Are probiotics, prebiotics, and synbiotics beneficial in primary thyroid diseases? A systematic review with meta-analysis.

Karolina Zawadzka, Klaudia Kałuzińska, Mateusz J Świerz, Zuzanna Sawiec, Ewa Antonowicz, Monika Leończyk-Spórna, Ahmad Kamal Abadi, Małgorzata Trofimiuk-Müldner, Małgorzata M Bała

Journal: Annals of agricultural and environmental medicine : AAEM 2023;30(2):217-223

PMID: 37387369

Free Full Text on Institute of Rural Health View on PubMed

Plain Language Summary

Irregularities in intestinal microbial composition are thought to be correlated with thyroid dysfunction. Supplementation of prebiotics, probiotics and synbiotics are gaining momentum in recent times in improving health in general. This systematic review of randomised controlled trials was conducted to summarise the up-to-date evidence on the therapeutic potential of prebiotics, probiotics and synbiotics in the treatment of thyroid disease. The meta-analysis did not show beneficial effects on thyroid hormone balance, BMI or levothyroxine dosage reduction. Supplementation with Lactobacillus and Bifidobacterium resulted in improvement in constipation and a statistically non-significant reduction in thyroid-stimulating hormone in adult participants with hypothyroidism. Further robust long-term studies are required to evaluate the efficacy of prebiotics, probiotics and synbiotics in thyroid disease treatment as the availability of the number of studies included in this systematic review was limited. However, healthcare professionals can use the review to understand the current evidence in this area and the correlation between gut microbial alterations and thyroid disease.

Abstract

INTRODUCTION AND OBJECTIVE

A number of studies indicate the presence of a thyroid-gut axis and the important influence of the gut microbiota on thyroid function. As prebiotics, probiotics and synbiotics show therapeutic potential in the treatment of intestinal dysbiosis, the aim of this review is to evaluate the efficacy of their supplementation in primary thyroid diseases.

REVIEW METHODS

Electronic databases (Ovid MEDLINE, Embase, CENTRAL), registers of clinical trials, and grey literature up to 6 October 2022 were searched for randomised controlled trials (RCTs) meeting pre-specified inclusion criteria. The protocol was registered in PROSPERO (CRD42021235054).

BRIEF DESCRIPTION OF THE STATE OF KNOWLEDGE

After screening 1,721 references, two RCTs were identified, which included 136 hypothyroid participants in total. Meta-analysis of the results after eight weeks of supplementation with predominantly Lactobacillus and Bifidobacterium strains indicated a clinically and statistically nonsignificant decrease in TSH (MD -0.19 mIU/L; 95% CI -0.43 to 0.06; I= 0%), and no effect on fT levels (MD 0.01 pg/mL; 95% CI-0.16 to 0.18; I= 0%). Data from single studies indicated no significant change in the levels of fT4, thyroid auto-antibodies, BMI, levothyroxine doses, and severity of symptoms measured with validated scales. Only constipation scores showed significant improvement (MD -8.71 points in the Faecal Incontinence Questionnaire; 95% CI -15.85 to -1.57; I= 0%).

SUMMARY

Low-certainty evidence from two randomised trials, suggests that routine administration of probiotics, prebiotics or synbiotics may result in little to no benefit in patients with primary hypothyroidism.

Address: Students' Scientific Research Group of Systematic Reviews, Faculty of Medicine, Jagiellonian University Medical College, Kraków, Poland.; Doctoral School of Medical and Health Sciences, Jagiellonian University Medical College, Kraków, Poland.; Chair of Epidemiology and Preventive Medicine, Department of Hygiene and Dietetics, Faculty of Medicine, Jagiellonian University Medical College, Kraków, Poland.; Department of Computer Engineering, Faculty of Engineering, University of Arak, Arak, Iran.; Chair and Department of Endocrinology, Faculty of Medicine, Jagiellonian University Medical College, Kraków, Poland.

DOI: 10.26444/aaem/162732