Onions are widely used in cooking and are present in a broad range of dishes, sauces, and processed foods. The Onion marker on the 1019 IgG Food Antibodies – Bloodspot panel measures IgG antibodies directed against onion proteins. IgG antibodies indicate immune recognition after exposure. They do not diagnose an IgE-mediated allergy and should not be interpreted as a standalone reason for permanent elimination.
Like garlic, onions are high in fructans, a fermentable carbohydrate (FODMAP) that can trigger bloating, gas, abdominal discomfort, and altered bowel habits in sensitive individuals. As a result, symptoms after eating onions may be related to carbohydrate fermentation rather than immune-mediated reactivity. Distinguishing between IgG-related sensitivity and FODMAP intolerance is important for accurate interpretation.
Some individuals with elevated onion IgG levels report delayed symptoms such as bloating, abdominal pain, reflux, fatigue, headaches, sinus congestion, or skin irritation after consumption. Because onions are frequently consumed in small amounts across many meals, repeated exposure may influence antibody levels.
Onion
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