New insights into calcium, dairy and colon cancer

Abstract

This paper is to review recent information about the relationship of calcium and dairy foods to colon cancer. The review focuses on primary prevention, discusses the potential components in dairy foods that might be anti-neoplastic, reviews the epidemiologic information and describes intervention studies demonstrating efficacy of calcium and vitamin D in reducing colorectal polyp recurrence. Since vitamin D is important in cancer prevention, pertinent data is discussed and potential mechanisms of actions presented. Calcium and vitamin D are important agents for the primary prevention of colorectal neoplasia.

Roles of Hormones and Signaling Molecules in Describing the Relationship Between Obesity and Colon cancer

“…Epidemiological observations suggest that diet, drugs (namely non-steroid anti-inflammatory drugs), antioxidants, and calcium can delay colorectal cancer onset or cause regression of its precursor adenoma, thus suggesting that environment can constitute an important protective effect against colon cancer [15][16][17][18]. Similarly, odds ratios suggest that increasing BMI from 20 to 25 may increase risk by 50% and increasing BMI to 30 or more may double the risk of colon cancer [7].…”

Impact of cows’ milk estrogen on cancer risk

“…Milk intake was not associated with rectal cancer risk and thus in studies where colorectal cancer was the end point; summary RR was attenuated to 0.90 (0.81e1.00). Calcium in milk is believed to be the principal agent responsible for its protective action (Holt, 2008;Pufulete, 2008), although lipid components like conjugated linoleic acid, butyric acid and sphingomyelin (Larsson, Bergkvist, & Wolk, 2005;Parodi, 1997) and milk proteins, especially whey proteins (Parodi, 2007) may also contribute. Whether the small amount of bioactive estradiol in milk has any impact on colon carcinogenesis is unknown, but epidemiology suggests it causes no harm.…”

Vitamin D, Calcium, and Colorectal Neoplasia: New Insights on Mechanisms of Action

“…Calcium also has modest protective effects against colorectal neoplasia(2). Many epidemiological studies indicate a relationship between intake of calcium and/or vitamin D and colorectal adenoma and cancer incidence(2–4); some clinical trial data support this relationship as well (described in more detail below). Vitamin D and calcium have become agents of great interest and intensive study for the chemoprevention of colorectal cancer, and the report by Fedirko et al in this issue of the journal (5) addresses several gaps in this area of research.…”

“…In summary, epidemiological evidence provides support for calcium and vitamin D as a chemopreventive regimen for colorectal cancer (2–4, 19), and the study by Fedirko et al (5) is a timely and important contribution of translational science to understanding the underlying biology of vitamin D and/or calcium effects in colorectal carcinogenesis. This study offers additional support for induction of apoptosis as a mechanism of action of vitamin D and provides insight into the minimum dose of vitamin D that may be required to elicit a chemopreventive response in the colon.…”

“…However, a nested case-control study found a statistically significant inverse trend between baseline concentrations of 25(OH)D, the biomarker of vitamin D status, and colorectal cancer incidence among WHI participants overall (p-trend = 0.02)(17). As might be expected, the results of the WHI trial generated several new questions, including the possibilities that the women randomized to the trial already had sufficient vitamin D and calcium intake and thus would not experience increased benefit from the study supplement, or that the WHI dose of vitamin D was too low to provide any protection against developing colorectal cancer (4, 17). Regarding the latter possibility, although WHI women in the calcium plus vitamin D arm had a 28% increase in circulating 25(OH)D concentrations two years post-randomization(17), it has been hypothesized that consumption of the recommended adequate intake (AI) of 400 IU/day of vitamin D would be unlikely to confer marked biological effects among people aged 50–69 years [reviewed by Hollis in ref.…”