Four studies on vitamin use and cancer seem to reach different conclusions.

Thursday, 08/04/2010  |   Breast Cancer, Herb or Compound, Prostate Cancer  |  no comments

Four studies on vitamin use and cancer seem to reach different conclusions. Are vitamins a benefit or a danger? I guess like all of these studies it depends; depends on the type of vitamin, the form of the components ie methylate form or not, and the combinations of vitamins therein. I think it is wise to use vitamins with clear intention, that is, what is attempted by their use, what is being treated and for how long will they be used. The last study concluded that multivitamin/mineral supplement use may prevent cancer in individuals with poor or suboptimal nutritional status, which does make sense BUT we need to measure that nutritional status to ensure we are treating the correct deficiency. The last study also points out the difference in gender and the impact of vitamins – interesting.

Multivitamin use and breast cancer incidence in a prospective cohort of Swedish women.
Many women use multivitamins in the belief that these supplements will prevent chronic diseases such as cancer and cardiovascular disease. However, whether the use of multivitamins affects the risk of breast cancer is unclear. OBJECTIVE: We prospectively examined the association between multivitamin use and the incidence of invasive breast cancer in the Swedish Mammography Cohort. DESIGN: In 1997, 35,329 cancer-free women completed a self-administered questionnaire that solicited information on multivitamin use as well as other breast cancer risk factors. Relative risks (RRs) and 95% CIs were calculated by using Cox proportional hazard models and adjusted for breast cancer risk factors. RESULTS: During a mean follow-up of 9.5 y, 974 women were diagnosed with incident breast cancer. Multivitamin use was associated with a statistically significant increased risk of breast cancer. The multivariable RR of women who reported the use of multivitamins was 1.19 (95% CI: 1.04, 1.37). The association did not differ significantly by hormone receptor status of the breast tumour.
CONCLUSIONS: These results suggest that multivitamin use is associated with an increased risk of breast cancer. This observed association is of concern and merits further investigation.
Larsson SC, Akesson A, Bergkvist L, Wolk A. Am J Clin Nutr. 2010 Mar 24.
Multivitamin use and risk of prostate cancer in the National Institutes of Health-AARP Diet and Health Study.
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 (localised, advanced, and fatal) in 295,344 men enrolled in the National Institutes of Health (NIH)-AARP Diet and Health Study who were cancer free at enrolment in 1995 and 1996. During 5 years of follow-up, 10,241 participants were diagnosed with incident prostate cancer, including 8765 localised 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 localised 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 100,000 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, beta-carotene, or zinc.
CONCLUSION: These results suggest that regular multivitamin use is not associated with the risk of early or localised prostate cancer.
Lawson KA, Wright ME, Subar A, Mouw T, Hollenbeck A, Schatzkin A, Leitzmann MF. J Natl Cancer Inst. 2007 May 16;99(10):754-64.
The efficacy and safety of multivitamin and mineral supplement use to prevent cancer and chronic disease in adults: a systematic review for a National Institutes of Health state-of-the-science conference.
Multivitamin and mineral supplements are the most commonly used dietary supplements in the United States. PURPOSE: To synthesise studies on the efficacy and safety of multivitamin/mineral supplement use in primary prevention of cancer and chronic disease in the general population. DATA SOURCES: English-language literature search of the MEDLINE, EMBASE, and Cochrane databases through February 2006 and hand-searching of pertinent journals and articles. STUDY SELECTION: Randomised, controlled trials in adults were reviewed to assess efficacy, and randomised, controlled trials and observational studies in adults or children were reviewed to assess safety. DATA EXTRACTION: Paired reviewers extracted data and independently assessed study quality. DATA SYNTHESIS: 12 articles from 5 randomised, controlled trials that assessed efficacy and 8 articles from 4 randomised, controlled trials and 3 case reports on adverse effects were identified. Study quality was rated fair for the studies on cancer, cardiovascular disease, cataracts, or age-related macular degeneration and poor for the studies on hypertension. In a poorly nourished Chinese population, combined supplementation with beta-carotene, alpha-tocopherol, and selenium reduced the incidence of and mortality rate from gastric cancer and the overall mortality rate from cancer by 13% to 21%. In a French trial, combined supplementation with vitamin C, vitamin E, beta-carotene, selenium, and zinc reduced the rate of cancer by 31% in men but not in women. Multivitamin and mineral supplements had no significant effect on cardiovascular disease or cataracts, except that combined beta-carotene, selenium, alpha-tocopherol, retinol, and zinc supplementation reduced the mortality rate from stroke by 29% in the Linxian study and that a combination of 7 vitamins and minerals stabilised visual acuity loss in a small trial. Combined zinc and antioxidants slowed the progression of advanced age-related macular degeneration in high-risk persons. No consistent adverse effects of multivitamin and mineral supplements were evident. LIMITATIONS: Only randomised, controlled trials were considered for efficacy assessment. Special nutritional needs, such as use of folic acid by pregnant women to prevent birth defects, were not addressed. Findings may not apply to use of commercial multivitamin supplements by the general U.S. population.
CONCLUSIONS: Evidence is insufficient to prove the presence or absence of benefits from use of multivitamin and mineral supplements to prevent cancer and chronic disease.
Huang HY, Caballero B, Chang S, Alberg AJ, Semba RD, Schneyer CR, Wilson RF, Cheng TY, Vassy J, Prokopowicz G, Barnes GJ 2nd, Bass EB. Ann Intern Med. 2006 Sep 5;145(5):372-85. Epub 2006 Jul 31.
Multivitamin/mineral supplements and prevention of chronic disease.
To review and synthesise published literature on the efficacy of multivitamin/mineral supplements and certain single nutrient supplements in the primary prevention of chronic disease in the general adult population, and on the safety of multivitamin/mineral supplements and certain single nutrient supplements, likely to be included in multivitamin/mineral supplements, in the general population of adults and children. DATA SOURCES: All articles published through February 28, 2006, on MEDLINE, EMBASE, and the Cochrane databases. REVIEW METHODS: Each article underwent double reviews on title, abstract, and inclusion eligibility. Two reviewers performed data abstraction and quality assessment. Differences in opinion were resolved through consensus adjudication. RESULTS: Few trials have addressed the efficacy of multivitamin/mineral supplement use in chronic disease prevention in the general population of the United States. One trial on poorly nourished Chinese showed supplementation with combined Beta-carotene, vitamin E and selenium reduced gastric cancer incidence and mortality, and overall cancer mortality. In a French trial, combined vitamin C, vitamin E, Beta-carotene, selenium, and zinc reduced cancer risk in men but not in women. No cardiovascular benefit was evident in both trials. Multivitamin/mineral supplement use had no benefit for preventing cataract. Zinc/antioxidants had benefits for preventing advanced age-related macular degeneration in persons at high risk for the disease. With few exceptions, neither Beta-carotene nor vitamin E had benefits for preventing cancer, cardiovascular disease, cataract, and age-related macular degeneration. Beta-carotene supplementation increased lung cancer risk in smokers and persons exposed to asbestos. Folic acid alone or combined with vitamin B12 and/or vitamin B6 had no significant effects on cognitive function. Selenium may confer benefit for cancer prevention but not cardiovascular disease prevention. Calcium may prevent bone mineral density loss in postmenopausal women, and may reduce vertebral fractures, but not non-vertebral fractures. The evidence suggests dose-dependent benefits of vitamin D with/without calcium for retaining bone mineral density and preventing hip fracture, non-vertebral fracture and falls. We found no consistent pattern of increased adverse effects of multivitamin/mineral supplements except for skin yellowing by Beta-carotene.
CONCLUSIONS: Multivitamin/mineral supplement use may prevent cancer in individuals with poor or suboptimal nutritional status. The heterogeneity in the study populations limits generalisation to United States population. Multivitamin/mineral supplements conferred no benefit in preventing cardiovascular disease or cataract, and may prevent advanced age-related macular degeneration only in high-risk individuals. The overall quality and quantity of the literature on the safety of multivitamin/mineral supplements is limited.
Huang HY, Caballero B, Chang S, Alberg A, Semba R, Schneyer C, Wilson RF, Cheng TY, Prokopowicz G, Barnes GJ 2nd, Vassy J, Bass EB. Evid Rep Technol Assess (Full Rep). 2006 May;(139):1-117.

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