A recent study looked at the effect of die on gene expression of superoxide dismutase (remember this plays a role in our internal antioxidant defense systems). What the researchers found was that those eating more plants (vegetarians) had 3x the gene expression of superoxide dismutase.  Thus, this study would suggest that diet can impact mitochondrial oxidative stress.

But can this help me as an athlete?  Likely it can.  In another study, athletes who drank 75 ml of tomato juice for 60 days after their morning training session had about double the concentration of glutathione peroxidase than the control group.  They also improved their performance on a 12 min run test compared to the control group undergoing the same training. 

Distance runners have been shown to have DNA damage in 10% of their cells, both during and for up to two weeks after a long run, such as a marathon.  A more recent study found that even short bouts of intense exercise can cause an uptick in damage to the DNA.  To see if antioxidant rich foods could prevent this, researchers had subjects eat watercress (rich in antioxidants) two hours before a treadmill test.  Without the watercress free radicals in their blood went up after the exercise.  After eating the water cress there were significant reductions in free radical levels.  In fact levels were even lower than before the test.  When it came to measures of DNA damage, those who ate no watercress had increased damage, while those eating daily servings of watercress less DNA damage, BTW damaged DNA is not good for athletic performance in that it can limit aerobic capacity. 

Other foods shown to reduce exercise induced oxidative stress are from legumes and other plant foods (like fruit).  Flavonoids are potent inhibitors of Xanthine Oxidase (XO) activity.  XO is the main contributor of free radicals during exercise.  For more listen to this review by Dr. Greger. 

As it turns out, supplements or antioxidants that come in a pill form don’t show the same benefit. In fact, some supplements may worsen measures of oxidative stress or inhibit the bodies own defense systems.  No surprise really.  We’ve seen this with Vit A and Vit E supplements.  But more on that later.  Thus, as per usual, the best sources are whole foods.  There is likely a synergistic effect of these nutrients that isn’t present when you take the nutrients out of their natural packaging and put them into pill form.  

For my magic vegetable smoothie which incorporates tomato juice and greens, go here.