Antioxidants & Oxidative Stress & Vitamins & Brain Baste on 11 Jan 2008 08:18 am
Is Vitamin E Deficiency Good for Your Brain?
Source: JBC 7 Jan 2008 (Epub)
Article Type: Original Research
Authors: Cuddihy et al.
For many people vitamin E supplementation is still the magic bullet for preventing the onset of chronic diseases and even the maladies of aging. Although vitamin E in its various forms is certainly important for cell and organ function, the present paper by Cuddihy et al. is a nice example that mother nature created the activity pattern of biomolecules not in a one-way fashion but somewhat chaotic. But read yourself…..
“Vitamin E is the major lipid soluble chain-breaking antioxidant in mammals and plays an important role in normal development and physiology. Deficiency (whether dietary or genetic) results in primarily nervous system pathology, including cerebellar neurodegeneration and progressive ataxia (abnormal gait). However, despite the widely acknowledged antioxidant properties of vitamin E, only a few studies have directly correlated levels of reactive oxygen species with vitamin E availability in animal models. We explored the relationship between vitamin E and reactive oxygen species in two mouse models of vitamin E deficiency; dietary deficiency, and a genetic model (tocopherol transfer protein, Ttp-/-, mice).
Both groups of mice developed near-complete depletion of alpha-tocopherol (the major tocopherol in vitamin E) in most organs, but not brain, which was relatively resistant to loss of alpha-tocopherol. F4-neuroprostanes, an index of lipid peroxidation, were unexpectedly lower in brain of deficient mice compared to controls. In vivo oxidation of dihydroethidium by superoxide radical was also significantly lower in brain of deficient animals. Superoxide production by brain mitochondria isolated from vitamin E deficient and Ttp-/- mice, measured by electron paramagnetic resonance spectroscopy, demonstrated a biphasic dependence on exogenously added alpha-tocopherol. At low concentrations, alpha-tocopherol enhanced superoxide flux from mitochondria, a response which was reversed at higher concentrations.
Here we propose a mechanism, supported by molecular modeling, to explain decreased superoxide production during alpha-tocopherol deficiency, and speculate that this could be a beneficial response under conditions of alpha-tocopherol deficiency.”
Image taken from: dopaminejewelery.com
on 11 Jan 2008 at 5:16 pm 1.CP said …
How delightfully counter-intuitive. Clearly vitamin E deficiency is bad for you on the balance, with the ataxia and neurodegeneration suggesting that it’s specifically bad for the brain. Could these results possibly indicate that tocopherol has an important mechanism that is completely unrelated to superoxide?
By the way — happy new year, Baste, and welcome back!
on 12 Jan 2008 at 4:09 pm 2.Curious said …
Hm, ok but… why only look at alpha-tocopherol? Vitamin E is not only alpha-tocoherol but rather eight vitamers and it has been known for some time that supplementation of only alpha-tocopherol is not optimal but rather negative since it depletes the other vitamers. I do not see this beeing addressed at all.
on 14 Jan 2008 at 9:26 pm 3.CP said …
Curious — I hadn’t heard that before. I’d love to see a reference on that subject if you’ve got one handy.
on 15 Jan 2008 at 4:22 am 4.Baste said …
Hi CP, hi Curious,
thanks for you comments and the vitamin E article!
I agree:
a) that alpha-toc must not be underestimated in its importance for various body functions (especially in the brain) - although clinical signs of alpha-toc deficiency are very rare in otherwise healthy humans,
b) that alpha-toc is certainly more than a direct free radical/ROS scavenger, and
c) that there’s indeed a trend to look at other vitamine E derivatives, in particular gamma-toc, which is more abundant than alpha-toc in many human diets.
Below a list of recent articles especially addressing latter question:
Wolf G:
How an increased intake of alpha-tocopherol can suppress the bioavailability of gamma-tocopherol.
Nutr. Rev. 2006;64(6):295-9
Comment on Nutr. Rev. 64(6):295-9:
Parker RS:
A recent brief critical review on how an increased intake of alpha-tocopherol can suppress the bioavailability of gamma-tocopher.
Nutr. Rev. 2007;65(3):139
Devaraj S et al.:
Failure of vitamin E in clinical trials: is gamma-tocopherol the answer?
Nutr. Rev. 2005;63(8):290-3
Reboul E et al.:
Effect of the main dietary antioxidants (carotenoids, gamma-tocopherol, polyphenols, and vitamin C) on alpha-tocopherol absorption.
Eur. J. Clin. Nutr. 2007;61(10):1167-73
Yoshikawa S et al.:
The effect of gamma-tocopherol administration on alpha-tocopherol levels and metabolism in humans.
Eur J Clin Nutr. 2005;59(8):900-5.
Sundl I et al.:
The decrease in gamma-tocopherol in plasma and lipoprotein fractions levels off within two days of vitamin E supplementation.
Ann N Y Acad Sci. 2004;1031:378-80
Wagner KH et al.:
Gamma-tocopherol–an underestimated vitamin?
Ann Nutr Metab. 2004;48(3):169-88
Jiang Q et al.:
gamma-tocopherol, the major form of vitamin E in the US diet, deserves more attention.
Am J Clin Nutr. 2001;74(6):714-22