| 1. |
- Fairweather-Tait, S, et al.
(författare)
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The usefulness of in vitro models to predict the bioavailability of iron and zinc: A consensus statement from the HarvestPlus Expert Consultation
- 2005
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Ingår i: International Journal for Vitamin and Nutrition Research. - : Hogrefe Publishing Group. - 0300-9831 .- 1664-2821. ; 75:6, s. 371-374
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Tidskriftsartikel (refereegranskat)abstract
- A combination of dietary and host-related factors determines iron and zinc absorption, and several in vitro methods have been developed as preliminary screening tools for assessing bioavailability. An expert committee has reviewed evidence for their usefulness and reached a consensus. Dialyzability (with and without simulated digestion) gives some useful information but cannot predict the correct magnitude of response and may sometimes predict the wrong direction of response. Caco-2 cell systems (with and without simulated digestion) have been developed for iron availability, but the magnitude of different effects does not always agree with results obtained in human volunteers, and the data for zinc are too limited to draw conclusions about the validity of the method. Caco-2 methodologies vary significantly between laboratories and require experienced technicians and good quality cell culture facilities to obtain reproducible results. Algorithms can provide semi-quantitative information enabling diets to be classified as high, moderate, or low bioavailability. While in vitro methods can be used to generate ideas and develop hypotheses, they cannot be used alone for important decisions concerning; food fortification policy, selection of varieties for plant breeding programs, or for new product development in the food industry. Ultimately human studies are required for such determinations.
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| 2. |
- Filip, Rafal S., et al.
(författare)
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Alpha-ketoglutarate decreases serum levels of C-terminal cross-linking telopeptide of type I collagen (CTX) in postmenopausal women with osteopenia: Six-month study
- 2007
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Ingår i: International Journal for Vitamin and Nutrition Research. - : Hogrefe Publishing Group. - 0300-9831 .- 1664-2821. ; 77:2, s. 89-97
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Tidskriftsartikel (refereegranskat)abstract
- Several studies have shown that alpha-ketoglutaric acid (AKG) increases serum levels of proline and has beneficial effects on skeletal development. We studied the effect of alpha-ketoglutaric (AKG) acid calcium salt (6 g AKG and 1,68 Ca/day) or calcium alone (1.68 Ca/day) on serum C-terminal cross-linked telopeptide of type I collagen (CTX) and osteocalcin (OC), as well as lumbar spine bone mineral density (BMD) in a randomized, parallel group, double-blind, 6-month study conducted on 76 postmenopausal women with osteopenia. The maximum decrease of the mean CTX level in the AKG-Ca group was observed after 24 weeks (37.0%, p = 0.006). The differences in CTX between study groups were statistically significant after 12 weeks and 24 weeks. The OC serum level was not affected by treatments. The BMD of the AKG-Ca group increased 1.6% from baseline; however, the difference between treatment groups was estimated as 0.9% (non-significant). This study suggests the potential usefulness of AKG-Ca in osteopenic postmenopausal women. AKG-Ca induced beneficial changes in serum CTX, which was consistent with preserving the bone mass in the lumbar spine; however, the long-term effect needs to be further investigated.
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| 3. |
- van Kappel, Anne Linda, et al.
(författare)
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Plasma carotenoids in relation to food consumption in Granada (southern Spain) and Malmo (southern Sweden)
- 2001
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Ingår i: International Journal for Vitamin and Nutrition Research. - : Hogrefe Publishing Group. - 0300-9831 .- 1664-2821. ; 71:2, s. 97-102
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Tidskriftsartikel (refereegranskat)abstract
- We conducted a cross-sectional pilot study on healthy pre-menopausal women (aged 45-50 years) living in Granada, in the south of Spain (n = 39) and Malmo, in the south of Sweden (n = 38) in order to compare their plasma carotenoid levels and to investigate the relationship between the differences in food consumption. Plasma concentrations of six carotenoids were measured using high performance liquid chromatography, habitual diet (at individual level) was estimated by food frequency questionnaires and 24-hour diet recalls were used for standardised measurement of diet at group-level. We found that women in Granada consumed more fruit and vegetables than women in Malmo. Plasma concentrations of beta-cryptoxanthin, lycopene, zeaxanthin, total carotenoids and alpha-tocopherol were higher in Granada than in Malmo, although plasma concentrations of alpha-carotene and retinol were higher in Malmo. Both within and between study centres, consumption of fruit and vegetables correlated positively with plasma concentrations of different carotenoids. The study showed that differences in consumption of fruit and vegetables between the two European centres were reflected in plasma carotenoid concentrations.
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| 4. |
- Büttner, Barbara E, et al.
(författare)
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Quantification of isotope-labeled and unlabeled folates and folate catabolites in urine samples by stable isotope dilution assay.
- 2013
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Ingår i: International Journal for Vitamin and Nutrition Research. - : Hogrefe Publishing Group. - 0300-9831 .- 1664-2821. ; 83:2, s. 112-121
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Tidskriftsartikel (refereegranskat)abstract
- Dual-label stable isotope dilution assays for the simultaneous quantification of isotopologic folates in clinical samples offer the perspective for differentiating between unlabeled folates from endogenous body pools and administered [13C5]-labeled folates from a test dose when performing bioavailability trials. In contrast to intact folates, this methodology could hitherto not be applied to the quantification of the folate catabolites, p-aminobenzoyl glutamate and p-acetamidobenzoyl glutamate. In this study, [2H4]-p-aminobenzoyl glutamate, [2H4]-p-acetamidobenzoyl glutamate, and unlabeled p-acetamidobenzoyl glutamate were synthesized. The synthesis of the [2H4]-labeled compounds started at unlabeled p-aminobenzoic acid. For the formation of p-acetamidobenzoyl glutamate, p-aminobenzoyl glutamate was acetylated. The new substances were applied successfully in stable isotope dilution assays for the simultaneous quantification of the [13C5]-labeled and unlabeled folate catabolites, p-aminobenzoyl glutamate and p-acetamidobenzoyl glutamate, along with the predominant folate vitamers in urine. The assays were based on clean-up by strong anion exchange followed by liquid chromatography-tandem mass spectrometry detection. Assay sensitivity was sufficient to detect the folate catabolites in physiologic concentrations. The limit of detection was below 0.4 and 0.3 nmol/100 g for p-aminobenzoyl glutamate isotopologues and p-acetamidobenzoyl glutamate isotopologues in urine, respectively. The successful synthesis of [2H4]-p-aminobenzoyl glutamate, [2H4]-p-acetamidobenzoyl glutamate, and unlabeled p-acetamidobenzoyl glutamate and the implementation of these substances in stable isotope dilution assays allows dual-label designs that provide a more detailed insight into human folate metabolism.
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| 5. |
- Prawirohartono, Endy P, et al.
(författare)
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The impact of prenatal vitamin A and zinc supplementation on birth size and neonatal survival : a double-blind, randomized controlled trial in a rural area of Indonesia
- 2013
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Ingår i: International Journal for Vitamin and Nutrition Research. - : Hogrefe Publishing Group. - 0300-9831 .- 1664-2821. ; 83:1, s. 14-25
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Tidskriftsartikel (refereegranskat)abstract
- Background: Prenatal supplementation with rnicronutrients may increase birth weight and thus improve infant health and survival in settings where infants and children are at risk of micronutient deficiencies.Objective: To assess whether vitamin A and/or zinc supplementation given during pregnancy can improve birth weight, birth length, neonatal morbidity, or infant mortality. Methods: A double-blind, randomized controlled trial supplementing women (n=2173) in Central Java, Indonesia throughout pregnancy with vitamin A, zinc, combined vitamin A+zinc, or placebo.Results: Out of 2173 supplemented pregnant women, 1956 neonates could be evaluated. Overall, zinc supplementation improved birth length compared to placebo or combined vitamin A+zinc (48.8 vs. 48.5 cm, p = 0.04); vitamin A supplementation improved birth length compared to placebo or combined vitamin A+zinc (48.7 vs. 48.2 cm, p = 0.04). These effects remained after adjusting for maternal height, pre-pregnancy weight, and parity. There was no effect of supplementation on birth weight, the proportion of low birth weight, neonatal morbidity, or mortality.Conclusions: Prenatal zinc or vitamin A supplementation demonstrates a small but significant effect on birth length, but supplementation with zinc, vitamin A or a combination of zinc and vitamin A, have no effect on birth weight, neonatal morbidity, or mortality.
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| 6. |
- Sandberg, Ann-Sofie, 1951
(författare)
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The Use of Caco-2 Cells to Estimate Fe Absorption in Humans - a Critical Appraisal
- 2010
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Ingår i: International Journal for Vitamin and Nutrition Research. - : Hogrefe Publishing Group. - 0300-9831 .- 1664-2821. ; 80:4-5, s. 307-313
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Tidskriftsartikel (refereegranskat)abstract
- The Caco-2 cell model is widely used to assess the bioaccessibility/availability of iron from foods and diets. Analysis of iron uptake in this human epithelial cell line is usually preceded by a two-step digestion to simulate the conditions in the stomach and small intestine. Moreover, culturing the cells on inserts permits the measurement of iron transport. The cellular iron uptake is determined by direct measurements using radioisotopes, or indirectly by measurement of ferritin, the intracellular storage form of iron. There is a good correlation between Caco-2 cell uptake and human iron bioavailability for a number of dietary factors known to affect iron absorption. However, recent data suggest that in some cases there is no correlation. Possible reasons for such discrepancies, the benefits, and limitations of the Caco-2 cell model are discussed. In conclusion, in vitro experiments with Caco-2 cells are important tools for ranking foods with respect to bioavailability, for mechanistic studies of iron absorption, and for studies of dietary factors influencing absorption. The results need to be confirmed in humans.
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| 7. |
- Wang, B., et al.
(författare)
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An Association Study of SNP+45 T > G of the AdipoQ Gene with Type 2 Diabetes in Yi and Han People in China
- 2011
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Ingår i: International Journal for Vitamin and Nutrition Research. - : Hogrefe Publishing Group. - 0300-9831 .- 1664-2821. ; 81:6, s. 392-397
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Tidskriftsartikel (refereegranskat)abstract
- Background: The Yi people are considered the most primitive society in China, and live in the remote mountainous areas of Southwestern China. There have been no previous publications on genetic research concerning type 2 diabetes (T2D) in the Yi people. This is the first report that presents the association between SNP + 45 T > G (rs2241766) of the AdipoQ gene and T2D in Yi people. Our previous study showed that the prevalence of T2D in Yi people was lower than the national level in 2008. Genetic differences between Yi and Han people might be one possible explanation for this observation. Studies on the single nucleotide polymorphism SNP + 45 T > G (rs2241766) of the AdipoQ gene in Chinese Han people showed inconsistent results. This study was designed to identify genetic variants of the AdipoQ gene that contribute to the development of T2D in Yi and Han people. Methods: A case-control study on the association between SNP + 45 T > G (rs2241766) of the AdipoQ gene and T2D was carried out based on a cross-sectional study in the Liangshan area, Sichuan province in Southwestern China. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used to test for the presence of SNP + 45 T > G (rs2241766) in the AdipoQ gene. Results: Distributions of genotypes variants (TT/GG/TG) were not significantly different between T2D cases and controls both in Yi and Han people in China (p > 0.05). The allele frequencies (T/G) demonstrated a non-significant association with T2D, displaying OR of 1.1 (95 % CI: 0.8, 1.6) in Yi people and OR of 1.0 (95 % CI: 0.7, 1.4) in Han people. Conclusions: The SNP + 45 (rs2241766) of the AdipoQ gene is not associated with T2D neither in Yi nor in Han people in southwestern China.
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| 8. |
- Johansson, Clara, et al.
(författare)
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Down-regulation of oxidative DNA lesions in human mononuclear cells after antioxidant supplementation correlates to increase of gamma-tocopherol
- 2008
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Ingår i: International Journal for Vitamin and Nutrition Research. - : Hogrefe Publishing Group. - 0300-9831 .- 1664-2821. ; 78:4-5, s. 183-194
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Tidskriftsartikel (refereegranskat)abstract
- The protective effect of vitamin E supplements has been questioned, possibly because they often contain only alpha-tocopherol, and recent studies indicate that gamma-tocopherol also has important properties. The aim of this study was to investigate whether the levels of DNA lesions in middle-aged, overweight males could be reduced by consumption of low doses of an antioxidant supplement for six weeks, designed to imitate a balanced diet. The participants (n=60) were randomly divided into: placebo, single-, and double-dose groups. Genotoxic and oxidative DNA lesions in mononuclear cells were measured with the Comet assay, before and after supplement administration. Furthermore, a cell study was performed to investigate if pre-incubation of a human lung cell line (A549) with alpha- and gamma-tocopherol (5 and 50 microM for 23 hours) could protect against induced oxidative DNA lesions as measured by the Comet assay. The level of oxidative DNA lesions in the double-dose group was significantly lower than in the control group. Oxidative DNA lesions correlated only to changes in serum gamma-tocopherol, and not alpha-tocopherol. In the cell study, only gamma-tocopherol protected cells against induced oxidative DNA lesions. We therefore hypothesize that gamma-tocopheol rather than alpha-tocopherol is involved in reducing oxidative DNA lesions.
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| 9. |
- Karppi, J., et al.
(författare)
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Effects of astaxanthin supplementation on lipid peroxidation
- 2007
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Ingår i: International Journal for Vitamin and Nutrition Research. - : Hogrefe Publishing Group. - 0300-9831 .- 1664-2821. ; 77:1
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Tidskriftsartikel (refereegranskat)abstract
- Astaxanthin, the main carotenoid pigment in aquatic animals, has greater antioxidant activity in vitro (protecting against lipid peroxidation) and a more polar configuration than other carotenoids. We investigated the effect of three-month astaxanthin supplementation on lipid peroxidation in healthy non-smoking Finnish men, aged 19-33 years by using a randomized double-blind study design. Also absorption of astaxanthin from capsules into bloodstream and its safety were evaluated. The intervention group received two 4-mg astaxanthin (Astaxin®) capsules daily, and the control group two identical-looking placebo capsules. Astaxanthin supplementation elevated plasma astaxanthin levels to 0.032 µmol/L (p < 0.001 for the change compared with the placebo group). We observed that levels of plasma 12- and 15-hydroxy fatty acids were reduced statistically significantly in the astaxanthin group (p = 0.048 and p = 0.047 respectively) during supplementation, but not in the placebo group and the change of 15-hydroxy fatty acid was almost significantly greater (p = 0.056) in the astaxanthin group, as compared with the placebo group. The present study suggests that intestinal absorption of astaxanthin delivered as capsules is adequate, and well tolerated. Supplementation with astaxanthin may decrease in vivo oxidation of fatty acids in healthy men. © Hogrefe & Huber Publishers.
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| 10. |
- Lynch, Sean R., et al.
(författare)
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A comparison of physical properties, screening procedures and a human efficacy trial for predicting the bioavailability of commercial elemental iron powders used for food fortification
- 2007
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Ingår i: INTERNATIONAL JOURNAL FOR VITAMIN AND NUTRITION RESEARCH. - : Hogrefe Publishing Group. - 0300-9831 .- 1664-2821. ; 77:2, s. 107-124
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Tidskriftsartikel (refereegranskat)abstract
- Elemental iron powders are widely used to fortify staple foods. Experimental evidence indicates that there is considerable variation in the bioavailability of different products. For some powders, it may be too low to permit a significant impact on iron status. This study was designed to evaluate possible approaches to screening commercial iron powders for predicted bioavailability, to identify products that have the potential to improve iron status, and to ascertain whether bioavailability is related to the method of manufacture. Nine commercial iron powders were allocated to one of five types based on the production process; carbonyl, electrolytic, hydrogen-reduced (H-reduced), carbon monoxide-reduced (CO-reduced), and other reduced. Structure by scanning electron microscopy and physical properties (pycnometric and apparent density, particle size distribution, Fisher subsieve size, and surface area) were determined on all samples. Selected samples (one or more of each type depending on the cost of the assay) were then subjected to five screening procedures that have previously been advocated for predicting bioavailability in humans - dissolution rate in 0.1 mol/L HCl, dialyzability and Caco-2 cell iron uptake, both after simulated in vitro gastrointestinal digestion, relative bioavailability (RBV) with respect to ferrous sulfate by the AOAC rat hemoglobin repletion method, and plasma iron tolerance tests in human volunteers. The results for particle size distribution, surface area, Fisher subsieve size, dissolution rate in 0.1 mol/L HCl, and RBV in rats were significantly correlated and consistent for powders of the same type. However, values for different powder types were significantly different. There was no correlation between either dialyzability or Caco-2 cell uptake and the predicted bioavailability estimates based on the physical properties, dissolution rates, RBV in rats, or human efficacy data. Although human plasma iron tolerance tests were in general agreement with the other measures of predicted bioavailability, they did not provide information that would have improved the precision of bioavailability estimates based on physical properties, dissolution in HCl and/or RBV in rats. Our observations indicate that the dissolution rate in 0.1 mol/L HCl under standardized conditions is highly predictive of potential bioavailability and that it would be the most practical approach to developing a reliable and sensitive screening procedure for predicting and monitoring the bioavailability of commercial elemental iron powder products. Some, but not all, of the carbonyl and electrolytic iron powders had the highest predicted bioavailability values. The predicted bioavailability for the reduced iron products was lower and variable, with the lowest values being recorded for the carbon monoxide and other reduced iron products. Two powder types were selected for a human efficacy trial, electrolytic (because it is the iron powder type recommended by WHO) and hydrogen-reduced (because of its widespread use). Electrolytic/A131 and H-reduced/AC-325 had relative efficacies compared with ferrous sulfate monohydrate of 77% and 49%, respectively, based on the change in body iron stores in Thai women with low iron stores, who received an additional 12 mg iron per day, six days per week for 35 weeks in wheat-based snacks. We conclude that there is significant variability in the bioavailability of the commercial iron powders that we evaluated (those used for food fortification at the time that our studies were initiated), and that bioavailability is related in part to production method. The bioavailability of some carbonyl and electrolytic iron powders may be adequate for effective food fortification. The reduced iron powders that we tested are unlikely to have an adequate impact on iron nutrition at the fortification levels currently employed, although preliminary analysis of a new H-reduced product indicates that it may be possible to improve the bioavailability of individual powders of this type of product. We did find significant differences among products in both the electrolytic and carbonyl categories. Therefore, all products should be screened rigorously.
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