Without doubt caffeine can affect sleep –
both the time it takes you to fall asleep and
the duration of sleep. But we are not all
affected to the same degree. While some
can drink a cup coffee at bedtime without
adverse effect, others can have a coffee at
breakfast and find themselves tossing and
turning that night. This can partly be
explained by habituation – the more coffee
you drink, the less it affects you – but
undoubtedly we all have an individual
sensitivity to caffeine. In fact there is a gene
we can test for which tells you if you are a
good caffeine metaboliser or not. For the
majority I simply recommend avoiding
caffeine from mid-afternoon to prevent any
unwanted effect on sleep.
Coffee has been shown to be of benefit in
the treatment of asthma, probably by acting
as a bronchodilator. As far back as the late
1800s there are reports of caffeine being
used to assist breathing in asthmatics. More
recently two large scale population studies
– one in Italy and the other the USA – have
found the risk of asthma to be almost 30%
lower in coffee-drinkers compared to
non-coffee drinkers.
Much is made of the antioxidant content of
tea, but coffee has in fact been shown to
have a greater total antioxidant power than
other beverages including green or black
tea, herbal tea or cocoa. The types of
antioxidants present, and how well they are
absorbed, are of course different in each
beverage, and it remains to be seen
whether those characteristic of coffee really
do prove to be protective against chronic
diseases such as cardiovascular disease and
cancer. Epidemiological studies have failed
to come to definitive conclusions about
associations between coffee consumption
and cardiovascular disease. In part this has
been due to confounding where coffee
drinking acts as a marker for some other
lifestyle factor that is known to increase
risk (e.g., smoking).
Several studies have found that coffee does
increase blood levels of homocysteine. But
while homocysteine levels were originally
thought to be a risk factor, this has more
recently been questioned and opinion is
divided. Either way since the effect of
coffee is relatively minor it seems unlikely
that there is any real effect on risk of
cardiovascular disease.
As far as coffee consumption and cancer
goes, there have been numerous casecontrol and cohort studies to look for an
association. A 2,000 review concluded that
there was no evidence to suggest a link
between moderate coffee consumption and
cancer of any site. It seems clear that for
both CVD and cancer prevention there are
far more important dietary changes to make
than trying to cut down your coffee intake.
explain how coffee lowers diabetes risk.
However not all studies agree and much
more research is needed to draw firm
conclusions.
You might think that the effects of coffee
on the gut are unquestionable. But even
here there is conflicting evidence. There is
certainly evidence that coffee can
exacerbate heartburn in some people,
although not all. If you suffer regularly you
could try switching to decaf as that seems
to help some – but again the published
research gives conflicting results. Since
decaf affects some just as much as regular
coffee it seems likely that some other
constituent of coffee is the cause. There is
no evidence that coffee increases the risk of
stomach ulcers or causes indigestion.
nosh magazine
conclusions cannot be drawn from only
two studies but these results have
prompted further research. There is better
evidence for a link with Parkinson’s
disease. A recent meta-analysis of 13
studies to meet the inclusion criteria,
demonstrated a 31 per cent reduction in
risk of developing Parkinson’s in those who
drank coffee compared to those who did
not. This reduction in risk was even greater
among men and the relationship was linear
meaning that the more coffee they drank
the lower their risk became. In women the
picture was found to be complicated by
whether or not hormone replacement
therapy was used post-menopause.
Consumption of coffee lowered the risk of
Parkinson’s in women who did not use
HRT, but raised risk in those who did. This
suggests there may be some interaction
between a component of coffee and
exogenous oestrogen use, but we need
more research before firm conclusions can
be made. Nevertheless taken together these
results tell a promising story for the
benefits of coffee on the short and long
term functioning of the brain.
To me the biggest issues with coffee are how
you take it and the portion size. What was
once a regular size is now a small, and the
large size in some coffee chains are
bucket-sized. Add to this a shot of syrup
(usually equivalent to seven teaspoons of
sugar!) and full fat milk or cream, and you
have a significant number of extra kilojoules
in your day. And that’s before you add the
slice of banana bread on the counter.
So, my conclusion is, if like me you love
your coffee, enjoy one or two in the
morning. Take it black or with milk (skim
if you’re cutting kilojoules for weight
control), and skip the fancy extras and the
extra large sized cups. Then, in the
afternoon switch to tea. N
The other big chronic disease affecting
Australians is type 2 diabetes and there
may be good news for coffee lovers here.
The famous Nurses Health Study in the US
reported early in 2006 that moderate
consumption of both coffee and
decaffeinated coffee may lower the risk of
type 2 diabetes in younger and middleaged women. Caffeine could clearly not
explain the effect and so researchers are
now looking at other constituents of coffee
for possible answers. A second study
published last year showed positive effects
of coffee on several markers of glucose
metabolism. Coffee consumption was
linked to lower blood glucose levels, both
in the fasting and postprandial state, and
lower insulin levels. Over time this could
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