מולטיויטמינים מעלים סיכון לסרטן הערמונית

http://newsvote.bbc.co.uk/mpapps/pagetools/print/news.bbc.co.uk/2/hi/health/6657795.stm

http://www.nfc.co.il/Archive/001-D-131152-00.html?tag=11-52-35

שילוב של עודף מולטיויטמינים ותוספים שונים (סלניום, אבץ, ב- קרוטן) ובמיוחד עם רקע גנטי מעלים סיכון עד פי 6 לסרטן קטלני. להלן קטעים מהמאמר: JNCI Journal of the National Cancer Institute 2007 99(10):754-764 Multivitamin Use AND Risk of Prostate Cancer in the National Institutes of Health–AARP Diet AND Health Study ABSTRACT Background: Multivitamin supplements are used by millions of Americans because of their potential health benefits, but the relationship between multivitamin use AND prostate cancer is unclear. Methods: We prospectively investigated the association between multivitamin use AND risk of prostate cancer (localized, advanced, AND fatal) in 295344 men enrolled in the National Institutes of Health (NIH)–AARP Diet AND Health Study who were cancer free at enrollment in 1995 AND 1996. During 5 years of follow-up, 10241 participants were diagnosed with incident prostate cancer, including 8765 localized AND 1476 advanced cancers. In a separate mortality analysis with 6 years of follow-up, 179 cases of fatal prostate cancer were ascertained. Multivitamin use was assessed at baseline as part of a self-administered, mailed food-frequency questionnaire. Relative risks (RRs) AND 95% confidence intervals (CIs) were calculated by use of Cox proportional hazards regression, adjusted for established OR suspected prostate cancer risk factors. Results: No association was observed between multivitamin use AND risk of localized prostate cancer. However, we found an increased risk of advanced AND fatal prostate cancers (RR = 1.32, 95% CI = 1.04 to 1.67 AND RR = 1.98, 95% CI = 1.07 to 3.66, respectively) among men reporting excessive use of multivitamins (more than seven times per week) when compared with never users. The incidence rates per 100000 person-years for advanced AND fatal prostate cancers for those who took a multivitamin more than seven times per week were 143.8 AND 18.9, respectively, compared with 113.4 AND 11.4 in never users. The positive associations with excessive multivitamin use were strongest in men with a family history of prostate cancer OR who took individual micronutrient supplements, including selenium, -carotene, OR zinc. Conclusion: These results suggest that regular multivitamin use is not associated with the risk of early OR localized prostate cancer. The possibility that men taking high levels of multivitamins along with other supplements have increased risk of advanced AND fatal prostate cancers is of concern AND merits further evaluation. ----------------------------------------------------------- Selenium: Despite the small number of participants, heavy multivitamin users who were also taking a selenium supplement had a statistically significant 5.8-fold increased risk of fatal prostate cancer, whereas among nonusers of a selenium supplement, there was no association between fatal prostate cancer AND multivitamin use (P value for test of interaction = .037). Heavy multivitamin use versus never use was associated with an increased risk of both advanced prostate cancer (RR = 2.48, 95% CI = 1.45 to 4.23) AND fatal prostate cancer (RR = 16.41, 95% CI = 2.62 to 102.68) among men with a positive family history of prostate cancer, whereas no association was apparent among those without a family history (RR = 0.97, 95% CI = 0.70 to 1.34; RR = 1.07, 95% CI = 0.44 to 2.58) (Table 5). Zinc: Among men who reported taking a zinc supplement, multivitamin use at more than seven versus seven OR fewer times per week was associated with an increased risk of fatal prostate cancer (RR = 4.36, 95% CI = 1.83 to 10.39), whereas no association with multivitamins was observed for men not taking a zinc supplement (RR = 1.13, 95%CI = 0.46 to 2.80; P value for test of interaction = .042). Thus, the apparent adverse effect of multivitamin use on prostate cancer seen among the subgroup of men defined by a positive family history of prostate cancer AND zinc supplement use was stronger in heavy versus nonheavy use of multivitamins. Previous data linking supplemental zinc to increased risk of prostate cancer are sparse, but one study found that dosage of zinc at greater than 100 mg/day was related to an increased risk of advanced prostate cancer (34). The apparent adverse effect of multivitamin supplements in combination with supplemental zinc on prostate cancer risk could be due to nonessential, potentially harmful trace elements contained in zinc supplements, such as cadmium (35,36), a known carcinogen (37). -carotene: Our observation of an increase in advanced prostate cancer with heavy multivitamin use in combination with a -carotene supplement use is troubling, given results from the ATBC study showing that -carotene supplementation caused a 23% increase in total prostate cancer AND a statistically significant 35% increase in the incidence of clinically relevant disease (stages II–IV) (20,29). The risk of advanced prostate cancer AND prostate cancer mortality associated with heavy multivitamin use was highest in men who reported concomitant use of selenium, -carotene, OR zinc supplements, OR who had a positive family history of prostate cancer. Although there was no main effect of multivitamin use on localized prostate cancer, we found an increased risk of localized prostate cancer among those who took multivitamins more than seven times per week versus never use, in men also taking vitamin E, selenium, OR folate supplements.