Diets consisting of high plant-based intake are associated with a reduced risk of prostate cancer, while diets high in dairy are associated with an increased risk of prostate cancer, according to a study published in The Journal of the American Osteopathic Association.
The researchers conducted a literature of Ovid Medline, PubMed, and Embase for English-language publications from 2006 to February 2017, yielding 47 articles that were eligible for inclusion. There were two very large cohort studies (≥100,000 participants), six large cohort studies (≥40,000 participants), 11 medium cohort studies (≥10,000 participants), 10 small cohort studies (<10,000 participants), 13 case-control studies, four meta-analyses, and one population study investigating diet and prostate cancer risk.
Dairy intake increases prostate cancer risk
Most studies showed that plant-based foods are associated with either a decreased or unchanged risk of prostate cancer, while animal-based foods, particularly dairy products, are associated with either an increased or unchanged risk of prostate cancer.
Two prospective cohort demonstrated that a vegetarian diet decreased the incidence of all cancers (relative risk [RR] = 0.89; 95% CI, 0.83-0.96), while three studies did not show this association. Three studies showed that a vegan diet decreased the risk for prostate cancer (RR=0.81; 95% CI, 0.66-0.98; hazard ratio [HR] = 0.64; 95% CI, 0.48-0.83). Two studies found that increased intake of vegetable decreased the risk for prostate cancer (RR=0.81; 95% CI, 0.66-0.98; RR=0.41; 95% CI, 0.22-0.74), while six studies found no difference in risk.
Researchers assessed one large population study that linked meat intake to higher prostate cancer mortality. Another prospective study observed an increased incidence of advanced prostate cancer among those who ate meat six or seven days per week compared with those who ate meat just once a week (HR=1.75; 95% CI, 1.03-2.97).
The authors noted that dairy consumption increases concentrations of insulin-like growth factor 1, which is associated with the growth of various cancer types. Casein and whey, the predominant proteins in milk, have been shown to cause prostate cancer cell growth.