Michael Greger M.D. FACLM asks in his Nutritonfacts.org Blog, “What are the effects of spinach and berries on oxidative stress, inflammation, and muscle soreness in athletes?”
Higher fruit and vegetable consumption was “positively associated with muscle power” in adolescents, but they aren’t the ones who really need it. What about the consumption of fruits and vegetables and the risk of frailty in older adults? Researchers found that higher fruit and vegetable consumption was “associated with a lower short-term risk of frailty in a dose-response manner,” meaning more fruits or vegetables and less frailty. Those were observational studies, though, which, alone, can’t prove cause and effect. What happens when you put foods to the test?
As he discussed in his video Flashback Friday: Foods to Improve Athletic Performance and Recovery, there was “no positive influence of ingesting chia seed oil on human running performance,” but an effect was found for “spinach supplementation on exercise-induced oxidative stress.” Spinach supplementation? That just meant researchers gave some guys fresh, raw spinach leaves—one gram per kilo of body weight, which turned out to be about a quarter of a bunch a day—for two weeks and then had them run a half-marathon. They found that “chronic daily oral supplementation of spinach”—like eating a salad—“has alleviating effects on known markers of oxidative stress and muscle damage…”
As you can see at 1:16 in his video, when you run a half-marathon without supplementing with spinach, you get a big spike in oxidative stress and blood malondialdehyde levels that stay up for hours or even days later. In the spinach group, there isn’t much change before and after two weeks of spinach, but you can really see the difference after you put the body under pressure. After the rigors of a half-marathon, your body, supplemented with spinach, is better able to deal with the stress.
What happens when you look at muscle damage, as measured by creatine kinase (CK) leakage from the muscles? (CK is an enzyme that should be in your muscles, not leaking out into your blood.) Researchers found that levels started at about 100 U/L and went up to 200 U/L right after the half-marathon, two hours later. The next day is when you really feel that delayed onset muscle soreness, though. Without spinach supplementation, CK levels reached 600 U/L the day after the half-marathon before coming back down. But on spinach? You get a similar immediate post-race bump in CK leakage, but spinach really shines that next day: You don’t get the same next-day spike. So, for a competitive athlete, that quicker recovery may get you training harder again even sooner. The researchers attributed this to spinach’s anti-inflammatory effects.