This is the other half of the vitamin C topic. (aka ascorbic acid; ascorbate)
Oral vitamin C from food or supplements is mostly not associated with reduced PCa risk. Studies mostly looked at vitamin C intake & the risk of a future PCa diagnosis.
Is there benefit after diagnosis? The vitamin C gurus who promote high-dose IVC say no.
SOME EFFECT on risk:
[Pos1] 2009 - Italy:
"for vitamin C the inverse association was of borderline statistical significance (OR = 0.86 ...)."
[Pos2] 2005 - U.S.
"Compared with men in the lowest quartile of intake, reduced risks were observed for men in the highest quartile of intake of vitamin C (OR = 0.49 ...)"
NO EFFECT on risk:
[Neg1] The Physicians' Health Study II Randomized Controlled Trial (2009)
"In this large, long-term trial of male physicians, neither vitamin E nor C supplementation reduced the risk of prostate or total cancer."
[Neg2] A 2006 U.S. study:
"Dietary and supplemental vitamin C intakes were not associated with a reduced risk of prostate cancer."
[Neg3] A 2005 U.S. study:
"The median plasma concentration of vitamin C for the cohort was 1.17 mg/dL, which is in the normal to high range for older men."
"The age-adjusted relative risk of prostate cancer for the highest quartile (median = 1.47 mg/dL ...) compared with the lowest quartile (median = 0.83 mg/dL ...) of plasma vitamin C concentration was 1.31" (!)
[Neg4] A 2003 U.S. study:
"In both cohorts, cases and controls had similar concentrations of alpha-carotene, beta-carotene, total carotene, beta-cryptoxanthin, lutein, lycopene, retinol, and ascorbic acid"
[Neg5] A 2002 Dutch study:
"For intake of retinol, vitamins C and E and other carotenoids (alpha-carotene, beta-carotene, lycopene, and lutein/zeaxanthin) no effect on overall prostate cancer risk was found."
[Neg6] A 2000 Swiss study found no benefit & reported:
"Increased cancer mortality risks associated with low plasma cholesterol were not explained by the confounding effect of antioxidant vitamins, but were attributed in part to the effect of preexisting cancer."
[Neg7] A 1996 U.S. study reported:
"During the 30-year follow-up, prostate cancer developed in 132 men {of 1,899 middle-aged men}. There was no indication that consumption of beta-carotene or vitamin C was related to increased or decreased risk of prostate cancer."
[Neg8] 1996 German study.
[Neg9] 1985 Hawaii
-Patrick
[Pos1] ncbi.nlm.nih.gov/pubmed/194...
[Pos2] ncbi.nlm.nih.gov/pubmed/163...
[Neg1] jama.jamanetwork.com/articl...
[Neg2] jnci.oxfordjournals.org/con...
[Neg3] ncbi.nlm.nih.gov/pubmed/159...
[Neg4] ncbi.nlm.nih.gov/pubmed/125...
[Neg5] ncbi.nlm.nih.gov/pubmed/121...
[Neg6] ajcn.nutrition.org/content/...
[Neg7] ncbi.nlm.nih.gov/pubmed/886...
