An estimated one out of five adults—and one out of ten teens—have non-alcoholic fatty liver disease.
That’s an accumulation of excessive fat in the liver not from drinking alcohol. An estimated 10 to 20 percent of people with this disease have liver inflammation and liver cell injury that can progress to cirrhosis and liver failure.
Can the beverages you drink increase your risk of getting this disease?
“Obesity and diabetes clearly increase the risk of fatty liver disease, but there’s also some evidence that fructose plays a role,” says researcher Kimber Stanhope of the University of California at Davis. Fructose is a major component of some beverages because table sugar is half fructose, half glucose.
Last year, Framingham Heart Study researchers reported that people who drank at least one sugar beverage a day had a higher risk of fatty liver disease. (The Framingham Study has been monitoring the health of three generations of Massachusetts residents since 1948.)
But few other studies have looked at this. And only a few studies have measured what happens to the liver when people consume sugars. “It’s amazing to think that we have only two intervention studies that looked at how sugars affect liver fat using current imaging technology,” says Stanhope.
the two studies
One funded by the Corn Refiners Association – its members manufacture high-fructose corn syrup — had serious flaws. The other study was top-notch.
Danish researchers gave 47 overweight adults one liter a day of either Coca-Cola (sweetened with table sugar), or lower-fat milk, or Diet Coke, or water. That’s the amount in about three cans of soda. After six months, liver fat increased only in the sugary-Coke drinkers, who also gained more muscle fat and more deep-belly fat. Liver fat did not increase in those who drank the diet soda, milk, or water.
“Before this Danish study, nobody had any data to show that, under reasonable conditions, consuming sugar-sweetened beverages could cause fatty liver,” says Stanhope. Clearly, fructose causes the liver to make fat, she notes.
The key question is:
“How much of this fat does the liver keep and how much does it send out into the blood?” wonders Stanhope.
If the liver keeps enough fat in its own cells, that could make the organ insulin resistant and start a vicious cycle. “As insulin resistance in the liver develops, fat making in the liver gets worse,” explains Stanhope. And then insulin resistance gets worse.
But we need more studies, she cautions. “We don’t have sufficient evidence to definitively conclude that high-fructose corn syrup or sucrose with its fructose causes fatty liver disease. But my prediction is that someday soon we will.”
Should people minimize sugar drinks in the meantime?
“Absolutely,” says Stanhope. “If you put together the diet intervention studies with the epidemiological studies, there’s a strong suggestion that sugar is not good for our health.” What’s more, she adds, “It’s a risk-free proposition to reduce your consumption of added sugar, but if you ignore the data and believe the sugar industry, that’s a health risk.”
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