Why Bodybuilders Should Say No To NAC

Suppplements containing N-acetylcysteine as an antioxidant supposedly aid muscle recovery. Now it looks like they do the exact opposite.

N-Acetylcysteine

In case you haven’t yet heard about this supplement wonder, N-acetylcysteine (NAC) is a modified form of the amino acid cysteine and helps the body make the antioxidant enzyme glutathione.

So far doctors used this effect to treat chronic bronchopulmonary disease, to alleviate toxicity of chemotherapy, help people with weak immune systems due to HIV and to treat acetaminophen (Tylenol) overdose. The rate of success between each of these varies, but it looks promising.

NAC Makes Your Workouts Worse?

However, many people buy NAC despite not suffering from the above ailments. For them the magic is in the word “antioxidant.”

Bodybuilders discovered NAC more than ten years ago, praising it for letting them recover faster. Bodybuilding.com, home to a vast online supplement store, naturally wasn’t shy to pick up on that and have one of their “experts” recommend it:

Naturally training athletes can benefit from supplemental use of NAC because of its ability to protect the immune system from harmful oxidants that result from environmental pollution, regular metabolic functions and intense exercise.

You find similar statements on various other bodybuilding websites and forums, many echoing the “helps you recover faster.” Nobody, it seems, had much incentive to ask if there was anything more than anecdotal evidence. Whatever they wrote about N-acetylcysteine you have to take at face value.

This makes a new piece of research I came across very interesting. It delivers real evidence and comes to a much different conclusion:

Although thiol-based antioxidant supplementation enhances [glutathione] availability in skeletal muscle, it disrupts the skeletal muscle inflammatory response and repair capability, potentially because of a blunted activation of redox-sensitive signaling pathways.

Let me translate this: the muscles of athletes who used NAC didn’t fully recover and their performance got worse. The antioxidant ability of NAC did the exact opposite of what people assumed on bodybuilding forums.

In my opinion, you could also shred old tires, press them in pill form and sell them with a nice profit, as long you put “antioxidant” on the bottle. Someone’s going to buy into it.

No Surprise, Really

Feel free to believe N-acetylcysteine lets you recover faster or even makes your muscles bigger, but if you want me to believe it, point me at some evidence that is at least as reliable as what I linked above.

Given this evidence and the other research about the usefulness of multivitamin supplements and antioxidants, it seems the best thing to do to recover is to simply give your body rest and carry on with a balanced nutrition as usual.

Picture courtesy of “worak“.