For example, one older study on rats with induced higher levels found that onion juice helped bring those levels closer to normal over several days, with effects that appeared dose- and time-dependent. Other work with dried onion powder in animal models also noted reductions in serum markers.
Quercetin itself has been tested in small human trials. In one randomized study involving men with mildly elevated levels, daily supplementation equivalent to amounts found in about 100 grams of red onions was associated with a modest drop in
