Nutritional interventions in the treatment of Hashimoto’s disease: A systematic review

Table 1 Description of the studies included in the integrative review, according to the type of treatment investigated

Ref.	Country	Type of study	Number of participants, gender and age	Objectives	Groups and treatments	Parameters evaluated	Main results
Lactose-free diet
Asik et al[15]	Türkiye	Case-control	50 patients with HT (Female: 48; Male: 02). Average age: 47.9 ± 8.73 years	To evaluate the prevalence of lactose intolerance in patients with HT and the effects of lactose restriction on thyroid function in these patients	Groups: 1: Lactose intolerant (n = 48); 2: No lactose intolerance (n = 12); Time: 8 weeks	TSH, fT4, calcium, and parathormone (PTH)	The TSH levels decreased in patients with HT and lactose intolerance. Patients without lactose intolerance did not have significant changes in TSH levels. The other parameters did not change after lactose restriction
Gluten-free diet
Krysiak et al[16]	Poland	Case-control	34 women with HT. Average age: Group A = 30 ± 5 years; Group B = 31 ± 6 years	To investigate whether a gluten-free diet affects thyroid function in women with HT	Group A: Gluten-free diet (n = 16); Group B: Gluten-containing diet (n = 18); Time: 6 months	Titers of TPOAb and TgAb; serum levels of TSH, fT3, fT4 and 25-hydroxyvitamin D	In group A, TPOAb and TgAb levels decreased and Vitamin D increased. TSH, fT3, and fT4 levels remained unchanged. In group B, the evaluated parameters remained unchanged
Gluten-free diet for patients with CD and HT
Virili et al[17]	Italy	Case report	103 individuals with HT and/or CD (Female: 92; Male: 11); Age: Patients with HT: 41 (33-51); Patients with HT and CD: 39 (33-50)	To analyze the need to increase fT4 in CD patients adhering to a gluten-free diet	Patients with isolated HT: Gluten-containing diet; Patients with HT and CD: Gluten-free diet; Time: 15 months	TSH, TPOAb, weight and BMI	It was observed that there was a need to increase the fT4 dose by up to 50% in patients with HT and CD who were non-adherent to a gluten-free diet. However, this can be reversed if a gluten-free diet is implemented. Normal thyroid levels were observed after the gluten-free diet, but the same result was obtained after increasing the fT4 dose in patients who were non-adherent to the diet
Gluten-free diet associated with healthy lifestyle and nutritional follow-up
Pobłocki et al[18]	Poland	Case-control	62 women with HT. Average age: 38.86 ± 4.28 years	To evaluate whether the use of a gluten-free diet is effective in patients with HT	Group selection: Gluten-free diet (n = 31); Control group: Average Pole’s diet (n = 31); Time: 12 months	Serum levels of TSH, fT3, fT4, and Titers of TPOAb and TgAb, weight and BMI	There was a reduction in TSH in the study group and an increase in fT4 levels, the other parameters did not change in either group
Gluten-free diet with selenium supplementation
Velija et al[19]	United Kingdom	Case-control	98 women with HT. Average age: 39.60 ± 7.36 years	To validate the positive effect of HT patients adhering to a gluten-free diet and selenium supplementation on the recovery of thyroid function	Group A: Receiving 200 μg selenium in the form of L-selenomethionine orally and gluten-free diet (n = 50); Group B: Receiving 200 μg selenium without any dietary treatment (n = 48); Time: 6 months	Titers of TPOAb and TgAb, and serum levels of TSH, fT3, fT4	At the end of the study, euthyroidism was restored in 74% of group A participants, and in 58.3% of group B participants. TSH, TPOAb and TgAb levels were significantly reduced in both group after six months of treatment. Serum TPOAb titer in group A had a more significant decrease (by 49%) than those in group B (by 34%)
Calorie reduction and food exclusion diet
Ostrowska et al[20]	Poland	Case-control	100 women with HT and obesity. Average age: Group A = 42.7 ± 10.51 years; Group B = 41.02 ± 11.96 years	To evaluate the influence of calorie reduction diets, with and without food exclusion, on thyroid parameters in women	Group A: Calorie reduction and food exclusion diet (n = 50); Group B: Calorie reduction diet without excluding foods (n = 50). Average reduction of 1000 kcal/day in both diets. Time: 6 months	Titers of TPOab and TgAb, and serum levels of TSH, fT3, fT4, weight and BMI	In both groups, loss of body mass and decrease in BMI were observed, in group A this loss was greater. Both groups obtained decreases in the parameters of TSH, TPOAb, TgAb, and an increase in fT3 and fT4 in group A
Paleo diet with exclusion of gluten, grains, dairy and micronutrient supplementation
Avard and Grant[21]	Australia	Case report	Woman with HT, 23 years	To validate whether an approach to modulating the intestinal microbiota and reducing inflammation can be used as methods to regulate intestinal permeability and favor the course of HT treatment	Paleo diet with exclusion of gluten, grains, dairy, low-protein with micronutrient supplementation (vitamin C, D, B1, B4, B5, B6, B12, zinc, selenium, iron a N-Acetyl cysteine) and probiotics. Time: 15 months	Serum levels of TSH, fT4, zinc, ferritin, Vitamin D and B12, Titers of TPOAb and TgAb	Reduction in TSH and TgAb levels and significant improvement in the symptoms that most affected the patient (daytime naps, exhaustion, stress and mood swings, excessive fatigue, hair loss, nighttime insomnia), only intestinal transit, which despite improving, remained unstable
Autoimmune diet and lifestyle changes
Abbott et al[22]	United States	Pilot study	16 women with HT. Average age: 35.6 ± 5.7 years	To determine the efficacy of a multi-disciplinary diet and lifestyle intervention for improving the quality of life,clinical symptom burden, and thyroid function in a population of middle-aged women with HT	Online health coaching program focused on the implementation of a phased elimination diet known as the Autoimmune Protocol. Time: 10 weeks	Complete metabolic profile, serum levels of TSH fT3, fT4, titers of TPOAb, TgAb, CRP, symptom and quality of life questionnaires	No changes in TSH, fT3, fT4, TPOAb, TgAb. Improvement in health and quality of life. Clinical symptoms with significant decrease. In the CRP test there was a decrease of 29%
Autoimmune and hypocaloric Paleo diet (1200 kcal)
Al-Bayyari[23]	Jordan	Case report	Woman with HT, 49 years	To observe the effect of a modified paleo immune diet on anthropometry, body composition, insulin, lipid profile and thyroid function of the patient analyzed	Modified autoimmune paleo low-calorie diet (1200 kcal). Time: 6 months	Anthropometric measurements, body composition, fasting blood glucose and insulin, serum levels of HDL-c, LDL-c, triglycerides, fT3, fT4, TSH, and titers of TPOAb	Reduction in anthropometric measurements, body composition, triglycerides, LDL, TSH, TPOAb, and insulin. There were no changes in fT3, fT4. There was an increase in HDL-c

HT: Hashimoto’s thyroiditis; fT4: Free thyroxine; fT3: Free triiodothyronine; TPOAb: Anti-thyroid peroxidase antibodies; TgAb: Anti-thyroglobulin antibodies; BMI: Body mass index; CRP: C-reactive protein; TSH: Thyrotropin; CD: Celiac disease; HDL-c: High-density lipoprotein cholesterol; LDL-c: Low-density lipoprotein cholesterol; PTH: Parathyroid hormone.