Obligatory disclaimer: I am not a medical doctor, and the content of this website was created for informational purposes only. Such content is not intended as a substitute for medical advice, treatment or diagnosis.
In previous posts we’ve talked about the starvation response (aka starvation mode), metabolic adaptation (aka metabolic damage), the thermic effect of food, and thermogenesis. We’re currently running a series on macronutrients, and in our previous posts we’ve paid special attention to carbohydrates, proteins, and lipids, focusing on their classification, how they are digested, and their food sources.
In this week’s post we’ll deal with alcohol (specifically ethyl alcohol, also known as ethanol), but we’ll mostly stick to its digestion. This is because of a couple of reasons: 1) alcohol is terrible when it comes to nutritional content and 2) the other mass-produced sorts of alcohol (like methanol and propanol) are toxic to the point of causing blindness or death. Just like before, given the sort of content that we’ll be dealing with in this post, rather than rely on scientific papers, we’ll use the following references:
- Gropper, S. S., & Smith, J. L. (2012). Advanced nutrition and human metabolism. Cengage Learning.
- Wildman, R. E., & Medeiros, D. M. (2014). Advanced human nutrition. CRC press.
- Hankey, C., & Whelan, K. (Eds.). (2018). Advanced Nutrition and Dietetics in Obesity. John Wiley & Sons.
What is alcohol?
As may be obvious, alcohols are neither proteins, carbohydrates or lipids. They are also, unsurprisingly, not macronutrients, but they do make up an important part of the average diet, so we might as well become acquainted them. Ethanol’s structure most closely resembles that of carbohydrates, and its digestion is similar to that of fatty acids. To keep things simple, ethanol’s chemical structure is that of a short hydrocarbon chain with a hydroxyl group on one of its ends. Unsurprisingly then, it is a source of calories although it carries no additional nutritional contents, and is therefore said that those are “empty calories”.
Biological “functions” of lipids
Even though alcohol doesn’t have any nutritional value, its moderate consumption has been linked to an elevation of high-density lipoprotein (HDL) and a decrease of serum lipoprotein, both of which are related to a decrease in cardiovascular disease risk.
By the same token, though, excessive alcohol intake may lead to alcoholism and its ugly consequences: fatty liver, hepatic disease (cirrhosis), metabolic tolerance and lactic acidosis.
Once ingested, alcohol is absorbed through the entire gastrointestinal tract, although most of the absorption occurs in the smaller intestine. After that, it is transported through the entire bloodstream without any form of processing. As alcohol is transported through different tissues and organs, it is then oxidized, first producing acetaldehyde and then acetate. As you’re surely aware of, the liver is the organ primarily responsible for alcohol degradation, and it, alongside peripheral organs, then continues the metallization of acetate through several different enzyme systems.
So now we know a little more about an important part of our diet: alcohol. We have an idea of what it is, and how it is digested. Next week we’ll deal with the glycemic response / glycemic index. Hope you enjoyed this week’s post, and see you next week!
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