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Calcium intake and prostate cancer among African Americans: effect modification by vitamin D receptor calcium absorption genotype.

ABSTRACT: High dietary intake of calcium has been classified as a probable cause of prostate cancer, although the mechanism underlying the association between dietary calcium and prostate cancer risk is unclear. The vitamin D receptor (VDR) is a key regulator of calcium absorption. In the small intestine, VDR expression is regulated by the CDX-2 transcription factor, which binds a polymorphic site in the VDR gene promoter. We examined VDR Cdx2 genotype and calcium intake, assessed by a food frequency questionnaire, in 533 African-American prostate cancer cases (256 with advanced stage at diagnosis, 277 with localized stage) and 250 African-American controls who participated in the California Collaborative Prostate Cancer Study. We examined the effects of genotype, calcium intake, and diet-gene interactions by conditional logistic regression. Compared with men in the lowest quartile of calcium intake, men in the highest quartile had an approximately twofold increased risk of localized and advanced prostate cancer (odds ratio [OR]?=?2.20, 95% confidence interval [CI]?=?1.40, 3.46), with a significant dose-response. Poor absorbers of calcium (VDR Cdx2 GG genotype) had a significantly lower risk of advanced prostate cancer (OR?=?0.41, 95% CI?=?0.19, 0.90). The gene-calcium interaction was statistically significant (p?=?0.03). Among men with calcium intake below the median (680?mg/day), carriers of the G allele had an approximately 50% decreased risk compared with men with the AA genotype. These findings suggest a link between prostate cancer risk and high intestinal absorption of calcium.

SUBMITTER: Rowland GW

PROVIDER: S-EPMC3234334 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature

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Calcium intake and prostate cancer among African Americans: effect modification by vitamin D receptor calcium absorption genotype.

Rowland Glovioell W GW Schwartz Gary G GG John Esther M EM Ingles Sue Ann SA

Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 20120101 1

High dietary intake of calcium has been classified as a probable cause of prostate cancer, although the mechanism underlying the association between dietary calcium and prostate cancer risk is unclear. The vitamin D receptor (VDR) is a key regulator of calcium absorption. In the small intestine, VDR expression is regulated by the CDX-2 transcription factor, which binds a polymorphic site in the VDR gene promoter. We examined VDR Cdx2 genotype and calcium intake, assessed by a food frequency ques ...[more]

PMID: 21887707

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Project description:There is controversy over whether African Americans have higher vitamin D requirements than recommended by the Institute of Medicine. We previously reported that maintaining serum 25(OH)D above 30 ng/mL does not prevent age-related bone loss. Herein, we report that bone strength is also unaffected by maintaining this level in this population.IntroductionThe role of vitamin D in bone strength has not been investigated in the African American (AA) population.MethodsA 3-year randomized controlled trial was designed to examine the effect of vitamin D supplementation on physical performance, bone loss, and bone strength in healthy older AA women. A total of 260 postmenopausal AA women, ages ≥ 60 years were randomized to a vitamin D3 or placebo arm. Vitamin D3 dose was adjusted to maintain serum 25OHD > 30 ng/mL. Bone mineral density, femoral axis length, and femoral neck (FN) width were measured by dual-energy X-ray absorptiometry. Composite indices of FN strength [compression strength index (CSI), bending strength index (BSI), and impact strength index (ISI)] were computed.ResultsThe mean age of participants was 68.2 ± 4.9 years. Baseline characteristics between groups were similar. The average dose of vitamin D3 was 3490 ± 1465 IU/day in the active group. The mean serum 25OHD was 46.8 ± 1.2 ng/mL versus 20.7 ± 1.1 ng/mL in the active versus placebo group. Serum 25OHD did not correlate with any composite indices. The longitudinal differences observed in FN width, CSI, BSI, and ISI in both groups were not statistically significant (all p values > 0.05). Further, there was no group × time interaction effect for any of the composite indices (all p values > 0.05).ConclusionMaintaining serum 25OHD > 30 ng/mL (75 nmol/L) does not affect bone strength in older AA women. There is no evidence to support vitamin D intake greater than the recommended RDA by the Institute of Medicine in this population for bone strength.

Dataset Information

Calcium intake and prostate cancer among African Americans: effect modification by vitamin D receptor calcium absorption genotype.

Publications

Calcium intake and prostate cancer among African Americans: effect modification by vitamin D receptor calcium absorption genotype.

Similar Datasets

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