Sitting protected by the rib cage on the right side of your belly and weighing about 1.3 kilograms (3 pounds), the liver has several essential biological functions, including detoxification and the synthesis of proteins and biochemicals necessary for digestion and growth. And while the best-known cause of this large, meaty organ's failure is alcohol abuse, it is not the only one.

You can't live without a liver. It's the body's main metabolic organ and performs numerous vital functions.

"Among other things, the liver helps to regulate fat and sugar metabolism as well as vitamin and mineral levels, and it stores important nutrients such as sugar, fats, vitamins and minerals," says Markus Cornberg, medical director of the German Liver Foundation.

It's also the body's detox headquarters, filtering toxic substances out of your blood. What's more, it produces many vital substances, such as proteins that, among other things, help your blood to coagulate.

If the liver is ill, we may not know it for years. "Symptoms such as fatigue or difficulty concentrating are often very nonspecific," says Ingo van Thiel, an adviser and writer for the German Liver Patients Association, a nonprofit organization that provides advice for liver patients.

The liver feels no pain, says van Thiel. "But some patients have pressure pain in the upper right quadrant of their abdomen if their liver is enlarged and puts pressure on surrounding tissues," he adds.

Comparatively few people with a liver disorder show telltale symptoms such as jaundice – yellowing of the skin and the whites of the eyes. "In the final stages though, severe symptoms such as abdominal dropsy (accumulation of excess fluid), sudden blood vomiting or brain disorders are possible," van Thiel says. "That's when some finally realize they're sick."

Although most people associate liver disease with alcohol abuse, it's just one of three main causes. The other two are a fatty liver – too much fat stored in liver cells – not due to alcohol consumption, and hepatitis B and C viruses.

So to keep your liver healthy, it's not enough to monitor your alcohol consumption. Smoking is harmful too. And you should cut down on sweetened beverages and juices, as they can cause a build-up of fat in the organ and possibly lead to a fatty liver.

"We're very concerned about fatty liver disease caused by metabolic syndrome," says van Thiel, referring to a combination of excess body weight, high blood pressure and high levels of fats and sugar in the blood that can do the liver serious harm.

No medications for a fatty liver have been developed yet. But coffee consumption, for example, can be beneficial. "It has a protective effect and can lower elevated liver values" and thereby reduce the risk of cirrhosis (scarring) and liver cancer, says Cornberg.

If you've got a healthy liver, there's no special regimen or diet to keep it that way, according to Cornberg, who adds: "A balanced diet with fresh and natural foods, and an active lifestyle are helpful nonetheless."

Proper nutrition can also play a positive role if your liver isn't healthy. "This is particularly true for people with a storage disease such as hemochromatosis (iron overload) or Wilson's disease (copper overload), for cirrhosis patients and for people with fatty liver disease," Cornberg says.

Screening is available for infection with the hepatitis viruses A, B, C or D, which cause liver inflammation. You can also get vaccinated against hepatitis A and B.

"The vaccines are safe, well tolerated and provide reliable protection against these viral infections," says Cornberg. "The hepatitis B vaccine also protects against infection with the hepatitis D virus."

Infection with either virus can cause chronic hepatitis and lead to cirrhosis and liver cancer, Cornberg warns, "so the vaccines also protect against cancer." While there's no vaccine for hepatitis C, "the disease is now curable with hardly any side effects in almost all patients."