Vitamins and prostate cancer risk

Dietary Consumption of Antioxidant Vitamins in Relation to Prostate Cancer Risk in Japanese Men: The Japan Public Health Center-based Prospective Study

BACKGROUND

Many epidemiological studies have investigated dietary intake of antioxidant vitamins in relation to prostate cancer risk in Western countries, but the results are inconsistent. However, few studies have reported this relationship in Asian countries.

METHODS

We investigated the association between intake of vitamins, including lycopene, α-carotene, β-carotene, vitamin C, vitamin E, with prostate cancer risk in the Japan Public Health Center-based Prospective (JPHC) study. 40,720 men without history of cancer finished the food frequency questionnaire (FFQ) and were included in the study. Hazard ratios (HRs) and 95% confidence intervals (CIs) of prostate cancer risk were calculated according to the quintiles of energy-adjusted intake of vitamins using Cox models.

RESULTS

After an average of 15.2 years (617,599 person-years in total) of follow-up, 1,386 cases of prostate cancer were identified, including 944 localized cases and 340 advanced cases. No associations were observed in consumption of antioxidant vitamins, including α-carotene, β-carotene, vitamin C, and vitamin E, and prostate cancer risk. Although higher lycopene intake was associated with increased risk of prostate cancer (highest vs lowest quintile, HR 1.24; 95% CI, 1.04-1.47; P for trend = 0.01), there was a null association of lycopene intake with risk of prostate cancer detected by subjective symptoms (HR 1.12; 95% CI, 0.79-1.58; P for trend = 0.11).

CONCLUSION

Our study suggested no association between antioxidant intake of vitamins and prostate cancer risk.

The role of micronutrients in the risk of urinary tract cancer

Prostate, bladder and kidney cancers remain the most common urological malignancies worldwide, and the prevention and treatment of these diseases pose a challenge to clinicians. In recent decades, many studies have been conducted to assess the association between supplementation with selected vitamins and elements and urinary tract tumour initiation and development. Here, we review the relationship between vitamins A, B, D, and E, in addition to calcium, selenium, and zinc, and the risk of developing prostate, kidney and bladder cancer. A relatively consistent body of evidence suggests that large daily doses of calcium (> 2,000 mg/day) increase the risk of prostate cancer. Similarly, supplementation with 400 IU/day of vitamin E carries a significant risk of prostate cancer. However, there have been many conflicting results regarding the effect of these nutrients on kidney and bladder neoplasms. Moreover, the role of other compounds in urinary tract carcinogenesis needs further clarification.

Positive association between circulating 25-hydroxyvitamin D levels and prostate cancer risk: new findings from an updated meta-analysis

PURPOSE

To investigate and clarify the relationship between circulating 25-hydroxyvitamin D level and prostate cancer risk.

METHODS

We conducted the meta-analysis to better evaluate the association. Terms "25-Hydroxyvitamin D"/"vitamin D" and "prostate cancer" were used for literature search.

RESULTS

We identified 21 relevant publications from databases of PubMed and MEDLINE and included 11,941 cases and 13,870 controls in the meta-analysis. Overall studies revealed a significant 17 % elevated risk of prostate cancer for individuals with higher level of 25-hydroxyvitamin D (OR = 1.17, 95 % CI = 1.05-1.30, P  = 0.004), and no publication bias was found in the calculations (P  = 0.629). Subgroup analysis confirmed the association from nested case-control study group, studies from USA group and studies using serum samples group (nested case-control studies: OR = 1.17, 95 % CI = 1.08-1.27, P < 0.001; USA: OR = 1.15, 95 % CI = 1.03-1.29, P = 0.017; serum: OR = 1.20, 95 % CI = 1.01-1.42, P = 0.042); moreover, sensitivity tests also indicated significant results in studies from Europe and studies conducting with plasma samples after exclusion of some influential single study from the analysis, respectively (Europe: OR = 1.21, 95 % CI = 1.04-1.40, P = 0.014; plasma: OR = 1.13, 95 % CI = 1.00-1.27, P = 0.05).

CONCLUSIONS

Our meta-analysis, for the first time, suggested significant positive relationship between high level of 25-hydroxyvitamin D and increased risk of prostate cancer, reminding us that more concern should be taken into account during assessing the effect of 25-hydroxyvitamin D.

Laboratory medicine best practice guideline: vitamins a, e and the carotenoids in blood

Despite apparent method similarities between laboratories there appear to be confounding factors inhibiting uniform reporting and standardisation of vitamin assays. The Australasian Association of Clinical Biochemists (AACB) Vitamins Working Party, in conjunction with The Royal College of Pathologists of Australasia Quality Assurance Programs, has formulated a guideline to improve performance, reproducibility and accuracy of fat-soluble vitamin results. The aim of the guideline is to identify critical pre-analytical, analytical and post-analytical components of the analysis of vitamins A, E and carotenoids in blood to promote best practice and harmonisation. This best practice guideline has been developed with reference to the Centers for Disease Control and Prevention (CDC) "Laboratory Medicine Best Practices: Developing an Evidence-Based Review and Evaluation Process". The CDC document cites an evaluation framework for generating best practice recommendations that are specific to laboratory medicine. These 50 recommendations proposed herein, were generated from a comprehensive literature search and the extensive combined experience of the AACB Vitamins Working Party members. They were formulated based on comparison between an impact assessment rating and strength of evidence and were classified as either: (1) strongly recommend, (2) recommend, (3) no recommendation for or against, or (4) recommend against. These best practice recommendations represent the consensus views, in association with peer reviewed evidence of the AACB Vitamins Working Party, towards best practice for the collection, analysis and interpretation of vitamins A, E and carotenoids in blood.

Molecular mechanisms underlying the potentially adverse effects of folate

The importance of proper consumption of dietary folate for human health has been highlighted by an extensive number of publications over several decades. Fortification of grain products with folic acid was initiated with the specific intent to prevent neural tube defects, and the scope of this endeavor is unique in that its target population (women of the periconceptional period) is many times smaller than the population it affects (everyone who ingests fortified grain products). Folate fortification has been wildly successful in terms of its goal; since its inception, the incidence of neural tube defects has markedly decreased. In the wake of this public health triumph, it is important to catalog both the serendipitous benefits and potential side effects of folic acid supplementation. The vitamin is generally regarded as a harmless nutrient based on studies evaluating the safe upper limits of folate intake. In recent years, however, a concern has been raised with respect to a potential downside to folate supplementation; namely, its proposed ability to enhance proliferation of malignant tumors. The current review summarizes the available literature on the effects of folate supplementation and the molecular mechanisms by which high doses of folate may have negative consequences on human health, especially with regard to cancer.

Prostate cancer and diet: food for thought?

• There is now increasing evidence that diet plays a major role in prostate cancer biology and tumorigenesis. • In a health conscious society, it is becoming increasingly common for Urologists to be asked about the impact of diet on prostate cancer. • In the present review, we explore the current evidence for the role of different dietary components and its' effect on prostate cancer prevention and progression. • A literature search was conducted using PubMed® to identify key studies. • There was some evidence to suggest that green tea, isoflavones, lycopenes, cruciferous vegetables and omega 3 polyunsaturated fatty acid intake to be beneficial in the prevention and/or progression of prostate cancer. • There was also evidence to suggest that a high total fat, meat (especially well cooked) and multivitamin intake may be associated with an increased risk of developing prostate cancer. • To date publications have been highly heterogeneous and variable in quality and design. More robust, high quality research trials are needed to help us understand the complex relationship between diet and prostate cancer.