Beer : Health and Nutrition

142 Chapter Six
Brain and cognitive function
One of the most alarming trends in recent years in the US has been the habit of binge
drinking among young people. Students, newly freed from constraints, partake of ludicrous
drinking rituals, frequently with tragic consequences. These episodes generally
involve high-alcohol, low-volume beverages rather than beer, whose sheer volume is
not commensurate with excessive consumption in short periods of time. Having said
that, there is no question that any signi cant intake of alcohol has at least some impact
on the brain. Modest intakes may be bene cial, excessive intakes are certainly not.
Those who have imbibed excessive amounts of alcohol and who sleep or lose consciousness
run the risk of swallowing their tongue due to a relaxation of the airways
through inhibition of medullary centres of the brain. They may inhale vomit because
the preventive re ex centres in the brain are anaesthetised.
The Royal College of Physicians guidelines on the relationship between the alcohol
content of blood and mental and motor response are:
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30 mg/100 mL in blood (2 British units) makes the drinker relaxed.
At 50 mg/100 mL (3 units) the consumer is cheerful, with some loss of inhibitions.
At 80 mg/100 mL there is an impairment of driving ability.
150 mg/100 mL leads to a loss of self-control.
By the time 400 mg/100 mL is reached, the drinker is oblivious to events and surroundings.
A further 8 drinks will result in coma.
Those who take 30 drinks in one evening are likely to die.
The amount of alcohol that will be found in the blood depends on various factors, of which
sex and body weight are two signi cant ones. Table 6.3 allows an approximate computation
of the blood alcohol that will arise from consumption of different numbers of drinks.
Alcohol is being metabolised as it is being drunk. Clearly there are far greater risks
when the alcohol does not take a lot of drinking. Thus the sheer volume of beer relative
to alcohol content makes the short-term risks from its consumption less than for
the drinking of spirits.
An average person’s body clears alcohol at the rate of 15 mg per 100 mL blood per
hour. That is, one unit of alcohol is removed hourly. The rate is not in uenced by the
amount of alcohol – i.e. higher concentrations of alcohol are not metabolised at a faster
rate. Therefore excessive drinking can have carryover effects the next day. The ability
to metabolise alcohol decreases with age.
Tremoliere et al. (1975) compared the rate of alcohol utilisation in the body after
challenging with beer, wine or spirits. Fourteen subjects with empty stomachs were
given 0.5 g alcohol per kg body weight as beer, wine or whisky over periods of 15 days