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Efficacy of a 2-Month Very Low-Calorie Ketogenic Diet (VLCKD) Compared to a Standard Low-Calorie Diet in Reducing Visceral and Liver Fat Accumulation in Patients With Obesity.
Cunha, GM, Guzman, G, Correa De Mello, LL, Trein, B, Spina, L, Bussade, I, Marques Prata, J, Sajoux, I, Countinho, W
Frontiers in endocrinology. 2020;11:607
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Excess fat in the liver, known as non-alcoholic fatty liver disease (NAFLD), has been shown to increase the risk of chronic diseases such as type 2 diabetes. Standard treatment regimens consist of low-calorie (LC) diets and exercise, however these may be ineffective at reversing fat accumulation in the liver. A very low-calorie ketogenic diet (VLCKD) has been proposed as an alternative treatment for NAFLD. This randomised control pilot study of 39 individuals with obesity aimed to compare LC diet and VLCKD on fat accumulation and indicators for NAFLD for two months. The results showed greater weight loss, abdominal fat reduction, liver fat reduction and improvements in liver function with VLCKD compared to the LC diet. Cholesterol was significantly reduced by both diets. However liver stiffness remained unchanged. The authors concluded that VLCKD was more successful at reducing liver fat and abdominal fat accumulation than current standard therapy and has the potential to improve NAFLD. Health care professionals could use this study to improve liver and abdominal fat loss in patients with obesity to improve NAFLD, when standard therapy has been inadequate.
Abstract
Background: Currently the treatment of non-alcoholic fatty liver disease (NAFLD) is based on weight loss through lifestyle changes, such as exercise combined with calorie-restricted dieting. Objectives: To assess the effects of a commercially available weight loss program based on a very low-calorie ketogenic diet (VLCKD) on visceral adipose tissue (VAT) and liver fat content compared to a standard low-calorie (LC) diet. As a secondary aim, we evaluated the effect on liver stiffness measurements. Methods: Open, randomized controlled, prospective pilot study. Patients were randomized and treated either with an LC or a VLCKD and received orientation and encouragement to physical activity equally for both groups. VAT, liver fat fraction, and liver stiffness were measured at baseline and after 2 months of treatment using magnetic resonance imaging. Paired t-tests were used for comparison of continuous variables between visits and unpaired test between groups. Categorical variables were compared using the χ2-test. Pearson correlation was used to assess the association between VAT, anthropometric measures, and hepatic fat fraction. A significance level of the results was established at p < 0.05. Results: Thirty-nine patients (20 with VLCKD and 19 with LC) were evaluated at baseline and 2 months of intervention. Relative weight loss at 2 months was -9.59 ± 2.87% in the VLCKD group and -1.87 ± 2.4% in the LC group (p < 0.001). Mean reductions in VAT were -32.0 cm2 for VLCKD group and -12.58 cm2 for LC group (p < 0.05). Reductions in liver fat fraction were significantly more pronounced in the VLCKD group than in the LC group (4.77 vs. 0.79%; p < 0.005). Conclusion: Patients undergoing a VLCKD achieved superior weight loss, with significant VAT and liver fat fraction reductions when compared to the standard LC diet. The weight loss and rapid mobilization of liver fat demonstrated with VLCKD could serve as an effective alternative for the treatment of NAFLD. Clinical Trial Registration: ClinicalTrials.gov, identifier: NCT04322110.
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Effect of purple sweet potato leaf consumption on the modulation of the antioxidative status in basketball players during training.
Chang, WH, Chen, CM, Hu, SP, Kan, NW, Chiu, CC, Liu, JF
Asia Pacific journal of clinical nutrition. 2007;16(3):455-61
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Purple sweet potato leaves (PSPLs) have a high polyphenol content and have been shown to exhibit free-radical scavenging properties. During a training period athletes experience exercise-induced oxidative stress, and many studies have indicated that polyphenols can help prevent oxidative damage. Currently there is limited information on the physiologic and biochemical effects of dietary PSPLs in humans. The aim of this crossover study was to examine the effect of PSPLs on a variety of antioxidant status biomarkers in fifteen elite basketball players. Participants were enrolled for seven weeks and consumed a PSPL-rich diet and a control diet with a washout period in between. This study found that PSPL consumption for two weeks led to a significant increase in total plasma polyphenol concentration and vitamin E and C levels, and demonstrated a protective effect on lipid and DNA oxidation. The authors conclude that can a polyphenol-rich diet can modulate the anti-oxidative status of athletes during a training period.
Abstract
The aim of this study was to evaluate the effect of purple sweet potato leaves (PSPLs) consumption on antioxidative status and its modulation of that status in basketball players during training period. Fifteen elite basketball players were enrolled in this study. The seven-week study consisted of a run-in (week 1), PSPLs diet (daily consumption of 200 g PSPLs) (weeks 2, 3), washout (weeks 4, 5), and control diet (low polyphenol, with the amount of carotenoids adjusted to the same level as that of PSPLs) (weeks 6, 7). Blood and urine samples were taken for biochemical analysis. Compared with the control group, the results showed that PSPLs consumption led to a significant increase of plasma polyphenol concentration and vitamin E and C levels. Low density lipoprotein (LDL) lag time was significantly longer in the PSPLs group. A significant decrease of urinary 8-hydroxy-2-deoxyguanosine (8-OHdG) was noted; however, there was no significant change in plasma glutathione (GSH), total antioxidant status (TAS) and malondialdehyde + 4-hydroxy-2(E)-nonenal level after consuming the PSPLs diet. In conclusion, consumption of PSPLs diet for 2 weeks may reduce lipid and DNA oxidation that can modulate the antioxidative status of basketball players during training period.
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Metabolism of phytanic acid and 3-methyl-adipic acid excretion in patients with adult Refsum disease.
Wierzbicki, AS, Mayne, PD, Lloyd, MD, Burston, D, Mei, G, Sidey, MC, Feher, MD, Gibberd, FB
Journal of lipid research. 2003;44(8):1481-8
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Phytanic acid (PA) is a branched-chain fatty acid, found in many animal products, that, unlike most fatty acids, cannot be metabolised by beta-oxidation. Instead, it undergoes alpha-oxidation in the peroxisome. Adult Refsum Disease is a genetic neurological disease, in which alpha-oxidation is impaired, resulting in the accumulation of PA in nerves and fat tissues. Other pathways for the metabolism of PA are not fully understood, such as omega-oxidation, which results in the production of 3-methyl-organic acids (3-MAA). This study assessed the contribution of the omega-oxidation pathway to the metabolism of PA by measuring 3-MAA excretion in patients with ARD. Eleven patients with ARD were put on a low-PA diet for 12 weeks. Blood, urine and tissue samples were taken at the start and end of the 12-week period to assess levels of PA and its metabolites. The low-PA diet led to an average 21% fall in blood PA levels over 12 weeks. The capacity of the omega-oxidation pathway was 6.9mg PA/day. The authors concluded that the omega-oxidation pathway can metabolise PA ingested by patients with ARD. Therefore, omega-oxidation is a potential target for therapeutic intervention to reduce PA levels in ARD patients.
Abstract
Adult Refsum disease (ARD) is associated with defective alpha-oxidation of phytanic acid (PA). omega-Oxidation of PA to 3-methyl-adipic acid (3-MAA) occurs although its clinical significance is unclear. In a 40 day study of a new ARD patient, where the plasma half-life of PA was 22.4 days, omega-oxidation accounted for 30% initially and later all PA excretion. Plasma and adipose tissue PA and 3-MAA excretion were measured in a cross-sectional study of 11 patients. The capacity of the omega-oxidation pathway was 6.9 (2.8-19.4) mg [20.4 (8.3-57.4) micromol] PA/day. 3-MAA excretion correlated with plasma PA levels (r = 0.61; P = 0.03) but not adipose tissue PA content. omega-Oxidation during a 56 h fast was studied in five patients. 3-MAA excretion increased by 208 +/- 58% in parallel with the 158 (125-603)% rise in plasma PA. Plasma PA doubled every 29 h, while 3-MAA excretion followed second-order kinetics. Acute sequelae of ARD were noted in three patients (60%) after fasting. The omega-oxidation pathway can metabolise PA ingested by patients with ARD, but this activity is dependent on plasma PA concentration. omega-Oxidation forms a functional reserve capacity that enables patients with ARD undergoing acute stress to cope with limited increases in plasma PA levels.