I've heard some recent talk by athletes of their concerns of a post-workout smoothie containing berries and greens. Athletes are hearing that they should avoid berries and greens for at least 4 hours post workout in order to optimize recovery. The case for avoiding antioxidant rich foods immediately after exercise is based on research saying that "antioxidant supplements seem to be working against the beneficial effects of exercise: Promoting, rather than reducing, oxidative stress." In other words, antioxidants can actually increase inflammation, rather than decreasing it.
As a Board Certified Sport Dietitian, I'd like to share my thoughts on this topic. But first I'd like to say that this is a topic that needs much more quality research before we (nutrition experts) can make a general recommendation to apply to all athletes.
- A free radical is an unstable molecule that’s missing at least one electron in its outermost orbit, which causes it to be negatively charged. Exercise increases the concentration of free radicals. Your body can also be exposed to free radicals from environmental sources, such as cigarette smoke, air pollution, and sunlight. Free radicals can cause “oxidative stress,” a process that can trigger cell damage. Free radicals have been to blame for many degenerative diseases, cancers and advanced aging.
- Antioxidants are substances that inhibit free radicals. Antioxidants supply free radicals with an electron and stop the chain reaction of the free radical stealing elections from healthy molecules.
- As a way to reduce free radical production, we have been told to increase antioxidant concentrations. A well balanced healthy diet should be rich in antioxidant rich foods. We should not be afraid to eat antioxidant rich foods throughout the day.
- For athletes, exercise can lead to an increase in free radical production during endurance and anaerobic exercise. For a while, experts were advocating for the use of supplements post exercise as a way to combat exercise-related free-radical to quicken recovery and to reduce post workout soreness. However, research has shown that increased free radical production post-exercise serves as an important signaling mechanism for favorable training adaptations. Most of the research has been on high dosage oral forms of antioxidant supplementation (A, C and E) - not food sources. From this research, it became clear that athletes should not supplement with antioxidants as it may be detrimental to training and performance. There is good evidence that athletes (and active individuals) should not supplement with antioxidants - I agree strongly with this (plates not pills).
Practical applications:
- There are few studies that I am aware of on comparing food sources of antioxidants (ex. blueberries) with the impact on oxidative stress. I don't feel we can yet make a clear statement that all antioxidant foods should be avoided 4-6 hours post workout.
- In research, the doses of antioxidants consumed are usually 10-17 times grater than the RDA. I feel comfortable saying that if you want to enjoy a 1/4 cup of blueberries, a small handful of spinach or 2 strawberries in your smoothie, this should not negatively impact your recovery process.
- To speed the recovery process the focus should start with protein/carbs/fluids/sodium. If this is done correctly, antioxidant rich foods do not need much of a spotlight post workout and can be instead, enjoyed later in the day. I feel comfortable saying that if you have a milk/protein and a handful granola post workout, you can still enjoy a bowl of oatmeal with goji berries and raspberries and not worry about negatively impacting your recovery.
- It can be misleading to say that all antioxidants should be avoided post workout and for how long. If you crave a glass of orange juice after a workout, you shouldn't be afraid to consume it. Putting fear into consuming real food can be troublesome.
- This is also one of those scenarios that we must see sport nutrition applications as "synergy" - we can't blame or put attention to just one nutrient. We don't know if post workout antioxidant supplement combined with protein will hinder performance. Also, different types of exercise induce different stressors in different people. Most studies are just on antioxidants and on small subjects (mostly men).
- I feel the better way to make this recommendation is to say there has been a long-standing belief that all oxidative stress is harmful for athletes. This has led to a widespread consumption of antioxidants. Because antioxidants are among the most commonly used supplements by athletes, we now know that antioxidant supplementation provides no beneficial effects on health and performance. Avoid antioxidant supplements and no need to overemphasize consumption of antioxidant-rich foods post workout.
I hope this helps to clear up any confusion.