1.5g of Vitamin C do not Alter Neutrophil Function in Athletes: ROS & SOA Elevations Remain Unchanged

The verdict is still out there on whether antioxidant supplementation before or around exercise is a good or a bad thing for professional athletes. A recent study by Yamai et al. (Yamai. 2011) which investigated the effect of 1.5g of vitamin C /day on the neutrophil function of judoists found no evidence for either of the propositions - neutrophil counts were not statistically different between the two groups of the 22 male judoists after a 7-day intensified training camp for:

[...]although the typical changes seen following a single bout of normal exercise, namely an increase in SOA [serum opsonic activity] and ROS [reactive oxygen species], and a decrease in PA [neutrophil phagocytic activity], were recorded following the pre- and post-camp ULEs in both groups, significant difference in change rates were not seen between both groups.

These results go hand in hand with many other more recent investigations into the beneficial effects of vitamin C and combinations of antioxidants (a factor the scientists raise in their discussion of the results) on exercise performance in (elite) athletes. So, even if vitamin C won't hurt you, it probably won't help either.

Dietary Oxidized Frying Oil Impairs Pancreatic Insulin Release. Vitamin E Helps!

It certainly is no coincidence that a recent study on the detrimental effects of oxidized frying oil (OFA) was published in the British Journal of Nutrition. Afterall, it suggests that the British are at risk of dying out, if they just listened to their appetite and kept over-consuming "Fish and Chips".

After feeding rats with either soy (HF) or oxidized frying oil (HO) over a period of 8 weeks the researchers found:

[...] mice in the HO group showed glucose intolerance and hypoinsulinaemia, and their islets showed impaired glucose-stimulated insulin secretion (P,0·05; HO group v. LF and HF groups). Significantly higher oxidative stress and a lower mitochondrial membrane potential were observed in the islets in the HO group compared with the LF and HF groups. Immunoblots showed that the reduction in insulin levels in HO islets was associated with activation of the c-Jun NH2-terminal kinase and a reduction in levels of pancreatic and duodenal homeobox

Furthermore, they found that, "when dietary OFO-induced tissue vitamin E depletion was prevented by high-dose vitamin E supplementation (500 IU(1·06 mmol all-rac-a-tocopherol acetate)/kg diet; [...] the OFO-mediated reduction in islet size and impairment of glucose tolerance and insulin secretion were significantly attenuated."

So, obviously it is the interplay of oxidation and lack of antioxidants (in this case vitamin E) which collectively initiate these metabolic changes, which consequently are at the bottom of what is often called "the metabolic syndrome". Bottom line: Beware of oxidized fats and support your antioxidant capacity by healthy food choices and supplements.