What are antioxidants and how do they work?
Vitamin C is a supplement that many people take, especially those who take a big interest in their health, fitness and nutrition. And for good reason - vitamin C, especially in supplemented doses, has many benefits. This is because vitamin C is what’s known as an antioxidant. Vitamins E is also a well-known antioxidant. They play a really important protective role in our bodies. They are produced by our bodies and are also found in certain foods.
Our cells continually produce free radicals. These free radicals are known as reactive oxygen species or ROS for short. Production of such ROS is part of normal day-to-day processes. But like anything, too great a production of ROS can be troublesome and can contribute to oxidative stress in the body. This may damage your DNA and other important structures in your cells. Chronic oxidative stress can increase your risk of chronic diseases such as heart disease, type 2 diabetes and cancer. Free radicals also cause damage in muscle as well as other tissues.
This is where antioxidants such as vitamin C come into play and help to defend your cells against these free radicals or ROS. But ROS are not all bad. Like anything, balance is key. Too much ROS can be implicated in chronic diseases but a certain amount of ROS are also needed. This is because they can also serve as important signalling mechanisms inside our bodies. ROS play a particularly important role in exercise. This is because are particularly important signalling molecules during cellular stress, and actually signal for initiating muscle growth and recovery after a workout.
This is because in order for muscles to adapt and grow, they need to be placed under progressive pressure. ROS play a key role in this as they help to signal for muscle growth and recovery to take place.
What are the benefits of vitamin C supplementation?
A major benefit of vitamin C supplements reduced duration and intensity of cold and flu symptoms. Research has shown that the greatest effect on cold and flu duration has been seen in those who are very physically active, such as those with physically demanding jobs such as construction workers and those who train to a high intensity regularly. This means that vitamin C supplements can be helpful to add into your diet, especially when you’re training a lot.
They sound helpful! But could they also be a hindrance?
For many years, research on antioxidant supplements such as vitamin C focused on their immune supporting benefits, especially for active groups of the population.
Antioxidants such as vitamin C were then studied with the view of possibly helping with post-workout muscle soreness and improved recovery. However, results from these studies have been mixed and have shown that antioxidant supplementation of vitamins C and E can actually be more harmful than good. But recent research has now pointed to possible downsides of antioxidant supplementation, especially in people who exercise regularly. As mentioned previously, ROS actually play a particularly important role in exercise, initiating muscle growth and recovery after a workout. Antioxidant supplementation post workout has been shown to dampen down this cellular mechanism which can in turn, reduce muscle growth and recovery aka gains.
How does this happen?
There are a few mechanisms in which high doses of antioxidants such as vitamin C and E in supplement form can hinder performance, recovery and gains.
Decreased Exercise Performance
A 2008 study by Gomez-Cabrera et al. examined the effect of a supplement of 1000mg of vitamin C on training efficiency in males. They found that supplementation resulted in reduced exercise-induced expression of important factors that usually result in training adaptations and improved performance, including key transcription factors involved in mitochondrial biogenesis. They concluded that vitamin C supplementation decreased overall performance because it reduced the overall training adaptations needed to promote muscle growth and improved performance.
While in theory, antioxidants can promote recovery, when given in high dose supplemental form they may have the opposite effect. A 2006 study by Close et al. examined the effect of 1000mg of vitamin C given 2 hours pre exercise. The aim of the study was to see if vitamin C could reduce muscle soreness and improve recovery. However, the study found that vitamin C failed to reduced delayed onset muscle soreness (DOMS). They also proposed that supplementation might reduce overall recovery ability.
Reduced Insulin Sensitivity
A key area of research is that on antioxidant supplementation and insulin sensitivity aka how our body responds to insulin. Exercise is known to improve insulin sensitivity. This was studided in a 2009 study by Ristow et al. This study consisted of two main groups of participants (each group consisted of both untrained and experienced trainees) who were examined, given a training protocol for a number of weeks and insulin sensitivity was tested pre and post. One group was given a high dose vitamin C supplement (500mg twice a day) and E supplement (400IU once a day) while the other group was not.
Researchers found that untrained and pre-trained participants who did not receive supplementation had better insulin sensitivity after 4 weeks of exercise. However, the untrained and pre-trained participants taking vitamin C and E had no change in insulin sensitivity after 4 weeks of exercise.
This is thought to be due to the fact that exercise increases certain proteins involved in insulin sensitivity. However, high dose antioxidant supplementation seems to block the production of these proteins and subsequent improves in insulin sensitivity.
This is particularly important to bear in mind when you remember that exercise is a common intervention to improve insulin sensitivity in people with type-2 diabetes. If high dose supplements of vitamin C and/or E are taken around exercise, this may cancel out the positive effects of exercise on insulin sensitivity.
What about antioxidant in food form?
Antioxidants can also be sourced from foods such as blueberries, dark chocolate, strawberries and artichokes to name a few. However, when sourced from foods, antioxidants such as vitamin C, do not appear to interfere with performance, recovery or muscle growth. It is thought that this might be due to the fact that they’re in their whole food form and that the overall dosage is much lower than what’s found in supplements. Food based antioxidants are amazing to include in your diet and should not be limited, even post workout.
Context and Timing are Key!
We don’t want you to go off and think that your vitamin C supplement are ruining your progress. As we mentioned previously, vitamin C is great to add in, especially in the colder winter months, to help ward off unwanted colds. But what you could do is consider the timing of your supplement. The best thing is to avoid taking antioxidants in supplement form before or after your workout. So for example, if you train in the morning, you could take your vitamin C supplement in the evening with your dinner.
Evidence is mounting that antioxidant supplements should be avoided in the hours around training time. While supplements such as vitamin C offer great benefits for immune health, they should be taken a number of hours away from training.
Food sources of antioxidants, do not need to be limited or avoided around training, and offer a huge array of health benefits. So keep piling your blueberries onto your post-workout oats!