It
is a little bit curious and amusing to us that our blog postings about alcohol
seem to generate the most "buzz". One of our recent postings
prompted a question about what happens to alcohol once it is consumed. We
found some amazing information on the subject that includes diagrams of alcohol
molecules, hydrogen atoms, and stuff that perhaps we would recognize if we had
taken chemistry. But alas, we did not. So we would prefer to use
just a little science, and try to explain the rest in Warrior terms, as we describe how alcohol is
metabolized in the human body.
When
you drink alcohol approximately 2 to 8 percent is lost through urine, sweat,
and breath. The remaining 92 to 98 percent is metabolized by your body.
When ethyl alcohol is broken down in our bodies it is first converted to
acetaldehyde. Acetaldehyde is converted to acetate by other enzymes and is eventually metabolized to carbon dioxide and water. Since we promised to minimize the science we will skip the
bit about enzymes and stripping of hydrogen atoms and simply point out that
acetaldehyde is a poison which is a close relative of formaldehyde.
Okay,
we need to talk about enzymes for just a second. There are three enzymes
that can convert alcohol to acetaldehyde; alcohol dehydrogenase (ADH),
cytochrome P450 (CYP2E1), and catalase.
Alcohol
dehydrogenase is an enzyme that removes hydrogen atoms from the alcohol
molecule. ADH is the worker bee of the alcohol enzymes as it breaks down
the majority of the alcohol that enters our bodies. ADH is actually the
name for a family of enzymes that break down alcohol. Researchers have
identified as many as ten varieties of ADH, each of which has a slightly
different molecular structure. These differences can explain why
individuals can react differently to alcohol. More on this later.
Hopefully our bodies are not relying on the next enzyme, cytochrome P450, to metabolize
our alcohol. Why? In light social drinkers nearly all the alcohol
we consume is taken care of by ADH. However, cytochrome P450 becomes quite
active in metabolizing alcohol in chronic heavy drinkers and this enzyme does
its work in the liver.
The
third enzyme, catalase, metabolizes alcohol in the brain, and as such, is of
particular interest to researchers. The acetaldehyde that is released
into the brain by the metabolism of alcohol by catalase has the potential to
combine with neurotransmitters to form new compounds called THIQs
(tetrahydroisoquinolines). Some researchers believe that THIQs are
responsible for alcohol addiction and that the presence of THIQs distinguishes
addicted drinkers from social drinkers. Other researchers dispute this
hypothesis.
The
end result of alcohol metabolism produces excess amounts of NADH (Nicotinamide
Adenine Dinucleotide plus Hydrogen) in our bodies. It is this excess of
NADH that can lead to acidosis from lactic acid build-up and hypoglycemia from
lack of glucose synthesis. Getting back to plain English, it can also lead to weight gain, fatty liver,
and heart attack.
As mentioned above, alcohol can affect
individuals in different ways. For instance, if a woman and a man of the
same weight drink the same amount of alcohol under the exact same
circumstances, the woman will on average have a much high blood alcohol content
(BAC) than the man. This is because women have much less of the enzyme
ADH in their stomachs than men do. If, however, the same man and woman
are given an injection of alcohol instead of drinking it they will tend to
have the same BAC. This is because when the alcohol is injected it bypasses the ADH in the stomach.
Ethnicity can also have an impact on alcohol
metabolism. Most individuals use a form of ADH called ALD2 to metabolize
the acetaldehyde. However, East Asians and American Indians produce a
form of ADH called ALD2*2 which is only about 8% as efficient as ALD2 at
metabolizing acetaldehyde. As a result they end up with large amounts of
the poisonous compound acetaldehyde in their bodies when they drink alcohol.
This causes their faces to flush and leads to headaches, nausea, vomiting,
heart palpatations and other extreme physical symptoms. In fact, the drug
antabuse acts in the same way to make people sick if they drink alcohol.
Antabuse binds with the enzyme ADH and prevents it from breaking down the
acetaldehyde produced by the metabolism of alcohol. Acetaldehyde levels
then build and cause the aforementioned symptoms.
It is true that you can build up a tolerance
to alcohol. Frequent heavy drinkers produce more ADH than other people
and then become less intoxicated on larger quantities of alcohol. Heavy
drinkers can metabolize up to 38 ml (over 2 standard drinks) of alcohol per
hour while the average person metabolizes around 13 ml, or about 0.7 standard
drinks per hour. On the flip side, a phenomenon known as reverse
tolerance can occur in people with liver damage. They produce less ADH
and can become more intoxicated on smaller doses of alcohol.
And it appears that it is not our imagination
that as we get older we don't seem to tolerate the effects of alcohol as well.
It seems that hormone changes that women experience at menopause can
cause them to become intoxicated on smaller amounts of alcohol. And men,
you are not immune either. As men age, they tend to produce less ADH and
are more likely to become intoxicated on smaller amounts of alcohol than
younger men.
Wow! Even with eliminating a lot of the
"science talk" that is a lot of information. So here's a
distraction for the next bit of information. Blues man Charlie Patton
used to say, "If you eat a lot of fat meat you don't get so drunk".
Well, it seems there is some science behind that too. The small
intestine is many times more efficient than the stomach at absorbing alcohol so
if you want the alcohol to be absorbed into the bloodstream slowly, you want to
keep the alcohol in the stomach as long as possible. There is a valve between
the stomach and small intestines called the pyloric valve. When this
valve is closed the alcohol will stay in the stomach, and this valve stays
closed when the stomach is full of food. And what about that fat meat?
Fatty and heavy foods tend to stay in the stomach longer than sugars and
vegetables.
So now that we have figured out HOW our bodies
metabolize what we drink, does WHAT we drink matter? Some people say that
alcohol is alcohol and it doesn't matter. But once again science, along
with some predictable behavioral patterns, show us that what we drink does
matter. For instance, many people will get more intoxicated when drinking
straight vodka as opposed to beer. This is because they will consume a
higher concentration of alcohol in a shorter period of time. Flavor also
tends to influence the rate of drinking. People tend to drink strongly
flavored drinks more slowly so someone consuming whiskey will typically consume
his or her drink slower than someone consuming a vodka beverage.
Another factor to consider is carbonation.
Carbonation speeds the absorption of alcohol so people drinking alcoholic
beverages with carbonation will become intoxicated more quickly than people
drinking the same amount of alcohol per hour in non-carbonated drinks.
And just as when we compare regular soda with diet soda in a person's
daily diet, diet soda comes out the loser in the alcoholic beverage arena as
well. People drinking mixed drinks made with diet soda will become
intoxicated more quickly and achieve higher BACs than people drinking identical
drinks made with regular soda. Researchers in Adelaide, Australia found
that the stomach emptied into the small intestine in 21.1 minutes for people
who drank mixed drinks with diet soda compared to 36.3 minutes for people who
drank drinks mixed with regular soda. You're just not going to win that
diet soda war with us any which way you mix it!
No comments:
Post a Comment