This is the second of two posts, so please follow up with the first part if you did not go through it, for the full story.
Now, let’s look at ethanol (drinking alcohol):
To see what makes it so different from glucose, here is what happens in the liver when you have an alcoholic drink. As you can guess ethanol is not necessary for any biological process, so a majority of it is processed like a toxin in the liver. 10% will get processed in the stomach and intestines and another 10% gets processed by the kidneys, muscle and the brain. This is the first big difference between glucose and ethanol. The liver has to work four times as hard because it processes 80% of alcohol that comes in. Ethanol doesn’t need insulin to get into the cells, it just diffusers in there and is converted to acetaldehyde. Acetaldehyde generates something called Reactive Oxygen Species (ROS). ROS damage proteins in the body, can cause cancer and are thought to be the key factor in ageing. This is how antioxidants are supposed to combat ageing because they deal with these ROSs. The acetaldehyde then gets converted down to acetate and goes into the mitochondria like last time. With glucose, only 20% of the substrate went to the liver and maybe half of what went to the liver, went to the mitochondria because the rest went to glycogen. So what alcohol is doing is overloading your mitochondria.
So a bunch of acetate comes in, goes through the TCA cycle and you’re left with a ton of citrate. The same three enzymes that start new fat making are stimulated and you end up with a lot of bad fat (VLDL). These will go to your fat stores primarily your visceral fat. This is the stuff that causes a lot of health issues and surround your organs giving you a big gut. This is why people get beer bellies because that’s the area that gets filled with the fat produced by alcohol.
So the liver has all of this fat being produced that doesn’t want sitting around inside it, so it will also export some of the fat out in the form of free fatty acids. These can get into the muscle causing muscle insulin resistance which is very problematic. Some of the fat won’t even be able to get out of the liver, so you’ll have a fat droplet just sitting in the liver and now you have your alcoholic fatty liver disease.
So, the excess of Acyl-CoA, the ethanol and the reactive oxygen species activate an enzyme called JNK-1 which is the bridge between metabolism and inflammation. This ends up further damaging the liver and promote insulin resistance within the liver by inactivating IRS-1, that insulin receptor from before. This means that the pancreas has to work a lot harder and pump more insulin out to do its job.
Now, let’s look at Sugar:
Sugar is made up of equal parts, glucose and fructose. Fructose is what causes the problem, so let’s see how it’s metabolised very similarly to ethanol. Here’s that’s going on in the liver when you have a glass of something sweet like orange juice.
Like ethanol, fructose is not necessary to the body, so it’s treated like a foreign substance and almost 100% of it is processed in the liver. It comes in, gets metabolised down to pyruvate and enters the mitochondria. Now we have the same situation where everything goes straight to the liver, does not get stored into glycogen and overload your liver cells’ mitochondria. The pyruvate goes through the TCA cycle, produces a bunch of citrate and that gets converted down to VLDL. This leads to increased risk of heart disease and visceral fat accumulation. Now you’ve got a soda-belly.
Like before, it also exits the cell as free fatty acids leading to insulin resistance in the muscle. Not all the fat can get out of the cell so fat accumulates in the liver and now you get non-alcoholic fatty liver disease (NAFLD).
Non-alcoholic fatty liver disease (NAFLD) has emerged as the leading cause of chronic liver disease in children and adolescents in the United States.
The same JNK-1 cable and get stimulated which promote inflammation and JNK-1 acts on the same IRS insulin receptor, causing insulin resistance in the liver.
All of this is actually illustrated really well in the movie ‘That Sugar Film’. Damon Gameau goes on a diet with plenty of low-fat and so-called healthy foods like yoghurt, wholegrain cereals, fruit juice and fruit smoothies. The aim is to eat foods that are marketed as ‘healthy’, while reaching the average sugar intake of the typical Australian which is about 40 teaspoons. His results demonstrate all these biochemical processes we just talked about. He gained 8.5 kg and an extra 7% total body fat, mainly in the form of visceral fat. His heart disease risk went up, he’s developed insulin resistance and after only 18 days he developed non-alcoholic fatty liver disease. What I thought was interesting was that he didn’t change the amount of calories he was consuming, yet he packed on such a significant amount of fat.
Actually there is another element to fructose metabolism that makes it generate so much fat. Fructose form something called Xylulose-5-phosphate and this further stimulates the De Novo Lipogenesis enzymes leading to even more fat-making. That explains the obesity epidemic. Also, when it is getting converted to fructose 1-phosphate, it produces uric acid. Uric acid raises your blood pressure and now, you get hypertension too.
Oh, and Coca-Cola still wants to pretend that obesity is all about calories and a calorie is just a calories, no matter where it comes from. One thing I should mention is that fibre helps prevent the sugar in fruit from becoming a problem. Fibre reduces the rate of intestinal absorption, meaning your liver can easily handle the steady stream of sugar from a piece of fruit. The fibre will also fill you up. So, four apples might actually be a lot of food to take in one sitting but you can get four whole apples worth of sugar delivered to your liver in a few seconds from one glass of apple juice. One night of tequila shot isn’t going to cause your liver to explode but having a shot of whiskey with every meal and for a snack would do some serious damage. By the same token having a big piece of cake with ice cream at a birthday party isn’t that big of a deal but most of us are loading up on sugar all throughout the day without noticing it.
We’ll have a breakfast of cereal and juice, then a Starbucks in a pseudo milkshake thing on the way to work, have a sandwich with low-fat yogurt for lunch, a granola bar for a snack then some pasta with a salad for dinner. But we are not realizing that the yoga has as much sugar as candy, the granola bar has as much sugar as a package of Oreos, and even your pasta sauce and salad dressing has sugar pumped into it. 80% of the 600,000 packaged food items on the market have added sugar in them. By the way, you are not going to have any of that protective fibre you find in whole fruit or vegetables; the fibre has been removed to improve the shelf life of the products. The average American child sees 30,000 TV commercials a year, advertising fast foods or candy. While something like ‘Kid Beer’ sounds jokishly evil, maybe it’s not all that different from these fun colourful, sugar-packed items kids have access to wherever they go.
LINK TO PART I