By Clif Cleaveland

Add fatty liver to the list of obesity-related illnesses afflicting more of today’s children. The incidence of non-alcoholic fatty liver (NAFL) — a condition in which droplets of fat accumulate within liver cells — has paralleled the rise in childhood obesity.

From 1980 to 2006, the incidence of obesity in children aged six to 11 rose from 6.5 percent to 17 percent. In the meantime, the percentage of 11- to 17-year-olds considered obese rose from 5 percent to 17.6 percent. In Southern states the incidence of childhood obesity is even higher. Up to one-half of these overweight children may have NAFL.

Children with NAFL usually have no symptoms. An increase in certain blood tests that measure liver function will be the only abnormal finding at first. For many children the disorder will not progress. For others, fatty deposits stimulate inflammation (non-alcoholic steatohepatitis or NASH) that may progress to scarring and cirrhosis. Sometimes the progression may occur over an interval as short as a few months. Whereas inflammatory changes may be reversible with diet and exercise, cirrhosis is not. Children with severe cirrhosis must have liver transplants to survive.

The liver undergoes similar changes in response to excess consumption of alcohol. Worldwide research has focused upon the dietary and environmental causes of NAFL in children and adults. Among obese children, those most likely to have NAFL suffer from the metabolic syndrome. This is an association of central obesity (big bellies), high blood pressure, elevated levels of fasting blood sugar and triglycerides (a blood fat), and reduced HDL “good” cholesterol. NAFL is, in effect, the liver component of the metabolic syndrome.

Because blood tests of liver function do not separate fatty liver from the much more serious NASH, biopsy is the only sure method for determining the status of the liver in an individual with abnormal blood tests.

Studies on mice and other laboratory animals show that increased dietary intake of fructose and fat and decreased exercise produce the full range of abnormalities from NAFL to NASH to cirrhosis. High fructose intake leads to insulin resistance and the production of a breakdown product that damages liver cells. Fructose, unlike glucose, fails to trigger signals that suppress appetite. Although fructose is a naturally occurring sugar, liver cells seem limited in their ability to handle a sudden or high concentration of this particular sugar.

When the dietary histories of children with biopsy-confirmed NAFL are compared with children with normal liver function, affected children are found to consume two to three times as much fructose as healthy children.

The consumption of fructose has risen sharply in recent years in the United States and other industrialized countries. High fructose corn syrup (HFCS) is widely found in soft drinks, breakfast cereals, cookies, energy bars and many prepared foods. It is both cheaper and sweeter than sucrose or table sugar.

Among Americans, the average daily intake of fructose is 54.7 grams or 10 percent of daily calorie consumption. For adolescents, average fructose consumption is 72.8 grams per day or 12 percent of total calories. A quarter of adolescents obtain at least 15 percent of their calories from fructose.

Recent televised advertisements from manufacturers of HFCS state that the product is safe in moderation. However the many products that now contain HFCS do not list the actual quantity of the sweetener contained in the product. Thus, it is impossible to determine how much HFCS we actually consume in a typical day.

To protect the health of our children and grandchildren, we must:

* Monitor weight regularly.

* Take very seriously excessive weight gain and seek professional evaluation of the child.

* Encourage consumption of foods low in fat and added sugars, especially fructose.

* Encourage regular physical activity.

* Set a good example for children by our patterns of eating and exercise.

* Insist on healthy food choices in school lunchrooms and the removal of carbonated drink and candy machines from schools.

* Support physical education programs as part of school curricula.

* Enlist the support of restaurants, especially fast-food chains, to post prominently the sugar and fat content of menu items and to offer healthier food and beverage choices for children.

The health and economic consequences of childhood obesity are staggering. We must reverse this epidemic.

Contact Clif Cleaveland at cleaveland1000@comcast.net.