The Bac(chus) experiment: blood alcohol concentrations after wine tasting

Abstract

Blood alcohol concentrations (BACs) were measured in ten volunteers after a wine tast-ing event with and without the swallowing of 15 mL of each wine. In case ten wines were tasted within one hour without swallowing, buccal mucosa absorption did not result in problematic BAC's; however in case 15 mL of each wine was swallowed, BAC's may exceed the legal driving limit of most countries. It is recommended to eat beforehand, but also to wait at least one hour after the session before driving back home.

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[Wine Studies 2012; 2:e1] [page 1]
The Bac(chus) experiment:
blood alcohol concentrations
after wine tasting
Albert van de Wiel,1David Moolenaar,1
Jos Wielders2
1Internal Medicine; 2Clinical Chemistry,
Meander Medisch, Centrum - Amersfoort,
The Netherlands
Abstract
Blood alcohol concentrations (BACs) were
measured in ten volunteers after a wine tast-
ing event with and without the swallowing of
15 mL of each wine. In case ten wines were
tasted within one hour without swallowing,
buccal mucosa absorption did not result in
problematic BAC’s; however in case 15 mL of
each wine was swallowed, BAC’s may exceed
the legal driving limit of most countries. It is
recommended to eat beforehand, but also to
wait at least one hour after the session before
driving back home.
Introduction
Wine tasting events are part of the culture of
wine drinking and have become popular even
in non-wine growing countries. During such a
session a number of wines are tasted and dis-
cussed mostly supervised and commented by a
connoisseur. Sometimes the session is fol-
lowed by a dinner, but sometimes it stands on
its own. Although the wines are not fully con-
sumed, even the contact of the wine with the
buccal mucosa may lead to alcohol absorption.
Whether this causes a significant increase in
blood alcohol concentration (BAC), which may
be relevant with regard to joining traffic after
the session is hardly known. We therefore
organized two sessions of wine tasting. In the
first session the wine was only rinsed through
the mouth and it was not allowed to swallow
the wine. In the second session, two weeks
later, the wine was rinsed through the mouth
and about 15 mL of each wine was consumed.
Blood alcohol concentrations were measured
fifteen minutes after the session.
Materials and Methods
Ten hospital employees, including the three
authors, participated in the Bacchus experi-
ment. The six men and four women, ages rang-
ing from 30-60 years, were all healthy volun-
teers, using no medication and were not
known with alcohol or drugs abuse. Liver bio-
chemistry including gamma glutamyl pepti-
dase, aspartate aminotransferase, alanin
aminotransferase and carboxy deficient trans-
ferrin as well as routine hematological tests
including mean corpuscular volume prior to
the study were normal in all.
Study protocol
The participants abstained from consuming
alcohol 24 h before each experiment. During
the day of the wine tasting, which started at
6.00 p.m., they had had normal breakfast and
lunch. The time interval between lunch and
the start of the wine tasting was the same for
all participants being 4.5 h. During each ses-
sion ten wines, five white ones and five red
ones were tasted. Alcohol percentages of the
wines ranged from 11.5-13.5%.
The actual protocol of the wine tasting was
developed in consultation with a professional
wine taster and wine journalist. In the first
experiment the participants were asked to
rinse 15 mL of the wine through the mouth
during two periods of fifteen seconds with an
interval of one minute. After each period of fif-
teen seconds the mouth was washed with
water. Interval time between each wine was
five minutes except between wine five and
six, switch from white to red, when it was ten
minutes.
In the second session, which took place two
weeks after the first one, the protocol was
identical with the exception that after the sec-
ond rinsing 15 mL of the wine was consumed.
No bread or food were consumed during the
sessions.
Fifteen minutes after the last wine, so about
one hour after the start of the experiment,
blood samples were taken for BAC analysis by
an enzymatic method on a Beckman Counter
Analyzer.
Results
Table 1 shows gender, weight, height and
body mass index (BMI) of the ten participants.
Volunteers 1-7 also participated in the second
experiment in which 15 mL of each wine was
consumed. In the first experiment BAC’s were
detectable but stayed low and under the legal
driving limit of the Netherlands (Figure 1A).
However in the second experiment five of the
seven volunteers reached a BAC above this
limit (Figure 1B). The two lowest BAC levels
were observed in the two men with the great-
est height, the two highest levels in two
women with the lowest BMI.
Discussion
Although wine tastings have become very
popular, little is known about their effect on
blood alcohol concentrations. This study shows
the results of two ends of the spectrum of such
a wine tasting event. On the one end wines are
only tasted by rinsing through the mouth and
no wine is swallowed, reflecting purely the
absorption of alcohol by the buccal mucosa. On
the other end the wine was not only rinsed but
also 15 mL of each wine was consumed reflect-
ing both buccal and intestinal absorption.
During most wine tasting events some wine
will be swallowed and therefore the second
experiment probably reflects best the situation
in practice. In that case the participants risk
reaching a BAC above the legal driving limit,
which may have great consequences especial-
ly if they want to drive a car after the session
and thus relevant information for each individ-
ual who enjoys their glass of wine. The highest
BAC levels were observed in two women with
the lowest BMI, indicating that peak levels are
also related to gender and BMI.
Alcohol is a small, light and weakly charged
molecule that is easily absorbed from the
mucosa through the process of diffusion.1The
rate of absorption depends on the location,
being quicker in the small bowel and slower in
the stomach, and whether or not the stomach
is empty, absorption being faster with an
empty stomach. Furthermore the alcohol con-
centration of the drink plays a role; concentra-
tions exceeding 20 vol% inhibit gastric empty-
ing and absorption.2Although it is known from
studies going back to the forties of the last cen-
tury, that alcohol is absorbed by the buccal
mucosa, data on this topic are limited.
Depending on the alcohol concentration of the
drink, about half of it is absorbed within 15-20
Wine Studies 2012; volume 2:e1
Correspondence: Albert van de Wiel, Internal
Medicine, Meander Medisch, Centrum, PO Box
1502 - 3800 BM Amersfoort, The Netherlands.
Tel. +31.338.502.444 - Fax: +31.338.502.695.
E-mail: a.vande.wiel@meandermc.nl
Key words: wine, wine tasting, blood alcohol con-
centration.
Received for publication: 5 December 2011.
Revision received: 9 Jnauary 2012.
Accepted for publication: 9 January 2012.
This work is licensed under a Creative Commons
Attribution 3.0 License (by-nc 3.0).
©Copyright A. van de Wielet al., 2012
Licensee PAGEPress, Italy
Wine Studies 2012; 2:e1
doi:10.4081/ws.2012.e1
Non-commercial use only

[page 2] [Wine Studies 2012; 2:e1]
s, with higher concentrations taking longer.
Almost all alcohol and its metabolites are
removed from the body by the liver; only a
small proportion is excreted unchanged
through sweat and urine. It takes about one
hour to eliminate the alcohol being present in
one glass of wine.
There is an argument to be made that BAC’s
in our second experiment overestimates the
effects when participating a wine tasting event
in daily practice. The wines were consumed on
a relatively empty stomach and no food, not
even a piece of bread, was consumed. Food
may have an inhibitory effect on gastric motil-
ity and slow the passage of alcohol from the
stomach to the duodenum, where most of the
alcohol is absorbed. In some wine tasting
events bread is served and can be consumed
between the wines. Ten wines were tasted and
partly consumed within 50 min, while in many
tastings more time will be used on information
and discussion about the properties and quali-
ties of the wines. BAC’s were measured fifteen
minutes after the last wine, so about 60-70 min
after the start of the session. In that period
most of the alcohol is absorbed while hardly
any alcohol is metabolized. So, one may
assume that the peak concentration is meas-
ured and most participants of a wine tasting
will not leave the place immediately at that
time. On the other hand during many tastings
the actual amount of wine consumed may be
higher than in our experiment or people will
have an extra glass of the wine they prefer.
In our second experiment 15 mL of each wine
was ingested totaling 150 mL corresponding
with 1.5-2 glasses. Since it takes about one hour
to break down the alcohol content of one glass,
it can be calculated how much time is needed to
reach a safe level to join traffic. In practice it is
recommendable to overestimate one’s con-
sumption rather than to try to be precise.
We can conclude that in a wine tasting event
not much of the alcohol will be absorbed by the
buccal mucosa and this will not lead to prob-
lematic BAC’s. However when some of the
wine is actually consumed, which is the actual
situation in most sessions, BAC’s may exceed
the legal driving limit and the participant
should be aware of this. Not only eating before-
hand, but waiting some time (in relation with
the amount consumed) after the session is
recommended before driving back home.
References
1. Wilson CW. The pharmacological actions
of alcohol in relation to nutrition. Proc
Nutr Soc 1972;31:91-8.
2. Paton A. Alcohol in the body. BMJ
2005;330:85-7.
Article
Table 1. Gender, weight, height and body mass index of the ten participants.
Participant no. Sex Weight (kg) Height (cm) BMI
1 Male 90 185 26,3
2 Male 85 180 26,2
3 Male 95 195 25,0
4 Female 70 185 20,5
5 Female 65 175 21,2
6 Male 75 195 19,7
7 Male 80 190 22,2
8 Female 60 180 18,5
9 Female 60 178 18,9
10 Female 55 160 21,5
BMI, body mass index.
Figure 1. Blood alcohol concentration (BAC) after wine tasting with only buccal absorp-
tion (A) an with buccal and intestinal absorption (B).
Non-commercial use only