We have probably all been told at some point to eat up our vegetables
because they are good for us. While we may not have believed it
at the time, theres now a lot of work to suggest that Mum may
have been right on this point. Fresh fruit and vegetables are
a good source of antioxidants, and it is these antioxidants which
are now thought to help to prevent illnesses such as cardiovascular
disease and cancer. For those who do not care for vegetables,
the news that red wine was a good source of antioxidants was very
welcome! In fact, this message seems to have got across to the
consumer quite well and its a popular perception now that red
wine is good for your health.
But what are antioxidants and why should they be good for you?
Antioxidants can be many different compounds but they all share
the property that they are able to quench, or neutralise free
radicals. In theory, the more antioxidants in your cells, the
less free radicals. This is important because its free radicals
themselves which are suspected to be involved with starting cancers
and speeding up the progression of cardiovascular disease.
Antioxidants in cider
For the health conscious consumer who needs a break from the Bordeaux,
theres other options. Any beverage made from fresh fruit or vegetables
is likely to have antioxidants - take cider for example. Cider
is made from apples, and apples contain an abundance of antioxidants
such as quercetin in the apple peel and hydroxycinnamic acids.
Not surprisingly, apple juice and cider also contain antioxidants.
In a joint project with the Institute of Food Research at Norwich
we measured the amount of antioxidants in 18 UK ciders. To do
this, some of the cider was added to a solution containing free
radicals and then the amount of free radicals knocked out by the
beverage was measured. This simple lab-based test comes up with
a score for that particular cider. In our study, we found that
the antioxidant activity score for ciders ranged between 100 and
2595 units for a 250 ml serving.
How good is this score for ciders? It is in fact very good. The
beauty of this method of measuring antioxidant activity is that
it can be used to compare scores for foods and beverages in other
studies. For example, looking at the table below its clear that
cider is one of the top choices for antioxidant content!
Antioxidant activities of selected foods and beverages
From Paganga et al (1999)
*BRI/IFR project data
(mmol Trolox equivalents)
|Red wine (Rioja-Bordeaux)
|Black Tea (0.25%)
|Green Tea (0.25%)
|Apple juice (long life)
So for consumers who enjoy an occasional glass of cider in the
evening or down the pub, they can rest assured that they are also
getting a pretty healthy dose of antioxidants!
Although this sounds straightforward, life is never that easy.
There is another important factor that has to be considered
that is bioavailability. In a nutshell, its not just how much
is in the food but rather how well you can absorb it. Clearly,
if the gut cannot absorb the antioxidants, they will never get
into the cells! The ease with which we can absorb any compound
is called the bioavailability and this needs to be measured for
each food and beverage individually to get an accurate picture
of how good a source of antioxidants it is.
Antioxidants in beer
Cereal grains are a good source of antioxidants and not surprisingly
beer, which is made from malted barley, also contains antioxidants.
Therefore we decided to measure the bioavailability of one of
these antioxidants, ferulic acid which comes from the barley cell
This study was conducted in collaboration with Professor Catherine
Rice-Evans and her team at Guys hospital and has just been published
(Bourne et al 2000). The strategy of this study was to give 6
male volunteers a large dose of low alcohol beer, then follow
the appearance of ferulic acid in the urine. The idea is that
if ferulic acid appears in the urine this indicates that it must
have been absorbed into the blood stream and therefore have been
absorbed by the gut. Additionally, the speed at which it appears
in the urine gives an indication of how long the ferulic acid
stayed in the bloodstream and by implication whether it would
remain in the body long enough to knock out oxygen radicals.
The results were very interesting. All of the ferulic acid present
in the beer was absorbed by the volunteers. This is very different
to the situation seen for a fruit such as the tomato. If volunteers
eat fresh tomatoes they will maybe absorb only up to 25% of the
ferulic acid in them, the rest remaining in the gut.
This difference in absorption of ferulic acid from tomatoes and
beer can be easily seen in the figure. The reason for this is
quite likely because the ferulic acid in the tomato is tied up
in the cell walls and is physically prevented from passing through
the gut wall. In contrast, the ferulic acid in beer is unbound
and free in solution and is presumably easy to absorb. Another
observation was that the ferulic acid stayed in the blood for
longer than other antioxidants such as vitamin C. Ferulic acid
would therefore be expected to be in the body for long enough
to help with keeping free radicals at bay.
A note of caution.
Research is now telling us the amounts of antioxidants in our
food and drink, and also how well we absorb them. However, two
important questions remain in this story. First, once absorbed,
do antioxidants get to the right tissue? Second, do antioxidants
actually do any good when they get there? These are still active
areas of investigation and so the case for the health benefits
of antioxidants while receiving a lot of attention, is not yet
The take home message for beer, and indeed any food or beverage,
is that antioxidant content must be assessed by both the total
amount of antioxidant present AND how easily it is absorbed. The
results so far indicate that beer should be a good source of antioxidants
in the diet.
The health benefits associated with moderate alcohol consumption
are now fairly widely accepted and the consumer is generally getting
more interested in foods and beverages which can promote health
the so-called functional foods.
Red wine, cider and beer all contain antioxidants and it is reasonable
to consider moderate consumption of these beverages as making
a positive contribution to a healthy diet.
L. Bourne et al (2000) Bioavailability of ferulic acid from beer.
Free Radical Research, 32:273-280
G. Paganga et al (1999) The polyphenolic content of fruit and
vegetables and their antioxidant activities. What does a serving
constitute? Free Radical Research 30:153-162
Brewing Research International, Lyttel Hall, Nutfield, Surrey,
RH1 4HY, UK