beta-carotene and Hypothyroidism

Thyroid hormones may influence risk of cancer through their role in cell differentiation, growth, and metabolism. One study of circulating thyroid hormones supports this hypothesis with respect to prostate cancer. We undertook a prospective analysis of thyroid hormones and prostate cancer risk in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study.. Within the ATBC Study, a randomized controlled trial of α-tocopherol and β-carotene supplements and cancer incidence in male smokers, 402 prostate cancer cases were sampled. Controls were matched 2:1 to cases on age and date of blood collection. Odds ratios (OR) and 95% confidence intervals (CI) of prostate cancer were estimated for quintiles of serum total and free thyroxine (T4), thyroid-stimulating hormone (TSH), thyroid-binding globulin (TBG), and by categories of thyroid status.. Men with serum higher TSH had a decreased risk of prostate cancer compared to men with lower TSH (Q5 vs. Q1-4: OR = 0.70, 95% CI: 0.51-0.97, p = 0.03). When the T4 and TSH measurements were combined to define men as hypothyroid, euthyroid or hyperthyroid, hypothyroid men had a lower risk of prostate cancer compared to euthyroid men (OR = 0.48, 95% CI = 0.28-0.81, p = 0.006). We observed no association between hyperthyroid status and risk, although the number of hyperthyroid men with prostate cancer was small (n = 9).. In this prospective study of smokers, men with elevated TSH and those classified as being in a hypothyroid state were at decreased risk of prostate cancer. Future studies should examine the association in other populations, particularly non-smokers and other racial/ethnic groups.

Topics: Aged; alpha-Tocopherol; beta Carotene; Case-Control Studies; Genetic Association Studies; Humans; Hypothyroidism; Male; Middle Aged; Prostatic Neoplasms; Risk Factors; Thyroid Function Tests; Thyrotropin; Thyroxine

Free radical-mediated oxidative stress has been implicated in the etiopathogenesis of several autoimmune disorders. Also, there is growing evidence supporting the role of reactive oxygen species in the pathogenesis of thyroid disorders. The aim of this study was to investigate the influence of hypothyroidism, hyperthyroidism, and their treatments on the metabolic state of oxidative stress, and antioxidant status markers.. A total of 20 newly diagnosed patients with overt hypothyroidism due to Hashimoto's thyroiditis, 20 patients with overt hyperthyroidism due to Graves' disease, and 20 healthy subjects as the control group were enrolled in the study. Fasting blood samples (12 h), taken at the initiation, after the 30th and 60th day of therapy were analyzed for malondialdehyde, nitrite, vitamin E, vitamin A, beta-carotene, ascorbate, and myeloperoxidase and superoxide dismutase activity. No patient presented additional risk factors for increased reactive oxygen species levels.. Malondialdehyde, nitrite, vitamin E, and myeloperoxidase activity increased in patients with hypothyroidism. After 2 months, the levels of nitrite and vitamin E were reduced to control levels by treatment. The patients with hyperthyroidism had increased levels of malondialdehyde and myeloperoxidase activity in comparison with the controls. Treatment with propylthiouracil attenuated these increments after 1 month.. Our results reveal an increased generation of reactive oxygen species and impairment of the antioxidant system in patients with hyperthyroidism, and particularly in patients with hypothyroidism. These findings indicate that thyroid hormones have a strong impact on oxidative stress and the antioxidant system.

Topics: Adult; Antioxidants; Antithyroid Agents; beta Carotene; Female; Humans; Hyperthyroidism; Hypothyroidism; Male; Malondialdehyde; Middle Aged; Nitrites; Oxidative Stress; Peroxidase; Propylthiouracil; Reactive Oxygen Species; Superoxide Dismutase; Thyroxine; Vitamin A; Vitamin E

Retinoid status with reference to beta-carotene and retinol has been studied in women suffering from hyper- and hypothyroid conditions. The interrelationship between the retinoids and triiodothyronine and thyroxine hormones has been established from the cases mentioned after estimation of the respective compounds from the blood serum. It has been found that there is an increase in beta-carotene and retinol in the hypothyroid and a decrease of the same in the hyperthyroid conditions respectively.

Topics: Adolescent; Adult; beta Carotene; Female; Humans; Hyperthyroidism; Hypothyroidism; Middle Aged; Retinoids; Thyroid Hormones; Thyroxine; Triiodothyronine; Vitamin A

In this study, the effect of different levels of thyroid hormone and metabolic activity on low density lipoprotein (LDL) oxidation was investigated. Thus, in 16 patients with hyperthyroidism, 16 with hypothyroidism, and 16 age- and sex-matched healthy normolipidemic control subjects, the native LDL content in lipid peroxides, vitamin E, beta-carotene, and lycopene, as well as the susceptibility of these particles to undergo lipid peroxidation, was assessed. Hyperthyroidism was associated with significantly higher lipid peroxidation, as characterized by a higher native LDL content in lipid peroxides, a lower lag phase, and a higher oxidation rate than in the other two groups. This elevated lipid peroxidation was associated with a lower LDL antioxidant concentration. Interestingly, hypothyroid patients showed an intermediate behavior. In fact, in hypothyroidism, LDL oxidation was significantly lower than in hyperthyroidism but higher than in the control group. Hypothyroidism was also characterized by the highest beta-carotene LDL content, whereas vitamin E was significantly lower than in control subjects. In hyperthyroidism but not in the other two groups, LDL oxidation was strongly influenced by free thyroxine blood content. In fact in this group, the native LDL lipid peroxide content and the lag phase were directly and indirectly, respectively, related to free thyroxine blood levels. On the contrary, in hypothyroidism LDL oxidation was strongly and significantly related to serum lipids. In conclusion, both hypothyroidism and hyperthyroidism are characterized by higher levels of LDL oxidation when compared with normolipidemic control subjects. In hyperthyroid patients, the increased lipid peroxidation was strictly related to free thyroxine levels, whereas in hypothyroidism it was strongly influenced by serum lipids.

Topics: Antioxidants; beta Carotene; Carotenoids; Fatty Acids, Nonesterified; Female; Humans; Hyperthyroidism; Hypothyroidism; Lipid Peroxidation; Lipoproteins, LDL; Lycopene; Male; Middle Aged; Thyroid Gland; Vitamin E

The conversion of beta-carotene (provitamin A) to 2 molecules of vitamin A (retinol) is accelerated by thyroxine and hyperthyroidism, respectively. The characteristic yellow tint of the skin in hypothyroidism is due to hyper-beta-carotenemia. Both in hyper- and hypothyroidism in a retinol deficiency has been observed in literature. In a series of 36 patients (16 hyper-, 8 hypo-, and 12 euthyroid) serum samples were analyzed for retinol and beta-carotene levels (high pressure liquid chromatography) as well as retinol binding protein (radial immune diffusion), prealbumin (nephelometry), and serum zinc values (atomic absorption spectrometry) were established. The beta-carotene serum level in the hypothyroid group (mean 1.1 microgram/ml) was significantly higher (p < 0.05) in relation to euthyroid controls (0.6 microgram/ml), the hyperthyroid group showed significantly lower values (0.3 microgram/ml). RBP and prealbumin concentrations were significantly lower (p < 0.05) in hyperthyroid as against eu- and hypothyroid patients. Surprisingly, in all 3 groups the retinol levels were not significantly different, although the hyperthyroid group was slightly lower (0.6 microgram/ml) than the mean value of 0.7 micrograms/ml in the other groups. A vitamin A and protein rich food, customary in Central Europe, seems to rule out any vitamin A deficiency both in hyper- and hypothyroidism. However, the beta-carotene values are significantly higher in hypothyroidism, while in hyperthyroidism they were lower. As intrahepatic zinc content plays an important role in the synthesis of RBP and its secretion together with retinol, we also analyzed this component: The serum zinc levels in hyperthyroid patients were clearly higher (79.1 micrograms/dl) than in the hypothyroid group with 57 micrograms/dl (p < 0.05).

Topics: Adult; Aged; beta Carotene; Carotenoids; Female; Humans; Hyperthyroidism; Hypothyroidism; Male; Middle Aged; Prealbumin; Reference Values; Retinol-Binding Proteins; Vitamin A; Zinc

Topics: Adolescent; Adult; beta Carotene; Carotenoids; Humans; Hypothyroidism; Vitamin A Deficiency