b vitamin breast no good

b vitamin breast no good - British Journal of Cancer(2008...

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Dietary intake of selected B vitamins in relation to risk of major cancers in women GC Kabat * ,1 , AB Miller 2 , M Jain 2 and TE Rohan 1 1 Department of Epidemiology and Population Health, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Room 1301, NY 10461, USA; 2 Department of Public Health Sciences, University of Toronto, Toronto, Canada Although folic acid has been investigated for its potential to inhibit carcinogenesis, few epidemiologic studies have assessed the effects of intake of thiamin, riboflavin, and niacin, which may reduce cancer risk by acting as cofactors in folate metabolism or by other mechanisms. Using data from a large cohort of Canadian women, we examined the association of dietary intake of these nutrients, as well as intake of folate, methionine, and alcohol, with cancers of the breast, endometrium, ovary, colorectum, and lung ascertained during an average of 16.4 years of follow-up. After exclusions, the following numbers of incident cases were available for analysis: breast, n ¼ 2491; endometrium, n ¼ 426; ovary, n ¼ 264; colorectum, n ¼ 617; and lung, n ¼ 358. Cox proportional hazard models were used to estimate risk of each cancer with individual nutrients and to explore possible effect modification by combinations of nutrients on cancer risk. Few significant associations of intake of individual B vitamins with the five cancers were observed. Alcohol consumption showed a modest positive association with breast cancer risk but not with risk of the other cancers. There was no evidence of effect modification among the nutrients. This large study provides little support for an association of dietary intake thiamin, riboflavin, niacin, folate, or methionine with five major cancers in women. British Journal of Cancer (2008) 99, 816–821. doi:10.1038/sj.bjc.6604540 www.bjcancer.com Published online 29 July 2008 2008 Cancer Research UK Keywords: dietary folate; thiamin; riboflavin; niacin; methionine; female neoplasms ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Interest in the potential of folate to reduce the risk of common cancers stems from the important role of this B vitamin in one- carbon metabolism. Optimal one-carbon metabolism is necessary for the synthesis of the purines, adenine and guanine, and the conversion of uridylate to thymidylate, which blocks the misincorporation of uracil into DNA (Choi and Mason, 2000; Ziegler and Lim, 2007). Dysregulation of one-carbon metabolism and DNA methylation is believed to promote carcinogenesis (Kim, 2004). Other B vitamins, including thiamin (vitamin B1), riboflavin (vitamin B2), and niacin (vitamin B3) may also play a role in carcinogenesis, either by acting as cofactors in folate metabolism (riboflavin (Powers, 2003, 2005)) or by their independent roles in DNA synthesis (thiamin (Boros, 2000)), maintaining genomic stability, DNA repair, and regulation of cell division and apoptosis (niacin (Jacobson et al , 1995; Ames, 2001; Kirkland, 2003)). Epidemiological evidence regarding the association of folate and
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This note was uploaded on 11/06/2010 for the course NS 1150 taught by Professor Levitsky during the Spring '05 term at Cornell.

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b vitamin breast no good - British Journal of Cancer(2008...

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