Tuber Crops Consumption and Increased Incidence of Solitary Thyroid Nodules among Women Living in Karunagappally, Kerala, India

Abstract

Background: The prevalence of solitary thyroid nodules (nodules) is higher among the residents of Kerala’s coastal region. Diet may contribute to the development of nodules, which can turn into malignant by interfering with thyroid hormone production and function. The purpose of this study is to find potential dietary factors related to thyroid diseases/nodules among women in Karunagappally, India. Methods: A questionnaire survey regarding the frequency of the dietary intake was performed along with clinical diagnostic procedures of thyroid diseases in 2012 among asymptomatic and voluntarily participating women in Karunagappally. Logistic regression models adjusted for age and education were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Bonferroni correction was applied for multiple comparisons. Results: Among the 524 subjects, 75 (14%) were detected with nodules and 145 (28%) with thyroiditis. The logistic regression analyses, adjusting for age and education, revealed that a higher frequency of intake of goitrogenic food, such as cruciferous vegetables and tuber crops, such as roots and tubers were positively associated with the risk of nodules (P for trend 0.024 and 0.002, respectively) and though not statistically significant, tapioca also increased the risk. Consumption of the following meats and seafood at least once a week was significantly associated with the risk of nodules, with odds ratio magnitudes of around two; chicken, mutton, beef, shell, mussel, crab, and sepia. Frequent consumption (1 - 2 times/week) of chicken, mutton, and beef was associated with increased risk of nodules (Bonferroni-adjusted p = 0.012, 0.017, and 0.006, respectively), with beef intake ≥ 3 times/week further elevating risk ( p = 0.023). Seafood intake (shellfish, mussels, crab, sepia) and smoked foods were also positively associated with nodule risk. While considered to be a risk factor for other cancers, frequent pickle intake showed a protective role against both the nodules (P for trend 0.022) and thyroiditis (P for trend 0.017) with significant reductions in risk observed at ≥3 times/week. Conclusion: The results obtained show dietary factors might be related to the risk of solitary thyroid nodules among women in Karunagappally.