April 26, 2017
2 min read

High-quality diet linked to lower CRC risk across racial, ethnic groups

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Researchers associated high-quality dietary patterns defined by four different diet quality indexes with a reduced risk for colorectal cancer across a number of racial and ethnic groups.

“Previous studies on diet quality indexes and colorectal cancer have been performed mostly among whites,” Song-Yi Park, PhD, of the Cancer Epidemiology Program at the University of Hawaii Cancer Center in Honolulu, and colleagues wrote. “Therefore, we investigated the associations between the four diet quality indexes and colorectal cancer risk in the racially heterogeneous [Multiethnic Cohort Study] population and studied whether associations varied by race/ethnicity, sex, and anatomical subsite.”

Park and colleagues evaluated data on 190,949 individuals aged 45 to 75 years whose dietary patterns were scored using four dietary quality indexes commonly used in U.S. populations, including the Healthy Eating Index 2010 (HEI-2010), the Alternative Healthy Eating Index 2010 (AHEI-2010), the alternate Mediterranean diet score (aMED) and the Dietary Approaches to Stop Hypertension (DASH) score.

All four indexes assessed consumption of fruits, vegetables, nuts, legumes, fish, whole grains, protein, dairy, oils/fats, alcohol, red and processed meat, refined grains, empty calories, sugar sweetened beverages and sodium.

Five major race/ethnicities were represented: African American, Native Hawaiian, Japanese American, Latino and white.

Overall, 4,770 invasive colorectal cancers occurred over an average of 16 years of follow-up, including 3,663 colon cancers, 1,072 rectal cancers and 35 cases with synchronous colon and rectal tumors.

Higher scores on all four dietary quality indexes were associated with a decreasing risk for colorectal cancer in both men and women after adjusting for age and race/ethnicity (P for trend .003).

These associations were only significant for cancers of the left colon and rectum, not the right colon, for all four indexes. Further, the associations were less strong for African Americans compared with other racial/ethnic groups, and they were no longer significant for the AHEI-2010 and aMED scores when multivariate analysis was restricted to women.

Hazard ratios for CRC risk associated with the highest vs. lowest quintiles of all indexes were as follows:

  • HEI-2010: 0.69 (95% CI, 0.59-0.8) for men and 0.82 (95% CI, 0.7-0.96) for women;
  • AHEI-2010: 0.75 (95% CI, 0.65-0.85) for men and 0.9 (95% CI, 0.78-1.04) for women;
  • aMED: 0.84 (95% CI, 0.73-0.97) for men and 0.96 (95% CI, 0.82-1.13) for women;
  • DASH: 0.75 (95% CI, 0.66-0.86) for men and 0.86 (95% CI, 0.75-1) for women.

“Since the incidence rate of colorectal cancer is higher among African Americans than any other racial group in the [Multiethnic Cohort Study], females, and in the U.S., the possibility that overall diet quality may play less of a role in colorectal cancer in African Americans warrants further investigation,” Park and colleagues noted.

“It is notable that the associations of the HEI-2010 and AHEI-2010 with colorectal cancer were observed only in U.S. born and not in foreign-born Latinos,” they added. “We speculate that the dietary indexes predict risk of colorectal cancer better in U.S.-born Latinos because of their more Americanized diet and a higher incidence of the disease compared to foreign-born Latinos.”

The investigators concluded that high-quality diets are associated with a lower risk for colorectal cancer across most racial/ethnic groups. – by Adam Leitenberger

Disclosures: The researchers report no relevant financial disclosures.