Until now, most of the research conducted on the relationship between diet and colorectal cancer has focused on the ten years prior to a cancer diagnosis. But these types of cancer can take decades to develop, so researchers were interested to see if looking back at the diet over the lifetime might give a better picture of dietary influences on colorectal cancer development.
As part of the NIH-AARP study, 292,797 men and women answered detailed questions about their dietary habits ten years previously and at ages 12 to 13. This information was then correlated with the risk of developing colorectal cancer over subsequent years.
Here’s what the researchers found when they looked at dietary patterns at different times of life on colorectal cancer risk.
Diet eaten ten years previously: Higher intakes of calcium, vitamin A, vitamin C, fruit, and milk were associated with a lower risk of colon cancer. Higher intakes of total fat, red meat, and processed meat were associated with a greater risk of colon cancer. Higher milk intake was associated with lower rectal cancer risk, whereas processed meat seemed to increase rectal cancer risk.
Adolescent diet: Vitamin A and vegetable consumption both seemed to protect against colon cancer development.
To get a sense of how lifetime diet affects colorectal cancer risk, the researchers looked at certain dietary habits that were present at both time points that they investigated. Here’s what they found:
“For certain dietary exposures, the protective or deleterious effect was present only when individuals were high consumers in both adolescence and recent adulthood,” the researchers noted. “We found evidence that the pattern of exposure over the life course was particularly relevant for a protective effect of fruit against colon cancer and of calcium against rectal cancer and for the adverse relations between processed meat and colon cancer and between red meat and rectal cancer.”
Colorectal cancer is the third most common cancer worldwide. Most cases of colorectal cancer don’t show up until at least age 50, but it can occur at any age. People with a personal or family history of colon cancer or polyps are at higher risk of developing colorectal cancer, as are people with inflammatory bowel disease.
Colorectal cancer, if caught early, is very treatable. But as with most conditions, an ounce of prevention is worth a pound of cure. Here are some steps that you can take to lower your risk of colorectal cancer.
(Am J Clin Nutr 2011;94:1607–19)