Steatohepatitis is a condition in which the liver becomes inflamed and accumulates fat. It was formerly found almost exclusively in alcoholics. In the 1980s, a new condition was described called nonalcoholic steatohepatitis (NASH), basically steatohepatitis without the alcoholism. Today, NASH is thought to affect more than 2% of the adult American population. The liver has many important functions. It's not an organ you want to break.
This week, I've been reading about how to fatten your liver. First up: industrial vegetable oil. The study that initially sent me on this nerd safari was recently published in the Journal of Nutrition. It's titled "Increased Apoptosis in High-Fat Diet–Induced Nonalcoholic Steatohepatitis in Rats Is Associated with c-Jun NH2-Terminal Kinase Activation and Elevated Proapoptotic Bax". Quite a mouthful. The important thing for the purpose of this post is that the investigators fed rats a high-fat diet, which induced NASH.
Anytime a study mentions a "high-fat diet", I immediately look to see what they were actually feeding the animals. To my utter amazement, there was no information on the composition of the high-fat diet in the methods section, only a reference to another paper. Apparently fat composition is irrelevant. Despite the fact that a high-fat diet from coconut oil or butter does not produce NASH in rats. Fortunately, I was able to track down the reference. The only difference between the standard diet and the high-fat diet was the addition of a large amount of corn oil and the subtraction of carbohydrate (dextrin maltose).
Corn oil is one of the worst vegetable oils. You've eaten corn so you know it's not an oily seed. To concentrate the oil and make it palatable, manufacturers use organic solvents, high heat, and several rounds of chemical treatment. It's also extremely rich in n-6 linoleic acid. The consumption of corn oil and other n-6 rich oils has risen dramatically in the US in the last 30 years, making them prime suspects in NASH. They have replaced the natural (more saturated) fats we once got from meat and milk.
Next up: fructose. Feeding rats an extreme amount of fructose (60% of calories) gives them nonalcoholic fatty liver disease (NAFLD), NASH's younger sibling, even when the fat in their chow is lard. Given the upward trend of US fructose consumption (mostly from high-fructose corn syrup), and the refined sugar consumed everywhere else (50% fructose), it's also high on my list of suspects.
Here's my prescription for homemade foie gras: take one serving of soybean oil fried french fries, a basket of corn oil fried chicken nuggets, a healthy salad drenched in cottonseed oil ranch dressing, and wash it all down with a tall cup of soda. It's worked for millions of Americans!