Intrahepatic fat, not visceral fat, is linked with metabolic complications of obesity. Elisa Fabbrini et al. PNAS Published online before print August 24, 2009, doi: 10.1073/pnas.0904944106>The abstract of the above study is pretty tough going. Fortunately, you can read a clearer explanation of what this study found in this report in Diabetes in Control
Diabetes in Control:Liver Fat Has Greater Impact on Health than Abdominal Fat
A new study reported last week gives important information about an important factor that causes fats to be deposited in the liver: Fructose.
Fructose overconsumption causes dyslipedemia Lê KA, et al. Am J Clin Nutr. 2009 Jun;89(6):1760-5. Epub 2009 Apr 29.
In this study twenty-four human males, 8 normal who were the controls and 16 "healthy offspring of patients with type 2 diabetes" were fed two different diets, each for a week. The first was a control diet (the makeup not specified in the study abstract but undoubtedly it was the the usual high carbohydrate diet favored by nutritionists). Then all the subjects they were fed a diet that contained 3.5 g of fructose per kilogram of the subject's fat free mass and 35% more calories than the control diet.
This is a lot of fructose. Back of the envelope calculations suggest it would be 145 grams of fructose for a 140 lb woman at the high end of normal BMI and 255 grams for a 200 lb man with 20% body fat.
Liver and muscle tissue were studied with 1-H magnetic resonance spectroscopy and insulin resistance was also measured with a two step insulin clamp.
The finding here was that the high fructose/high calorie diet raised intrahepatic cellular lipids--i.e. fats in the liver cells--by 76% in normal people and 79% in those with relatives with Type 2 diabetes.
The high fructose/high calorie diet raised intramuscular cellular lipids much more in controls than people with diabetic relatives--47% in the normals, 24% in those with diabetic relatives. This probably reflects the insulin resistance of the people with diabetic heritages. The high fructose/high calorie diet raised VLDL-triacylglycerols, the lipid fraction most closely linked with heart disease, +51% in controls and 110% in the people with diabetic relatives.
The high fructose/high calorie diet raised fasting hepatic glucose output 4% in control: +4% and 5% in those with diabetic relatives. The researchers also concluded that it decreased the subjects' liver insulin sensitivity.
With this in mind, you'd want to ask yourself what kind of diet would provide 3.5 grams of fructose per pound of body weight each day. Research using data from the 1970s found that
For most sex/age groups nonalcoholic beverages (eg, soft drinks and fruit-flavored drinks) and grain products (eg, sweet bakery products) were the major sources of fructose.There is only a tiny amount of fructose in wheat, so the fructose attributed to in baked goods here came from the sugar and corn syrup they contained. Table sugar, sucrose, is made of glucose bonded to fructose, and is one half fructose. High fructose corn syrup may be anywhere from 55% fructose to 90% fructose. There is no way of knowing the actual percentage of fructose in any food you buy that lists high fructose corn syrup on the label.
The 1970s data showed that the average person's intake of fructose from all sources averaged 37 grams a day, with young males eating an average of 54 grams a day. Since the 1970s, our food supply has been invaded by high fructose corn syrup which you will find in everything from bread to soup to beans to salad dressing. With 41 grams of high fructose corn syrup in every 12 ounce can of Pepsi, it's likely that the average daily intake is at least double that common in the 1970s. And then there are all those milkshakes-sold-as-coffee-and-tea like the Starbucks Apple Chai Infusion with its 74 g of sugars. . . .
So while the average person might not be eating as much fructose as the amount used in the study that showed high fructose intake causing liver fat build up, they may be eating up to 2/3rds that amount. Given the massive impact the high fructose diet had on liver fat, this latest study adds convincing evidence that fructose does, in fact, play a big part in the so-called "obesity epidemic" and in the rising incidence of Type 2 diabetes.
Another study also reported last week linked second hand smoke to liver fat. This is a mouse study, so it has to be taken with a grain of salt. Still, we know that people who smoke have much higher rates of heart disease than those who don't, so it is worth considering
Science Daily: Second-hand smoking results in liver disease study finds
The exact mechanism occurring in the mouse study is reported thus:
They found that second-hand smoke exposure inhibits AMPK activity, which, in turn, causes an increase in activity of SREBP. When SREBP is more active, more fatty acids get synthesized. The result is NAFLD [non-alcoholic fatty liver disease] induced by second-hand smoke.As you can see when you visit the web page where I discuss what research knows about the real causes of Type 2 diabetes, there is no one cause. Type 2 Diabetes appears to require the presence of an underlying a genetic flaw but it gets triggered by a long list of environmental factors ranging from pesticides, to pharmaceutical drugs, to industrial pollutants and now apparently fructose and cigarette smoke.
This makes any real solution to the "Diabetes epidemic" unlikely. Heavy manufacturers and big agriculture don't plan to stop polluting our water and air. In fact, they have become very skilled at evading existing regulations. Two thirds of the foods available in our supermarkets and fast food outlets are filled with fructose and transfat as well as thyro-toxic, autoimmune provoking soy--as well as a laundry list of chemical ingredients the average consumer cannot begin to identify.
The less money people have the more likely they are to eat the cheap fructose and soy filled foods available. When you have only two bucks for lunch and that will buy you a soy and fructose taco for $.69 and a soda, you buy it.
There's a movement to replace some of the corn syrup in our food with sucrose--which is still half fructose. Unfortunately, there is no movement to remove sugars from things like chicken dinner and soup.
Since most of us were eating the fructose-filled foods for decades before diagnosis, we'd all like to know what it takes to reverse the fatty build up in our livers. There isn't any clear answer on this. Lowering your carbohydrate intake and cutting down on fructose may not budge the fat that is already in your liver. Most of the people who are severely insulin resistant who eat low carbohydrate diets for long periods of time appear to stay insulin resistant.
There are a host of fraudulent "liver cleanse" products out there which do nothing but cleanse your wallet. Don't fall for them. Lemon juice does not magically remove "toxins" from your liver. The liver removes toxins from the liver since that is a big part of its job. But it doesn't seem to be able to remove the fats that clog its own tissue. Metformin may or may not help. Beyond that, who knows?
I'd love to hear from research savvy readers about any treatment you have seen where there is solid data, not paid for by a supplement manufacturer, that links a treatment with the reduction of liver fat and improvement in non-alcholic fatty liver disease.