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Nutrition Research Part One
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Nutrition Research Part 1
By Jamie Hale
In my new book there will be seventy one similar studies presented.
Polyunsaturated fatty acids of marine origin upregulate mitochondrial biogenesis and induce beta-oxidation in white fat.
Flachs P, Horakova O, Brauner P, Rossmeisl M, Pecina P, Franssen-van Hal N, Ruzickova J, Sponarova J, Drahota Z, Vlcek C, Keijer J, Houstek J, Kopecky J.
Department of Adipose Tissue Biology, Institute of Physiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20, Prague, Czech Republic, -email-.
AIMS/HYPOTHESIS: Intake of n-3 polyunsaturated fatty acids reduces adipose tissue mass, preferentially in the abdomen. The more pronounced effect of marine-derived eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids on adiposity, compared with their precursor alpha-linolenic acid, may be mediated by changes in gene expression and metabolism in white fat. METHODS: The effects of EPA/DHA concentrate (6% EPA, 51% DHA) admixed to form two types of high-fat diet were studied in C57BL/6J mice. Oligonucleotide microarrays, cDNA PCR subtraction and quantitative real-time RT-PCR were used to characterise gene expression. Mitochondrial proteins were quantified using immunoblots. Fatty acid oxidation and synthesis were measured in adipose tissue fragments. RESULTS: Expression screens revealed upregulation of genes for mitochondrial proteins, predominantly in epididymal fat when EPA/DHA concentrate was admixed to a semisynthetic high-fat diet rich in alpha-linolenic acid. This was associated with a three-fold stimulation of the expression of genes encoding regulatory factors for mitochondrial biogenesis and oxidative metabolism (peroxisome proliferator-activated receptor gamma coactivator 1 alpha [Ppargc1a, also known as Pgc1alpha] and nuclear respiratory factor-1 [Nrf1] respectively). Expression of genes for carnitine palmitoyltransferase 1A and fatty acid oxidation was increased in epididymal but not subcutaneous fat. In the former depot, lipogenesis was depressed. Similar changes in adipose gene expression were detected after replacement of as little as 15% of lipids in the composite high-fat diet with EPA/DHA concentrate, while the development of obesity was reduced. The expression of Ppargc1a and Nrf1 was also stimulated by n-3 polyunsaturated fatty acids in 3T3-L1 cells. CONCLUSIONS/INTERPRETATION: The anti-adipogenic effect of EPA/DHA may involve a metabolic switch in adipocytes that includes enhancement of beta-oxidation and upregulation of mitochondrial biogenesis.
PMID: 16205884 [PubMed - as supplied by publisher]
DECREASED PDH ACTIVATION AND GLYCOGENOLYSIS DURING EXERCISE FOLLOWING FAT ADAPTATION WITH CARBOHYDRATE RESTORATION.
Stellingwerff T, Spriet LL, Watt MJ, Kimber NE, Hargreaves M, Hawley JA, Burke LM.
Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.
Five days of a high fat diet while training, followed by 1 day of carbohydrate (CHO) restoration, increases rates of whole-body fat oxidation and decreases CHO oxidation during aerobic cycling. The mechanisms responsible for these shifts in fuel oxidation are unknown, but would involve up and down regulation of key regulatory enzymes in the pathways of skeletal muscle fat and CHO metabolism, respectively. This study measured muscle pyruvate dehydrogenase (PDH) and hormone sensitive lipase (HSL) activities pre- and post 20 min of cycling at 70% of VO2peak and 1 min of sprinting at 150% peak power output (PPO). Estimations of muscle glycogenolysis were made during the initial min of exercise at 70% VO2peak and during the 1 min sprint. Seven male cyclists undertook this exercise protocol on two occasions. For 5 days, subjects consumed in random order either a high-CHO (HCHO) diet (10.3 g(.)kg(-1)(.)day(-1) CHO or ~70% of total energy intake) or an isoenergetic high-fat (FAT-adapt) diet (4.6 g(.)kg(-1)(.)day(-1) FAT or 67% of total energy) while undertaking supervised aerobic endurance training. On day 6 for both treatments, subjects ingested a high CHO diet and rested before their experimental trials on day 7. This CHO restoration resulted in similar resting glycogen contents (FAT-adapt: 873 +/- 121 vs. HCHO: 868 +/- 120 umoles glucosyl units (.)g(-1) dw). However, the respiratory exchange ratio was lower during cycling at 70% VO2 peak in the FAT-adapt trial, which resulted in a ~45% increase and a ~30% decrease in fat and CHO oxidation respectively. PDH activity was lower at rest and throughout exercise at 70% VO2peak (1.69 +/- 0.25 vs 2.39 +/- 0.19 mmol(.)kg(-1) ww(.)min(-1)) and the 1 min sprint in the FAT-adapt compared to HCHO trial. Estimates of glycogenolysis during the first min of exercise at 70% VO2peak and the 1 min sprint were also lower following FAT-adapt (9.1 +/- 1.1 vs 13.4 +/- 2.1 and 37.3 +/- 5.1 vs 50.5 +/- 2.7 glucosyl units(.)kg(-1) dw(.)min(-1)). HSL activity was ~20% higher (P=0.12) during exercise at 70% VO2peak following FAT-adapt. These results indicate that the previously reported decreases in whole body CHO oxidation and increases in fat oxidation following the FAT-adapt protocol are a function of metabolic changes within skeletal muscle. The metabolic signals responsible for the shift in muscle substrate use during cycling at 70% VO2peak remain unclear but lower accumulation of free ADP and AMP following the FAT-adapt trial may be responsible for the decreased glycogenolysis and PDH activation during sprinting.
PMID: 16188909 [PubMed - as supplied by publisher]
Nutrition. 2005 Sep 22; [Epub ahead of print]
Breath acetone predicts plasma ketone bodies in children with epilepsy on a ketogenic diet.
Musa-Veloso K, Likhodii SS, Rarama E, Benoit S, Liu YM, Chartrand D, Curtis R, Carmant L, Lortie A, Comeau FJ, Cunnane SC.
Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada.
OBJECTIVE: The high-fat ketogenic diet has long been used to treat refractory childhood seizures, but whether there is a relation between the degree of ketosis and effectiveness of seizure control remains unclear. Frequent measurements of plasma ketones are difficult in children so the goal was to determine the utility of breath acetone as a marker of systemic ketosis and seizure control in children given the ketogenic diet because of seizures refractory to medication. METHODS: In experiment I, breath acetone and plasma ketones were assessed every 2 h during an 8-h test day in seven children. In experiment II, a preliminary assessment of the possible relation between breath acetone and seizure frequency was made over 14 d in five children and one adolescent on the ketogenic diet. RESULTS: Breath acetone was positively and curvilinearly related to plasma acetone (r(2) = 0.99, P < 0.0001), plasma acetoacetate (r(2) = 0.89, P < 0.0001), and plasma beta-hydroxybutyrate (r(2) = 0.94, P < 0.0001). No significant relation was found between breath acetone and seizure frequency or change in seizure frequency. CONCLUSIONS: Breath acetone is indicative of systemic ketosis while on the ketogenic diet. However, owing to the wide range of seizure types and plasma acetone, more subjects will be needed to determine whether there is a clear link between breath acetone and seizure frequency or decreased seizure frequency while on the high-fat ketogenic diet.
: J Nutr. 2005 Oct;135(10):2387-91
Reduced glycemic index and glycemic load diets do not increase the effects of energy restriction on weight loss and insulin sensitivity in obese men and women.
Raatz SK, Torkelson CJ, Redmon JB, Reck KP, Kwong CA, Swanson JE, Liu C, Thomas W, Bantle JP.
General Clinical Research Center.
Reducing the dietary glycemic load and the glycemic index was proposed as a novel approach to weight reduction. A parallel-design, randomized 12-wk controlled feeding trial with a 24-wk follow-up phase was conducted to test the hypothesis that a hypocaloric diet designed to reduce the glycemic load and the glycemic index would result in greater sustained weight loss than other hypocaloric diets. Obese subjects (n = 29) were randomly assigned to 1 of 3 diets providing 3138 kJ less than estimated energy needs: high glycemic index (HGI), low glycemic index (LGI), or high fat (HF). For the first 12 wk, all food was provided to subjects (feeding phase). Subjects (n = 22) were instructed to follow the assigned diet for 24 additional weeks (free-living phase). Total body weight was obtained and body composition was assessed by skinfold measurements. Insulin sensitivity was assessed by the homeostasis model (HOMA). At 12 wk, weight changes from baseline were significant in all groups but not different among groups (-9.3 +/- 1.3 kg for the HGI diet, -9.9 +/- 1.4 kg for the LGI diet, and -8.4 +/- 1.5 kg for the HF diet). All groups improved in insulin sensitivity at the end of the feeding phase of the study. During the free-living phase, all groups maintained their initial weight loss and their improved insulin sensitivity. Weight loss and improved insulin sensitivity scores were independent of diet composition. In summary, lowering the glycemic load and glycemic index of weight reduction diets does not provide any added benefit to energy restriction in promoting weight loss in obese subjects
1: J Appl Physiol. 2005 Sep 1;
FAT ADAPTATION FOLLOWED BY CARBOHYDRATE-LOADING COMPROMISES HIGH-INTENSITY SPRINT PERFORMANCE.
Havemann L, West SJ, Goedecke JH, Macdonald IA, St Clair Gibson A, Noakes TD, Lambert EV.
Department of Human Biology, University of Cape Town, Cape Town, South Africa.
The aim of this study was to investigate the effect of a high-fat diet (HFD) followed by 1-d of carbohydrate (CHO) loading on substrate utilization, heart rate variability (HRV), effort perception (RPE), muscle recruitment (EMG) and performance during a 100-km cycling time-trial. In this randomized single-blind crossover study, 8 well-trained cyclists completed two trials, ingesting either a high-CHO diet (HCD) (68% CHO energy) or an iso-energetic high-fat diet (HFD) (68% fat energy) for 6 days, followed by 1-d of CHO-loading (8-10g CHO/kg). Subjects completed a 100-km time-trial on day 1 and a 1-hr cycle at 70% of VO2peak on days 3, 5 and 7, during which resting HRV and resting and exercising respiratory exchange ratio (RER) were measured. On day 8, subjects completed a 100-km performance time-trial, during which blood samples were drawn and EMG was recorded. Ingestion of the HFD reduced RER at rest (p<0.005) and during exercise (p<0.01) and increased plasma FFA levels (p<0.01), indicating increased fat utilization. There was a tendency for the low frequency power component of HRV to be greater for HFD-CHO (p=0.056), suggestive of increased sympathetic activation. Overall 100-km time-trial performance was not different between diets, however 1-km sprint power output following HFD-CHO was lower (p<0.05) compared to HCD-CHO. Despite a reduced power output with HFD-CHO, RPE, heart rate and EMG were not different between trials. In conclusion, the HFD-CHO dietary strategy increased fat oxidation, but compromised high intensity sprint performance, possibly by increased sympathetic activation or altered contractile function.
PMID: 16141377 [PubMed - as supplied by publisher]
J Nutr. 2005 Sep;135(9):2082-9.
A systematic review of the effects of nuts on blood lipid profiles in humans.
Mukuddem-Petersen J, Oosthuizen W, Jerling JC.
School of Physiology, Nutrition and Consumer Science, North-West University (Potchefstroom Campus), Potchefstroom, South Africa.
The inverse association of nut consumption and risk markers of coronary heart disease (lipids) has sparked the interest of the scientific and lay community. The objective of this study was to conduct a systematic review to investigate the effects of nuts on the lipid profile. Medline and Web of Science databases were searched from the start of the database to August 2004 and supplemented by cross-checking reference lists of relevant publications. Human intervention trials with the objective of investigating independent effects of nuts on lipid concentrations were included. From the literature search, 415 publications were screened and 23 studies were included. These papers received a rating based upon the methodology as it appeared in the publication. No formal statistical analysis was performed due to the large differences in study designs of the dietary intervention trials. The results of 3 almond (50-100 g/d), 2 peanut (35-68 g/d), 1 pecan nut (72 g/d), and 4 walnut (40-84 g/d) studies showed decreases in total cholesterol between 2 and 16% and LDL cholesterol between 2 and 19% compared with subjects consuming control diets. Consumption of macadamia nuts (50-100 g/d) produced less convincing results. In conclusion, consumption of approximately 50-100 g ( approximately 1.5-3.5 servings) of nuts >/= 5 times/wk as part of a heart-healthy diet with total fat content (high in mono- and/or polyunsaturated fatty acids) of approximately 35% of energy may significantly decrease total cholesterol and LDL cholesterol in normo- and hyperlipidemic individuals
Eur J Clin Nutr. 2005 Aug 31
A randomized controlled trial of dietary fiber intake on serum lipids.
Chen J, He J, Wildman RP, Reynolds K, Streiffer RH, Whelton PK.
[1] 1Department of Medicine, Tulane University School of Medicine, New Orleans, LA, USA [2] 2Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, USA.
Objective:Clinical trials have indicated that water-soluble fiber from oats reduces serum cholesterol among hypercholesterolemic patients on a low-fat diet. We examined the effect of dietary fiber intake on serum lipids among persons without hypercholesterolemia.Design:Randomized controlled trial.Setting and subjects:We recruited 110 participants who were aged 30-65 years and had a serum cholesterol level <240 mg/dl from community.Intervention:Study participants were randomly assigned to receive 8 g per day of water-soluble fiber from oat bran or a control intervention.Results:At baseline, the mean levels of serum cholesterol and other measured variables were comparable between the high-fiber and control groups. Over the 3-month intervention, mean changes (95% confidence interval (CI)) in total, HDL-, and LDL-cholesterol were -2.42 mg/dl (-8.90 to 4.05 mg/dl; P=0.46), -0.24 mg/dl (-2.19 to 1.71 mg/dl; P=0.81), and -1.96 mg/dl (-7.32 to 3.40 mg/dl; P=0.47) in the fiber group and -0.02 mg/dl (-5.29 to 5.26 mg/dl; P=0.99), 1.42 mg/dl (-0.74 to 3.59 mg/dl; P=0.19), and -0.64 mg/dl (-5.30 to 4.03 mg/dl; P=0.79) in the control group, respectively. The net changes (95% confidence interval) in total, HDL-, and LDL-cholesterol were -2.40 mg/dl (-10.6 to 5.81 mg/dl; P=0.56), -1.66 mg/dl (-4.55 to 1.22 mg/dl; P=0.26) and -1.33 mg/dl (-8.33 to 5.68 mg/dl; P=0.71), respectively.Conclusions:Our study does not support the hypothesis that water-soluble fiber intake from oat bran reduces total and LDL-cholesterol in study participants with a normal serum cholesterol level.European Journal of Clinical Nutrition advance online publication, 31 August 2005; doi:10.1038/sj.ejcn.1602268.
Obes Res. 2005 Aug;13(8):1344-53
Effect of energy-reduced diets high in dairy products and fiber on weight loss in obese adults.
Thompson WG, Rostad Holdman N, Janzow DJ, Slezak JM, Morris KL, Zemel MB.
Mayo Clinic Graduate School of Medicine, Division of Preventive and Occupational Medicine, Rochester, MN 55905, USA. -email-
OBJECTIVE: Studies suggest that high-dairy and high-fiber/low-glycemic index diets may facilitate weight loss, but data are conflicting. The effects on weight loss and body fat of a high-dairy diet and a diet high in dairy and fiber and low in glycemic index were compared with a standard diet. RESEARCH METHODS AND PROCEDURES: Ninety obese subjects were recruited into a randomized trial of three diets designed to provide a calorie deficit of 500 calories/d over a 48-week period. The study compared a moderate (not low)-calcium diet with a high-calcium diet. RESULTS: Seventy-two subjects completed the study. Significant weight and fat loss occurred with all three diets. A diet with 1400 mg of calcium did not result in greater weight (11.8 +/- 6.1 kg) or fat (9.0 +/- 6.0 kg) loss than a diet with 800 mg of calcium (10.0 +/- 6.8 and 7.5 +/- 6.6 kg, respectively). A diet with 1400 mg of calcium, increased fiber content, and fewer high-glycemic index foods did not result in greater weight (10.6 +/- 6.8 kg) or fat (8.5 +/- 7.8 kg) loss than the standard diet with 800 mg of calcium. Lipid profile, high-sensitivity C-reactive protein, leptin, fasting glucose, and insulin improved significantly, but there were no significant differences between the experimental diets and the control diet. DISCUSSION: We found no evidence that diets higher than 800 mg of calcium in dairy products or higher in fiber and lower in glycemic index enhance weight reduction beyond what is seen with calorie restriction alone.

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