Consuming a high-quality diet, consistent with the Dietary Guidelines for Americans 2005, may reduce the risk of pancreatic cancer, a dietary pattern analysis study found. “This finding contrasts with previous studies showing limited associations with specific foods or nutrients,” the authors reported in the Journal of the National Cancer Institute (JNCI).
Dietary pattern analysis, however, “may better predict disease risk than individual food or nutrient intakes for several reasons,” the authors stated. These reasons include possible biologic interaction or synergy between foods and it may be easier to detect diet-related associations with disease by comparing overall diets of poor or high quality rather than intake of an isolated food or nutrient.
Adherence to the Dietary Guidelines for Americans 2005 was measured by the Healthy Eating Index 2005 (HEI-2005). Using responses to food frequency questionnaires returned in 1995 and 1996, the investigators calculated the HEI-2005 score for 537,218 men and women in the National Institutes of Health-American Association of Retired Persons Diet and Health Study, including 2,383 identified with incident, exocrine pancreatic cancer.
Participants who met the most dietary guidelines had a statistically significant reduced risk of pancreatic cancer compared with those who met the fewest guidelines (hazard ratio [HR] = 0.85, 95% CI = 0.74 to 0.97). There was also a statistically significant interaction with the HEI-2005 score and body mass index (BMI) among men (P = .03) but not in women (P = .24). This interaction was stronger among overweight and obese men than among men of normal weight.
“HEI-2005 was not specifically designed for the purpose of overall cancer prevention,” the authors noted. “Also, the [food frequency questionnaire] measured consumption in categories, thus not capturing specific food intakes beyond the maximum category. However, the HEI-2005 score accounts for total calories and was designed to include limits for moderation components, accounting for excess consumption of foods thought to contribute to poor health outcomes.”
An editorial accompanying the JNCI article pointed out that in the time since the article was submitted, the U.S. Department of Agriculture and the National Cancer Institute “have released another update to the index, the HEI–2010. This more recent index incorporates specific dietary guidance that was added to the 2010 Dietary Guidelines for Americans, including increased evidence that inclusion of finfish and shellfish and limitations on refined grain consumption were important components of healthy dietary patterns. Other components of the HEI–2005 were renamed or slightly modified for the HEI–2010 to better reflect current evidence.”
Three large U.S. cohorts, including the NIH-AARP cohort, are being analyzed with the HEI–2010 and other dietary pattern indices, such as the Mediterranean Diet Score, in relation to cancer-specific, cardiovascular-specific, and total mortality.
“Using data from the NIH–AARP Diet and Health Study, the Multi-Ethnic Cohort Study, and the Women’s Health Initiative, investigators in the Dietary Patterns Methods Project are applying consistent and standardized methodology across the cohorts to examine the associations of index-based scoring systems for dietary patterns with total and disease-specific mortality outcomes,” the editorial continued.
Similar to the results of the earlier study, “it is hoped that the type of evidence obtained from Dietary Patterns Methods Project analyses can inform public health nutrition guidance in more meaningful and practical ways than would reductionist analyses focusing on single foods or nutrients.” ■