Prospective studies of dairy product and calcium intakes and prostate cancer risk: A meta-analysis
ABSTRACT The Dietary Guidelines for Americans 2005 recommends that Americans increase their intake of dairy products. However, some studies have reported that increasing dairy product intake is associated with an increased risk of prostate cancer. We conducted a meta-analysis to examine associations between intakes of calcium and dairy products and the risk of prostate cancer.
We searched Medline for prospective studies published in English-language journals from 1966 through May 2005. We identified 12 publications that used total, advanced, or fatal prostate cancer as end points and reported associations as relative risks (RRs) with 95% confidence intervals (CIs) by category of dairy product or calcium intake. Data were extracted using standardized data forms. Random-effects models were used to pool study results and to assess dose-response relationships between dairy product or calcium intakes and the risk of prostate cancer. We conducted sensitivity analyses by changing criteria for inclusion of studies or by using fixed-effects models. All statistical tests were two-sided.
Men with the highest intake of dairy products (RR =1.11 [95% CI = 1.00 to 1.22], P = .047) and calcium (RR = 1.39 [95% CI = 1.09 to 1.77], P = .018) were more likely to develop prostate cancer than men with the lowest intake. Dose-response analyses suggested that dairy product and calcium intakes were each positively associated with the risk of prostate cancer (Ptrend = .029 and .014, respectively). Sensitivity analyses generally supported these associations, although the statistical significance was attenuated. The pooled relative risks of advanced prostate cancer were 1.33 (95% CI = 1.00 to 1.78; P = .055) for the highest versus lowest intake categories of dairy products and 1.46 (95% CI = 0.65 to 3.25; P > .2) for the highest versus lowest intake categories of calcium.
High intake of dairy products and calcium may be associated with an increased risk of prostate cancer, although the increase appears to be small.
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ABSTRACT: High calcium intake has been associated with an increased risk of advanced-stage and high-grade prostate cancer. Several studies have found a positive association between phosphorus intake and prostate cancer risk. We investigated the joint association between calcium and phosphorus and risk of prostate cancer in the Health Professionals Follow-Up Study, with a focus on lethal and high-grade disease. In total, 47,885 men in the cohort reported diet data in 1986 and every 4 y thereafter. From 1986 to 2010, 5861 cases of prostate cancer were identified, including 789 lethal cancers (fatal or metastatic). We used Cox proportional hazards models to assess the association between calcium and phosphorus intake and prostate cancer, with adjustment for potential confounding. Calcium intakes >2000 mg/d were associated with greater risk of total prostate cancer and lethal and high-grade cancers. These associations were attenuated and no longer statistically significant when phosphorus intake was adjusted for. Phosphorus intake was associated with greater risk of total, lethal, and high-grade cancers, independent of calcium and intakes of red meat, white meat, dairy, and fish. In latency analysis, calcium and phosphorus had independent effects for different time periods between exposure and diagnosis. Calcium intake was associated with an increased risk of advanced-stage and high-grade disease 12-16 y after exposure, whereas high phosphorus was associated with increased risk of advanced-stage and high-grade disease 0-8 y after exposure. Phosphorus is independently associated with risk of lethal and high-grade prostate cancer. Calcium may not have a strong independent effect on prostate cancer risk except with long latency periods. © 2015 American Society for Nutrition.American Journal of Clinical Nutrition 01/2015; 101(1):173-83. DOI:10.3945/ajcn.114.088716 · 6.92 Impact Factor
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ABSTRACT: Cancer is the most widely recognized reason for human deaths globally. Conventional anticancer therapies, including chemotherapy and radiation, are very costly and induce severe side effects on the individual. The discovery of natural anticancer compounds like peptides may thus be a better alternative for cancer prevention and management. The anticancer peptides also exist in the amino acid chain of milk proteins and can be generated during proteolytic activities such as gastrointestinal digestion or food processing including fermentation. This paper presents an exhaustive overview of the contemporary literature on antitumor activities of peptides released from milk proteins. In addition, caseins and whey proteins have been evaluated for anticancer potential using the AntiCP database, a web-based prediction server. Proline and lysine, respectively, dominate at various positions in anticancer peptides obtained from caseins and whey proteins. The remarkable number of potential anticancer peptides revealed milk proteins as favorable candidates for the development of anticancer agents or milk and milk products for reduction of cancer risks. Moreover, anticancer peptides liberated from milk proteins can be identified from fermented dairy products. Although current findings of correlation between dairy food intakes and cancer risks lack consistency, dairy-derived peptides show promise as candidates for cancer therapy. This critical review supports the notion that milk proteins are not only a nutritious part of a normal daily diet but also have potential for prevention and/or management of cancer.Comprehensive Reviews in Food Science and Food Safety 01/2015; DOI:10.1111/1541-4337.12126 · 3.54 Impact Factor
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ABSTRACT: Prostate cancer is the most common cancer in Western countries, but it is less common in East Asian populations. Diet and lifestyle are suspected to affect prostate cancer development. Milk and dairy products are consumed in different amounts worldwide depending on the degree of lactose tolerance in a population: consumption is traditionally high in Caucasian and low in Asian populations. Hence, several epidemiological studies examined the association of milk and dairy consumption and prostate cancer risk with ambiguous results, such that meta-analyses of cohort studies tend to show moderate positive associations, but also state that heterogeneity between studies is high due to the differences in dairy food types consumed and assessed in a study. In addition to dietary dairy intake, calcium, which is abundant in dairy products, also has been evaluated in relation to prostate cancer. Compared with dairy products, results for calcium tend to show stronger positive associations with prostate cancer risk, although associations are still heterogeneous. This is likely due to the varying amounts of calcium consumed in certain populations and varying sources of calcium, i.e., dairy versus nondairy sources. Because it is unclear whether calcium is responsible for the increase in prostate cancer risk, more research on potential biological mechanisms is necessary to establish a link with dairy products. These studies need to clarify whether calcium affects prostate cancer initiation or progression to identify how diet may potentially have an effect on early or late disease.03/2014; 4(1):66-71. DOI:10.1007/s13668-014-0106-2