Association of obesity or metabolic syndrome with various allergic diseases: An overview of reviews

Summary The relationship between obesity, metabolic syndrome, related disorders, and various allergic diseases remains unclear. An overview of reviews investigating potential associations between obesity or metabolic syndrome and various allergic diseases was conducted. MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched. Systematic reviews and meta‐analyses with summary effect size and corresponding 95% confidence intervals for at least one outcome (asthma, atopic dermatitis, and various allergic diseases) were included. This study encompassed 17 systematic review articles and 29 eligible meta‐analyses. All included meta‐analyses indicated a positive association between obesity/overweight and asthma. Three meta‐analyses from one review demonstrated a positive association between obesity/overweight and the risk of atopic dermatitis. However, no meta‐analyses focused on the associations between obesity/overweight or metabolic syndrome and allergic rhinitis, allergic conjunctivitis, or other allergic conditions. All included reviews employed poor methodology according to the AMSTAR‐2 assessment tools. Our findings suggest that obesity likely increases the risk of asthma. However, evidence for associations with other allergic diseases is limited. Furthermore, no meta‐analyses were conducted to assess the relationship between metabolic syndrome and allergic diseases. Further studies are necessary to elucidate the associations between obesity and the full spectrum of allergic diseases.