Red meat, desserts linked to colon cancer

Women who eat a typical 'Western diet', high in red meats, sweets, fried food and refined grains, have a 50 per cent greater risk of colon cancer than those who consume less of these foods, according to a study published in the recent issue of the Archives of Internal Medicine​.

A team from Simmons College School of Health Studies in Boston and the Harvard School of Public Health in the US looked at associations between major dietary patterns and the risk of colon and rectal cancer in women. They say the study provided further evidence that changing the typical Western diet to include more wholegrains and fruit and vegetables may reduce the risk of colon cancer.

"We have identified a dietary pattern of 'Western foods' that women should look at carefully,"​ said study leader Professor Teresa Fung. "Women should consume less of those foods, and instead eat more fruits and vegetables, whole grains, and the like, which may help reduce their risk of colon cancer."​

According to the researchers, previous studies have found associations between foods or nutrients and risk of colorectal cancer, but results have not always been consistent.

The researchers used dietary information from questionnaires collected in 1984, 1986, 1990 and 1994 from 76,402 women aged 38-63 without a history of cancer in 1984. (The women were participants in the Nurses' Health Study, which started in 1976 and involved more than 120, 000 women aged 30-55.)

Two major dietary patterns were identified: 'prudent' and 'Western'. Women classified as prudent eaters ate more fruit, vegetables, legumes, fish, poultry and whole grains, while their Western diet counterparts consumed more processed and red meats, sweets and desserts, french fries and refined grains.

During the 12 years of follow up, Fung and the other researchers identified 445 cases of colon cancer and 101 cases of rectal cancer. They observed a roughly 50 per cent increase in risk for colon cancer in women ranked 'most' Western eaters, versus the mildest Western eaters. There were no associations between dietary patterns and rectal cancer.

The authors write: "In conclusion, we found that a diet high in red and processed meats, refined grains, and other characteristics of the Western pattern was associated with a higher risk of colon cancer in women. On the other hand, a diet high in whole grains, fruits and vegetables and other characteristics of the prudent pattern may be inversely associated with colon cancer."​

Another study out this week finds that family history is not a reliable predictor of colon cancer genes, and confirms the role played by dietary behaviour.

Researchers at the University of North Carolina at Chapel Hill found that people with a family history of colon cancer were just as likely as people without a family history to have high-risk diets that included lots of cooked red meat and low amounts of folate, a vitamin that may help prevent colon cancer.

"The predictive value of family history for identifying persons with at-risk genotypes or environmental risk factors is low,"​ said Temitope O. Keku."Modification of these factors could have broad benefits and interventions could be targeted to persons with a family history regardless of their genes."​

Keku and colleagues analyzed the DNA of 230 black and white adults with a family history of colon cancer, looking for cancer-related variations in four different genes. The researchers also collected information on the study participants' eating habits and their use of nonsteroidal anti-inflammatory drugs like aspirin or ibuprofen, which seem to have a protective effect against colon cancer.

The prevalence of cancer-related variations of a gene called NAT2 was significantly higher among individuals with a family history of colon cancer. Individuals with the NAT2 variant who also reported regular red meat consumption were also more likely to have a family history of colon cancer.

The researchers also found that participants with a family history had a higher prevalence of cancer-related variants of the PPARG gene in combination with low levels of aspirin use.

Despite these findings, family history is a poor predictor of whether an individual has a colon cancer-related gene or diet or medication risk factors, Keku and colleagues conclude. There was no significant difference in how often individuals with a family history participated in colon cancer screenings compared with those who did not have a family history, although regular screenings are recommended for those with close relatives who have the disease.

The study was published in the February issue of the American Journal of Preventive Medicine​. Both were supported by the US National Institutes of Health.