Probiotic Supplementation Enhances the Effects of a Nutritional Intervention on Quality of Life in Women with Hashimoto's Thyroiditis-A Double-Blind Randomised Study.

The short version

This double-blind randomised study with 64 women who have Hashimoto's thyroiditis explored whether adding a probiotic to nutrition education changes how they feel and function. Hashimoto's thyroiditis is an autoimmune condition in which the immune system attacks the thyroid gland, the gland in the neck that governs metabolism, and it is usually tracked through antibodies called anti-TPO (anti-thyroid peroxidase). Probiotics are live bacteria taken as supplements; the one tested here, Lactiplantibacillus plantarum 299v (Lp299v), is a strain studied for gut symptoms, and the researchers asked whether it adds to the benefits of dietary education. The study took place at a dietetics clinic in Warsaw, Poland. All participants were women aged 18 to 64 with stable thyroid function, most taking levothyroxine. For 12 weeks everyone attended six individual sessions with a dietitian and received a personalised menu. Half also took one Lp299v capsule daily (10 billion bacteria), while half took an identical dummy capsule. Quality of life was scored with the ThyPROpl thyroid questionnaire (0-100, lower is better) and gut symptoms with the GSRS (Gastrointestinal Symptom Rating Scale); blood pressure, body composition, diet quality and anti-TPO were also measured. Both groups reported better quality of life, but the probiotic group improved more. Overall scores dropped by 25.0 points with the probiotic (from 60.94 to 35.94, p = 0.006) versus 14.9 points with placebo (from 54.69 to 39.84, p = 0.043), and the probiotic group improved significantly in 12 of 14 areas while the placebo group improved in 3 of 14. Constipation, abdominal pain and reflux scores favoured the probiotic, and blood pressure, especially systolic, fell more in that group. Anti-TPO antibody levels and body mass index did not change in either group (the immune marker itself did not improve). Diet quality scores rose in both groups, from about 11 to 18.5 points with the probiotic and from about 12 to 19 with placebo, showing that the education alone changed eating habits. The authors conclude that education plus Lp299v improved quality of life and blood pressure without changing the thyroid antibody marker, and suggest that longer and larger trials are needed. The evidence has clear limits: a single clinic, participants recruited through social media, self-reported food diaries, a placebo arm with only about 57% statistical power for overall quality of life, and improvement in both arms, so a placebo or education effect cannot be ruled out. The results apply to euthyroid women with Hashimoto's over 12 weeks and say nothing about long-term outcomes.

Key findings

• In this double-blind trial, 64 women with Hashimoto's thyroiditis (an autoimmune disease in which the immune system attacks the thyroid gland) had 12 weeks of dietitian-led nutrition education, and half also took the probiotic Lactiplantibacillus plantarum 299v (Lp299v) daily.
• Thyroid-related quality-of-life burden fell by 25.0 points with the probiotic and by 14.9 points with placebo (p = 0.006 and p = 0.043), with significant improvement in 12 of 14 domains versus 3 of 14.
• The probiotic group also had larger improvements in constipation, abdominal pain and reflux scores and a greater fall in systolic blood pressure.
• Anti-TPO (anti-thyroid peroxidase, the antibody that attacks the thyroid) and BMI did not improve in either group, so the quality-of-life gains were not accompanied by a change in this immune marker.
• The trial was small, ran at one clinic for 12 weeks, and both groups improved, so the authors call for larger, longer trials.

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