Most people are aware by now that obesity is associated with an increased risk of heart disease, type 2 diabetes and certain kinds of cancer.
But few people know of its connection with a once-rare-but-now-all-too-common liver disease known as nonalcoholic steatohepatis, or NASH.
Yet NASH is a condition that we’re going to be hearing about with increasing frequency in the very near future. For, as reporter Anahad O’Connor points out in an article published Saturday in the New York Times, NASH is “a growing strain on liver clinics and the fastest rising cause of liver transplants” in the United States.
Inflaming the liver
NASH is a condition in which the liver becomes inflamed, due to an excess build-up of fat within the liver’s cells. If the inflammation goes on unabated, bands of fibrous scar tissue form, and the liver cells begin to clump together — a condition known as cirrhosis.
NASH is therefore almost identical to the liver damage experienced by heavy drinkers, but, as O’Connor points out, “in this case the damage is done not by alcohol, but by poor diet and excess weight.”
“The equivalent of this is foie gras,” one expert tells O’Connor. “You have to force feed ducks to get fatty liver, but people seem to be able to develop it on their own.”
Currently, there is no treatment for NASH. Patients are strongly advised, however, to reduce their weight, eat a healthy diet and exercise regularly. Such efforts can help improve the condition or even reverse it “to some extent,” according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).
A fast-growing concern
NIDDK estimates that about 2 to 5 percent of American adults have NASH, and another 10 to 20 percent have a “fatty liver,” a benign condition that may or may not lead to liver inflammation.
U.S. health officials expect those percentages to increase as the country’s obesity epidemic continues.
Even more disturbing, however, is the finding that 10 percent of children in the United States now have fatty livers. NIDDK doesn’t provide any estimates on how many of those children will progress to developing full-blown NASH or even cirrhosis in their teens or 20s, but health officials are very concerned that it will be a substantial number.
“Adult natural history studies suggest that this is a slowly progressing disease, and liver-related death rates range from 5% to 11% over 7 to 18 years, respectively,” wrote the authors of a 2008 paper on the topic. “Thus, potentially, about 10% of today’s teens could require liver transplant or die a liver-related death before reaching the age of 35 years.”
Transplants up tenfold
Already, the impact of the NASH on transplants has been nothing but stunning.
“A study by the Mayo Clinic found that the percentage of all transplants performed nationwide because of NASH had reached 10 percent by 2009, up from 1 percent in 2001, even as the rates for hepatitis C, alcoholic liver disease and other conditions remained stable,” reports O’Connor. “NASH is projected to surpass hepatitis C as the leading cause of liver transplants by 2020, in part because of new drugs that can effectively cure hepatitis C, but also because of the rapid growth of fatty liver disease.”
At the University of California, Los Angeles — the site of one of the country’s major transplant hospitals — nearly 25 percent of all liver transplants are now NASH-related, he adds. That’s up from 3 percent in 2002.
“If the prevalence of NASH continues to increase at its current rate and effective treatments are not found, about 25 million Americans will have the disease by 2025, and 5 million will need new livers,” writes O’Conner.
Compare that to the 6,000 to 7,000 liver transplants now being done each year in the U.S., and you can see how the situation will be untenable.
Currently, about 17,000 American adults and children have been medically approved for liver-transplant surgery, and about 1,500 die each year while waiting for a donated liver to become available, according to the American Liver Foundation.
Not only the result of extra weight
Another disturbing factor about this condition is that, in children at least, its incident rate is rising faster than the rate of childhood obesity.
This suggests that something else — not just extra weight — is contributing to the fatty livers. Some studies have found, for example, that “when children with fatty liver consume sugar, they produce far more triglycerides [a type of fat] than children without the disease, and this may be exacerbating fat accumulation in the liver,” reports O’Connor.
Indeed, eliminating sugary drinks sometimes helps children with the condition, although it’s not clear if that improvement is the result of cutting out the sugar or to the weight loss that comes with cutting back on calories.