Research Review: Postworkout vitamins — help or hindrance? |

In the past, athletes have believed that post-workout supplements such as creatine and beta-alanine can help them bulk up and boost their performance. However, there is little evidence to suggest that they do. Let’s take a look at what people have said in relation to this topic.

Every day, when we exercise, our bodies burn a lot of energy. Some of that energy is used to replenish muscle and other bodily tissues. The rest is converted into heat. What remains is the portion of our energy that is used to repair and rebuild muscle tissue. The muscle repair process takes place in the body’s cells. The more active the muscle tissue, the quicker and more complete the repair process. So, the faster you can restore your muscle tissue, the faster you can recover from workouts.

For the past few years, I’ve been researching the benefits of postworkout vitamins (called PWV), and, over time, I’ve noticed that a vast number of these products claim to help you lose weight and even lose fat. The more I read, though, the more I realized that there are few studies on how effective these products are at helping you burn fat, maintain fat loss and perform better.

We are all aware that exercising is beneficial to our health. If you have type 2 diabetes, exercise seems to be more effective than metformin in reducing insulin resistance (the most used anti-diabetic drug).

But I have a question: why is exercise beneficial to your health?

Stress may be beneficial to your health.

The majority of individuals overlook the fact that exercise is a kind of stress. I’m sure those of you who exercise on a daily basis are aware that exercise is stressful — or should be if you’re doing it correctly.

I’m not talking about stressful situations like “you’ve been delayed in traffic for the past three hours on your way home from work” or “seeing your money vanish in the stock market.” (I apologize if bringing it up stresses you out.)

No, I’m referring about the kind of stress that makes you feel better later – it may take a while, but you will feel better eventually.


Excessive anxiety


Eventually, good stress…

Let’s suppose you’ve done a lot of squats, lunges, and even deadlifting in your leg exercise. Then you attempt to descend the stairwell to the locker room. Walking down the stairs is a lot more difficult than you recall if your exercise was already stressful. Perhaps the following day, your legs are painful and stiff so you waddle about like a penguin.

Why? Because your body has been stressed and is now attempting to recuperate and adjust.

The whole premise of exercise is overcompensation. After a stressful event, your body overcompensates so that it can manage the stress/exercise the next time you go to the gym. If you work out but don’t push yourself, your body won’t have to overcompensate since it hasn’t been stressed enough.

Why am I bringing up the subject of stress? Because that explains why the results of this week’s research were as they were. Consider how the intervention affects stress (or the reaction to stress) while you read this review.

Oxidative stress and exercise

As part of their regular day-to-day activities, our cells generate free radicals, also known as reactive oxygen species (ROS). Consider it the body’s natural “rusting” process. Muscle and other tissues are both damaged by free radicals. The existence of a greater number of free radicals indicates damage and is regarded as “bad.”

For the most part, we have a solid antioxidant system in place to take care of them — a regular polish with a little biological Rustoleum, to put it that way. When we exercise, though, some processes are accelerated, and we generate more free radicals. The body is unable to catch up immediately.

So, would consuming more antioxidants help us recover more quickly from the stress of exercise?

Vitamins C and E have an important function to play.

If you’re curious, our natural antioxidant system contains catalase, superoxide dismutase, glutathione peroxidase, and a variety of non-enzymatic antioxidants such as glutathione, ubiquinone, flavonoids… as well as the more well-known vitamins C and E.

Since the 1970s, vitamin C and E have been researched for their benefits on exercise performance. However, the findings have proven perplexing. Vitamin C and E seem to be beneficial at times, but not at others. (2)

The researchers are still working on it because hope springs eternal.

Question for investigation

This week, I look at a research on antioxidants and how they may counteract exercise advantages such as improved insulin sensitivity. (Okay, so I gave away the conclusion, but weren’t you going to read the study’s title? But you’re still curious about antioxidants, exercise, and why they don’t get along.)

Antioxidants inhibit the health-promoting benefits of physical exercise in adults, according to Ristow et al. The Proceedings of the National Academy of Sciences of the United States of America were published on May 11, 2009. [Epub before print]


In reality, there were two investigations in one:

  1. An open label trial (in which both the subjects and the researchers know who received the vitamins and who did not)
  2. A placebo-controlled, double-blind study (neither the participants nor the researchers knew who was getting the vitamins)

With the exception of who knows what, both trials used the identical 28-day vitamin (C and E) supplementation and exercise regimen. Because the findings of the two investigations were similar, the researchers merged them into one larger study.


  • 20 inexperienced young guys
    • 8 from the “open-label research”
    • 12 results from a “double-blind study”
  • 20 inexperienced young guys
    • 8 from the “open-label research”
    • 12 results from a “double-blind study”

They were between the ages of 25 and 35, with a BMI of less than 27 on average. They were also very healthy:

  • There is no inflammatory illness, either acute or chronic.
  • There is no metabolic illness (including diabetes)
  • There is no history of high blood pressure in your family.
  • There is no cardiovascular disease, peripheral artery disease, or thyroid illness.
  • There will be no medicines, alcohol, cigarettes, or other drugs used.

Here’s the rub: despite the fact that this research focused on insulin sensitivity and was interpreted with type II diabetics in mind, none of the participants had type II diabetes, pre-diabetes, or type I diabetes.

That’s correct, despite the fact that this research will almost certainly be utilized to make supplements recommendations for diabetics during exercise, there are no diabetics in the study.

I bring this up because it’s common for a research that looks at one group to be applied to another. Results from a research with a group of healthy, young males, for example, are misinterpreted as referring to sick, much older individuals. Alternatively, research on fat older women are applied to fit young males. Healthy individuals are studied in the same way as patients with a specific illness are studied. The list goes on.

What’s more, this is self-evident: healthy is not the same as sick — by definition — so expecting everything would be the same in both groups is ridiculous.


What criteria did the researchers use to determine who was trained and who was not? Simply put, the participants were asked how much physical exercise they performed in a week.

A person was considered “trained” if he said that he worked more than 6 hours per week. He was deemed “untrained” if he claimed he worked less than 2 hours each week. (What happened to the individuals who worked 2.1–5.9 hours per week… “undecided”?)

The trained group had a greater VO2 max (the maximum amount of oxygen the body can utilize) and more lean body mass (aka fat free mass). This isn’t surprising, but it’s always nice to discover evidence that backs up widely held beliefs. Because the researchers didn’t look at body fat, no comparisons could be done between trained and untrained people.


The vitamin group (also known as the antioxidant group) received 500 mg of vitamin C (ascorbic acid) twice a day and 400 IU of vitamin E (RRR-/D-a-tocopherol) once a day. This equates to 1000 mg of vitamin C and 400 IU of vitamin E each day, which is much more than Health Canada’s recommended levels of 60 mg of vitamin C and 40 IU of vitamin E. (a fairly standard recommendation worldwide).

What was the purpose of the exercise?

One of my pet peeves with exercise research is how they’re described, particularly when they’re not published in exercise-specific publications. They’re studies that don’t go into great depth regarding the “workout.” The phrase “physical exercise” encompasses a wide range of activities, including weight training, jogging, stretching, and so on.

The findings of this research were published, but almost as an afterthought, with little information. 20 minutes of bicycling or jogging, 45 minutes of circuit training, and 20 minutes of warming up and cooling down (total of 85 minutes – 5 days/week for 4 weeks) were the exercises described. There is no indication of intensity, circuit type, or warm-up or cool-down. I’m guessing the circuit is a weight-training circuit, although it’s not obvious.


Muscle oxidative stress rises as a result of exercise.

Researchers compared the muscle of the individuals before and after three days of exercise. The details aren’t essential, but if you’re curious, the researchers used TBARS to assess oxidative stress (thiobarbituric acid-reactive substances). The more TBARS there are, the more reactive oxygen species there are (free radicals).

Free radicals in muscle more than quadrupled after three days of exercise without supplementation. However, free radicals did not rise at all after three days of exercise with vitamin C and E intake!

This is intriguing and makes sense since vitamin C and E are antioxidants, which means they prevent free radicals from causing tissue damage by blocking chemical processes (called oxidation).

Anyone taking vitamin C and E (in food or pill form) should be pleased. The purpose of anti-oxidants such as vitamin E and C is to prevent free radical damage. And this research backs up that notion, but there’s a caveat.

Is it possible to have too much of a good thing? Exercise-induced gains in insulin sensitivity are prevented by antioxidants.

The researchers were able to determine the individuals’ insulin sensitivity using two particular tests: glucose infusion rate (GIR) and adiponectin (a fat-derived protein that improves insulin sensitivity). Insulin sensitivity increases when GIR and adiponectin levels rise.

They discovered that after 4 weeks of exercise, untrained and pre-trained individuals with no supplementation had improved insulin sensitivity. There’s nothing surprising about it. GIR and adiponectin tests have shown that exercise improves insulin sensitivity. This is why physical activity helps people with type 2 diabetes, which is characterized by insulin resistance.

But here’s the kicker: After four weeks of exercise, the insulin sensitivity of the untrained and pre-trained individuals consuming vitamin C and E remained unchanged.

In other words, exercise without additional anti-oxidants increased insulin sensitivity, while exercise with additional anti-oxidants had no effect. There was no difference between trained and untrained individuals.

How is it possible?

The researchers next looked at additional proteins that are thought to be involved in insulin sensitivity. Specific proteins instruct your body on how to react to various stressors. It’s similar to the telephone game you played in elementary school, although it’s a little more precise (good; otherwise, our bodies would be instructed to “keep heart pumping” instead of “meat cart needle”).

Diverse proteins elicit different reactions in the body. There is no reaction if there is no change in protein. PGC-1a, PCG1-b, SOD1, SOD2, and GPx1 are proteins that instruct your body to improve insulin sensitivity. If they aren’t there, your body doesn’t improve insulin sensitivity for whatever reason.

All of these proteins are increased by regular exercise. It did not, however, in individuals who took vitamin C and E tablets. There is no change in insulin sensitivity without a change in these “signaling” proteins.


Supplementing with vitamins C and E prevents free radical buildup after exercise, which is likely why insulin sensitivity does not improve.

The sequence of events that usually occurs is shown in Figure 1. As you can see, the presence of antioxidants (in red) nearly completely prevents these events from occurring. Antioxidants effectively inhibit many of the positive effects of exercise by preventing the normal stress-response sequence.


In conclusion

I’d want to point out a few things before you quit eating oranges and almonds (both of which are high in vitamin E).

First, the amount of vitamin C used in this study is 20 times the recommended amount. And the amount of vitamin E is 10 times what is recommended. This isn’t to say that “recommended” is perfect but it does put things in perspective. So in this study there is a lot of vitamin C & E. This means that normal intake will probably not mess up your exercise program.

However, if you supplement often and are worried about insulin sensitivity, I would advise you to rethink those tablets. Based on this research, I would not suggest supplementing with vitamin C and E before beginning an exercise program if you are a type II diabetic, pre-diabetic, or have a high risk of diabetes.

If you believe it is necessary to add additional vitamin C and E after seeing the effect of exercise on your insulin sensitivity, try a little amount and observe if your insulin sensitivity declines. Stop taking vitamin C and E if this happens.

Simply said, employ common sense. Begin by focusing only on exercise and nutrition to observe how you respond. Then, if you feel driven to take vitamins, take some and keep track of your progress.

For those of you who don’t have insulin sensitivity problems, I’d wait to see whether this research is repeated many times before becoming too concerned. Take your vitamin C and E an hour after you workout if you’re truly worried. The free radicals will have more time to perform their work before being stopped by the vitamins.


To see the information sources mentioned in this article, go here.

Toxicology. 2003 Jul 15;189(1-2):41-54. 1. Urso ML, Clarkson PM. Oxidative stress, exercise, and antioxidant supplementation.

2. I. Margaritis, A. S. Rousseau. Is it true that physical activity alters antioxidant requirements? 2008 Jun;21(1):3-12 in Nutr Res Rev.

Find out more.

Want to be in the greatest form of your life and keep it for the rest of your life? Check out the 5-day body transformation programs below.

What’s the greatest part? They are completely free.

Simply click one of the links below to access the free courses.

The postworkout vitamin trend is a tricky one, as many will argue that the best way to get the most out of your workout is through a balanced diet. However, athletes and those who exercise regularly know that a little extra something can help, and there are many products on the market that claim to be the perfect answer.. Read more about vitamins to take before workout and let us know what you think.

Related Tags

This article broadly covered the following related topics:

  • muscle recovery
  • vitamins after workout
  • multivitamin pre or post workout
  • post workout supplements
  • vitamin c muscle growth

Most Popular

To Top