Selenio & diabete

**Eagle** · 04-01-2008, 14:43:04

Beta Carotene, epr oltre 2 anni ... nessun beneficio, e nessun maleficio ...

J Natl Cancer Inst. 1999 Dec 15;91(24):2102-6. Links
Comment in: J Natl Cancer Inst. 1999 Dec 15;91(24):2068-9. Beta-carotene supplementation and incidence of cancer and cardiovascular disease: the Women's Health Study.

Lee IM, Cook NR, Manson JE, Buring JE, Hennekens CH.
Division of Preventive Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, and Boston, MA 02215, USA. i-min.lee@channing.harvard.edu
BACKGROUND: In observational studies, individuals with high intakes of fruits and vegetables containing beta-carotene experience lower risks of developing cancer. However, the few randomized trials of beta-carotene supplementation show no overall benefits; some even suggest harm. This trial was designed to test the effects of beta-carotene supplementation in women. METHODS: The Women's Health Study is a randomized, double-blind, placebo-controlled trial originally testing aspirin, vitamin E, and beta-carotene in the prevention of cancer and cardiovascular disease among 39 876 women aged 45 years or older. The beta-carotene component was terminated early after a median treatment duration of 2.1 years (range = 0.00-2. 72 years). Statistical tests were two-sided. RESULTS: Among women randomly assigned to receive beta-carotene (50 mg on alternate days; n = 19 939) or placebo (n =19 937), there were no statistically significant differences in incidence of cancer, cardiovascular disease, or total mortality after a median of 4.1 years (2.1 years' treatment plus another 2.0 years' follow-up). There were 378 cancers in the beta-carotene group and 369 cancers in the placebo group (relative risk [RR] = 1.03; 95% confidence interval [CI] = 0.89-1. 18). There were no statistically significant differences for any site-specific cancer or during years 1 and 2 combined and years 3 and up combined. For cardiovascular disease, there were no statistically significant differences for myocardial infarction (42 in the beta-carotene group versus 50 in the placebo group), stroke (61 versus 43), deaths from cardiovascular causes (14 versus 12), or the combined end point of these three events (116 versus 102; among women with more than one event, only the first was counted). Deaths from any cause were similar in the two groups (59 versus 55). Among smokers at baseline (13% of all women), there were no statistically significant differences in overall incidence of cancer (RR = 1.11; 95% CI = 0.78-1.58) or cardiovascular disease (RR = 1.01; 95% CI = 0. 62-1.63). CONCLUSION: Among apparently healthy women, there was no benefit or harm from beta-carotene supplementation for a limited period on the incidence of cancer and of cardiovascular disease.

**Eagle** · 04-01-2008, 14:44:46

Vitamina E e beta carotene ... e' ovviamente un tema discusso, non voglio mica dire che certamente fanno male, pero' e' LAMPANTE che siamo distanti anni luce dal poter dire che fanno certamente solo e soltanto bene, spt in mega dosi ...

N Engl J Med. 1994 Apr 14;330(15):1029-35. Links
Comment in: ACP J Club. 1994 Nov-Dec;121(3):74. N Engl J Med. 1994 Apr 14;330(15):1080-1. N Engl J Med. 1994 Jun 2;330(22):1608-9. N Engl J Med. 1994 Sep 1;331(9):611-2; author reply 613. N Engl J Med. 1994 Sep 1;331(9):611; author reply 613-4. N Engl J Med. 1994 Sep 1;331(9):612-3. N Engl J Med. 1994 Sep 1;331(9):612; author reply 613. N Engl J Med. 1994 Sep 1;331(9):612; author reply 613. N Engl J Med. 1994 Sep 1;331(9):612; author reply 613. The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers. The Alpha-Tocopherol, Beta Carotene Cancer Prevention Study Group.

[No authors listed] BACKGROUND. Epidemiologic evidence indicates that diets high in carotenoid-rich fruits and vegetables, as well as high serum levels of vitamin E (alpha-tocopherol) and beta carotene, are associated with a reduced risk of lung cancer. METHODS. We performed a randomized, double-blind, placebo-controlled primary-prevention trial to determine whether daily supplementation with alpha-tocopherol, beta carotene, or both would reduce the incidence of lung cancer and other cancers. A total of 29,133 male smokers 50 to 69 years of age from southwestern Finland were randomly assigned to one of four regimens: alpha-tocopherol (50 mg per day) alone, beta carotene (20 mg per day) alone, both alpha-tocopherol and beta carotene, or placebo. Follow-up continued for five to eight years. RESULTS. Among the 876 new cases of lung cancer diagnosed during the trial, no reduction in incidence was observed among the men who received alpha-tocopherol (change in incidence as compared with those who did not, -2 percent; 95 percent confidence interval, -14 to 12 percent). Unexpectedly, we observed a higher incidence of lung cancer among the men who received beta carotene than among those who did not (change in incidence, 18 percent; 95 percent confidence interval, 3 to 36 percent). We found no evidence of an interaction between alpha-tocopherol and beta carotene with respect to the incidence of lung cancer. Fewer cases of prostate cancer were diagnosed among those who received alpha-tocopherol than among those who did not. Beta carotene had little or no effect on the incidence of cancer other than lung cancer. Alpha-tocopherol had no apparent effect on total mortality, although more deaths from hemorrhagic stroke were observed among the men who received this supplement than among those who did not. Total mortality was 8 percent higher (95 percent confidence interval, 1 to 16 percent) among the participants who received beta carotene than among those who did not, primarily because there were more deaths from lung cancer and ischemic heart disease. CONCLUSIONS. We found no reduction in the incidence of lung cancer among male smokers after five to eight years of dietary supplementation with alpha-tocopherol or beta carotene. In fact, this trial raises the possibility that these supplements may actually have harmful as well as beneficial effects.

**Eagle** · 04-01-2008, 14:45:35

E ancora ...

JAMA. 2005 Jul 6;294(1):56-65. Links
Comment in: ACP J Club. 2006 Jan-Feb;144(1):8-9. Evid Based Med. 2006 Feb;11(1):11. J Fam Pract. 2005 Oct;54(10):838-9. JAMA. 2005 Jul 6;294(1):105-6. JAMA. 2005 Jul 6;294(1):107-9. JAMA. 2005 Nov 16;294(19):2432; author reply 2432. Vitamin E in the primary prevention of cardiovascular disease and cancer: the Women's Health Study: a randomized controlled trial.

Lee IM, Cook NR, Gaziano JM, Gordon D, Ridker PM, Manson JE, Hennekens CH, Buring JE.
Division of Preventive Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02215, USA. ilee@rics.bwh.harvard.edu
CONTEXT: Basic research provides plausible mechanisms and observational studies suggest that apparently healthy persons, who self-select for high intakes of vitamin E through diet or supplements, have decreased risks of cardiovascular disease and cancer. Randomized trials do not generally support benefits of vitamin E, but there are few trials of long duration among initially healthy persons. OBJECTIVE: To test whether vitamin E supplementation decreases risks of cardiovascular disease and cancer among healthy women. DESIGN, SETTING, AND PARTICIPANTS: In the Women's Health Study conducted between 1992 and 2004, 39 876 apparently healthy US women aged at least 45 years were randomly assigned to receive vitamin E or placebo and aspirin or placebo, using a 2 x 2 factorial design, and were followed up for an average of 10.1 years. INTERVENTION: Administration of 600 IU of natural-source vitamin E on alternate days. MAIN OUTCOME MEASURES: Primary outcomes were a composite end point of first major cardiovascular event (nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death) and total invasive cancer. RESULTS: During follow-up, there were 482 major cardiovascular events in the vitamin E group and 517 in the placebo group, a nonsignificant 7% risk reduction (relative risk [RR], 0.93; 95% confidence interval [CI], 0.82-1.05; P = .26). There were no significant effects on the incidences of myocardial infarction (RR, 1.01; 95% CI, 0.82-1.23; P = .96) or stroke (RR, 0.98; 95% CI, 0.82-1.17; P = .82), as well as ischemic or hemorrhagic stroke. For cardiovascular death, there was a significant 24% reduction (RR, 0.76; 95% CI, 0.59-0.98; P = .03). There was no significant effect on the incidences of total cancer (1437 cases in the vitamin E group and 1428 in the placebo group; RR, 1.01; 95% CI, 0.94-1.08; P = .87) or breast (RR, 1.00; 95% CI, 0.90-1.12; P = .95), lung (RR, 1.09; 95% CI, 0.83-1.44; P = .52), or colon cancers (RR, 1.00; 95% CI, 0.77-1.31; P = .99). Cancer deaths also did not differ significantly between groups. There was no significant effect of vitamin E on total mortality (636 in the vitamin E group and 615 in the placebo group; RR, 1.04; 95% CI, 0.93-1.16; P = .53). CONCLUSIONS: The data from this large trial indicated that 600 IU of natural-source vitamin E taken every other day provided no overall benefit for major cardiovascular events or cancer, did not affect total mortality, and decreased cardiovascular mortality in healthy women. These data do not support recommending vitamin E supplementation for cardiovascular disease or cancer prevention among healthy women.

**Superfustakkion** · 04-01-2008, 14:52:56

vorrei pure riflettere ma non sò l'inglese...

cmq dimmi quali cibi contengono più selenio cosi li togliamo di mezzo

***ikuape86*** · 04-01-2008, 14:59:31

eagle quanti studi che dicono il contrario ci sono? tantissimi...io dico ma di chi ci dobbiamo fidare?

**Eagle** · 04-01-2008, 15:39:45

Originariamente Scritto da ikuape86 Visualizza Messaggio

eagle quanti studi che dicono il contrario ci sono? tantissimi...io dico ma di chi ci dobbiamo fidare?

Guarda, mi sono fatto un giro in alcune banche dati, con le parole chiave selenio e diabete, e di studi sull'uomo che vedano un effetto preventivo non ne ho trovato neanche uno.

Ho trovato questo, che punta anche lui verso un effetto non certamente positivo, e tanti studi su ratti, scimmie, cavie varie, cellule ...

Eagle

Diabetes Care. 2007 Apr;30(4):829-34. Links
Serum selenium and diabetes in U.S. adults.

Bleys J, Navas-Acien A, Guallar E.
Department of Epidemiology, the Welch Center for Prevention, Epidemiology, and Clinical Research, Baltimore, Maryland 21205, USA. jbleys@jhsph.edu
OBJECTIVE: The purpose of this study was to examine the relationship between serum selenium levels and the prevalence of diabetes among U.S. adults. RESEARCH DESIGN AND METHODS: We conducted a cross-sectional analysis of 8,876 adults > or =20 years of age who participated in the Third National Health and Nutrition Examination Survey. Diabetes was defined as the presence of a fasting plasma glucose > or =126 mg/dl, a self-report of a physician diagnosis of diabetes, or current use of insulin or oral hypoglycemic medication. Serum selenium was measured by atomic absorption spectrometry. RESULTS: Mean serum selenium levels in participants with and without diabetes were 126.5 and 125.7 ng/ml, respectively. Age-, sex-, race-, and BMI-adjusted mean selenium levels were 126.8 ng/ml in participants with diabetes and 124.7 ng/ml in participants without diabetes (adjusted difference 2.1 ng/ml [95% CI 0.4-3.8]; P = 0.02). The multivariable adjusted odds ratio for diabetes comparing the highest to the lowest quintile of serum selenium was 1.57 [1.16-2.13]. However, the association between high serum selenium and the prevalence of diabetes was nonlinear, with no clear trend in quintiles 2-4. CONCLUSIONS: In a probability sample of the U.S. population, high serum selenium levels were positively associated with the prevalence of diabetes. Until findings from prospective studies and randomized controlled trials are available, selenium intake, including selenium supplementation, should not be recommended for primary or secondary diabetes prevention in populations with adequate selenium status such as the U.S. population.