Scientists have reported that eating broccoli three to five times per week can lower the risk of many types of cancer, including breast, prostate and colon cancers. But a new study aimed to determine whether the cruciferous vegetable had any effect on liver cancer.
Initial findings are promising. The University of Illinois study not only found that including broccoli in the diet may protect against liver cancer, but it may also aid in countering the development of fatty liver or nonalcoholic fatty liver disease (NAFLD).
This is especially good news because, NAFLD can cause malfunction of the liver and lead to hepatocellular carcinoma (HCC), a liver cancer with a high mortality rate. And this type of liver disease is becoming prevalent among Americans as the rate of obesity in the United States escalates.
"We decided that liver cancer needed to be studied particularly because of the obesity epidemic in the U.S. It is already in the literature that obesity enhances the risk for liver cancer and this is particularly true for men. They have almost a five-fold greater risk for liver cancer if they are obese," says Elizabeth Jeffery, a U of I emeritus professor of nutrition.
Jeffery says that the majority of the U.S. population eats a diet high in saturated fats and added sugars. However, both of these are stored in the liver and can be converted to body fat. Consuming a high-fat, high-sugar diet and having excess body fat is linked with the development of NAFLD.
"We called this a Westernized-style diet in the study because we wanted to model how so many of us are eating today," Jeffery says.
Previous research suggests that broccoli, which contains bioactive compounds, may impede the accumulation of fat in the liver and protect against NAFLD in mice.
Therefore, Jeffery and her team wanted to find out whether feeding broccoli to mice with a known liver cancer-causing carcinogen would have any beneficial effects. The researchers studied four groups of mice: some were on a control diet or the Westernized diet, and some were given or not given broccoli.
"We wanted to look at this liver carcinogen in mice that were either obese or not obese," Jeffery explains. "We did not do it using a genetic strain of obese mice, but mice that became obese the way that people do, by eating a high-fat, high-sugar diet."
Although the researchers were predominantly interested in broccoli's effect on the formation and progression of cancerous tumors in the liver, Jeffery explained that they also wanted to observe the health of the liver and how the liver was metabolizing lipids because of the high-fat diet. "There is almost no information about broccoli and high-fat associated diseases," she says.
The study shows that in mice on the Westernized diet both the number of cancer nodules and the size of the cancer nodules increased in the liver. But when broccoli was added to the diet, the number of nodules decreased. Size was not affected.
With NAFLD, lipid globules form on the liver. During the study, the researchers observed these globules in the livers of the mice on the Westernized diet.
"We found that the Westernized diet did increase fatty liver, but we saw that the broccoli protected against it. Broccoli stopped too much uptake of fat into the liver by decreasing the uptake and increasing the output of lipid from the liver," she says.
Jeffery notes that adding broccoli to the diet of the mice did not make them "thin," or affect their body weight, but it did bring the liver under control, ultimately making them healthier.
"This is one of the things that makes this very exciting for us," she says. "I think it's very difficult, particularly given the choices in fast food restaurants, for everybody to eat a lower-fat diet. But more and more now you can get broccoli almost everywhere you go. Most restaurants will offer broccoli, and it's really a good idea to have it with your meal," Jeffery adds.
Jeffery's previous research shows that eating broccoli freshly chopped or lightly steamed is the best way to get to the vegetables' cancer-fighting compound, sulforaphane.
Although the researchers only used broccoli in the study, Jeffery adds that other cruciferous vegetables, such as cauliflower or Brussels sprouts, may have the same effect.
Before you start eating inordinate amounts of broccoli at every meal every day, there are a few serious factors to consider. The last thing you want to do is get sick with Disease A in an effort to avoid getting Disease B.
Talk with your doctor before you start adding or incrementing the amount of broccoli you consume in your diet. Your doctor will be able to advise you on whether — given your medical history — it's a good idea in the first place, and also help you determine how much of it you should it and how often. Too much of anything is a bad thing.
Moreover, cruciferous vegetables may affect or interfere with certain medications, including — but not limited to — haloperidol, theophylline and warfarin. They also contain enzymes that can interfere with the formation of thyroid hormone in those who are iodine deficient, and induce goiter formation.