Apple cider vinegar is sold as a fix for weight, blood sugar, digestion and skin. The research is thinner than the enthusiasm — and the side effect people ignore is one you cannot undo.
What the research actually shows
The most-cited studies are small and short. A few found modest reductions in post-meal blood sugar spikes, which is the most plausible effect and has a reasonable mechanism behind it. Weight-loss findings are weaker: the handful of studies reporting an effect involve small numbers of people and differences of a few pounds over months, easily explained by other changes in the diet.
Notably, the NIH has not issued consumer guidance on apple cider vinegar the way it has for vitamin D, magnesium or probiotics — a reasonable signal about where the evidence stands.
The tooth enamel problem
This is the part that gets skipped. Vinegar is acidic, and enamel does not grow back. Sipping diluted vinegar through the day, or taking undiluted shots, has been linked to enamel erosion. If you drink it, dilute it well, drink it through a straw, and rinse with water afterwards — but do not brush immediately, because brushing softened enamel makes it worse.
Gummies are not a loophole
ACV gummies solve the taste and the enamel issue, but they typically contain a fraction of the acetic acid in a tablespoon of vinegar, plus added sugar. If the (already modest) effect depends on the acetic acid, a sweetened gummy with very little of it is unlikely to deliver much.
Safety notes
Vinegar can worsen reflux in some people, may lower potassium at high intakes, and can add to the effect of diabetes medication and diuretics. People with gastroparesis are usually advised to avoid it, as it can slow stomach emptying further.
Our take
A splash of vinegar in a salad dressing is a perfectly good habit. As a weight-loss strategy, it is not one — and we are not going to sell you a bottle by pretending otherwise. For approaches with real support, see fiber and protein.