Thyroid-Modulating Activities of Olive and Its Polyphenols: A Systematic Review.

Olive oil, which is commonly used in the Mediterranean diet, is known for its health benefits related to the reduction of the risks of cancer, coronary heart disease, hypertension, and neurodegenerative disease. These unique properties are attributed to the phytochemicals with potent antioxidant activities in olive oil. Olive leaf also harbours similar bioactive compounds. Several studies have reported the effects of olive phenolics, olive oil, and leaf extract in the modulation of thyroid activities. A systematic review of the literature was conducted to identify relevant studies on the effects of olive derivatives on thyroid function. A comprehensive search was conducted in October 2020 using the PubMed, Scopus, and Web of Science databases. Cellular, animal, and human studies reporting the effects of olive derivatives, including olive phenolics, olive oil, and leaf extracts on thyroid function were considered. The literature search found 445 articles on this topic, but only nine articles were included based on the inclusion and exclusion criteria. All included articles were animal studies involving the administration of olive oil, olive leaf extract, or olive pomace residues orally. These olive derivatives were consistently demonstrated to have thyroid-stimulating activities in euthyroid or hypothyroid animals, but their mechanisms of action are unknown. Despite the positive results, validation of the beneficial health effects of olive derivatives in the human population is lacking. In conclusion, olive derivatives, especially olive oil and leaf extract, could stimulate thyroid function. Olive pomace residue is not suitable for pharmaceutical or health supplementation purposes. Therapeutic applications of olive oil and leaf extract, especially in individuals with hypothyroidism, require further validation through human studies.

Thyroxine and triiodothyronine content in commercially available thyroid health supplements.

BACKGROUND: As defined by the Dietary Supplement Health and Education Act 1997, such substances as herbs and dietary supplements fall under general Food and Drug Administration supervision but have not been closely regulated to date. We examined the thyroid hormone content in readily available dietary health supplements marketed for "thyroid support." METHODS: Ten commercially available thyroid dietary supplements were purchased. Thyroid supplements were dissolved in 10 mL of acetonitrile and water with 0.1% trifloroacetic acid and analyzed using high-performance liquid chromatography for the presence of both thyroxine (T4) and triiodothyronine (T3) using levothyroxine and liothyronine as a positive controls and standards. RESULTS: The amount of T4 and T3 was measured separately for each supplement sample. Nine out of 10 supplements revealed a detectable amount of T3 (1.3-25.4 µg/tablet) and 5 of 10 contained T4 (5.77-22.9 µg/tablet). Taken at the recommended dose, 5 supplements delivered T3 quantities of greater than 10 µg/day, and 4 delivered T4 quantities ranging from 8.57 to 91.6 µg/day. CONCLUSIONS: The majority of dietary thyroid supplements studied contained clinically relevant amounts of T4 and T3, some of which exceeded common treatment doses for hypothyroidism. These amounts of thyroid hormone, found in easily accessible dietary supplements, potentially expose patients to the risk of alterations in thyroid levels even to the point of developing iatrogenic thyrotoxicosis. The current study results emphasize the importance of patient and provider education regarding the use of dietary supplements and highlight the need for greater regulation of these products, which hold potential danger to public health.

Iodine fortification of vegetables improves human iodine nutrition: in vivo evidence for a new model of iodine prophylaxis.

BACKGROUND: Iodine deficiency is the result of insufficient intake of dietary iodine and as a consequence causes multiple adverse effects. About 2 billion individuals in the world are affected by iodine deficiency. It has been found that the most effective way to control iodine deficiency is through the universal salt iodization. However, salt iodization alone may not be sufficient to assure adequate iodine nutrition. In most industrialized countries, excess consumption of salt has become recognized as a health risk. Therefore, biofortification of vegetables with iodine offers an excellent opportunity to increase iodine intake. AIM AND METHODS: The aim of this study was to test the efficiency of a new model of iodine prophylaxis in a group of 50 healthy volunteers through the intake of vegetables (potatoes, cherry tomatoes, carrots, and green salad) fortified with iodine. Each serving of vegetables consisted of 100 g of potatoes, carrots, tomatoes, or salad containing 45 mg of iodine (30% of the Recommended Daily Allowance), and the volunteers consumed a single serving of vegetables, as preferred, each day for 2 weeks. Urinary iodine (UI) excretion was measured before and after intake of vegetables. RESULTS: The UI concentration measured in volunteers before the intake of vegetables was 98.3 mg/L (basal value), increasing to 117.5 mg/L during the intake of vegetables. Seven days after the discontinuation of vegetable intake, UI was 85 mg/L. UI concentration increment was 19.6% compared with the basal value; therefore, the difference was statistically significant (P = .035). CONCLUSIONS: Biofortification of vegetables with iodine provides a mild but significative increase in UI concentration and, together with the habitual use of iodized salt, may contribute to improve the iodine nutritional status of the population without risks of iodine excess.

Iodine deficiency disorders after a decade of universal salt iodization in a severe iodine deficiency region in China.

BACKGROUND & OBJECTIVE: Universal salt iodization (USI) was implemented in all counties of China in 1995. This study was undertaken to assess the status of iodine deficiency disorders control and prevention after 10 years of implementation of USI in a severe iodine deficiency region in China. METHODS: Thirty primary school were selected in Gansu province utilizing cluster sampling methodology for the years 1995 and 2005. In each selected school, 40 children aged 8-10 yr were randomly selected for thyroid and IQ examination, and urinary samples were collected from 12. On the spot casual urine samples and salt samples were collected from a subset of children included in the study. In 2005, casual urine samples were also collected from 50 pregnant and lactating women in each cluster. Effect of health education was studied by a combination method of giving questionnaires to and observing students and families. RESULTS: The total goiter rates (TGR) were found to be 13.5 and 38.7 per cent in 2005 and 1995 respectively. The medians urinary iodine excretion levels of children were 191.8 and 119.9 mICROg/l in 2005 and 1995. The median urinary iodine excretion level of women was 161.9 mICROg/l. The mean intelligence quotient (IQ) was 96.9 in 2005 significantly more than that in 1997 (P<0.05). The health education pass rate of children and women were 21.1 and 51.1 per cent respectively. INTERPRETATION & CONCLUSION: After ten years of universal salt iodization (USI), iodine nutrition of people improved and the current iodine nutrition status of population was adequate. Decrease in TGR and increase in IQ showed that IDD control and prevention had made great progress through ten years USI, salt iodization played the key role in IDD control and prevention for sustained elimination of IDD, the programme of USI and other measures like health education should be persisted and enforced.

Should we treat elevated thyroid stimulating hormone levels in obese children and adolescents?

OBJECTIVE: To examine the prevalence of abnormal thyroid function tests among obese children and adolescents, and to study the effect of thyroid hormone supplementation on body weight, linear growth and lipid profiles in these children. DESIGN: Thyroid function tests and lipid profiles were measured in 196 obese children and adolescents. Thyroid auto-antibodies were measured in children with hyperthyrotropinemia (elevated thyroid stimulating hormone (TSH) and normal free thyroxine-FT4). All children with hyperthyrotropinemia participated in a combined dietary-behavioral-physical activity weight management intervention. Fifteen of the obese children with hyperthyrotropinemia were also treated with thyroid hormone substitution for 6 months and were compared to non-treated subjects (n = 26). RESULTS: Forty-one obese children had hyperthyrotropinemia (20.9%). Positive thyroid auto-antibodies were only found in 19.5% of these children. Treatment had no significant effect on body weight, linear growth and lipid profile, except for causing a greater decrease in triglyceride levels. TSH levels returned to normal ranges in the majority of children with hyperthyrotropinemia who participated in the combined intervention, irrespective of thyroxine treatment. CONCLUSIONS: Hyperthyrotropinemia is relatively common in obese children, but autoimmune thyroid disease accounts for a minority of the cases. TSH levels returned to normal in the majority of patients even without thyroid hormone administration. No beneficial effects on body weight, body mass index, linear growth and body lipids were found in treated subjects, suggesting that thyroid substitution is not necessary in most cases.