Nutritionists recommend adults and children consume at least two cups of vegetables a day and for good reason, too. Scientists from South Dakota State University recently found compounds in broccoli are capable of preventing the relapse of certain cancers by destroying cancerous stem cells. Experts say broccoli's high levels of sulforaphane make it a nightmare for most cancers.

Now, a recent study conducted by researchers from the University of Illinois College of Agricultural, Consumer and Environmental Sciences suggests a diet high in this cruciferous vegetable can help lower a person’s risk for liver cancer. "The normal story about broccoli and health is that it can protect against a number of different cancers. But nobody had looked at liver cancer," said Elizabeth Jeffery, an emeritus professor of nutrition at Illinois, in a statement.

Jeffery continued: "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 5-fold greater risk for liver cancer if they are obese."

Jeffery and her colleagues put four groups of mice on either a Westernized-style diet or a control diet. The so-called Westernized diet referred to one high in saturated fats and added sugar, both of which are stored in the liver and can be converted to fat. In these groups, mice either received broccoli from their diet or no broccoli at all.

People who consume a high amount of fat, sugar, and have excess body weight are thought to be at greater risk for nonalcoholic fatty liver disease (NAFLD), which can lead to liver cancer.

"We called this a Westernized-style diet in the study because we wanted to model how so many of us are eating today," Jeffery explained. "We wanted to look at this liver carcinogen in mice that were either obese or not obese. 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."

The research team found that mice on a Westernized diet ended up experiencing an increase in both the number of cancer nodules and the size of cancer nodules in the liver. Liver nodule refers to a growth inside the liver that is made up of hepatocytes— cells that make up liver tissue. Not only can NAFLD result in a malfunction of the liver, it can also lead to hepatocellular carcinoma (HCC), the most common and most lethal form of liver cancer.

While the size of nodules did not decrease among mice that were given broccoli, the number of nodules did decrease.

"That was what we really set out to show," said Jeffery. "But on top of that we were looking at the liver health. There are actually two ways of getting fatty liver; one, by eating a high-fat, high-sugar diet and the other by drinking too much alcohol. In this case, it is called non-alcoholic fatty liver, because we didn't use the alcohol. And it is something that is becoming prevalent among Americans. This disease means you are no longer controlling the amount of fat that is accumulating in your liver."

Jeffery noted that prior research has shown the way people prepare cruciferous vegetables — freshly chopped or lightly steamed — can preserve high levels of the cancer-fighting compound. This study only covered broccoli, but researchers believe other vegetables, including kale, cauliflower, and Brussel sprouts, can have the same effect. Although adding broccoli to the diet of mice did not make them "thin" or affect their body weight, it did make them healthier by controlling their liver function.

"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 added.

Broccoli and other cruciferous vegetables most certainly have their upsides. Packed with antioxidants and cancer-fighting properties, broccoli has been linked to the prevention of various cancers, including oral, breast, head and neck, and now liver cancer. But despite how healthy broccoli is, like all things, it should be enjoyed in moderation.

A recent study showed that too much kale or broccoli can lead to the development of hypothyroidism, a condition that occurs when the thyroid doesn't produce enough hormones. We can lessen the impact of broccoli's thyroid-disruptive properties by enjoying it in its raw form, according to a study published in the Journal of Agriculture and Food Chemistry. To see what other foods are healthier when eaten raw, click here.

Source: Chen Y, Wallig M, Jeffery E. Dietary broccoli lessens development of fatty liver and liver cancer in mice given diethylnitrosamine and fed a Western or control diet. Journal of Nutrition. 2016.