Summary / Extracts
Diets rich in rapidly-digested carbohydrates not only expand waistlines,
but may also cause fatty liver, a condition that can lead to liver
failure and death, finds a new study in mice.
[Remember the Atkins Insulin claims ?]
When sugar melts out of high-glycemic index food, Ludwig explains, it
drives up production of insulin, which tells the body to make and store
fat. Nowhere is this message felt more strongly than in the liver,
because the pancreas, which makes insulin, dumps the hormone directly
into the liver, where concentrations can be many times higher than in
the rest of the body. Fat buildup in the liver, or fatty liver, is
usually symptomless, but it increases the risk for liver inflammation,
which can progress to hepatitis and, in some cases, liver failure.
A previous study found that Italians who ate higher-glycemic index diets
had fattier livers, but the study wasn't tightly controlled. The new
study makes clear that the type of carbohydrate can cause fatty liver in
animals, independent of other elements of diet or lifestyle.
Fatty liver is becoming more common in Americans, especially in
children, says Ludwig.
The mouse study was funded by the National Institutes of Diabetes and
Digestive Kidney Diseases and the Charles H. Hood Foundation.
To enroll in the clinical trial, which is currently recruiting patients,
subjects must be 8 to 17 years old, overweight, and have had an abnormal
liver test or been told they might have fat in their liver. Interested
families should contact Marta Ramon Krauel, MD, at Children's Hospital
Boston, 617-355-2003.
============== End Summary / Extracts =================
http://www.sciencedaily.com/releases/2007/09/070921130735.htm
Quick-burning Carbs May Cause Fatty Liver: Low-glycemic Diet Protected Mice
Science Daily — Diets rich in rapidly-digested carbohydrates not only
expand waistlines, but may also cause fatty liver, a condition that can
lead to liver failure and death, finds a new study in mice.
If confirmed in humans, the findings suggest that fatty liver disease --
on the upsurge among Americans as a byproduct of the obesity epidemic --
may be preventable and possibly treatable through dietary changes.
The researchers, led by David Ludwig, MD, PhD, director of the Optimal
Weight for Life program at Children's Hospital Boston, fed mice either
a high- or a low-glycemic index diet. High-glycemic index foods,
including white bread, white rice, most prepared breakfast cereals and
concentrated sugar, raise blood sugar quickly. Low-glycemic index foods,
like most vegetables, fruits, beans and unprocessed grains, raise blood
sugar slowly.
On the high-glycemic index diet, mice ate a type of cornstarch that is
digested quickly whereas on the low-glycemic index diet, mice ate a type
of cornstarch that is digested slowly. The diets had equal amounts of
total calories, fat, protein, and carbohydrate, and the mice were
otherwise treated identically.
After six months, the mice weighed the same. However, mice on the
low-glycemic index diet were lean, with normal amounts of fat in
throughout their bodies. Mice on the high-glycemic index diet had twice
the normal amount of fat in their bodies, blood and livers.
When sugar melts out of high-glycemic index food, Ludwig explains, it
drives up production of insulin, which tells the body to make and store
fat. Nowhere is this message felt more strongly than in the liver,
because the pancreas, which makes insulin, dumps the hormone directly
into the liver, where concentrations can be many times higher than in
the rest of the body. Fat buildup in the liver, or fatty liver, is
usually symptomless, but it increases the risk for liver inflammation,
which can progress to hepatitis and, in some cases, liver failure.
Fatty liver is becoming more common in Americans, especially in
children, says Ludwig. Many cases in adults can be explained by
alcoholism, but not the pediatric cases. Where just one case of fatty
liver was reported in children in 1980, now between 1 in 4 and 1 in 2
overweight American children are estimated to have the condition. As
these millions of children age, some will progress to full-blown liver
disease.
"This is a silent but dangerous epidemic," says Ludwig. "Just as type 2
diabetes exploded into our consciousness in the 1990s, so we think fatty
liver will in the coming decade."
A previous study found that Italians who ate higher-glycemic index diets
had fattier livers, but the study wasn't tightly controlled. The new
study makes clear that the type of carbohydrate can cause fatty liver in
animals, independent of other elements of diet or lifestyle.
"Our experiment creates a very strong argument that a high-glycemic
index diet causes, and a low-glycemic index diet prevents, fatty liver
in humans," says Ludwig.
Ludwig and colleagues now hope to confirm this in a just-launched
clinical trial -- and to show that a low-glycemic index diet can reverse
fatty liver in overweight children. The children, aged 8 to 17, will be
randomized to either the low-glycemic diet or a low-fat diet.
Low-fat diets are currently the standard treatment, Ludwig says, but
many children with fatty liver don't respond to them. "We think it is a
misconception that the fat you're eating goes into the liver," he says.
Ludwig hypothesizes that obesity, sedentary lifestyles and increased
consumption of refined carbohydrates are "synergistically" fueling a
fatty liver epidemic in children. Ironically, low-fat diets have only
made matters worse, replacing fat with sugar or starchy foods that
actually increase fat deposition in the body.
"Two low-fat Twinkies, billed as a health food, contain the same amount
of sugar as an oral glucose tolerance test -- a test used to determine
how much sugar someone can digest," Ludwig says. He notes that the
French delicacy pate de fois gras -- the fatty liver of a duck or goose
-- is produced by over-feeding the animals with high-glycemic index grains.
The mouse study was funded by the National Institutes of Diabetes and
Digestive Kidney Diseases and the Charles H. Hood Foundation.
To enroll in the clinical trial, which is currently recruiting patients,
subjects must be 8 to 17 years old, overweight, and have had an abnormal
liver test or been told they might have fat in their liver. Interested
families should contact Marta Ramon Krauel, MD, at Children's Hospital
Boston, 617-355-2003.
The study appears in the September issue of the journal Obesity.
Note: This story has been adapted from a news release issued by
Children's Hospital Boston.