What to watch with Homocystein and allergy?

The link between homocysteine and allergy is not well established in the scientific literature. Homocysteine is a byproduct of methionine metabolism, regulated by B vitamins (folate, B12, B6). Elevated levels are a known cardiovascular risk factor and may influence immune function through oxidative stress and methylation deficits. Some studies suggest associations with asthma or allergic rhinitis, but the evidence is mostly mechanistic and insufficient for clinical recommendations. DNA tests for MTHFR variants (e.g., C677T) are common, but their effect on homocysteine is modest and heavily modified by diet and lifestyle. In allergic individuals with high homocysteine, the first step should be to rule out B-vitamin deficiencies. Lowering homocysteine without a clear indication is not advised. Be cautious of marketing claims: homocysteine is not a direct allergy biomarker.