Beer : Health and Nutrition

Energy
The Composition of Beer in Relation to Nutrition and Health 97
Too often in nutritional texts all beers are lumped together with one generalised compositional
listing. It must be borne in mind, though, that beers can differ enormously in
their composition, depending on their strength and how they were made, including the
grist materials employed (see Chapter 3). Thus the alcohol content may range from in
excess of 10% (v/v) in beers produced in Trappist monasteries to < 0.05% in the alcohol-free
products. Most beers worldwide have an alcohol content in the range 3–6%
(v/v). Note that ethanol has an energy contribution of 7 kcal per g (c.f. protein 4 kcal/g
and carbohydrate 3.75 kcal/g). Additionally, conventionally fermented beers may retain
some 25% of the starch in a partially degraded, non-fermentable form which will also
contribute to the calorie count. By contrast, so-called light beers generally contain
minimal levels of carbohydrate. Some two-thirds of the energy value in a regular beer
originates in the alcohol.
Brewers use the following formula (ASBC 1992) to calculate the calori c value of
a beer:
kcal in 100 g beer = 6.9(A) + 4(B – C)
where A = alcohol (% by weight), B = real extract (% by weight) and C = ash
(% by weight)
The ‘real extract’ is a measure of the total dissolved solids in the beer. The major
components of this are residual unfermented carbohydrates, some protein and ash
(inorganics). The myriad of avour components contributes relatively little and can be
ignored in this context. The ash has no calori c value and is therefore subtracted from
the residual extract number.
Martin (1982) suggested a more exact formula, which takes into consideration more
precisely the individual contributions of the major beer components:
Calori c value (kcal/100 mL) = [ethanol (g/100 mL) × 7] + [total carbohydrates
(as glucose g/100 mL) × 3.75] + [proteins (g/100 mL) × 4]
Tables 5.1 to 5.4 compare the calori c values of a diversity of beer brands, respectively
ales, lagers, wheat beers and seasonal beers.
Ethanol is just as assimilable as other sources of energy (Hawkins & Kalant 1972;
Wei et al. 1972). Forsander (1998) has amply shown why he claims that, as a source of
energy, ‘ethanol should be an excellent nutrient’. It is used by the body as ef ciently as
other energy sources, it requires no digestion by the body before it enters the bloodstream
by diffusion, and it is transferred to all cells without the need for an energy-demanding
transport system.