A diet with plenty of whole grains can decrease risk of liver cancer by nearly 40 percent, according to a new study published in JAMA Oncology on Thursday.
Hepatocellular carcinoma, or HCC, a primary form of liver cancer, is the second leading cause of death from cancer worldwide and is projected to be among the top three causes of cancer-related death in the U.S. by 2030, according to the study.
Dr. Xuehong Zhang, associate epidemiologist at Brigham & Women's Hospital and assistant professor at Harvard Medical School, and his researchers studied more than 125,000 patients — 77,241 women and 48,214 men — in the United States. They found that increased intake of whole grains decreases the risk of developing this dangerous form of liver cancer.
Patients who consumed the largest amount of whole grains had a 37 percent lower risk of developing HCC than those who ate minimal whole grains.
The study also demonstrated a high-bran diet reduced the risk of liver cancer by 30 percent, while a high-germ diet reduced the risk by 11 percent.
The study said that incorporating high levels of whole grains into a daily diet circumvents "insulin resistance, hyperinsulinemia, and inflammation," all hallmarks of HCC.
Over the course of about 24 years, the study's patients, mainly in their 50s and 60s, answered "food frequency questionnaires" using categories of whole grain and fiber intake ranging from "never or less than once per month" to "6 or more times per day."
"Whole grains are a major source of dietary fiber and consist of bran, germ, and endosperm, compared with refined grains that contain only the endosperm," the JAMA Oncology article explained.
Compared with other types of grains, such as refined or enriched grains, whole grains are better sources of B vitamins, iron, folate, selenium, potassium and magnesium, according to the Mayo Clinic.
Foods that are highest in whole grains are whole-oat oatmeal, brown rice, quinoa, popcorn, and whole-wheat bread, pasta or crackers.
A diet rich in whole grains also lowers risk of obesity, diabetes and nonalcoholic fatty liver disease, which are known predispositions to liver cancer and other life-threatening illnesses.
According to the study, an increased intake of fruit and vegetable fiber did not lower patients' risk of HCC.
Zhang said although more research is necessary, "if our findings are confirmed, increasing whole grain consumption may serve as a possible strategy for prevention of primary HCC."