSFA group)), linseed oil high-fat diet (containing n-3 polyunsaturated fatty acid (n-3 PUFA group)), soybean oil high-fat diet (containing n-6 polyunsaturated fatty acid (n-6 PUFA group)), olive oil high-fat diet (containing monounsaturated fatty acid (MUFA group)) and 8% hydrogenated soybean oil high-fat diet (containing trans fatty acid (TFA group)) respectively for 16 weeks. Our results revealed that the mean escape latency was significantly prolonged in LCSFA group, and the latency to cross the platform location of n-6 PUFA and TFA groups were increased significantly. The differences of inflammatory markers and toll-like receptor-myeloid differentiation factor-88-nuclear factor kappa-B (TLR-MyD88-NF-κB) inflammatory signaling pathway expressions among all groups reached statistical significances. Compared to basal diet, high-fat diets enriched in LCSFA, MCSFA, n-6 PUFA, MUFA, and TFA might exert detrimental effects on cognitive function in obese mice via regulating the inflammatory markers and inflammatory signaling pathway in brain and intestine. High-fat diet enriched in n-3 PUFA might exhibit different effect on modulating inflammatory responses in different tissues and might benefit to cognitive function.

Dietary influence on adiponectin in patients with type 2 diabetes.

Here, we evaluate the effects of a diet rich in low-glycaemic index carbohydrates and fibre (CHO/Fibre diet) or monounsaturated fatty acids (MUFA diet), on fasting and postprandial adiponectin concentrations and their relationship with the beneficial effects of the experimental diets on postprandial glucose metabolism and liver fat in type 2 diabetes (T2D). Fasting and postprandial adiponectin plasma concentrations were measured before and after dietary interventions in the participants to a randomized controlled trial (NCT01025856), wherein 37 men and 8 women with T2D, aged 35-70years, followed a CHO/Fibre diet or a MUFA diet for an 8-week period. Hepatic fat content by 1 H NMR and fasting and postprandial plasma glucose and insulin measurements were also available. Fasting adiponectin plasma levels did not change after both diets. Postprandial adiponectin significantly increased after the CHO/fibre diet (9.9±1.6μg/mL vs. 10.8±2.3μg/mL; P=.033) but not after the MUFA diet (10.6±1.8μg/mL vs. 10.6±1.6μg/mL; P=.935) with a significant difference between changes (P=.035). In the combined CHO/Fibre and MUFA groups, fasting and postprandial adiponectin significantly and inversely correlated with postprandial insulin iAUC at baseline and after intervention, and with liver fat content after intervention. A diet rich in CHO/Fibre increased postprandial plasma adiponectin significantly more than a MUFA diet in patients with T2D. Independently of diet, adiponectin levels associated with postprandial insulin concentrations. The dietary interventions modulated the relationship between adiponectin and liver fat.

Hepatic cholesterol synthesis and lipoprotein levels impaired by dietary fructose and saturated fatty acids in mice: Insight on PCSK9 and CD36.

The aim of this study was to investigate the uncertain effects of high saturated fatty acids (SFAs) or fructose intake on cholesterol and lipoproteins with an insight of proprotein convertase subtilisin/kexin type 9 (PCSK9)- and cluster of differentiation 36 (CD36)-induced mechanisms. Forty male C57 BL/6 mice (8 wks of age) were divided into four groups and fed ad libitum with standard chow or three isocaloric diets containing high SFAs (SFA group), monounsaturated fatty acids (MUFA group, vehicle), or fructose for 15 wks. Subsequently, mice were sacrificed and blood, liver, and heart were collected for further analysis. Consequently, fructose or SFA intake resulted in higher plasma and liver total cholesterol (TC) levels, plasma low-density lipoprotein cholesterol (LDL-C), non-high-density lipoprotein cholesterol (HDL-C), apolipoprotein (Apo)-B levels, TC/HDL-C, and LDL-C/HDL-C ratios, and lower plasma levels of HDL-C and Apo-A1 (P < 0.05). Levels of 3-hydroxy-3-methylglutaryl-CoA reductase and acetyl-CoA acetyltransferase 1 enzymes in liver and CD36 levels in plasma were elevated by high SFAs and fructose intake (P < 0.05), whereas plasma PCSK9 levels were not significantly changed. Fructose and SFA intake increased PCSK9 and CD36 levels in the heart, along with increased CD36 levels in the liver (P < 0.05). Furthermore, plasma LDL-C was found to be positively correlated with liver PCSK9 (r=0.85, P=0.02), and CD36 (r=0.70, P=0.02) in the SFA and fructose groups. High intakes of dietary SFAs and fructose might induce dysregulations in the cholesterol synthesis and blood lipoprotein levels via proposed nutrient-sensitive biomarkers PCSK9 and CD36 in liver and extrahepatic tissues involved in cholesterol homeostasis.

285-LB: Short-Term Effect of Saturated and Monounsaturated Fatty Acids on Hepatic Energy Metabolism

Nonalcoholic fatty liver disease (NAFLD) is the most common form of liver disease affecting about 30% of the U.S. population. The prognosis for simple liver steatosis is relatively benign; however, chronic inflammation and progressive fibrosis may lead to nonalcoholic steatohepatitis (NASH) and later to cirrhosis and hepatocellular carcinoma. There is no established treatment to stop progression from NAFLD to NASH to date. Therefore, we developed a protocol to investigate the acute impact of saturated (SFA) and monounsaturated (MUFA) fatty acids on liver energy metabolism and their potential lipotoxic effects. Conscious, unrestrained, overnight fasted 12 weeks old male C57Bl/6J mice were given continuous, intravenous infusions of either saline, 20% lard oil or 20% olive oil emulsions (as described in Stein DT et al. J Clin Invest. 1997; 100 (2): 398-403) for 5 hrs. Lipid infusion was accompanied by primed, continuous infusion of [6,6-2H2] glucose (16mg/kg/min for 5 min and 0.8 mg/kg/min continuously) and sodium [13C3]lactate (200 μM/kg/min 5 min and 40 μM/kg/min continuously) intravenously for 4 and 2 hrs, respectively. Both plasma and liver free fatty acids were upregulated in SFA and MUFA groups. However, liver triglycerides, alanine aminotransferase (ALT) and aspartate transaminase (AST) were significantly increased, whereas plasma insulin and glucose levels significantly decreased, only in the MUFA group. 13C and 2H-enrichment of plasma glucose and liver alanine, glutamate, lactate and urea obtained at the end of the study were measured by GC-MS and used to regress liver metabolic fluxes using a flexible flux modeling platform (INCA). We observed that both SFA and MUFA increased the absolute rate of dihydroxyacetone phosphate (DHAP) flux from glycerol. Absolute flux of acetyl-CoA production was shifted from synthesis through pyruvate dehydrogenase toward increased contribution from fatty acid oxidation. On the other hand, only MUFA decreased the gluconeogenesis rate. Disclosure T. Bednarski: None. M. Rahim: None. J. Young: Consultant; Self; Pfizer Inc. Stock/Shareholder; Self; Metalytics. Funding National Institutes of Health (R01DK106348)

The Effect of Different High Fat Diets on Plasma Concentration and Hepatic Expression of Retinol‐Binding Protein 4 in Rats

Retinol‐binding protein 4 (RBP4) has been associated with insulin resistance and hepatic steatosis. Production of hepatic insulin resistance by high‐fat diets depends on their fatty acid composition. Here, the effect of three high‐fat diets on plasma concentration and hepatic expression of RBP4 (Rbp4) was compared with respect to insulin resistance, dyslipidemia, and hepatic steatosis.Weight‐matched groups (N=10/group) of male Sprague‐Dawley rats received one of four diets for eight weeks: low‐fat control (LF, 15% kcal as fat), or a high‐fat (HF, 55% kcal as fat) safflower oil (polyunsaturated), olive oil (cis‐monounsaturated, MUFA) or a trans‐fat (trans‐MUFA) diet. Blood samples were collected as a time course study at wks 3, 6, and 9 (N=16), and after an eight‐week feeding in the fasted or refed (fat‐free, high carbohydrate meal) state (N=40). Liver samples were collected at wk 9 in the fasted or refed state to compare plasma concentration and hepatic expression of RBP4 (Rbp4) and its response to insulin. Plasma RBP4 concentrations were measured by enzyme‐linked immunosorbent assay (ELISA). Hepatic expression of Rbp4 and other genes (e.g. Srebf, Fasn) was measured by real‐time PCR.Body weights and percent body fat of all HF groups were similar at wk 9. Plasma RBP4 concentrations were higher in the trans‐fat vs. the LF group at wk 3, 6, and 9 (p&lt; 0.05). The olive oil and the trans‐fat group had elevated plasma RBP4 at wk 9 vs. the LF group (p&lt;0.05). Liver expression of Rbp4 under fasted or re‐fed conditions did not differ among the groups, a finding consistent with a non‐hepatic (e.g. adipose tissue) source of RBP4. The olive oil group had higher fasting plasma insulin levels (p&lt;0.05), higher HOMA‐IR values (p&lt;0.005), higher liver lipid concentration (p &lt; 0.05) vs. other groups. Expression of hepatic genes in the lipogenic pathway was positively correlated with plasma triglyceride levels in both the olive oil and trans‐fat groups (p&lt; 0.05), and the olive oil group had greater stimulation of lipogenic gene expression by refeeding than did other groups (p&lt;0.05). The HF safflower group did not show differences from the LF group at wk 9.The HF olive oil (cis‐MUFA) diet was associated with elevated plasma RBP4, hyperinsulinemia, hepatic steatosis and insulin resistance, as well as an enhanced hepatic expression of lipogenic genes. The HF trans‐fat (trans‐MUFA) diet was also associated with elevated plasma RBP4 and increased lipogenic gene expression, and both MUFA groups showed this expression to be correlated with plasma triglyceride levels. These findings show that HF diet‐induced increases in RBP4 are dependent on the type of fat and suggest that non‐hepatic RBP4 may promote hepatic expression of lipogenic genes.

A comparison of the trans fatty acid content of uncooked and cooked lean meat, edible offal and adipose tissue from New Zealand beef and lamb

The concentrations of a group of trans fatty acids (FA) (not all isomers) in the lean tissue from 17 beef cuts and 18 lamb cuts were determined on raw and cooked within-cut composite samples (each containing lean tissue from at least 7 animals) as well as on composite samples (each from at least 9 animals) of raw and cooked edible offal items (5 items each from cattle and lamb), and single composite samples of subcutaneous and intermuscular adipose tissue for beef and lamb. For analysis, different cuts or offal items were the experimental unit as individual animal data were not available. Trans FAs were an average of 4.6% of total FA, with trans MUFA making up about 76% of the total. This value was higher for offal items than lean meat (78.9% vs. 73.4%; P=0.026), and higher for beef than lamb (79.4% vs. 72.9%; P=0.007). Of the trans MUFA, trans vaccenic acid (TVA, C18:1 t11) made up about 75% of the total, and this percentage was higher for lean meat than in offal (77.9% vs. 71.7%, P=0.001), and higher for lamb than beef (84.0% vs. 65.6%; P<0.0001). Of the non-MUFA fatty acids, the CLA C18:2 c9 t11 (rumenic acid (RA)) made up about 99% of the total, and was a higher percentage of total FAs in lamb than in beef (1.64% vs. 0.61%; P<0.0001). Trans FA levels following cooking were unaffected as a percentage of total FA, but were higher per unit weight of the product because the fat percentage was higher. It is concluded that the trans FA of beef and lamb are dominated by the seemingly beneficial FA (TVA and RA) for both the MUFA and non-MUFA groups.

Variation of Fatty Acid Content in Zamorano-Type Ovine Cheese According to the Milk Conjugated Linoleic Acid Content

A total of 30 Zamorano-type cheeses were manufactured in order to study the effects of milk conjugated linoleic acid (CLA) content, ripening time, and interactions between both effects on fatty acid (FA) profile. Cheeses elaborated from milk with a high CLA content showed higher contents of vaccenic, oleic, alpha-linolenic (ALA), CLA, monounsaturated (MUFA) and polyunsaturated (PUFA) FA, and lower contents of capric, lauric, myristic, palmitic, estearic, linoleic, and saturated (SFA) FA than cheese from milk with a low CLA content. Content of unsaturated C18 FA along with MUFA and PUFA groups increased throughout the ripening, while SFA content decreased. The interactions between milk CLA content and ripening time were significant for palmitic, linoleic, CLA, SFA, and omega-6/omega-3 ratio in Zamorano-type cheese. Decreases in cheese omega-6/omega-3 ratio were obtained from milk with a high CLA content; this ratio worsened over ripening in cheeses from low-CLA milk. In conclusion, these results emphasize the importance of the initial CLA content in milk with regard to improve the lipid profile in cheese for consumption.

Dietary Fat Increases Vitamin D-3 Absorption

BackgroundThe plasma 25-hydroxyvitamin D response to supplementation with vitamin D varies widely, but vitamin D absorption differences based on diet composition is poorly understood. ObjectivesWe tested the hypotheses that absorption of vitamin D-3 is greater when the supplement is taken with a meal containing fat than with a fat-free meal and that absorption is greater when the fat in the meal has a higher monounsaturated-to-polyunsaturated fatty acid ratio (MUFA:PUFA). DesignOpen, three-group, single-dose vitamin D-3 comparative absorption experiment. Participants/settingOur 1-day study was conducted in 50 healthy older men and women who were randomly assigned to one of three meal groups: fat-free meal, and a meal with 30% of calories as fat with a low (1:4) and one with a high (4:1) MUFA:PUFA. After a 12-hour fast, all subjects took a single 50,000 IU vitamin D-3 supplement with their test breakfast meal. Main outcome measuresPlasma vitamin D-3 was measured by liquid chromatography–mass spectrometry before and 10, 12 (the expected peak), and 14 hours after the dose. Statistical analyses performedMeans were compared with two-tailed t tests for independent samples. Group differences in vitamin D-3 absorption across the measurement time points were examined by analysis of variance with the repeated measures subcommand of the general linear models procedure. ResultsThe mean peak (12-hour) plasma vitamin D-3 level after the dose was 32% (95% CI 11% to 52%) greater in subjects consuming fat-containing compared with fat-free meals (P=0.003). Absorption did not differ significantly at any time point in the high and low MUFA and PUFA groups. ConclusionsThe presence of fat in a meal with which a vitamin D-3 supplement is taken significantly enhances absorption of the supplement, but the MUFA:PUFA of the fat in that meal does not influence its absorption.

Liver Fat Is Reduced by an Isoenergetic MUFA Diet in a Controlled Randomized Study in Type 2 Diabetic Patients

OBJECTIVETo evaluate the effects of qualitative dietary changes and the interaction with aerobic exercise training on liver fat content independent of weight loss in patients with type 2 diabetes.RESEARCH DESIGN AND METHODSWith use of a factorial 2 × 2 randomized parallel-group design, 37 men and 8 women, aged 35–70 years, with type 2 diabetes in satisfactory blood glucose control on diet or diet plus metformin treatment were assigned to one of the following groups for an 8-week period: 1) high-carbohydrate/high-fiber/low–glycemic index diet (CHO/fiber group), 2) high-MUFA diet (MUFA group), 3) high-carbohydrate/high-fiber/low–glycemic index diet plus physical activity program (CHO/fiber+Ex group), and 4) high-MUFA diet plus physical activity program (MUFA+Ex group). Before and after intervention, hepatic fat content was measured by 1H NMR.RESULTSDietary compliance was optimal and body weight remained stable in all groups. Liver fat content decreased more in MUFA (−29%) and MUFA+Ex (−25%) groups than in CHO/fiber (−4%) and CHO/fiber+Ex groups (−6%). Two-way repeated-measures ANOVA, including baseline values as covariate, showed a significant effect on liver fat content for diet (P = 0.006), with no effects for exercise training (P = 0.789) or diet-exercise interaction (P = 0.712).CONCLUSIONSAn isocaloric diet enriched in MUFA compared with a diet higher in carbohydrate and fiber was associated with a clinically relevant reduction of hepatic fat content in type 2 diabetic patients independent of an aerobic training program and should be considered for the nutritional management of hepatic steatosis in people with type 2 diabetes.

ESTIMATION OF FAT CONTENT AND FATTY ACIDS PROFILE IN THE MEAT OF SPINYCHEEK CRAYFISH (ORCONECTES LIMOSUS RAF.) FROM THE BRDA RIVER AND THE LAKE GOPŁO

The aim of the present paper was to compare the content of fat and the profile of fatty acids in the meat of the abdomen section of spiny-cheek crayfish caught from the Brda River with individuals obtained from the Lake Goplo. The meat of spiny-cheek crayfish from two reservoirs didn’t differ significantly as regards the fat content, however significant differences were report for most fatty acids (p<0,05). Reports show that the content of fat in crayfish meat is similar to the meat of low-fat fish which contain up to 2% of fat. In the group of SFA, the highest percentage share was recorded for C16:0, both in the meat of crayfish caught in the Brda River (21.33% of total acids) and in Lake Goplo (15.36% of total acids). In the MUFA group as the most abundant fatty acid was reported C18:1 n-9t, both in the meat of river crayfish (18.73% of total acids), and lake crayfish (25.52% of total acids). The PUFA analyses showed that the highest percentage share was reported for C20:5 n-3c in both groups.

Comparison of 3 ad libitum diets for weight-loss maintenance, risk of cardiovascular disease, and diabetes: a 6-mo randomized, controlled trial

Background:The optimal dietary content and type of fat and carbohydrate for weight management has been debated for decades. Objective:The objective was to compare the effects of 3 ad libitum diets on the maintenance of an initial weight loss of ≥8% and risk factors for CVD and diabetes during a 6-mo controlled dietary intervention. Design:Nondiabetic overweight or obese [mean ± SD body mass index (in kg/m2): 31.5 ± 2.6] men (n = 55) and women (n = 76) aged 28.2 ± 4.8 y were randomly assigned to a diet providing a moderate amount of fat (35–45% of energy) and >20% of fat as monounsaturated fatty acids (MUFA diet; n = 54), to a low-fat (20–30% of energy) diet (LF diet; n = 51), or to a control diet (35% of energy as fat; n = 26). Protein constituted 10–20% of energy in all 3 diets. All foods were provided free of charge from a purpose-built supermarket. Results:More subjects dropped out of the MUFA (28%) group than out of the LF group (16%) and control group (8%) (MUFA compared with control: P < 0.05). All groups regained weight (MUFA: 2.5 ± 0.7 kg; LF: 2.2 ± 0.7 kg; and control: 3.8 ± 0.8 kg; NS). Body fat regain was lower in the LF (0.6 ± 0.6%) and MUFA (1.6 ± 0.6%) groups than in the control group (2.6 ± 0.5%) (P < 0.05). In the MUFA group, fasting insulin decreased by 2.6 ± 3.5 pmol/L, the homeostasis model assessment of insulin resistance by 0.17 ± 0.13, and the ratio of LDL to HDL by 0.33 ± 0.13; in the LF group, these variables increased by 4.3 ± 3.0 pmol/L (P < 0.08) and 0.17 ± 0.10 (P < 0.05) and decreased by 0.02 ± 0.09 (P = 0.005), respectively; and in the control group, increased by 14.0 ± 4.3 pmol/L (P < 0.001), 0.57 ± 0.17 (P < 0.001), and 0.05 ± 0.14 (P = 0.036), respectively. Dietary adherence was high on the basis of fatty acid changes in adipose tissue. Conclusions:Diet composition had no major effect on preventing weight regain. However, both the LF and MUFA diets produced less body fat regain than did the control diet, and the dropout rate was lowest in the LF diet group, whereas fasting insulin decreased and the homeostasis model assessment of insulin resistance and ratio of LDL to HDL improved with the MUFA diet. This trial was registered at clinicaltrials.gov as NCT00274729.

Long-term effect of varying the source or amount of dietary carbohydrate on postprandial plasma glucose, insulin, triacylglycerol, and free fatty acid concentrations in subjects with impaired glucose tolerance

Reducing the glycemic load (GL) is considered beneficial for managing insulin resistance. The GL can be reduced either by reducing carbohydrate intake or by reducing the glycemic index (GI). We studied whether these 2 dietary maneuvers have the same long-term effects on postprandial plasma glucose, insulin, triacylglycerol, and free fatty acid (FFA) concentrations in subjects with impaired glucose tolerance (IGT). Thirty-four subjects with IGT were randomly assigned to high-carbohydrate, high-GI (high-GI); high-carbohydrate, low-GI (low-GI); and low-carbohydrate, high-monounsaturated fatty acid (MUFA) diets for 4 mo. Plasma glucose, insulin, and FFAs were measured from 0800 to 1600 at baseline in response to high-GI meals (60% carbohydrate, GI = 61, GL = 63) and after 4 mo in response to meals representative of the study diet. Carbohydrate intake (% of energy), GI, and GL in the high-GI, low-GI, and MUFA groups (breakfast and lunch meals combined), respectively, were 60%, 61, and 63; 60%, 53, and 55; and 49%, 61, and 52. Compared with the change after 4 mo of the high-GI diet, both the low-GI and MUFA diets reduced 0-8-h mean plasma glucose concentrations by 0.35 mmol/L (P < 0.05). Mean plasma insulin was approximately 20% higher (P < 0.05) and FFAs approximately 12% lower (P < 0.05) after the low-GI diet than after the high-GI diet, with no significant effect of MUFA. Changes in 0-8-h mean plasma triacylglycerols in the 3 treatment groups differed significantly: -0.14, 0.04, and 0.18 mmol/L, respectively, with the high-GI, MUFA, and low-GI diets. In subjects with IGT, reducing the GI of the diet for 4 mo reduced postprandial plasma glucose by the same amount as did reducing carbohydrate intake. The 2 dietary maneuvers had different effects on postprandial plasma insulin, triacylglycerols, and FFAs.

Do colonic short-chain fatty acids contribute to the long-term adaptation of blood lipids in subjects with type 2 diabetes consuming a high-fiber diet?

We recently obtained evidence of long-term adaptation of blood lipids to changes in intakes of carbohydrate and fiber in subjects with type 2 diabetes. We determined the effect of increased carbohydrate and fiber intakes on serum short-chain fatty acids (SCFAs) and the relation between changes in serum acetate and changes in blood lipids. Subjects with type 2 diabetes (n = 62) were randomly assigned to receive approximately 10% of energy from low-fiber breakfast cereal (LF diet), high-fiber breakfast cereal (HF diet), or monounsaturated fatty acids (MUFA diet) for 6 mo. Carbohydrate intakes were higher in the LF and HF groups than in the MUFA group (54% compared with 43%), and more fiber was consumed by the HF group (approximately 50 g/d) than by the LF or MUFA group (approximately 23 g/d). Fasting serum SCFAs did not change significantly over the first 3 mo. Between 3 and 6 mo, serum acetate tended (NS) to decrease in the LF group (from 69 +/- 4 to 59 +/- 5 micromol/L) and increase in the HF group (from 100 +/- 18 to 107 +/- 17 micromol/L), with no significant change in the MUFA group. Serum butyrate did not change significantly in the LF or MUFA group but increased in the HF group (from 2.5 +/- 0.5 to 3.1 +/- 0.6 micromol/L; P < 0.001). Changes in serum acetate from 0 to 3 mo were not related to changes in lipids. However, changes in serum acetate from 3 to 6 mo were positively related to changes in the ratio of total to HDL cholesterol (P = 0.041) and in fasting (P = 0.013) and postprandial (P = 0.016) triacylglycerols. In subjects with type 2 diabetes, changes in serum SCFAs in response to changes in carbohydrate and fiber intakes took many months to occur, and the changes in serum acetate were significantly related to the long-term adaptive changes in blood lipids.

β-Carotene 15,15′-Dioxygenase Activity and Cellular Retinol-Binding Protein Type II Level Are Enhanced by Dietary Unsaturated Triacylglycerols in Rat Intestines

The purpose of this study was to examine effects of dietary triacylglycerols on β-carotene 15,15′-dioxygenase (EC 1.13.11.21) activity and cellular retinol-binding protein [CRBP (II)] in rats. Six groups of eight rats (7-wk old) were fed one of the following diets: standard (STD; 2.5% soybean oil), saturated (SFA; 15% hydrogenated soybean oil), monounsaturated (MUFA; 15% olive oil), polyunsaturated (PUFA; 15% soybean oil) or clofibrate (CLF; 2.5% soybean oil + 0.2% clofibrate) for 3 wk. The dioxygenase specific activities of the intestinal homogenates in the MUFA and PUFA groups fed the high fat diets were 2.4 times that of the STD group fed a low fat diet (P < 0.01), whereas the activities of the SFA and CLF groups were not significantly different from that of the STD group. The level of CRBP (II) in the intestine of the PUFA group was 1.3-fold that of the STD group (P < 0.05), whereas there were no significant differences among the other groups. In a second experiment, the dioxygenase activity of rat intestine was followed over 3 wk of feeding the STD and PUFA diets. After the PUFA diet was consumed for 1 d, the activity was enhanced to 2.7 times the baseline level and remained thereafter at that high level, whereas the activity of the STD group remained at the low baseline level. Thus, dietary polyunsaturated triacylglycerols enhanced both β-carotene 15,15′-dioxygenase activity and CRBP (II) level in rat intestine. These results suggest that the dioxygenase and CRBP (II) are regulated by the same mechanism involving long-chain fatty acids and their metabolites.