Is allicin destroyed by stomach acid?

Does Stomach Acid Destroy Allicin in Garlic?

When you chop or crush fresh garlic, a biochemical reaction kicks in. The enzyme alliinase converts a compound called alliin into allicin—the substance responsible for garlic’s strong smell and many of its health benefits. But here’s the catch: this same enzyme, alliinase, is highly sensitive to acidity. Once it hits the stomach’s acidic environment, it gets irreversibly destroyed.

This means that even if you eat raw garlic, the window for allicin production is very short. By the time it reaches your stomach, the conditions are too harsh for alliinase to keep working, so very little allicin is formed—or survives. That’s why you won’t find allicin listed as an ingredient in most garlic supplements. Instead, manufacturers use garlic powder or granules, which preserve alliin and allow allicin to form only when the conditions are right—usually after leaving the stomach and entering the less acidic environment of the intestines.

Some advanced supplements use enteric coatings to protect the active compounds until they pass through the stomach, helping boost allicin availability. But even then, the process is far from perfect. Nature designed garlic to work in a certain way, and digestion doesn’t always cooperate.

So yes, stomach acid effectively shuts down the enzyme needed to create allicin. That doesn’t mean garlic loses all its benefits—far from it. But it does explain why the real magic of garlic happens quickly and locally, and why science is still refining the best way to deliver its power in supplement form.