Brent Tetri, MD
Brent Tetri, MD, gastroenterologist and professor of internal medicine at Saint Louis University School of Medicine, Missouri.
There’s a medical condition that is frightening physicians and patients alike because it is growing much more common. Called Non-Alcoholic Fatty Liver Disease (NAFLD or hepatic steatosis), it affects about a third of the American adult population (13% of children) and the numbers are rising. Many are unaware they have this problem, since in and of itself it rarely causes symptoms, but NAFLD can progress and, though it is rare, when it does it can lead to serious liver damage or even death.
A fatty liver has long been associated with long-term and excessive alcohol consumption, but this “non-alcoholic” version of the disease is not about drinking — it’s believed that its main cause is poor diet, notably, one loaded with simple sugars and complex carbohydrates.
Exactly how NAFLD develops is still being studied, but there seems to be a connection between disease progression and the combination of a sedentary lifestyle and metabolic syndrome. In Sweden, researchers asked 18 healthy, normal weight people to consume two meals loaded with carbohydrates and sugar a day, as well as to restrict their physical activity for one month, with the goal of a 5% to 15% increase in body weight. After just one week participants had elevated blood levels of ALT, an enzyme that when elevated indicates NAFLD. In another study, at Saint Louis University, researchers fed sedentary mice a diet that was 40% fat and included lots of high-fructose corn syrup. After a month, they too showed signs of liver damage and also had the beginnings of glucose intolerance, a marker of type 2 diabetes.
Brent Tetri, MD, professor of internal medicine at the Saint Louis University School of Medicine and an expert on NAFLD, was the lead author of the mice study. He explains that one of the liver’s functions is to turn carbohydrates into fat and send it off to be stored in adipose (fat) tissue as fuel reserves. This is the normal metabolism in action, but when people consume excessive amounts of carbohydrates — in particular from calorie-dense high-sugar and fatty foods — it overwhelms the liver’s ability to function, thereby slowing the delivery of fat into storage. The converted fat therefore lingers, clogging the liver. It is important to note that the fat in the liver is not what was consumed in food… rather it results from the liver’s conversion of carbohydrates from food into fat. Insulin resistance increases the problem even further, resulting in yet more fat accumulation in the liver.
At present there is no easy and truly reliable means to test for liver damage, just a test that measures levels in the blood. This is typically included in the routine blood tests conducted as part of adult exams. If you have children who are overweight and sedentary, request this test for them as well, given how pervasive obesity and poor eating habits have become.
Fortunately, it isn’t difficult to protect your liver and it is possible to reverse liver damage if you catch it early. It is, however, the same song we always sing, which people hear all the time and yet disregard… following a healthy diet and exercising regularly are the best strategies for maintaining a healthy liver, along with a healthy everything else. Dr. Tetri suggests following a Mediterranean diet with plenty of vegetables, some fruit and some whole grains, olive oil and fish. People with any damage to their livers should avoid alcohol, but Dr. Tetri says others can safely enjoy a moderate amount of red wine.
Limit fast food and sugar-laden deserts/snacks to once a week or so. Avoid trans fats, as these challenge the liver. Drink water instead of soda. Personally, I was horrified to hear from Dr. Tetri that the sugar from high-fructose corn syrup in just two super-sized sodas amounts to more than you could possibly hold in your hands… that’s a visual to call upon when you need help saying “no.” High fructose corn syrup, especially in high quantities, suppresses the satiety mechanism in the brain, the one that tells you “that’s enough, stop eating.” Dr. Tetri suspects that the reason people can polish off huge burgers and piles of French fries is the high-fructose corn syrup in the soda that comes with the meal.
Drugs and some not-so-good-for-you supplements may also be contributing to the surge in liver damage. Acetaminophen in high doses can be extremely toxic to the liver. Also, several popular herbal supplements (Dr. Tetri specifically mentioned kava kava, for weight loss, and germander, ironically used to support liver function) have potential to harm the liver. If you are concerned about liver health, consider working with a physician trained in the use of natural substances to promote health — there are supplements that might be quite effective when used properly, including milk thistle and possibly Vitamin E and other antioxidants. Look for further information on this important health topic in upcoming issues of Daily Health News.