Whole Grain Intake Linked to Lower Liver Cancer Risk, Harvard Researchers Discover

Researchers at the Harvard T.H. Chan School of Public Health found an association between high whole grain and fiber intake and a lower risk of liver cancer and chronic liver disease mortality, according to a study published in Nature Communications on Nov. 4.

The researchers used a sample of nearly 500,000 participants surveyed by the National Institutes of Health between 1995 and 1996. After a median time frame of 15.5 years, 940 participants had been diagnosed with primary liver cancer, and 993 had died as a result of chronic liver disease.

Researchers observed a 22 percent decrease in risk of liver cancer and 56 percent decrease in chronic liver disease mortality for participants who had the whole grain intake in the highest quintile. Similarly, they observed a 31 percent decrease in risk of liver cancer and 63 percent decrease in chronic liver disease mortality for participants who had fiber intake in the highest quintile.

Xuehong “Hong” Zhang — a cancer epidemiologist and assistant professor of nutrition at the School of Public Health who worked on the study — said it was a “prospective cohort study based on the NIH-AARP study.”

“We use the validated food frequency questionnaire to measure the intake of whole grain and fiber,” Zhang said. “We have accounted for major known liver cancer risk factors in the analysis, suggesting that the results we observe here for whole grain and fiber are likely independent of those known risk factors.”

Jessica Petrick — another study author and an epidemiologist at Boston University’s Slone Epidemiology Center — said the study “supports current dietary recommendations for cancer prevention.”

Though scientists don’t yet understand all the biological mechanisms underlying the association between diet and liver diseases, the study is a step towards understanding “some more of the dietary etiology of liver cancer, which is fairly poorly recorded,” Petrick said.

“The incidence of liver cancer in the U.S. is fairly rare compared to more common types of cancer,” she said.

The study also has implications for future research on diet and liver disease, such as its intersections with race and ethnicity.

According to Zhang, most of the participants in this study were non-Hispanic whites.

“It is desirable to study the relationship between diet and liver cancer or liver disease mortality in more diverse racial or ethnic populations, especially given the fact that liver cancer disproportionately affects minority populations,” he said. “To my knowledge, the studies in that area are relatively limited. More investigation in those populations is needed going forward.”

Despite the findings, Petrick said the public should be cautious about adjusting diets.

“I would make sure to recommend that they do talk with their physician or their dietician before making any dietary changes on their own. Because this is epidemiologic literature, it’s very broad,” Petrick said. “Every single person has their own individualized risk profile, and that should really be considered whenever they are making dietary changes.”