The Science of Alcohol Metabolism

Learn how alcohol affects the body.

In this video I discuss how alcohol affects the body, and some of the side effects of alcohol in the human body. I go through the path of alcohol in the body, the damage from alcohol, and what causes a hangover. I also discuss how drinking alcohol over time can harm your body, such as by causing a fatty liver.

We are going to take a little trip on what happens to alcohol in the body. Once it is consumed alcohol goes down the normal food path of digestion. From the mouth through the oesophagus and into the stomach. Here, about 20% of alcohol is absorbed through the stomach lining into the bloodstream, which means it is getting into the bloodstream very quickly. From the stomach, the alcohol that was not absorbed in the stomach next travels to the small intestine. One note here, if there is no food in the stomach, so an empty stomach, or if the alcohol is not consumed with any food, it gets to the small intestine very quickly.

 

In the small intestine, the rest of the alcohol is absorbed into the bloodstream and travels to the liver. So, in the liver, an enzyme called alcohol dehydrogenase, which is also present in the lining of the stomach, which we will call ADH, oxidizes the alcohol, or ethanol molecule. In basic terms this means that the enzyme comes in and changes the chemical structure of ethanol, so, ethanol becomes acetaldehyde. This substance is known to be toxic and carcinogenic, or poisonous and cancer-causing. This acetaldehyde is then metabolized down to a substance called acetic acid, which is less harmful to the body. Acetic acid can then be broken down into carbon dioxide and water. When alcohol is present, the liver will work on metabolizing it first.

 

So, fatty acids can accumulate, which is why so many heavy drinkers develop fatty livers. It is estimated that the liver can eliminate about 0.5oz of alcohol per hour, which is about 1 beer, or 1 glass of wine, or 1 shot. The heart then pumps the alcohol rich blood to the lungs. Some of the alcohol in the lungs is breathed out every time you exhale causing your breath to smell of liquor. The lungs send the alcohol-containing blood back to the heart where it is pumped to all parts of the body, including the brain. Once alcohol enters the brain, it slows down nerve cells that control your ability to move and think.

 

So, judgment becomes impaired and movement becomes disrupted. Some people will begin to sweat and most will smell like alcohol. Alcohol also decreases the body’s production of anti-diuretic hormone. The antidiuretic hormone helps your kidneys manage the amount of water in your body. The decrease of this hormone causes the kidneys to not reabsorb water; instead, it is excreted as urine, causing the body to become dehydrated. If alcohol consumption continues, it could lead to loss of consciousness. And massive alcohol consumption or binge drinking could lead to alcohol poisoning. This happens when there is a high concentration of alcohol in the bloodstream and this could result in coma, respiratory depression or possibly death.

Now let’s look at the aftereffects of alcohol over consumption…the dreaded hangover. The exact causes of a hangover are not completely understood, but there are several factors that may contribute to it. The chemical acetaldehyde is formed from ethanol, it is believed that this chemical is what causes the headaches associated with hangovers. The increase in urination leading to dehydration, which could cause the thirst, dry mouth and dizziness.

 

Some immune cells produce substances called cytokines, which can contribute to nausea and. Some alcoholic beverages increase the release of gastric acid in the stomach and delay the emptying of the contents in the stomach, which could be the reason for stomach pain associated with hangovers. Alcohol can also interfere with the liver's production of glucose, the main form of energy for cells, which could contribute to dizziness, disorientation and lack of energy. The long term effects of alcohol overconsumption include anaemia, which is a low amount of oxygen-carrying red blood cells. It can lead to cell death in the liver cells and brain cells, leading to these organs not functioning properly. The risk of heart failure increases; as does the risk of stomach and intestinal problems, and many heavy drinkers have high blood pressure.

 

Overconsumption of alcohol can also lead to relationship problems, depression, and employment problems. And these are just a few of the long term problems associated with constant overconsumption of alcohol. It is always about moderation. Limiting yourself to 1 or 2 drinks from time to time is probably a good strategy. As you can see, overconsumption of alcohol has a lot of negative effects on your body, and consistent overconsumption of alcohol has catastrophic effects on your body.

In some cultures, alcohol consumption is tolerated, in some others forbidden – because of its risks for health and society. Particularly, it's the dose which is crucial. So, what happens inside your body when you drink? Just watch the video!

ADH + ALDH Enzymes

The alcohol metabolism process is conducted by a family of Alcohol dehydrogenase enzymes (ADH) and Aldehyde dehydrogenase enzymes (ALDH) in the body1.  Alcohol is converted to Acetaldehyde by the ADH enzyme. Then Acetaldehyde is converted to Acetate by the ALDH enzyme. 

These enzymes require cofactors and coenzymes to perform their reactions.  In the human ADH and ALDH enzymes, Zinc is used to holds the alcohol in its place and Nicotinamide adenine dinucleotide (NAD) which is constructed from Nicotinamide, is used to break it down. 

When enzymes run out of cofactors they stop working. Acetaldehyde is a toxic molecule and when it builds up it causes hangover symptoms.

Cofactors & Coenzymes

So what are these cofactors and coenzymes? Cofactors and coenzymes are essential for enzymes function, without them the enzymes are inactive. Cofactors, mostly metal ions such as Zinc, and coenzymes, are inorganic and organic molecules that assist enzymes during the catalysis of reactions. 

The ADH and ALDH activity is solely dependent on the level of available cofactors and co-enzymes. Regardless of the level of the enzyme (genetic factors), the efficient activity of this enzyme is promoted when there are enough cofactors and coenzymes available to perform the reaction. 

The levels of these cofactors and coenzymes also deplete during alcohol consumption2. Lack of these cofactors & coenzymes leads to the inefficient metabolism of alcohol, and the build-up acetaldehyde.  Inefficient metabolism of alcohol is due to the low activity of ADH and ALDH enzyme3.  

You may be surprised to know that your body contains these cofactors and coenzymes naturally- but only enough to process about 1-2 standard drinks (depending on your weight, gender and other factors). Recoverthol simply helps to replenish the cofactors and coenzymes (i.e. the ingredients of Smart Drinking Supplements) that your body uses up when you drink.

That is why Recoverthol works best if you add it to your first drink to fortify you drink with an extra dose of these cofactors and coenzymes. Recoverthol’s unique formulation together with its targeted delivery method, allows necessary fuel to reach the ADH and ALDH enzymes at the same time as alcohol. This is why you add it to your first drink.

Acetaldehyde Build Up

Inefficient metabolism of alcohol leads to the build-up of acetaldehyde, a toxic molecule that is damaging to the body’s organs and causes the symptoms commonly known as a hangover.  Factors affecting the severity and onset of acetaldehyde build up depend on genetic factors, gender, age, weight, fatty liver syndrome (hepatic steatosis) and the amount of alcohol consumed. 

The concentration of the oxidized form of nicotinamide adenine dinucleotide (NAD+) reaches its rate-limiting state shortly after ingestion and remains constant.  Ethanol elimination is approximately zeroth order, supporting the suggestion that the reaction is limited by the amount of enzyme, co-enzyme, or both (D.M. Umulis et al).

Research has shown that people can carry different variations of the ADH and ALDH enzyme.  Some variants work more efficiently in metabolising alcohol than others.  This means that some people can have toxic acetaldehyde build up more rapidly in the body as they have either a fast variant of the ADH enzyme or a slow ALDH variant. 

The variant of ADH and ALDH enzyme that a person carries can also influence how much alcohol they consume.  Acetaldehyde builds up in the body may also increase an individual’s risk of developing an addiction to alcohol.  For example, a particular variant of the ADH enzyme called ADH1B*2 is common in people of Chinese, Japanese and Korean descent. 

This enzyme may protect individuals against alcoholism as ADH1B*2 metabolises alcohol very efficiently which leads to increased levels of acetaldehyde and causes unpleasant sensations such as nausea, facial flushing and a rapid heartbeat even when only moderate amounts of alcohol are consumed. 

Studies have also linked acetaldehyde to some of the behavioural and physiological effects that have previously been linked to alcohol itself.  Other factors affecting the severity and onset of acetaldehyde build-up also depend on gender, age, weight, fatty liver syndrome (hepatic steatosis) and the amount of alcohol consumed.

The body conducts the alcohol metabolism process at a rate of 0.016% per hour. It doesn’t matter if you are 6’4” or 4’6,” or if you drink red wine or moonshine.  Once your blood alcohol concentration (BAC) reaches a certain level, no matter how it got to that level, your body needs time to break the alcohol down and remove it from your system.

Liver Support Ideology?

The majority of commercial hangover supplements follow a liver support ideology. Our preliminary studies suggest that body systems other than the liver may have an important role to play in alcohol metabolism, especially in relation to the rapid onset of acetaldehyde build up in Asian flush syndrome. This leads to the investigation of alternative culprits such as the stomach and gut bacteria that also contain ADH, and contribute to alcohol metabolism. Although the use of liver tonic formulations may be beneficial to promote recovery from acetaldehyde build-up after alcohol consumption, Recoverthol works by preventing the acetaldehyde build up in the first place.

The science behind Recoverthol is very simple. It only contains the fuel that ADH and ALDH enzymes need naturally to do their job. You need to replenish these cofactors as you use them up during alcohol consumption. Recoverthol gives you an extra dose of these cofactors when you need them the most. That’s why you add it to your drink. This also allows these cofactors and coenzymes to reach the ADH and ALDH enzymes at the same time as alcohol does. Just like when you exercise you need to replenish the fluid you lose, you need to replenish these cofactors when you metabolise alcohol. Otherwise, you will run out of fuel for the enzymes, resulting in the acetaldehyde build-up.

What Causes Hangover symptoms?

There is no way to avoid or prevent a hangover, other than to avoid alcohol altogether.  There are seven major biochemical reactions to alcohol metabolism.

Alcohol, and too much of it, triggers a cascade of reactions in your body that contribute to the symptoms known as a hangover.  These include:

  • Increased Urination: Alcohol is a diuretic. For every 200 ml of alcohol consumed, you will produce 320ml of urine. Alcohol inhibits the secretion of vasopressin. When this enzyme is suppressed, water is sent right to your bladder (along with electrolytes) to be excreted, causing you to urinate more often.

  • Dehydration: Increased urination can lead you to become quickly dehydrated and as your body draws water from your brain to function that may leave you feeling fatigued or dizzy. 

  • Acetaldehyde build-up: When alcohol reaches your liver an enzyme called alcohol dehydrogenase breaks it down into acetaldehyde. Acetaldehyde is far more toxic than alcohol (by up to 30-fold).  So during the alcohol metabolism process, your body again attempts to break it down with the enzyme acetaldehyde dehydrogenase and glutathione, a powerful antioxidant that is crucial for liver detoxification (glutathione contains high levels of cysteine, which is why taking this in supplement form may help avoid hangover symptoms).  Together, this powerful alcohol metabolism detox duo can break down the acetaldehyde into harmless acetate (which is similar to vinegar). However, when you drink too much alcohol your stores of glutathione become depleted which allows acetaldehyde to build up in your body, causing the toxic hangover effect.  It should be noted that women have less acetaldehyde dehydrogenase and glutathione than men which is why women may have a more severe reaction to drinking the same amount of alcohol as a man of similar weight.

  • Congeners: Congeners are ingredients produced as byproducts of fermentation and distillation. They include acetone, acetaldehyde, tannins and some flavorants in different alcoholic beverages.  Congeners are thought to make the effects of a hangover worse and it slows the alcohol metabolism process.   They are found in higher amounts in darker liquors (such as brandy, whiskey, and red wine) than clear liquors like vodka or gin. 

  • Glutamine rebound: Alcohol inhibits glutamine, a natural stimulant in your body. This is partly why alcohol has a depressive effect that may make you fall asleep easily… at first.  After you’ve stopped drinking your body will work overtime increasing glutamine levels, which is why you’ll ultimately wake up more often and have a more restless night’s sleep after you drink.  This glutamine rebound may contribute to the fatigue, tremors, anxiety, restlessness and even increased blood pressure that is often felt during a hangover.

  • Disruptions to your stomach lining, blood vessels, and blood sugar: Alcohol is irritating to your stomach lining and leads to increased production of stomach acid.  This can cause nausea, vomiting and stomach pain. Alcohol can also lead to dips in your blood sugar level, which can lead to shakiness, mood swings, fatigue and seizures.  Also, alcohol may cause your blood vessels to expand which may trigger headaches.
    Inflammatory response: Finally, alcohol also provokes an inflammatory response in your body during the alcohol metabolism process in which your immune system may trigger agents that provoke hangover symptoms including memory problems, decreased appetite and trouble concentrating.

References:

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  3. Michael Hardman, Rachel A. Page, Mark S. Wiseman andKathryn E. Crow. REGULATION OF RATES OF ETHANOL METABOLISM AND LIVER [NAD+]/[NADH] RATIO. Department of Chemistry and Biochemistry Massey University Palmerston North New Zealand

  4. David M. Umulis1,  Nihat M. Gu¨rmen,  Prashant Singh, H. Scott Fogler A physiologically based model for ethanol and acetaldehyde metabolism in human beings. Alcohol 35 (2005) 3–12

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  9. Lee, M.H. & Kwak J.K. (2014). Red ginseng relieves the effects of alcohol consumption and hangover symptoms in healthy men: a randomized crossover study. Food Funct,5(3):528-34

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