Food intolerance/malabsorption in Hashimoto's thyroiditis

The clinical significance of the interaction between the gastrointestinal system and the thyroid gland remains unclear. Moreover, a correlation between food intolerance/malabsorption, and thyroid disease, including Hashimoto's thyroiditis, awaits elucidation.

This study set out with the objective of identifying food intolerance/malabsorption, including Fructose Malabsorption (FM), Histamine Intolerance (HIT), and Lactose Intolerance (LIT), in patients presenting with abdominal symptoms within the Irritable Bowel Syndrome (IBS) spectrum who had also Hashimoto's thyroiditis.

In this retrospective study, 221 patients with Hashimoto's thyroiditis, defined by elevated Thyroid Peroxidase Antibodies (TPO-Ab), were included. A subgroup of 50 abdominal asymptomatic Hashimoto's patients served as controls. Among 171 patients with abdominal symptoms FM and LIT were diagnosed using hydrogen breath tests, while HIT was defined by reduced serum diamine oxidase levels in combination with clinical response to a histamine-reduced diet.

Twenty-two were identified with FM, 40 with HIT and 42 with LIT; 19 had both LIT and FM, 31 had LIT and HIT, and 17 had LIT, FM, and HIT. However, there were no statistically significant differences in TSH or TPO-Ab levels between patients with FM, HIT, LIT, or their combinations (p = 0.739 and p = 0.460, respectively). Thyroid function and TPO-Ab levels were similar between symptomatic and asymptomatic patients.

In summary, this study assumes that food intolerance/malabsorption, including FM, HIT, and LIT, may coexist in patients with Hashimoto's thyroiditis who present with IBS-spectrum abdominal symptoms.