Alcohol is widely considered a toxin and its consumption is inhibited by taxes,  minor drinking laws, and cultural mores which shun debauchery and addiction.  When people are hooked on alcohol there are a network of support groups,  treatment clinics, and 12-step programs that help people get over it.

Alcohol is bad and most of make the assumption that we should drink as little of it as possible.

However, if you take a careful look at how it’s metabolized in your body, it’s striking how similar it is to a compound in the diet that doesn’t get the same amount of scrutiny: fructose.

Now, I know it’s axiomatic that sugar is bad for you because carbs get stored as fat, it causes an insulin release, and causes diabetes.  That’s all true.  However, if you compare their effects on the body fructose resembles alcohol almost as much as its more common comparison glucose.

Consider the following observations:

• The alcohol we consume is usually derived from fructose in fruits and starches.  They’re structurally very similar.
• Both alcohol and fructose are metabolized in the liver, whereas glucose is metabolized by all cells.
• In the liver fructose and alcohol go through a similar digestive process that produces similar byproducts.  This includes lactic acid, glycerol, acetic CoA, and VLDL cholesterol.  These compounds increase the occurrence of gout, fatty acid synthesis, blood triglycerides, and LDL (“bad”) cholesterol.   In many ways these compounds are the substrates of the metabolic syndrome.

The biggest difference between the two is that alcohol can be taken up by your brain and fructose can’t.  You know when you’ve had too much alcohol, but excessive fructose isn’t readily detected by the body.

You just stay hungry and slowly get more FAT.

Pictures Are Worth A Thousand Words

Take a look at the circled compounds in the following two diagrams.

Here’s how alcohol is metabolized in the body:

Take home points:

• Consuming lots of alcohol produces a lot of NADH, which greases the wheels on fatty acid synthesis inside the liver, particularly with glycerol.  It also causes your body to produce a lot of lactic acid.
• Acetate turns into Acetyl CoA, which is a precursor for fat and cholesterol, which is aided and abetted by fructose consumption.

Take a look at the following graph for fructose consumption:

Take home points:

• Fructose leads to Acetyl Coa (which also comes from acetate when you drink alcohol), which leads to fat and bad cholesterol seeping out into the body
• Going from glycerol to fatty acids is aided and abetted by NADH, and so is the step leading from pyruvate —> lactic acid

On Overdrive They Start to Look the Same

Fructose and alcohol are not the same thing.  They’re metabolized by different enzymes and have distinct effects on the body.

But at very high dosage levels the secondary effects they have on your metabolism and endocrine system begin to resemble one another.  Fructose is the only ingredient in the diet other than alcohol that leads to fatty acid in the liver, they both lead to higher levels of fatty acid production in the liver which seeps out into the blood, and both result in increased amounts of lactic acid, which has deleterious effects on the body.

You shouldn’t think of the two as equal, but hopefully this’ll create a valuable way of conceptualizing what’s happening in your body when you consume excess amounts of sugar.

References:

Zakhari, Samir, et. al. “How Is Alcohol Metabolized by the Body?”

URL: http://pubs.niaaa.nih.gov/publications/arh294/245-255.pdf

Tappy, Luc, et. al. “Metabolic Effects of Fructose and the Worldwide Increase in Obesity”

URL:  http://physrev.physiology.org/content/90/1/23.long