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by Vanessa Graham

National Beer Day, April 7th, isn’t just one more national day to tack on to the rest. It’s been around for almost a hundred years and commemorates the beginning of the end for alcohol prohibition in 1933. The 18th Amendment only forbade the sale of alcohol for about 14 years before the 21st Amendment canceled it out. The entire time Americans continued to drink profusely and organized crime flourished by smuggling booze to speakeasies, or secretive drinking establishments. After visiting and observing the situation, Albert Einstein commented, “The prestige of government has undoubtedly been lowered considerably by the Prohibition laws. For nothing is more destructive of respect for the government and the law of the land than passing laws which cannot be enforced.”

Prohibition had been led by the temperance movement, which influenced alcohol laws worldwide in the early 1900s, and had noble goals such as advancing society and reducing domestic violence. Many countries passed some form of alcohol control laws. In the US, total prohibition ultimately proved a poor method of controlling alcohol consumption and had massive economic costs. Some estimate the US lost almost a billion dollars for each year of prohibition, when the total income of the entire government was only around 7 billion dollars.

The government made beer with less than 5% alcohol legal on April 7th, 1933. The rest of the alcoholic beverages had to wait until December. The alcohol in beer is its primary feature, and responsible for most of the culture around beer. Let’s explore some beer facts and take a close look at the alcohol in beer, how it got there, and what kind of mood it creates, because beer is a little different than wine or distilled spirits.

Hand holding beer malts

What is the alcohol in beer?

Beer contains ethanol, which is a source of energy and the same substance that grants all alcoholic beverages their mind-altering powers. We have been aware that there is something specific that can be purified from alcoholic beverages for hundreds of years. Alchemists used to refer to distilled ethanol as aqua vitae, or the water of life.

Ethanol is the original VOC

Ethanol is extremely volatile, which means it evaporates at relatively low temperatures, like at room temperature. It’s also one of the most well-studied substances due to its simplicity and bioactivity.

Many consumer volatile organic compound (VOC) detectors are calibrated based on their reactivity to ethanol, because their metal-oxide sensors are cross-reactive to most VOCs and ethanol represents a good chemical that is organic (containing C-C and C-H bonds) and in the air in during comfortable indoor conditions. The VOC sensor in our Air Pro was calibrated at the factory using ethanol and is cross-reactive with many VOCs.

How does yeast make ethanol?

Ethanol is the by-product of fermentation, or growth, by one or more strains of the single-celled fungal organism yeast. Our bodies can grow using many different energy sources with all of our different cells, like proteins and fats, but the yeast that makes beer only eats sugar.

Both the ethanol and the carbonation in beer start out as sugars from barley grain, which in turn start out as carbon dioxide (CO2), water (H2O), and sunlight energy the mother plant absorbs to make starch. The starch can be metabolized to release that energy for its own use and eventually release the CO2 and H2O back into the environment.

Yeast is a fairly simple organism and can’t break starch down into sugar by itself. A grain is just a seed, so by soaking a grain in water enzymes are activated that break down the stored starch and start the growth process of a young barley sprout. Malting the grain stops the growth process by drying out the sprouted grain after the starch has been converted to sugar.

During fermentation, yeast cells break the sugars apart, carefully capturing the energy to use it to grow and multiply. Enzymes in the yeast break 6-carbon glucose from starch into a 3-carbon intermediate step, then finally remove one more carbon that becomes fizzy carbon dioxide, leaving the other two to compose ethanol.

Alcohol has a lot of calories

Each gram of ethanol has about 7 calories. Ethanol isn’t CO2 and H2O quite yet, and it’s toxic to yeast so they can’t use it for energy. Our bodies are happy to metabolize ethanol just as well as sugar. One pint of beer weighs about 473 grams, and in a 5% alcohol beer, that’s 24 grams of ethanol or 165 calories. More than three quarters of the calories in beer is alcohol.

Brewer sniffing and tasting a batch of beer

Why does alcohol seem to bring different moods in different drinks?

The main factors that have so far been identified in how a drinking session will impact your mood are expectation, setting, speed of consumption, and caffeine intake. Each one can have a significant impact on where you emotionally end up after drinking a few. Beer is most likely to result in a steady effect on the mood due to the lower alcohol intake, but can just as easily get out of control when consumed quickly.

What you bring to the table

A big part of intoxication is informed by our expectation of what drunk people act and feel like, which we start to build when we are small children. We bring most of our drunk mood with us when sober. People who are aggressive when sober are much more likely to be even more so when they lose control from alcohol, for example.

Alcohol and the culture around it produce a strong placebo effect. In a few studies, subjects who were given a non-alcoholic second round of drinks were often acting just as drunk as those with real alcohol. This placebo effect is different and stronger than with unfamiliar drugs in a clinical setting because most people have practiced behavior, a whole cultural approach to drinking, and a large group of people to go along with that strengthens the placebo effect.

Things can speed up when you don’t expect it

The faster we drink the bigger the shifts in mood and the more likely our behavior could change to uncontrolled levels, including being motivated to drink a lot more. In certain situations or when consuming drinks that hide the taste of alcohol, blood alcohol levels can spike and lead to stranger behavior. Distilled spirits have the highest proportion of alcohol to any other ingredients, and enter the bloodstream the fastest, followed by wine and beer, which are more similar, though wine is absorbed a little faster.

Congeners, or the residual plant and flavor material left over from the brewing process, also contribute to intoxication speed and hangovers. It is thought that we get used to congeners over time and have different tolerances to their varying effects.

There are also a few other ways alcohol can sneak into the bloodstream faster. Carbonated drinks, for example, raise blood alcohol more rapidly, so beers with less fizz might make for a steadier evening. The absence of food in our stomachs can also impact how quickly the ethanol gets in, because the food competes with the alcohol for absorption in the intestine. Even the sugar in a drink mixed with soda will slow down absorption more than a drink with artificial sweetener like aspartame because it’s not absorbed by the intestine.

Line of multi-colored beers under a row of beer taps

Ethanol has a wide impact

So far, there hasn’t been a specific set of neurotransmitter receptors that have been identified as targets for ethanol like with opiates or antidepressants. Researchers think ethanol works on dozens of different aspects in our neurology, resulting in a sum that is alcohol intoxication. This sum effect has a lot of its own characteristics but shares drug effects with benzodiazepines (like valium, Xanax or Ativan), barbiturates (often drugs ending in -ital) and general pain relievers (like Tylenol, aspirin, or opiates).

Ethanol has many mechanisms of action on the body, and medical researchers are coming to the conclusion that its impact on the GABA receptor is primarily responsible for both its calming and anti-anxiety effects and the combination of cognitive and motor impairment. It also acts directly on dopamine neurons in the reward and reinforcement areas of the brain. With chronic consumption, it can induce a state in the brain that fits a chemical definition of addiction.


One of the first metabolic steps for ethanol is for the body to convert it into acetaldehyde in the stomach by using the enzyme alcohol dehydrogenase. Acetaldehyde has predictable psychological effects, including making us feel more comfortable with where we are and what we are doing

Acetaldehyde is one of the ways that alcohol consumption helps to motivate more alcohol consumption, but substances that compete with acetaldehyde can decrease comfort with our setting and self-administration of alcohol. One acetaldehyde competitor is L-cysteine, a very common amino acid from many protein sources. More research needs to be done, but it’s likely that eating protein before drinking could impair acetaldehyde’s effect and reduce alcohol dependence.

Alcohol and caffeine are strange bedfellows

The interaction of caffeine and alcohol is fairly well-studied, and these two drugs interact in a rather intuitive way. Caffeine impairs alcohol’s ability to reduce alertness, but lets it induce feelings of pleasantness and reduce anxiety. On the flip side, negative overstimulation impacts accumulate and interact with the caffeine like heart palpitations, sleep disturbance, irritability, and tremors. Overall researchers agree that caffeine can mask alcohol intoxication and lead to more drinking and raise the risk of drinking too much.

Ethanol also has an impact on how your body can use adenosine, which is a substance that slowly accumulates throughout the day to make us sleepy, among other things. When there is ethanol in your blood, adenosine cannot be cleared from the brain, which is how it makes us sleepy. In theory this is a convenient self-regulatory aspect of ethanol that puts people to sleep before they can drink more. Caffeine, however, inhibits adenosine and keeps us awake while drunk. The two also work together to increase dopamine activity, so the combo feels better and can make dependence more likely.

How can I tell someone has had too much?

In one pint (16oz) of beer there is about 25 milliliters of ethanol, which if consumed in a short period of time raises the average person’s blood alcohol to around 0.04%. That is a level that is about half of the legal driving limit and is unlikely to result in alcohol poisoning.

Alcohol poisoning, or when an ethanol overdose comes with a serious risk of permanent injury or death, is generally thought to be over 0.4% and requires immediate hospitalization. However, over 0.3% is usually where someone goes in and out of being aware of their surroundings or in and out of consciousness altogether. This stage carries a low but real possibility of death and should also be taken seriously.

If in doubtremember that any person who is vomiting uncontrollably due to alcohol or who is breathing less than 8 times a minute or has breaths with more than 10 seconds between should be hospitalized immediately. Every minute they go without professional help is another part of their brain that will die from lack of oxygen and never work properly again. Even in the absence of death, alcohol poisoning can cause crippling mental and physical injuries that last a lifetime.

Knowing if we drink too much is a subject of discussion, but the top 10% of drinkers in America have 74 drinks a week, or more than 10 a day, which is too much. The American medical establishment says that any amount of alcohol is unhealthy and to limit drinking to 2 drinks per day for men and 1 for women to avoid alcohol-related diseases. This advice may seem so risk-averse as to be useless for many of us, so keep in mind that the Australian government recommends no more than 10 drinks per week and no more than 4 drinks per day to reduce the risk of alcohol-related diseases to less than 1%. Though it can be difficult to talk to a doctor about alcohol, try to ask your primary care provider for any advice.

For more on different ways to think about the science of health, keep your eye on this blog and on our Facebook, Instagram, and Twitter accounts.

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