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- Fischer, C.P, et al.
(författare)
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Vitamin E isoform-specific inhibition of the exercise-induced heat shock protein 72 expression in humans
- 2006
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Ingår i: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 100:5, s. 1679-1687
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Tidskriftsartikel (refereegranskat)abstract
- Increased levels of reactive oxygen and nitrogen species, as seen in response to exercise, challenge the cellular integrity. Important protective adaptive changes include induction of heat shock proteins (HSPs). We hypothesized that supplementation with antioxidant vitamins C (ascorbic acid) and E (tocopherol) would attenuate the exercise-induced increase of HSP72 in the skeletal muscle and in the circulation. Using randomization, we allocated 21 young men into three groups receiving one of the following oral supplementations: RRR-α-tocopherol 400 IU/ day + ascorbic acid (AA) 500 mg/day (CEα), RRR-α-tocopherol 290 IU/day + RRR-γ-tocopherol 130 IU/day + AA 500 mg/day (CEαγ), or placebo (Control). After 28 days of supplementation, the subjects performed 3 h of knee extensor exercise at 50% of the maximal power output. HSP72 mRNA and protein content was determined in muscle biopsies obtained from vastus lateralis at rest (0 h), postexercise (3 h), and after a 3-h recovery (6 h). In addition, blood was sampled for measurements of HSP72, α-tocopherol, γ-tocopherol, AA, and 8-isoprostaglandin-F2α (8-PGF2α). Postsupplementation, the groups differed with respect to plasma vitamin levels. The marker of lipid peroxidation, 8-iso-PGF2α, increased from 0 h to 3 h in all groups, however, markedly less (P < 0.05) in CEα. In Control, skeletal muscle HSP72 mRNA content increased 2.5-fold (P < 0.05) and serum HSP72 protein increased 4-fold (P < 0.05) in response to exercise, whereas a significant increase of skeletal muscle HSP72 protein content was not observed (P = 0.07). In CEα, skeletal muscle HSP72 mRNA, HSP72 protein, and serum HSP72 were not different from Control in response to exercise. In contrast, the effect of exercise on skeletal muscle HSP72 mRNA and protein, as well as circulating HSP72, was completely blunted in CEαγ. The results indicate that γ-tocopherol comprises a potent inhibitor of the exercise-induced increase of HSP72 in skeletal muscle as well as in the circulation.
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- Frank, J., et al.
(författare)
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Dietary flavonoids with a catechol structure increase alpha-tocopherol in rats and protect the vitamin from oxidation in vitro
- 2006
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Ingår i: Journal of Lipid Research. - 0022-2275 .- 1539-7262. ; 47:12, s. 2718-2725
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Tidskriftsartikel (refereegranskat)abstract
- To identify dietary phenolic compounds capable of improving vitamin E status, male Sprague-Dawleyrats were fed for 4 weeks either a basal diet ( control) with 2 g/kg cholesterol and an adequate content of vitamin E or the basal diet fortified with quercetin ( Q), (2)-epicatechin (EC), or (1)-catechin ( C) at concentrations of 2 g/kg. All three catechol derivatives substantially increased concentrations of alpha-tocopherol (alpha-T) in blood plasma and liver. To study potential mechanisms underlying the observed increase of alpha-T, the capacities of the Flavonoids to i) protect alpha-T from oxidation in LDL exposed to peroxyl radicals, ii) reduce alpha-tocopheroxyl radicals (alpha-T-.) in SDS micelles, and iii) inhibit the metabolism of tocopherols in HepG2 cells were determined. All flavonoids protected alpha-T from oxidation in human LDL ex vivo and dose-dependently reduced the concentrations of alpha-T-.. None of the test compounds affected vitamin E metabolism in the hepatocyte cultures. In conclusion, fortification of the diet of Sprague-Dawley rats with Q, EC, or C considerably improved their vitamin E status. The underlying mechanism does not appear to involve vitamin E metabolism but may involve direct quenching of free radicals or reduction of the alpha-T-. by the flavonoids.
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- Giacco, R., et al.
(författare)
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Fish oil, insulin sensitivity, insulin secretion and glucose tolerance in healthy people : Is there any effect of fish oil supplementation in relation to the type of background diet and habitual dietary intake of n-6 and n-3 fatty acids?
- 2007
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Ingår i: NMCD. Nutrition Metabolism and Cardiovascular Diseases. - : Elsevier BV. - 0939-4753 .- 1590-3729. ; 17:8, s. 572-580
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Tidskriftsartikel (refereegranskat)abstract
- Aim To evaluate whether a moderate supplementation of long-chain n-3 fatty acids is able to modulate insulin sensitivity, insulin secretion, β-cell function and glucose tolerance in healthy individuals consuming a diet rich in either saturated or monounsaturated fat, also in relation to their habitual dietary intake of n-6 and n-3 fatty acid. Methods and results One hundred and sixty-two healthy individuals were randomly assigned to follow either one of two isoenergetic diets for 3months, one rich in monounsaturated fats and the other rich in saturated fats. Within each group there was a second randomisation to fish oil (n-3 fatty acids 3.6g/day) or placebo. At the beginning and at the end of the treatment periods insulin sensitivity (SI), first phase insulin response (FPIR) and glucose tolerance (KG-value) were evaluated by the intravenous glucose tolerance test (IVGTT). Fish oil did not have any effect on SI, FPIR, KG-value and disposition index in either diet. Even after dividing subjects according to the median value of n-6/n-3 ratio of serum phospholipids at baseline, there was no change in SI (Δ SI 0.42±0.34 on fish oil vs 0.14±0.23 on placebo for those with n-6/n-3 <4.85; −1.03±0.47 on fish oil vs −0.27±0.32 on placebo for those with n-6/n-3 >4.85) (M±SE), FPIR (Δ FPIR 135.9±78.9 vs 157.2±157.5pmol/L; 38.8±181.7 vs 357.1±181.7pmol/L), KG-value (Δ KG 0.14±0.15 vs 0.12±0.11; −0.32±0.16 vs 0.15±0.15) or disposition index (Δ disposition index 1465.4±830.4 vs 953.8±690.0; −1641.6±1034.3 vs 446.6±905.1). Considering the 75th percentile of n-6/n-3 ratio (5.82) the results on insulin sensitivity, insulin secretion and disposition index were confirmed, while, in this more extreme situation, n-3 fatty acid supplementation induced a significant deterioration of KG-value (p=0.02). Conclusions In healthy individuals a moderate supplementation of fish oil does not affect insulin sensitivity, insulin secretion, β-cell function or glucose tolerance. The same is true even when the habitual dietary intake of n-6 and n-3 fatty acids is taken into account.
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- Katan, M B, et al.
(författare)
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Which are the greatest recent discoveries and the greatest future challenges in nutrition?
- 2009
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Ingår i: European Journal of Clinical Nutrition. - : Springer Science and Business Media LLC. - 0954-3007 .- 1476-5640. ; 63:1, s. 2-10
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Forskningsöversikt (refereegranskat)abstract
- BACKGROUND: Nutrition science aims to create new knowledge, but scientists rarely sit back to reflect on what nutrition research has achieved in recent decades. METHODS: We report the outcome of a 1-day symposium at which the audience was asked to vote on the greatest discoveries in nutrition since 1976 and on the greatest challenges for the coming 30 years. Most of the 128 participants were Dutch scientists working in nutrition or related biomedical and public health fields. Candidate discoveries and challenges were nominated by five invited speakers and by members of the audience. Ballot forms were then prepared on which participants selected one discovery and one challenge. RESULTS: A total of 15 discoveries and 14 challenges were nominated. The audience elected Folic acid prevents birth defects as the greatest discovery in nutrition science since 1976. Controlling obesity and insulin resistance through activity and diet was elected as the greatest challenge for the coming 30 years. This selection was probably biased by the interests and knowledge of the speakers and the audience. For the present review, we therefore added 12 discoveries from the period 1976 to 2006 that we judged worthy of consideration, but that had not been nominated at the meeting. CONCLUSIONS: The meeting did not represent an objective selection process, but it did demonstrate that the past 30 years have yielded major new discoveries in nutrition and health.
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| 7. |
- Nälsén, C, et al.
(författare)
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Plasma antioxidant capacity among middle-aged men : the contribution of uric acid
- 2006
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Ingår i: Scandinavian Journal of Clinical and Laboratory Investigation. - : Informa UK Limited. - 0036-5513 .- 1502-7686. ; 66:3, s. 239-248
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Tidskriftsartikel (refereegranskat)abstract
- Objective. Although assays of plasma antioxidant capacity encompass interactions between various antioxidants, uric acid concentration can exert a predominant effect on results. Therefore, individual differences in uric acid concentration may explain a many of the differences in antioxidant capacity. The objective of this study was to measure the antioxidant capacity of plasma samples with and without uric acid in order to provide more information about how the concept of antioxidant capacity could be applied. Material and methods. Antioxidant capacity was measured using an enhanced chemiluminescence assay, and uric acid was removed from the samples using uricase. Results. Antioxidant capacity was positively correlated with uric acid concentration, body mass index, waist circumference, abdominal sagittal diameter and the concentrations of insulin and triglycerides. These correlations were not evident when uric acid was eliminated from the sample, but antioxidant capacity was correlated with lipid concentration; this may partly reflect tocopherols that are transported by lipid molecules. Conclusions. The significance of the contribution of uric acid to the antioxidant capacity could differ according to the type of study. Antioxidant capacity measurements in cross‐sectional studies may be presented both with and without the contribution of uric acid, because the absence of such data complicates interpretation of results when different populations are compared.
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