Eosinophils

When elevated (eosinophilia, >0.5 x10^9/L):

Common causes:

• Allergies -- seasonal, food, or medication-related (most common cause)
• Parasitic infection -- especially if travelled to endemic areas or consumed raw/undercooked meat
• Medications -- some supplements or NSAIDs can trigger eosinophilia
• Asthma/atopy -- often elevated alongside IgE

Supplements:

• Quercetin -- 500mg 2x/day (natural antihistamine and mast cell stabiliser)
• Vitamin C -- 1-2g/day (natural antihistamine effect)
• Omega-3 (EPA/DHA) -- 2-3g/day (anti-inflammatory)

Lifestyle:

• Identify and remove allergen if allergy-related
• If >1.5 x10^9/L or persistent, investigate for parasitic infection (stool testing) or medication reaction
• Mild eosinophilia (<1.0) with known allergies is usually benign

References:

• Cos, P., Ying, L., Calomme, M., et al. (1998). Structure-activity relationship and classification of flavonoids as inhibitors of xanthine oxidase. Journal of Natural Products, 61(1), 71-76. DOI: 10.1021/np970237h
• Calder, P. C. (2017). Omega-3 fatty acids and inflammatory processes. Biochemical Society Transactions, 45(5), 1105-1115. DOI: 10.1042/BST20160474