(P30-036-23) Sugar Kelp (Saccharina latissima) Consumption Did Not Induce Toxic Features of Iodine in Diet-Induced Obesity Mice

Objectives: We previously demonstrated that sugar kelp (Saccharina latissima), a brown seaweed grown in the US, has anti-obesity effects. However, health concerns exist about the potential toxicity of seaweed consumption due to its high iodine contents. Therefore, this study was conducted to determine the potential toxicity of iodine high in sugar kelp while confirming its health benefits in diet-induced obesity mice.

Methods: Male C57BL/6J mice were fed a high-fat/high-sucrose/high-cholesterol diet (HF), a HF diet containing sugar kelp (HFSK; 6.0% dried sugar kelp powder w/w), or a HF diet containing the same amount of iodine present in 6% sugar kelp diet (HFID) for 14 weeks. Body weights were recorded weekly, and Echo MRI was performed to assess body composition at week 11. Blood and tissue samples were collected after 14 weeks of the experimental diets. Serum alanine aminotransferase (ALT) and complete blood count (CBC) were measured for toxicological evaluation. Also, gonadal white adipose tissue (gWAT) was used to investigate the effects of sugar kelp on inflammation.

Results: The HFSK group showed a significant reduction in final body weight, fat mass, and inflammatory gene expression in gWAT, while the HFID group did not elicit any significant effects compared with the HF control. Serum ALT level and the counts of white blood cells, red blood cells, hemoglobin, neutrophils, eosinophils, basophils, lymphocytes, monocytes, and platelets in the blood did not show any difference between groups. Mean platelet volume (MPV), an indicator of platelet size, was higher than normal ranges in all three groups; however, the HFID and HFSK showed significantly lower values than the control. Notably, HFSK and HFID groups showed significantly higher thyroid gland weights with altered morphology, including larger follicles, than the HF control.

Conclusions: The consumption of high iodine alone or through sugar kelp in an obesogenic diet did not elicit toxic features assessed by several blood markers; however, thyroid gland weight was induced by high iodine. Therefore, further studies are warranted to evaluate the effect of iodine, specifically on the thyroid gland and its related hormones.

Funding Sources: USDA NIFA