How Your Diet Can Wreck Liver Function

While heart disease and diabetes are significant threats to your health, there's a third dangerous condition that also stems from being overweight and sedentary, and it affects your liver. You might not think about this important organ much, but it may be time to do just that.

Eating and drinking too much alcohol can raise blood fats — cholesterol and triglycerides. In turn, fat can accumulate in your liver, a condition that now affects 30 percent of Americans, says Arifa Toor, MD, director of the Hepatology Center at the Dartmouth-Hitchcock Medical Center and an assistant professor at the Geisel School of Medicine at Dartmouth College.

Dr. Toor adds that you're more likely to develop fatty liver disease if you're overweight, have diabetes or prediabetes, have high blood pressure or drink too much alcohol.

Read more: Should I Stop Drinking Red Wine if I Have Fatty Liver?

Fatty liver used to be thought of as a condition affecting mostly heavy drinkers. It was first described in the absence of significant alcohol consumption in 1980 in the journal Mayo Clinic Proceedings.

With more and more Americans becoming overweight, there are more cases of fatty liver not due to excessive drinking but rather due to risk factors such as obesity, diabetes and insulin resistance, according to the National Institute of Diabetes and Digestive and Kidney Diseases. This form of the disease is called non-alcoholic fatty liver disease (NAFLD).

Regardless of the cause, fatty liver disease impairs liver function and can lead to more serious liver diseases once the liver becomes damaged, known as being scarred. Because fatty liver disease has no symptoms in the early stages, most people may not be aware that they have it for years.

"If you take 100 people with fatty liver disease, two or three will develop cirrhosis (scarring and loss of function of the liver) over their lifetime," says Dr. Toor. However, when nearly a third of the population has the disease, 2 percent represents a huge number of Americans, she adds.

A key risk factor for fatty liver is metabolic syndrome, defined as having excess abdominal fat, high triglycerides, low HDL (the good cholesterol), high blood pressure and a high fasting blood sugar, according to the National Heart, Lung, and Blood Institute. These same people are also at risk of developing heart and circulatory problems, diabetes and cancer. "Most people with fatty liver are going to die of cardiovascular disease or cancer," not liver failure, Dr. Toor says.

Blood tests for liver function measure two key liver enzymes, AST (aspartate aminotransferase) and ALT (alanine aminotransferase). According to Michigan Medicine, AST blood levels rise when the heart, liver, muscle, kidneys or pancreas is damaged. ALT occurs in the same tissues as AST, but mostly in the liver, notes Michigan Medicine. High levels may indicate liver disease or injury.

Liver enzyme levels can also be affected by other medical conditions and even medication. These conditions include thyroid disorders, liver cancer, autoimmune disorders, mononucleosis, sepsis and hemochromatosis (a buildup of iron), according to the Mayo Clinic. Drugs that can skew results and cause liver damage include acetaminophen (Tylenol) and some antibiotics, antifungals, antidepressants and statins, which are used to lower cholesterol.

"When I see someone with high ALT, liver disease is probably the second or third cause," Dr. Toor says. "Antibiotics is probably number one."

Non-alcoholic fatty liver disease "is one liver disease that can be addressed," Dr. Toor says. "Losing 10 percent of body weight can reduce fat in liver and improve scarring."

Vitamin E may be of some benefit, she says, and a November 2019 analysis in Postgraduate Medical Journal supports its use. "Statins might actually help the liver," Dr. Toor says, but adds that many primary doctors are reluctant to prescribe statins for patients with NAFLD.

A May 2017 report in the American Journal of Physiology concluded that the benefits of statins outweigh potential toxicity to the liver, especially in patients with both severe liver injury and high risk of heart disease. Statins may keep liver scarring from worsening to cirrhosis.

Read more: Best Vitamins for Your Liver