Effects of the Glucosinolate Sinigrin in Combination With a Noniodine Supplemented Diet on Serum Iodine and Thyroid Hormone Concentrations in Nonpregnant Mares.

This research examined how the combination of a type of glucosinolate known as sinigrin and a non-iodine supplemented diet impact the thyroid hormones and serum iodine levels in non-pregnant mares over a period of 12 weeks. The study found this combination resulted in lower iodine levels in the horses’ serum, an indicator that their thyroid function could be affected.

Study Setup and Participants

• The study was conducted on nineteen non-pregnant mares that were between 2 to 14 years.
• The mares were divided into three groups: a control group with 6 mares, a low(sinigrin) group with 7 mares that received 20 mmol of sinigrin each day, and a high(sinigrin) group with 6 mares that took 35 mmol of sinigrin daily.

Examinations Over Time

• The research included Thyrotropin-releasing hormone (TRH) stimulation tests and serum iodine measurements, which were conducted at the start and end (12th week) of the study.
• The concentrations of Total triiodothyronine (TT3), total thyroxine (TT4), and thyroid-stimulating hormone (TSH) were measured—both at the start and in the post-TRH samples.

Analyses and Comparisons

• The researchers calculated the difference between the post-TRH value and the baseline (referred to as Delta Δ) and fold change (FC) for TSH, TT3, and TT4. These computations provide insights into the degree of change in thyroid hormone levels as a result of the sinigrin-intake and the low-iodine diet.
• The data was analyzed, with findings being significant at a level of p<.05.

Findings

• The study found that both FC and Delta Δ TT4 and TT3 concentrations had a group and week interaction (p<.001), indicating that the quantities of these thyroid hormones varied between groups and weeks. The control group had higher values than both the low and high sinigrin groups in the 12th week.
• Similar results were observed for TT4 FC values, with the control group having more elevated hormone concentrations than the others at week 12 (p<.006).
• Iodine concentrations were found to have decreased (p<.002) over the study period in mares taking sinigrin.

Conclusion

• The study concluded that feeding mares a low-iodine diet along with either 20 or 35 mmol of sinigrin per day led to a decrease in serum iodine concentrations, hinting that this combination may impact the mares’ thyroid function.