by ecancer reporter Janet Fricker

Women who ate the most poultry during their teenage years were the least likely to develop colorectal adenomas in later life, finds a Nurses’ Health II study  published online in the American Journal of Epidemiology.

Furthermore substitution of fish or poultry for red meat during adolescence, the authors suggest, might reduce the risks of developing rectal and advanced adenomas.

Possible associations between red meat intakes and the risk of colorectal adenomas (the precursors of colorectal cancer) have been observed in some, but not all studies of adults.

Potential mechanisms that have been suggested through which red and processed meats might be involved in carcinogenesis include heterocyclic amines and related compounds formed during cooking, and N-nitroso compounds formed from nitrate or nitrites added to processed meats.

Most studies have investigated dietary exposure during adulthood, with very few studies exploring associations between childhood or adolescent diets and risks of colorectal cancer in later life.

In the current study Katharina Nimptsch and colleagues from the Harvard School of Public Health, Boston, examined the association between meat and fish intakes during adolescence and the risk of colorectal adenomas in later life among 19,771 women participating in the Nurses Health Study II.

This is an ongoing prospective cohort study of 116,671 female registered nurses who were aged between 25 and 42 years of age when they first answered questionnaires about lifestyles and medical histories in 1989.

For this particular analysis investigators included only women who had returned the self-administered food frequency questionnaires and reported that they had undergone at least one lower bowel endoscopy during the study period between 1998 and 2007.

Unprocessed red meat was defined as beef, lamb or pork; processed red meat as hot dog, bacon, salami or sausage; poultry as chicken or turkey; and fish as canned tuna, dark meat fish, breaded fish, or other fish.
Results show that when comparing women with the highest intakes of chicken during adolescence with women with the lowest intakes, high intakes were associated with a 20% reduction in risk of total colorectal cancer (OR = 0.80, 95% CI: 0.64, 0.99), a 29% lower risk of distal carcinoma (OR = 0.71, 95% CI: 0.51, 0.99), 49% lower risk of rectal carcinoma (OR = 0.51, 95% CI: 0.29, 0.90), and 40% lower risk of advanced adenoma (OR = 0.60, 95% CI: 0.38, 0.93).

Additionally when comparing those with highest intakes of red meat to those with lowest intakes, high intakes were not associated with colorectal adenoma (OR = 1.04, 95% CI 0.81 to 1.35). Also with fish the highest intakes were not associated with colorectal adenoma (OR = 0.96, 95% CI: 0.78, 1.17).

The authors found that replacing one serving per day of red meat with one serving per day of poultry was associated with a 41% decreased risk of rectal adenomas, and one serving per day of red meat with fish with a 35 % decreased risk.

“We observed significant inverse associations between higher intake of poultry during high school and the risk of colorectal adenomas later in life, independent of unprocessed and processed red meat intakes and fish intake,” write the authors.

While there is no well-established plausible mechanism to explain the link between poultry and reduced risks for adenoma, the authors speculate that poultry intakes during adolescence may simply be a marker of healthy diets or life styles.

In an accompanying commentary Nancy Potischman and Martha Linet, from Havard School of Public Health, Boston, write, “Although the evidence linking childhood and adolescent exposures with adult cancer risks is limited, the potential for public health recommendations and interventions underscores the importance of focusing new epidemiologic research efforts on this time period.”

References

K Nimptsch, A Bernstein, E Giovannucci, et al. Dietary Intakes of Red Meat, Poultry, and Fish During High School and Risk of Colorectal Adenomas in Women. American Journal of Epidemiology. DOI: 10.1093/aje/kwt099

N Potischman, M Linet, et al. Are Dietary Intakes and Other Exposures in Childhood and Adolescence Important for Adult Cancers? American Journal of Epidemiology. DOI: 10.1093/aje/kwt101