The Ancient Egyptians, experts at anatomy, were the first to become aware that liver damage could be caused by alcohol ingestion, and it is alcohol that has traditionally proven to be the leading cause of liver disease. But, just like those Ancient Egyptians, this idea now belongs in the past.
Non-alcohol-related fatty liver disease is now North America’s leading cause of liver disease. It even has an acronym (NAFLD), but interestingly, most people don’t know about it, and part of the reason for this might be that the medical community doesn’t really know what to do about it.
The tendency I see is for most doctors to advise people, if they have fat deposits in their liver and their liver seems to be irritated, that they need to lose weight, exercise more, and eat better: essentially all the conventional advice targeting people with unhealthy weight, eating habits and activity levels. In other words, the message is: if you have fat deposits in your liver, it is because you are overweight and unhealthy.
Before I suggest a different take on this, I want to explain a little bit about how we look for and evaluate possible liver disease in my family practice.
A liver enzyme called ALT is part of a routine blood panel for most people, and higher than normal levels of ALT would be one of the first signs we might see in somebody whose liver is starting to show problems. Currently, in Ontario, at the lab that we use, the upper limit of normal is 36. Out of interest, to give you an idea of how high the burden of liver disease is these days, when I was in medical school from 2003-2007, the upper limit for ALT was only 15-20. Our medical community/society has changed the upper limit of normal ALT in the last 15 years! My only guess as to why it has changed is that so many people now have higher ALTs than was previously the case.
A normal ALT does not necessarily mean that your liver must be normal, but, in most people, if their liver starts acting up (which, in the most general terms, we call hepatitis), the ALT does go up. A small elevation may just be a sign of something to come, but when someone is actually sick and feeling unwell, it’s not uncommon to see this number go up into the high triple digits. So, the first hint that there might be something wrong with the liver could very well be an elevated ALT, and in my practice, the vast majority of the time, if we follow this test up with a liver ultrasound, we find fatty deposits in the liver.
(It is possible to have fat deposits in your liver and have normal liver enzymes. These fat deposits would still be considered abnormal, but we generally reserve the term fatty liver disease for people with fat deposits in the liver and abnormal ALT levels.)
As I said before, throughout human history, fatty liver disease would almost always have been caused by alcohol, so this is given the very understandable name of “alcohol-related fatty liver disease” (AFLD). So, if you happen to have a high ALT and fat deposits in your liver, and you drink alcohol (whatever the amount) doctors would tend to call it alcohol-related fatty liver disease. But the vast majority of you will actually have non-alcohol-related fatty liver disease, even if you drink a little bit of alcohol, and aside from the general advice to eat better, be more active, and lose weight, all of which I do agree with, I think you should probably hear a little bit more about something else: the possible harms of fructose.
(As an aside, if you are interested in more advice about how to eat better, I do want to refer you to other videos I have recorded around that topic in general.)
So, what is so wrong with fructose? Through his passionate work, Dr. Robert Lustig1 has taught me that fructose is something optional in the human diet. We can survive entirely without it. You may be aware that this is a type of sugar, and specifically, it’s the type of sugar that comes from fruit. Eating too much fructose leads to fatty liver disease, and the reason for this is that our bodies and liver only have a limited capacity to digest fructose before they have to start turning it into fat deposits. So why is it only now that humans are eating too much fructose? Have not human beings always eaten fruit? Absolutely: many human societies ate lots of fruit going back thousands of years. That is not new. But what is new is drinking fruit juice.
You are probably aware of how much work goes into making fruit juice, and it’s only in the last couple of hundred years, with the help of the industrial revolution and the mechanization of food preparation, that everyone has been able to drink as much fruit juice as they can afford. But, even if it is real fruit juice, made from 100% real fruit, it’s still just the tasty stuff from the fruit, without the pulp and fiber.
We used to have to eat all of that fiber along with the fruit, and now, thanks to juices and the like, we can just get the sugary liquid. You may have heard that drinking one glass of orange juice gives you the juice of eight oranges, but could you ever imagine eating eight oranges in one sitting? Hopefully, I have convinced you that fruit juices may be part of the reason why people are consuming more fructose these days.
But we get fructose from more places than just juice. Fructose is one-half of a sucrose molecule, and sucrose is, of course, table sugar. At most, human beings and their love affair with sugar does not go back more than a few hundred years. The industrial revolution, not to mention colonialism and slavery, allowed us to add table sugar to drinks like coffee and tea, or to cook with it. This is all relatively new to the human diet.
Probably the largest source of fructose in a North American diet, though, comes from high-fructose corn syrup. You may be aware that, particularly in the United States, but even in Canada, corn is such a major agricultural crop that its byproducts are found throughout our food supply. High-fructose corn syrup is one such cheap and plentiful byproduct, and it is everywhere: in sweetened soft drinks, energy drinks, various processed foods, and desserts. It’s even used as a preservative. If you consume a lot of sweetened drinks or processed foods in general, chances are you are consuming a lot of fructose through high-fructose corn syrup.
My suggestion, if you are having trouble with non-alcohol-related fatty liver disease, is to start looking at food and product labels with one simple goal: find the fructose and/or sucrose in whatever you are consuming, and be mindful of the fact that this might be contributing to your fatty liver. I only rarely find patients now who do not drink alcohol and do not consume much in the way of fructose and yet still have signs of fatty liver disease, and we definitely look very hard to find other possible causes of liver disease in them.
To be clear, if you do have abnormal liver enzymes, even if you have signs of fatty liver, we do generally look for other causes of liver disease anyway, as it is easy to blame whatever is in front of us, whether it is alcohol or high-fructose consumption, when there are other causes of liver disease that should be ruled out with some basic blood work. So, along with that ultrasound we will ask to do of your liver, we will usually look for viruses causing hepatitis and other more uncommon liver diseases.
And if we do find out that you have abnormal liver enzymes, and you are going to make a change to your fructose and/or alcohol consumption, I absolutely recommend that we check in periodically, even every few months, with follow-up liver enzymes through blood work, to make sure things are going in the right direction.
So, please do make sure to seek medical attention from your family doctor if you think you might be at risk of having problems with alcohol and/or fructose consumption, but, to part on a positive note, I want to emphasize that we should all be thankful that, even if they have been affected by years of alcohol or poor diet, our livers are remarkable in their frequent ability to improve and get better with a bit of tender loving care.
