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Aaron Wright
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The Chemistry of Hangovers
While many people think that hangovers are caused directly by
alcohol (ethanol) itself, they are actually the result of several complex
chemical processes. From the dehydrating effect ethanol has on the body
to the presence of products from the breakdown of ethanol by liver
enzymes, many things come into play to turn a temporary state of lifted
inhibitions into a state of complete misery just hours later.
Let’s start with the troublesome little molecule that is at the root of
all this mess: ethanol. While alcohol is simply a general chemical term
that denotes an –OH hydroxyl group, ethanol is the name for the alcohol
that has an ethyl substituent group attached to the –OH. Ethanol
(C2H5OH) results from the fermentation of a monosaccharide, glucose.
Fermentation is an anaerobic biochemical process. Through fermentation
and enzyme catalysts obtained from yeast, glucose (C6H12O6) yields
2(C2H5OH) + CO2 (the CO2 is responsible for the bubbly goodness in
most spirits).
Fermentation (Zeit/Wiley 2011)
The above picture helps to illustrate the fermentation process,
showing the CO2 and ethanol products. Note that acetaldehyde plays a
role in the process. While this toxic compound does play a significant
role later on, it is typically eradicated, initially anyway, during the
fermentation of alcoholic beverages.
One of most significant ways your favorite cocktail makes you hate it the
next morning is through its dehydrating effect on the body. Aside from its
uncanny ability to make you throw up, thereby dehydrating you, there
are actually a couple more scientific ways it goes about accomplishing
dehydration. Ethanol works directly on the brain to depress the pituitary
gland’s production of ADH (antidiuretic hormone), specifically
vasopressin. Antidiuretic hormones work to retain water in the body,
whereas diuretics rush water through the body. Alcohol has a very strong
diuretic effect. After drinking about three shots of 100 proof spirits (50 g
of ethanol in 120 mL of liquid), one would eliminate in the hours that
follow between 600 and 1000 mL of water (roughly 1.5 to 2 pints)
(Zeit/Wiley 2011). Therefore, more alcohol consumption equals more
water loss, and a dramatic loss of water contributes greatly to a
hangover. Headaches, lethargy, and dry mouth are all symptoms of
dehydration.
While dehydration will be a factor in any alcoholic beverage you
consume, there are certain types of spirits that will contribute symptoms
that others don’t. It is well known in the drinking world that darker, or
colored alcohols (tequila, brandy, red wine, bourbon, dark rum, whiskey),
cause much more severe hangovers than lighter or clear drinks (gin, light
rum, vodka, white wine) (Waniek 2009). This is due to the presence of
congeners which are chemical compounds produced during fermentation
and maturation (Buddy 2006). Congeners include esters, acids,
aldehydes and higher alcohols (alcohols that contain more than two
carbon atoms). Strictly speaking they are impurities and toxic
compounds, but they are what give different alcoholic drinks their
different flavors. It is important to take heed in the advice of your friends
when they tell you to not mix liquors, especially dark ones. Different
liquors contain different congeners, which can make your hangover
exponentially worse. Their presence in the final product must be judged
very carefully, because too many would make it undrinkable.
Methanol is notorious for being one of the congeners that cause severe
hangovers. This is due to how the body metabolizes methanol. When we
metabolize ethanol, we get acetalaldehyde as an end product. With the
oxidation (the addition of oxygen to a compound) of methanol, however,
we get formaldehyde as an end product (Perry 2004). This is an optic
nerve toxin, and can be fatal in high doses. In cases of severe methanol
poisoning, formaldehyde can be smelled on the subject’s breath.
Almost all alcoholic beverages contain at least some methanol, which
arises as part of the fermentation process from pectins. Pectin is a
complex polysaccharide, and is found in the cell walls of plants. When it
comes to spirits, you can find it in high concentrations in pears, plums,
and cherries found in most brandies (which is partially the reason that
brandy causes the worst hangovers) (Zeit/Wiley 2011).
During fermentation, the ester groups are hydrolyzed, and methanol is
released (Zeit/Wiley 2011).
As stated above, acetalaldehyde is the end product of ethanol
metabolism. While the body regards ethanol as a poison, acetalaldehyde
is even more toxic. Acetalaldehyde is created when the alcohol in the liver
is broken down by an enzyme called alcohol dehydrogenase. At that
point, it is broken down by another enzyme, acetaldehyde
dehydrogenase, and another substance called glutathione, which
contains high quantities of cysteine (a substance with a high affinity for
acetalaldehyde) (Zeit/Wiley 2011). Ideally, the acetaldehyde
dehydrogenase and the glutathione will work together to form the
nontoxic acetate (similar to vinegar), ridding the body of all of ethanol’s
nasty end product. This process typically works well, leaving the
acetaldehyde only a short amount of time to do its damage when only a
few drinks are consumed.
(Zbeda 2011)
As we can see above, alcohol dehydrogenase first oxidizes ethanol into
acetalaldehyde with help of NAD+ reducing (accepting H+ ions). Next
NAD+ helps to convert the acetalaldehyde to the carboxylic acid, acetic
acid. This leaves us with an excess of NADH. The excess of NADH,
inhibits three enzymes of the Citric Acid Cycle (citrate synthase,
isocitrate dehydrogenase, and alpha-ketoglutarate dehydrogenase) which
basically shuts it down (Zeit/Wiley 2011). Pyruvate, the end product of
glycolysis, starts to accumulate, and the excess NADH causes lactate
dehydrogenase to produce lactate from pyruvate in order to get more
NAD+ and keep the body going. However, this takes pyruvate away from
other important pathways such as gluconeogenesis. This restricts the
liver’s ability to compensate for the drop in blood glucose levels,
especially for the brain. Because glucose is the primary energy source of
the brain, this lack of glucose contributes to symptoms such as fatigue,
weakness, mood disturbances, and decreased attention and
concentration (Perry 2004).
Diabetics especially need to be very careful when drinking. Alcohol
is processed in the body very similarly to how lipids are processed.
Therefore, drinking alcohol in people with diabetes can cause your blood
sugar to rise, at least at first. While light to moderate amounts of alcohol
can cause blood sugar to rise, excess alcohol can decrease the blood
sugar level, sometimes causing it to drop into dangerous levels
(especially in diabetics) (Buddy 2006). Remember that the liver is
responsible for gluconeogenesis, but it is also responsible for the
processing of ethanol. While providing the body with glucose is very
important, the body recognizes the expulsion of a poison such as ethanol
to be a higher priority. And as a consequence of the excess ethanol and
NADH (due to ethanol breakdown), the liver does not have the time or
resources to bring the blood glucose level back up to where it needs to be
fast enough for many diabetics (Buddy 2006).
Now that we’ve discussed how alcohol can wreak havoc on the
body after a night of festivities, let’s talk about what we can do to tame
those effects. First, let’s discuss some of the myths surrounding the
elusive hangover cure.
First and foremost, taking Tylenol before going to bed is a complete
failure when it comes to any type of preventative maintenance of
hangover symptoms. Not only would the effects of the acetaminophen
wear off before the onset of the hangover, but it can cause severe damage
to the liver. Acetaminophen alone is by far the most common cause of
liver failure in the United States, and combined with alcohol it can be
deadly (Zeit/Wiley 2011).
Drinking “the hair of the dog that bit you” (drinking a little more alcohol
in the morning) might provide a little relief, but it may be wise to fight
that temptation. Hangovers begin once the body starts dealing with all of
the crap that’s left after metabolizing the ethanol in the system. While
the body begins to deal with the ethanol you introduce into your system
the next morning, that only means it’s going to have to deal with more
toxins later on.
Eating burnt toast is another myth that actually has a little science
behind it. This refers to the carbon in the charred bread Carbon can act
like a filter in the body. Activated charcoal (a form of carbon) is used to
treat some types of poisonings, but it is not currently used to treat
alcohol poisoning (something that is vastly different from a regular
hangover) (Perry 2004).
One of the most popular myths is that eating a greasy meal the next
morning will help alleviate hangover symptoms. While eating fried or
fatty foods may only worsen matters with an already irritated stomach,
these types of foods actually can do some good in PREVENTING a
hangover, rather than curing it. Having anything in the stomach before
drinking will help at least some, but fatty foods in particular have a way
of sticking to the stomach lining which helps to slow down the alcohol
absorption process into the bloodstream (Waniek 2009). While this will
also increase the amount of time it takes to get a good buzz, it
dramatically increases your chances of feeling decent in the morning.
Lighter foods can provide energy and electrolytes that the body needs to
return to normal.
While the above supposed hangover cures may only delay the inevitable,
or not work at all, there are several measures you can take to go from
crappy to happy in half the time.
Eating bananas can be a very successful way to get your body back on
track. Along with the dehydration alcohol causes, the body also loses lots
of electrolytes that are in the water, including potassium (Perry 2004).
Potassium is vital to homeostasis in the body, and once it’s replenished,
your cells can start doing their job again with much more ease.
Another food that helps to lessen the hangover effect is eggs. Not only
does it provide energy like any other food would, but eggs contain high
amounts of cysteine, which is the substance that helps to break down
acetalaldehyde, the metabolic end product that is responsible for many
hangover symptoms (Waniek 2009).
.
Perhaps the most successful next day remedy for a hangover is good oldfashion H2O. Drinking plenty of water the next day will not only
replenish the lost water from alcohol’s diuretic effect, but it will also help
to dilute the leftover biological garbage that is the aftermath of ethanol
consumption (Waniek 2009). Sports drinks like Gatorade or Powerade
can even take it a step further and replenish many of the body’s
electrolytes along with the life-sustaining H2O. Water and sports drinks
will help even more if taken before going to bed that night, as that will
provide the body with more ammunition in the fight against ethanol.
H2O
ROCKS!
Well, there you have it, the ins and outs of the chemistry of
hangovers, as well as some pretty good info on how to (and how not to)
get rid of them. Cheers!
Works Cited
Perry, Lacy. "How Hangovers Work" 12 October
2004. HowStuffWorks.com.
<http://science.howstuffworks.com/environmental/life/humanbiology/hangover.htm> 15 April 2012.
"Chemistry of a Hangover - Alcohol and Its Consequences." ::
ChemViews Magazine. Chemie in Unserer Zeit/Wiley-VCH, 06 July 2011.
Web. 17 Apr. 2012.
<http://www.chemistryviews.org/details/ezine/1080019/Chemistry_of_
a_Hangover__Alcohol_and_its_Consequences_Part_3.html>.
T, Buddy. "Drinking Alcohol And Diabetes." About.com Alcoholism.
American Diabetes Association, 16 July 2006. Web. 11 Apr. 2012.
<http://alcoholism.about.com/od/diabetes/a/diabetes_risk.htm>.
Wanjek, Christopher. "Hangover Cures: What Works, What
Doesn't." LiveScience.com. LiveScience, 29 Dec. 2009. Web. 11 Apr. 2012.
<http://www.livescience.com/5960-hangover-cures-works.html>.
Zbeda, Robert. "Esophageal Cancer and the 'Asian Glow'"
Esophageal Cancer and the ‘Asian Glow’. DUJSonline, 2010. Web. 11
Apr. 2012. <http://dujs.dartmouth.edu/fall-2009/esophageal-cancerand-the-%25E2%2580%2598asian-glow%25E2%2580%2599>.