More Evidence that Helminths Protect Against Metabolic Diseases, Including Diabetes

Another great macrobiome article for you this week – two in one month!  Exciting times!  This one just appeared in the major journal, Frontiers in Endocrinology.  Researchers conducted a review of the existing literature, and meta-analysis of the data presented in the papers, looking for evidence to support the growing belief that helminths protect against metabolic diseases by supporting healthy glucose metabolism.[i]  With the ever-growing epidemic of obesity and metabolic diseases, including type 2 diabetes, solutions are desperately needed.  For example, current estimates have it that about 40% of people in the USA are obese, and the situation has done nothing but get worse for decades.  As they point out in this paper, “Currently at epidemic proportions globally, predictive modelling estimates that the incidence will further increase by 51% in 2045”

14 existing studies were deemed eligible to be included in the review, and 11 of these were used in the meta-analysis.  The studies covered 11 countries and included between and 158 and 9939 participants. In all cases, helminth colonization was achieved through natural exposure and thus, the helminths that had colonized these individuals were not those currently used in helminthic therapy.  The results of the analysis were as follows:

1. Of the 14 studies in the review, 9 found that helminths protected against diabetes.
2. 5 studies had enough data to give a clear picture of helminths’ effect on blood glucose. There was a “…significant decrease in fasting blood glucose in those with parasitic infections…”[ii] Interestingly, colonization with different worms did show differing results in these studies:  a particular soil-transmitted nematode had no effect whereas Schistosoma species led to a significant decrease, with mansoni showing the greatest effect.
3. Likewise, a significant reduction in A1c – a marker for average blood glucose levels over the past 3 months – was seen with helminth colonization. Active infection with a helminth called viverrine, or a previous infection with Schistosoma species led to “…significantly lowered” A1c.
4. The prevalence of metabolic syndrome was 56% lower in those with helminths as compared to the non-colonized population.
5. In those colonized with Schitosoma species, the prevalence of type 2 diabetes was 46% lower when compared to the non-colonized population.

The different results from varying helminths were really striking:  “While infection with helminths was generally associated with improved metabolic function, there were notable differences in efficacy between parasite species.”

The conclusion:  the existing evidence most  certainly confirms the negative association between type 2 diabetes and helminth:  “[We] strongly support the proposal that helminth parasites have the capacity to regulate obesity driven inflammation to mediate a positive effect on metabolic outcomes.” Of course enormous amounts of research are still needed.  The helminths endemic in the populations used in these papers are not appropriate for helmithic therapy as they are unsafe.  But the very fact that helminths do exert an glucose-regulating effect is a positive finding that will hopefully translate into useful treatments in the future.

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[i] Rennie C, Fernandez R, Donnelly S, McGrath K. The impact of helminth infection on the incidence of metabolic syndrome: a systematic review and meta-analysis. Front Endocrinol. 2021;12:728396. doi:10.3389/fendo.2021.728396

[ii] https://www.endocrinologyadvisor.com/home/topics/diabetes/type-2-diabetes/certain-parasites-may-help-metabolic-outcomes-in-humans/