Alcohol Metabolism 101: An Introduction
Considering all the changes that are happening around here (if you missed it, here’s my post “Times They Are A-Changin’” that will get you caught up on all the pertinent details), I thought it would be appropriate for my first post at TwelveWellness to discuss how the body processes alcohol and the implications it may or may not have upon our health and wellness.
Buckle up, friends. This is only the beginning of a wild and crazy ride.
Oh! Just a quick heads up: the first paragraph is a little “science-y”, but if you’re able to tough it out without having your head explode, you’ll be glad you did. Trust me.
That being said…
Alcohol Metabolism 101
How well the body processes (metabolizes) alcohol (ethanol) is dependent upon the enzymatic activity that converts and prepares it for elimination. The process begins in the liver where the enzyme alcohol dehydrogenase, or ADH, converts alcohol to acetaldehyde, a highly toxic and known carcinogen. The body then converts acetaldehyde into another less toxic intermediary, acetate, through the activity of another vital enzyme, acetaldehyde dehydrogenase, or ALDH. In this more manageable form, acetate is then combined with coenzyme A to form acetyl CoA, which is able to enter the Krebs cycle to generate ATP, or cellular energy. After all the usable parts of acetyl CoA have been repurposed, all that remains are molecules of carbon dioxide and water, which are easily excreted through the process of exhalation and urination.
Alcohol, ethanol, is a relatively high-energy food because it contributes approximately 7 Calories per gram to energy production or storage, whereas carbohydrates and proteins contribute 4 Calories per gram while fat contributes 9.
Now the good stuff. Assuming your head is still firmly attached to your neck.
In healthy adults, this process is quick and relatively harmless. Acetaldehyde is quickly converted to acetate, minimizing the body’s exposure to its toxic effects and allowing the body to efficiently follow the process through through to elimination.
Unfortunately, when the rate at which the body can metabolize alcohol is impaired or the amount consumed exceeds the body’s processing capability, the consequences can be quite severe (i.e. cancer, liver disease, pancreatitis, depression, and anxiety).
So, what are the primary factors that influence the body’s ability to metabolize alcohol?
Liver size and body mass are the most obvious determinants in how well the body metabolizes alcohol. All other variables held equal, the larger we are and the greater our liver’s capacity for processing ethanol, the more we are able to consume without inflicting a tremendous amount of harm. Unfortunately, all things are not typically held equal in life and genetic variations in enzymatic activity greatly influence the body’s ability to process and eliminate alcohol.
As mentioned, the liver is normally capable of rapidly converting toxic acetaldehyde to less harmful acetate so that the harm caused by ethanol is relatively minor. However, it has been found that some predisposed individuals may convert alcohol to acetaldehyde at twice the normal rate, while the subsequent conversion of acetaldehyde to acetate is abnormally slow. This altered enzymatic activity results in the excessive accumulation of acetaldehyde, which can damage liver cells, cause physical discomfort and help ‘protect’ some against the consequences of excessive or chronic alcohol consumption. Conversely, this also means that altered ADH or ALDH function that increases processing capacity can promote the elimination process, which may encourage greater consumption, essentially ‘predisposing’ an individual to the detrimental drinking behavior that can increase their susceptibility to disease.
On top of this, damaged liver cells not only interfere with the body’s ability to process potentially harmful substances and contribute to the development of disease, it impacts the body’s ability to utilize food nutrients needed for good health, which may explain why malnutrition is a major concern for individuals with heavy alcohol intake.
Just when you thought it couldn’t get any worse, at abnormally high levels, acetaldehyde can escape the liver and travel through the bloodstream to the brain, where it can interfere with the neurological processes responsible for creating normal feelings, behaviors and memories. When acetaldehyde reaches the brain it slows the production of valuable endorphins and urges the afflicted person to consume more alcohol in an attempt to reestablish feelings of normalcy.
Alcohol’s effect on mind and body? Check and check.
There are, of course, many spiritual and emotional consequences associated with prolonged exposure to alcohol, but that kind of conversation is based more on subjective interpretation rather than the objective scientific inquiry, which is what I wanted to be the primary focus of this piece. However, the spiritual consequence of alcohol use is a conversation that must be had if we wish to fully understand the impact that drinking has upon our entire being and I definitely plan to address this in the near future.
Hopefully this wasn’t too overwhelming, but if it was, know this: the body is typically well equipped to process and eliminate alcohol in an efficient manner. However, as the result of a genetic predisposition or dangerous drinking behavior, the body can lose the ability safely metabolize alcohol, which can have many detrimental effects upon the mind and body.