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).
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).


METHODS
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.
Free Radical Research Group, University of Otago, Christchurch, New Zealand. margreet.vissers@otago.ac.nz
Margreet C M
MC
Vissers
Stephanie M
SM
Bozonet
John F
JF
Pearson
Lewis J
LJ
Braithwaite
D029042:Actinidia / Q000737:chemistry*; D000818:Animals; D001205:Ascorbic Acid / Q000008:administration & dosage* / Q000493:pharmacokinetics; D001206:Ascorbic Acid Deficiency / Q000188:drug therapy / Q000378:metabolism*; D001682:Biological Availability; D004032:Diet; D004195:Disease Models, Animal; D004326:Drinking; D005638:Fruit / Q000737:chemistry*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010936:Plant Extracts / Q000008:administration & dosage* / Q000493:pharmacokinetics; D014018:Tissue Distribution; D014867:Water
D010936:Plant Extracts; D014867:Water; D001205:Ascorbic Acid