Exercise and oxidative stress – get your antioxidants from whole foods

Today’s post is a long but Heather the science geek wanted to shed a little light on all of this antioxidant stuff that we hear about and give a bit more in-depth background to support the take home message: eating plant-based whole foods, not relying on antioxidant supplements, is paramount to your recovery and will help you soak up all those hard Ironman training sessions.

A paradox in metabolism is that while the vast majority of complex life requires oxygen for its existence, oxygen is a highly reactive molecule can damage living organisms by producing reactive oxygen species (ROSs – nasty things like the RUSs in the Princess Bride). ROSs are highly reactive ions or small molecules that have unpaired valence shell electrons. Huh? what? Basically they are just hyped up molecules that have all this energy and want to react with stuff so they grab at anything… say lipids in the membranes of your mitochondria. Enough unquenched, super excited, ROSs nipping at things and you can get cell death. Because of this, organisms contain a complex network of antioxidant metabolites and enzymes that work together to prevent oxidative damage to cellular components like DNA, proteins and lipids. Reducing agents, (I’m double-O-carotene) like Beta Carotene and vitamin C neutralize ROS’s and prevent them from causing damage – “leave that cell membrane alone, it’s me your after!”

In general, antioxidant systems either prevent too many nasty ROSs from being formed, or remove them before they can damage vital components of the cell. However, just like all ‘zee Russians’ aren’t bad guys in Bond films – some reactive oxygen species do have useful functions in cells, such as signaling. The function of antioxidant systems is not to remove oxidants entirely, but instead to keep them at an optimum level.

“Okay, um these are supposed to be Ironman Triathlon Tips… Hewro!?” I’m getting there…During exercise, oxygen consumption can increase by a factor of more than 10. Us long distance triathlete types really like the aerobic stuff so we suck back a lot of O2. This leads to a large increase in the production of oxidants and results in damage that contributes to muscular fatigue during and after exercise. The inflammatory response that occurs after strenuous exercise is also associated with oxidative stress, especially in the 24 hours after an exercise session. The immune system response to damage done by exercise peaks 2 to 7 days after exercise (this is why staying on top of your diet is so important for optimum recovery, training… everything). During this process, free radicals are produced by neutrophils (the most abundant type of white blood cells in humans) to remove damaged tissue. They are some of the good ROSs. As a result, excessive antioxidant levels (e.x. from over supplementation) have the potential to actually inhibit recovery and adaptation mechanisms.

Antioxidants can cancel out the cell-damaging effects of free radicals, but oxidants are still needed to some degree. This may be why all those controlled studies using antioxidant vitamin supplements have observed no reduction in either the risk of developing heart disease, cancer, neurological disorders… or the rate of progression of existing disease. Other substances in fruit and vegetables (possibly flavonoids), or the delightfully complex mix of substances that make them so tasty, are what really contributes to the health of those who consume more fruit and vegetables.

So, don’t down a bunch of extra vitamin C and beta carotene pills thinking you are doing your body good. Eat some carrots, a pomegranate, broccoli, swiss chard, kiwis, berries, yams…. This list is long, appealing and a better buy.