Do Brassica Vegetables Affect Thyroid Function?—A Comprehensive Systematic Review

Abstract

Brassica vegetables are widely consumed all over the world, especially in North America, Asia, and Europe. They are a rich source of sulfur compounds, such as glucosinolates (GLSs) and isothiocyanates (ITCs), which provide health benefits but are also suspected of having a goitrogenic effect. Adhering to PRISMA guidelines, we conducted a systematic review to assess the impact of dietary interventions on thyroid function, in terms of the potential risk for people with thyroid dysfunctions. We analyzed the results of 123 articles of in vitro, animal, and human studies, describing the impact of brassica plants and extracts on thyroid mass and histology, blood levels of TSH, T3, T4, iodine uptake, and the effect on thyroid cancer cells. We also presented the mechanisms of the goitrogenic potential of GLSs and ITCs, the limitations of the studies included, as well as further research directions. The vast majority of the results cast doubt on previous assumptions claiming that brassica plants have antithyroid effects in humans. Instead, they indicate that including brassica vegetables in the daily diet, particularly when accompanied by adequate iodine intake, poses no adverse effects on thyroid function.

Effect of iodine species on biofortification of iodine in cabbage plants cultivated in hydroponic cultures

“…Cabbage is an important vegetable with strong nutraceutical properties; for instance, consuming 100 g of fresh leaves covers 44 and 72% of daily vitamins C and K requirements, respectively 17 . However, cabbage plants also contain metabolites such as glucosinolates and their derivatives which might be responsible for negatively influencing thyroid function by inhibiting the sodium/iodide symporter in the basolateral membrane of the thyroid cells and thyroid peroxidase activity 18 . Nevertheless, recent studies imply that the previos assumptions may only be valid when raw vegetables are eaten in high amount but when cooked and consumed with proper iodine intake it is safe.…”