Transcript: Preventing Exercise-Induced Oxidative Stress With Watercress
If oxidizing glucose to produce energy for our bodies is so messy, creating free radicals the way cars burning their fuel produce combustion by-products out the exhaust, even if we're just idling, living our day-to-day lives, what if we rev up our lives and start exercising, really start burning fuel? Then we create more free radicals, more oxidative stress and so we need to eat even more antioxidant-rich foods.
Why do we care about oxidative stress? Well, it's “implicated in virtually every known human disease and there is an increasing body of evidence linking free radical production to the process of aging.” Why? Because free radicals can damage DNA, our very genetic code. Well, if free radicals damage DNA, and exercise creates free radicals, does exercise damage our DNA if we don't have enough antioxidants in our system to douse the radicals? Yes, in fact, ultra-marathoners show evidence of DNA damage in about 10% of their cells tested during a race, which may last for up to two weeks after a marathon. But what about just short bouts of exercise? We didn't know until recently.
After just 5 minutes of moderate or intense cycling you can get an uptick in DNA damage. We think it's the oxidative stress, but "regardless of the mechanism of exercise-induced DNA damage” the fact that a very short bout of high-intensity exercise can cause an increase in damage to DNA is a cause for concern. But we can block oxidative damage with antioxidant-rich foods. Of course, when drug and supplement companies hear antioxidant rich foods they think, pills! You can't make billions on broccoli, so "Pharmacological antioxidant vitamins have been investigated for a prophylactic effect against exercise-induced oxidative stress.” However, large doses are often required and in pill form may ironically lead to a state of pro-oxidation and even more oxidative damage. For example, guys doing arm curls taking 500 mg of vitamin C appeared to have more muscle damage, inflammation, and oxidative stress.
So, instead of vitamin supplementation, how about supplementation with watercress, the badass of the broccoli family? What if, two hours before exercise, you eat a serving of raw watercress, then get thrown on a treadmill whose slope gets cranked up until you basically collapse? In the control group, without the watercress preload, which I imagine would describe most athletes, here's the amount of free radicals in their blood stream at rest and after exhaustive exercise, which is what you'd expect. So if you eat a super-healthy antioxidant-packed plant food like watercress before you exercise can you blunt this effect? Even better. You end up better than you started! At rest after the watercress you may start out with fewer free radicals, but only when you stress your body to exhaustion can you see the watercress really flex its antioxidant muscle.
What happens to DNA damage? Well, in a test tube, if you take some human blood cells bathed in free radicals, you can reduce the DNA damages it causes by 70% within minutes of dripping some watercress on them. But does that happen within the human body if you just eat it?
If you exercise without watercress in your system, DNA damage shoots up, but if you've been eating a single serving a day for two months your body's so juiced up on green leafy goodness you get no significant damage after punishing yourself on the treadmill. So - with a healthy diet, can you get all the benefits of strenuous exercise without the potential risks?
We know regular physical exercise is a key component of a healthy lifestyle, but it can elicit oxidative stress. To reduce that stress, some have suggested pills to improve one's antioxidant defense system, but "those eating more plant-based diets may naturally have an enhanced antioxidant defense system” without eating pills to counter exercise-induced oxidative stress, due to the increased quantities of plants alone! Remember that plant foods average 64 times more antioxidants than meat, fish, eggs, and dairy. And on top of that, the animal protein itself can have pro-oxidant effects. Anyone eating sufficient quantities of whole healthy plant foods could plausibly reach an antioxidant status similar to vegetarians. It's not just about what you're eating less of - saturated fat and cholesterol - but what you're eating more of, the phytonutrients. Whether it's about training longer or living longer, we've got to eat more plants.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Ariel Levitsky.
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