Opname vitamine C uit fruit veel effectiever dan van supplementen*
Uit een Nieuw Zeelandse studie, weliswaar met muizen blijkt dat de opname in het lichaam van
vitamine C na het eten van fruit veel effectiever is dan de opname na inname van supplementen. In de studie kregen muizen met een vitamine C tekort gedurende een maand of aanvulling met
kiwi’s of water verrijkt met een gelijkwaardige hoeveelheid vitamine C. De opname van de natuurlijke vitaminebron bleek vijf keer effectiever dan die van de supplementen. De resultaten van deze studie kunnen ook belangrijk zijn voor mensen zodat de wetenschappers nu ook een soortgelijk onderzoek bij mensen gaat voeren.
Dietary ascorbate intake affects steady state tissue concentrations in vitamin C–deficient mice: tissue deficiency after suboptimal intake and superior bioavailability from a food source (kiwifruit)1,2,3
1. Margreet CM Vissers,
2. Stephanie M Bozonet,
3. John F Pearson, and
4. Lewis J Braithwaite
+ Author Affiliations
1. 1From the Free Radical Research Group (MCMV, SMB, and LJB) and the Department of Pathology (MCMV, SMB, LJB, and JFP), University of Otago, Christchurch, New Zealand.
+ Author Notes
· ↵2 Supported by the University of Otago, Christchurch, New Zealand, and by a grant from Zespri International Limited, Mt Maunganui, New Zealand. (Zespri International is a nongovernment company that markets kiwifruit and develops new varieties. They provided only funding for this study, with no input into the study design, analysis, or interpretation of the data and were approached by MCMV in the first instance). LB was the recipient of a Summer Studentship from the Health Research Council of New Zealand.
· ↵3 Address correspondence to MCM Vissers, Free Radical Research Group, Department of Pathology, University of Otago, Christchurch, PO Box 4345, Christchurch 8011, New Zealand. E-mail: margreet.vissers@otago.ac.nz.
Abstract
Background: Humans acquire vitamin C (ascorbate) from their diet, and optimal tissue concentrations are required to maintain its enzyme cofactor and antioxidant activities. How dietary intake affects tissue concentrations is difficult to monitor and has generally been based on the measurement of plasma concentrations.
Objective: We aimed to determine the effect of various ascorbate intakes on tissue concentrations in the Gulo mouse model of vitamin C deficiency and to compare the effectiveness of delivery when ascorbate was added to the drinking water or obtained through a fruit source (kiwifruit).
Design: Gulo−/− mice were fed various amounts of ascorbate for 1 mo, either in their drinking water or as a kiwifruit gel. Tissue vitamin C content was measured and compared with concentrations in wild-type mice.
Results: Ascorbate concentrations in serum, liver, kidney, heart, and white blood cells were extremely labile and were well below concentrations observed in the wild-type mice when serum concentrations were below saturation. All tissues except for brain were rapidly depleted when intake was stopped. Consumption of a preparation of fresh kiwifruit (either green or gold varieties) resulted in up to 5 times more effective delivery to tissues than when ascorbate was administered via the drinking water.
Conclusions: Subsaturation concentrations of plasma ascorbate resulted in severe deficiency in many tissues, and saturating amounts were required to achieve tissue concentrations similar to those found in wild-type animals. It is possible that the bioavailability of ascorbate is superior from some foods, such as kiwifruit. These results have important implications for human nutrition.
(Mei 2011)
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