Effect of high-nitrate beetroot juice consumption on thyroid gland hormones and iodine levels in adults

Abstract Dietary nitrate supplementation has been widely investigated by the scientific community due to its beneficial effects on the cardiovascular system. However, there is evidence suggesting a possible effect of nitrate in scavenger iodine from the thyroid gland, which may affect thyroid hormone synthesis. Therefore, this study evaluated the effect of seven days of a nitrate-rich beetroot juice supplementation on thyroid hormones and iodine concentrations in healthy adults. Thirteen healthy adults were enrolled in a randomized, double-blind, crossover and placebo-controlled study. Participants ingested 140 mL of nitrate-rich beetroot juice (8.12 ± 3.61 mmol/day) or placebo (nitrate-depleted BJ) during one week. Before and after the supplementation period, blood and urine were drawn for analysis of thyroid hormones, iodine, nitrate and nitrite. No significant changes were observed in plasma triiodothyronine, thyroxine, nitrate and nitrite, and urinary iodine concentrations. In conclusion, these results suggest that one-week supplementation with a nitrate-rich beetroot juice intake does not affect thyroid function.