Nutrition and prostate cancer: review of the evidence

Objectives
Of the possible causes of cancer, nutritional factors are supposed to play a major role in preventable cancers. Regarding prostate cancer, nutritional data remain contradictory. This article aims to review current evidence on the relation between nutrition and prostate cancer.

Material and methods
A systematic literature search for meta-analyses, systematic reviews, and pooled analyses was conducted in the PubMed database from its inception to September 2019. Eligible studies had to assess the association between nutrition and risk of prostate cancer.

Results
Generally, no evidence was found for an association between most food items or groups, including fruit, vegetables, meat, tea, coffee, and risk of prostate cancer. There was an inconsistent and weak positive association between milk and dairy foods and prostate cancer. Carbohydrates, vitamins, and minerals were not associated with prostate cancer. Furthermore, no association was found with dietary patterns such as vegetarian or pesco-vegetarian, but increased adherence to a Mediterranean diet seemed to have a protective effect. In general, large heterogeneity between studies was observed. Studies included in meta-analyses were mostly observational, and therefore prone to several inherent biases.

Conclusions
The evidence on any potential association between diet and prostate cancer is weak. The reductionist approach considering individual nutritional factors is not suitable, and conducting more observational studies or small randomised trials evaluating the impact of individual nutritional factors on prostate cancer will not bring further answers. Large, well-designed, randomised, controlled trials are mandatory in order to clarify the relationship between nutrition and prostate cancer.