The liver can fully metabolize acetaldehyde, but the gut isn’t properly equipped to do the same
When you drink, most of the alcohol you consume gets digested in the liver using a two-step process (see diagram). Each step requires a different enzyme produce by your liver.
- Alcohol dehydrogenase (ADH) converts ethanol into acetaldehyde by removing hydrogen atoms—a process called oxidation.
- Acetaldehyde dehydrogenase (ALDH) then further oxidizes acetaldehyde into acetate by adding an oxygen atom, producing a more stable and innocuous compound.
However, some of the alcohol you drink never reaches your liver. Instead, it is metabolized in your gut, in large part by the microbes that reside there. Some microbes in the gut microbiome are equipped with the first enzyme, ADH, and can convert alcohol into acetaldehyde. But in contrast to your liver, they don’t make enough of the second enzyme, ALDH, to convert acetaldehyde into acetate. This is the major cause of acetaldehyde buildup in your body (Salaspuro, 1996).
Thus arises a clear hypothesis: If we can equip the gut microbiome to break down acetaldehyde into acetate, we can support the body’s ability to minimize the buildup of this toxic byproduct. While the liver is fully capable of metabolizing acetaldehyde, the gut is not—and that gap makes this approach especially valuable for those planning to have a drink or two.