Dairy foods, calcium, and colorectal cancer

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Hi All,

See the pdf-available below on Dairy foods, calcium, and colorectal

cancer.

Included after the Medline abstract is a mechanism discussion from

the pdf and at the end, is a press report of the article.

J Natl Cancer Inst. 2004 Jul 7;96(13):1015-22.

Dairy foods, calcium, and colorectal cancer: a pooled analysis of 10

cohort

studies.

Cho E, et al and Fraser GE, et al and Willett WC, et al and Hunter DJ.

....534 536 individuals ... 4992 incident cases of colorectal cancer

were diagnosed between 6 and 16 years of follow-up. ... RESULTS: Milk

intake was

related to a reduced risk of colorectal cancer. Compared with the

lowest

category of intake (<70 g/day), relative risks of colorectal cancer

for

increasing categories (70-174, 175-249, and > or =250 g/day) of milk

intake were

0.94 (95% CI = 0.86 to 1.02), 0.88 (95% CI = 0.81 to 0.96), and 0.85

(95% CI =

0.78 to 0.94), respectively (P(trend)<.001). Calcium intake was also

inversely

related to the risk of colorectal cancer. The relative risk for the

highest

versus the lowest quintile of intake was 0.86 (95% CI = 0.78 to 0.95;

P(trend)

=.02) for dietary calcium and 0.78 (95% CI = 0.69 to 0.88; P(trend)

<.001) for

total calcium (combining dietary and supplemental sources). These

results were

consistent across studies and sex. The inverse association for milk

was limited

to cancers of the distal colon (P(trend)<.001) and rectum (P(trend)

=.02).

CONCLUSION: Higher consumption of milk and calcium is associated with

a lower

risk of colorectal cancer.

PMID: 15240785 [PubMed - in process]

..... In our analyses, we could not distinguish clearly between

the effects of milk and calcium because of their strong correla-tion

in most studies. Calcium in milk is highly bioavailable,

which may make milk appear to be associated with colorectal

cancer risk independent of total calcium intake. Also, other

components in milk may contribute to the inverse association.

Dairy foods contain conjugated linoleic acid and lactoferrin,

which inhibit colonic carcinogenesis in animal models (53,54),

and the milk protein casein has antimutagenic activity on the

digestive tract (55). Certain microorganisms in fermented dairy

foods have also been hypothesized to reduce the risk of colo-rectal

cancer (12). In our study, fermented food products such as

yogurt or cheese, or fermented dairy fluids as a whole, were not

strongly associated with colorectal cancer risk, but we had a

limited ability to detect an association because the consumption

of these foods was relatively low in most of the cohort studies....

L. Zielinski

Press Release: Milk Consumption and Calcium Intake Associated with

Lower Colorectal Cancer Risk

J Natl Cancer Inst 2004; 96: 975 [Full Text]

Higher milk consumption and calcium intake are associated with a

lower risk of colorectal cancer, according to a new study that

appears in the July 7 issue of the Journal of the National Cancer

Institute.

Colorectal cancer is the third most common cancer worldwide.

Researchers have hypothesized that the different rates of colorectal

cancer incidence in various countries may be related to diet.

Although high calcium intake has been shown to inhibit colon cancer

in animal experiments, these effects have not been seen consistently

in human epidemiologic studies.

To better assess the relationship between consumption of dairy foods,

calcium intake, and colorectal cancer risk, Eunyoung Cho, Sc.D., of

Brigham and Women's Hospital and Harvard Medical School in Boston,

and colleagues conducted a pooled analysis of 10 cohort studies from

five countries. The studies included more than half a million

individuals, among whom nearly 5,000 individuals were diagnosed with

colorectal cancer during follow-up.

Among all of the food sources of calcium that the researchers

examined, only milk consumption was associated with a decreased risk

of colorectal cancer, particularly cancers of the distal colon and

rectum. The risk decreased with increasing milk consumption; compared

with people who consumed less than 70 grams/day (about 2.5 ounces) of

milk, people who consumed 175-249 g/day (6.2-8.9 oz.) had a 12%

reduction in risk of colorectal cancer and people who consumed more

than 250 g/day (8.9 oz.) had a 15% reduction in risk. Each two 8-oz.

glasses per day (500 g/day) increase in milk consumption was

associated with a 12% decrease in risk.

The study also found that higher total calcium intake was associated

with a decreased risk of colorectal cancer. Increasing calcium intake

to 1000 mg/day or more could result in 15% fewer cases of colorectal

cancer in women and 10% fewer cases in men, according to the authors.

" These data, in combination with the previous experimental studies

documenting a salutary effect of calcium supplementation on colonic

epithelial cell turnover and colorectal adenoma recurrence, support

the concept that moderate milk and calcium intake reduces the risk of

colorectal cancer, " the authors write.