You probably know that long-term, heavy alcohol intake can damage the liver. One possible result of such a habit is fatty liver disease (technically known as alcoholic steatohepatitis).
But you can drink little or no alcohol and still develop fatty liver disease. In fact, it’s estimated that about one-quarter of Americans, including some children, have nonalcoholic fatty liver disease (NAFLD). Lately, it has been getting media attention because of its alarming increase in prevalence, and several readers have asked us about it.
NAFLD is a spectrum of disorders, occurring when the liver has trouble processing fat (triglycerides) and this causes fat to accumulate in liver tissue. NAFLD is usually a silent disease, with few if any signs, symptoms or complications. But it may progress over the years, in which case symptoms such as fatigue, weakness, loss of appetite, nausea, abdominal pain and/or possibly jaundice (yellowing of skin and eyes) may develop.
If fat accumulation is accompanied by inflammation, the condition is called nonalcoholic steatohepatitis (NASH). Though this has a better prognosis than alcoholic steatohepatitis, it can result in cirrhosis (permanent damage and scarring) of liver tissue and ultimately liver failure or cancer.
The risk of these complications is greatest in people who also have type 2 diabetes. Before age 60, NAFLD affects more men, but after age 60, more women.
What causes NAFLD
NAFLD is strongly linked to obesity and diabetes (as well as prediabetes, a precursor to diabetes), and also to high blood levels of cholesterol and triglycerides. It’s unclear whether NAFLD is a cause or consequence of some of these factors. While more than 90 percent of very obese people have NAFLD, it can also occur in thin people with none of these risk factors. There seems to be a genetic element, since it tends to run in families.
Recently, Italian researchers, writing in BMC Medicine, found a strong link between NAFLD and low blood levels of vitamin D. This vitamin plays important roles in the liver, involving the immune system, inflammatory processes, insulin sensitivity and fatty acid metabolism. There’s no evidence so far, however, that supplemental vitamin D will help prevent or treat NAFLD.
To diagnose NAFLD, a doctor will examine the liver for enlargement and do blood tests for liver enzymes. Ultrasound may also be used. A biopsy is considered the gold standard to determine the degree of liver damage and monitor disease progression.
Putting your liver on a diet
There’s no specific therapy for fatty liver. But if you’re diagnosed with it and are overweight or obese, the obvious first step is to lose weight via a healthy diet and exercise. It’s best to lose the weight gradually, not rapidly. In fact, rapid weight loss can actually contribute to NAFLD. For the very obese, bariatric (weight loss) surgery may be an option.
Cut down on alcohol if you drink more than moderately—no more than a glass of wine a day, for example—or stop completely.
Also, cut down on foods and beverages sweetened with high-fructose corn syrup or sucrose, which are both major sources of fructose. Studies have linked fructose and/ or these sweeteners to NAFLD and to the progression to NASH. Consumption of high-fructose corn syrup, in particular, has skyrocketed in recent decades and parallels the increase in obesity and NAFLD, especially in children and adolescents.
If you have severe disease and weight loss doesn’t help, certain medications may be prescribed—to treat insulin resistance, for instance. Some studies have found that vitamin E (800 IU a day of the natural form) may also be somewhat effective. Discuss this with your doctor before starting.
Finally, if you have NAFLD you should be vaccinated against hepatitis A and B to protect your liver, unless you’re already immune.
Bottom line: Many factors that put you at risk for cardiovascular disease also increase the likelihood of developing NAFLD. The health of your liver is one more reason to take heart-healthy steps such as maintaining a desirable weight (via diet and exercise) and controlling blood cholesterol, triglycerides and blood sugar levels.