Do worms protect against the metabolic syndrome? A systematic review and meta-analysis.
OBJECTIVE
There is increasing evidence on the role of helminth infections in modifying autoimmune and allergic diseases. These infections may have similar effect in other inflammatory processes, such as insulin resistance. This review aims to examine the literature on the effect of helminthic infections on metabolic outcomes in humans.


METHODS
Using the PRISMA protocol, we searched the literature using PubMed, MEDLINE, and a manual review of reference lists. Human studies published in English after 1995 were included. Four papers were included in this review. Data was extracted and a meta-analysis was conducted using a random-effects model. Heterogeneity was assessed using Tau(2) and I(2) tests.


RESULTS
The included studies found that infection was associated with lower glucose levels, less insulin resistance, and/or a lower prevalence of metabolic syndrome (MetS) or type 2 diabetes mellitus (T2DM). Meta-analysis showed that participants with a previous or current helminth infection were 50% less likely to have an endpoint of metabolic dysfunction in comparison to uninfected participants (OR 0.50; 95% CI 0.38-0.66).


CONCLUSIONS
This review has shown that helminth infections can be associated with improved metabolic outcomes. Understanding of the mechanisms underlying this relationship could facilitate the development of novel strategies to prevent or delay T2DM.
College of Medicine & Dentistry, Division of Tropical Health and Medicine, James Cook University, Cairns, QLD, Australia. Electronic address: ella.tracey@my.jcu.edu.au.
Ella F
EF
Tracey
Centre for Chronic Disease Prevention, Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, QLD, Australia.
Robyn A
RA
McDermott
College of Medicine & Dentistry, Division of Tropical Health and Medicine, James Cook University, Cairns, QLD, Australia; Centre for Chronic Disease Prevention, Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, QLD, Australia.
Malcolm I
MI
McDonald
D000818:Animals; D003924:Diabetes Mellitus, Type 2 / Q000276:immunology* / Q000469:parasitology; D006373:Helminthiasis / Q000276:immunology*; D006801:Humans; D007333:Insulin Resistance / Q000276:immunology; D024821:Metabolic Syndrome / Q000276:immunology* / Q000469:parasitology; D065840:Protective Factors; D012547:Schistosoma / Q000276:immunology; D014258:Trichuris / Q000276:immunology
Helminths; Immunology; Metabolic syndrome; Type 2 diabetes mellitus