Isabella Sundl

Oxidative stress increases continuously with BMI and age with unfavourable profiles in males

Oxidative stress is a risk factor for chronic diseases and was previously shown to be independently associated with obesity. The authors investigated the relationship between body mass index (BMI), age and oxidative stress on 2190 subjects undergoing a health care examination. Total antioxidant status (TAS), total peroxides (TOC) and autoantibodies against oxidized LDL (oLAb) were used as oxidative stress biomarkers in addition to serum lipoproteins, bilirubin and uric acid. Gender-specific differences were observed for age, BMI, serum concentrations of bilirubin, low-density lipoprotein (LDL), uric acid and TAS, all of which were higher in males (p < 0.001), while high-density lipoprotein (HDL), HDL/LDL ratio and TOC were higher in females (p < 0.001). Total cholesterol (p < 0.05) and LDL were increased (p < 0.05), while HDL was decreased (p < 0.05) in overweight and obese subjects. This was accompanied by increased uric acid and TAS concentrations. Lowest oLAb titers were detected in obese subjects. In extremely obese subjects, increased TOC and decreased TAS were observed in spite of high uric acid levels. These results demonstrate that oxidative stress increases with increasing BMI and age, as a sequel to an impaired antioxidant status, the consumption of oLAbs, an increase of peroxides and uric acid and a disadvantaged lipid profile.

Increased concentrations of circulating vitamin E in carriers of the apolipoprotein A5 gene −1131T>C variant and associations with plasma lipids and lipid peroxidation

The aim of this study was to investigate the effects of the apolipoprotein A5 (APOA5) 1131T>C gene variant on vitamin E status and lipid profile. The gene variant was determined in 297 healthy nonsmoking men aged 20–75 years and recruited in the VITAGE Project. Effects of the genotype on vitamin E in plasma, LDL, and buccal mucosa cells (BMC) as well as on cholesterol and triglyceride (TG) concentrations in plasma and apolipoprotein A-I (apoA-I), apoB, apoE, apoC-III, and plasma fatty acids were determined. Plasma malondialdehyde concentrations as a marker of in vivo lipid peroxidation were determined. C allele carriers showed significantly higher TG, VLDL, and LDL in plasma, higher cholesterol in VLDL and intermediate density lipoprotein, and higher plasma fatty acids. Plasma α-tocopherol (but not γ-tocopherol, LDL α- and γ-tocopherol, or BMC total vitamin E) was increased significantly in C allele carriers compared with homozygote T allele carriers (P = 0.02), but not after adjustment for cholesterol or TG. Plasma malondialdehyde concentrations did not differ between genotypes. In conclusion, higher plasma lipids in the TC+CC genotype are efficiently protected against lipid peroxidation by higher α-tocopherol concentrations. Lipid-standardized vitamin E should be used to reliably assess vitamin E status in genetic association studies.

Effects of vitamin E depletion/repletion on biomarkers of oxidative stress in healthy aging.

Abstract: The effects on ex vivo LDL resistance to oxidation and biomarkers of in vivo oxidative stress in response to 3‐month dietary vitamin E restriction to 25% of recommended intake and 2‐month unrestricted dietary intake and supplementation with 800 IU/d were studied in 100 healthy, nonsmoking 20‐75‐year‐old volunteers. Significant changes in vitamin E status were associated with decreases and increases, respectively, in LDL resistance to oxidation in the depletion and supplementation period and with decreases in lipid peroxidation and oxidative DNA modification in the supplementation period. Healthy aging was not associated with enhanced susceptibility to oxidation in the depletion period.

Effects of orlistat therapy on plasma concentrations of oxygenated and hydrocarbon carotenoids

Orlistat is a lipase inhibitor that is applied for treating obesity. Lipases are required for digestion and absorption of dietary lipids and fat-soluble vitamins and carotenoids. The aim of this study was to compare the effects of orlistat therapy on plasma concentrations of oxygenated (β-cryptoxanthin, lutein/zeaxanthin) and hydrocarbon (α-, β-carotene, lycopene) carotenoids. Six patients with a body mass index (BMI)≥30 kg/m2 received 360 mg/d orlistat over 4.5 mon. Plasma carotenoid concentrations were determined at baseline (T0) and after 3 (T3) and 4.5 mon (T4.5) along with anthropometric, dietary, and biochemical indices, including plasma lipids, retinol, α- and γ-tocopherols, and FA. Baseline BMI was 32.7±1.97 kg/m2. Five of six patients lost weight; the average weight loss was 3.6±2.4% (P=0.47). There were no significant changes in dietary carotenoid intakes. In contrast, plasma α-and β-carotene concentrations decreased significantly from T0 to T4.5 by 45% (P=0.006) and 32% (P=0.013), respectively. Plasma lycopene decreased from T0 to T3 but increased again from T3 to T4.5, while β-cryptoxanthin and lutein/zeaxanthin concentrations did not change. There were no significant alterations in tocopherol, retinol, and FA concentrations. In conclusion, even though weight loss was not significant, orlistat therapy was associated with significant decreases in plasma concentrations of the highly lipophilic hydrocarbon carotenoids, α- and β-carotene.

The Decrease in γ‐Tocopherol in Plasma and Lipoprotein Fractions Levels Off within Two Days of Vitamin E Supplementation

Abstract: The effects of vitamin E supplementation on α‐ and γ‐tocopherol concentrations were studied in plasma and lipoprotein fractions of five healthy volunteers taking 1000 IU/day of RRR α‐tocopherol for 4 days. Although plasma α‐tocopherol increased, γ‐tocopherol decreased. Compared with baseline, γ‐/α‐tocopherol ratios decreased from 48 h onward (P < 0.001). They all leveled off within 48 h. From 12 h onward, γ‐/α‐tocopherol ratios were higher in VLDL and IDL than in LDL and HDL, indicating that γ‐tocopherol is better maintained in triglyceride‐rich lipoprotein fractions. These data suggest that vitamin E supplementation exceeding 2 days does not further decrease γ‐tocopherol concentrations.

Does aging affect the response of vitamin E status to vitamin E depletion and supplementation

Abstract: A vitamin E depletion/supplementation study was conducted in 100 healthy 20‐75‐year‐old volunteers. The responses of vitamin E status to 3‐week dietary vitamin E restriction to approximately 25% of recommended intake and 2‐month unrestricted dietary intake plus 800 IU/d of RRR‐α‐tocopherol were studied as a function of age. Plasma α‐tocopherol concentrations were closely related to cholesterol concentrations, which increased with age (P < 0.001). Upon dietary restriction, plasma α‐tocopherol concentrations decreased significantly (P < 0.001) but independently of age. Plasma α‐tocopherol responses to supplementation increased significantly with age, but this effect disappeared after standardization for cholesterol. γ‐Tocopherol concentrations decreased to less than 30% of baseline.