Alpha-glycosyl isoquercitrin (AGIQ) is a highly bioavailable derivative of quercetin, a flavonoid found in many fruits and vegetables. Its enhanced solubility and absorption compared to standard quercetin have led to interest in its potential for supporting allergy management, particularly for respiratory allergies such as allergic rhinitis. The scientific rationale largely stems from the known anti-allergic and anti-inflammatory properties of quercetin, which acts as a mast cell stabilizer and inhibits the release of histamine and other mediators involved in allergic responses.

The evidence base for AGIQ specifically is modest but growing. A handful of animal studies and a few small human clinical trials suggest that AGIQ can reduce symptoms of allergic rhinitis, such as sneezing and nasal congestion, possibly by suppressing IgE-mediated histamine release and modulating inflammatory cytokines. For example, a randomized, double-blind, placebo-controlled study (Kawai et al., 2009) found that AGIQ supplementation reduced occurrence and severity of allergic symptoms in subjects with seasonal allergies. However, the number of clinical trials is limited, and most have small sample sizes or are short in duration.

In summary, while there is a plausible scientific mechanism and some preliminary human data, the overall evidence is still emerging. Larger and more rigorous clinical studies are required to firmly establish the efficacy of AGIQ for respiratory allergies. Thus, the evidence rating is 2 out of 5, reflecting promising but limited support.