In the 23 January edition of Circulation, the American Heart Association (AHA) published an article entitled
Wine and your heart. This article presented a view on whether
wine and indeed any alcoholic beverages could be considered as
beneficial to human health, and in particular, cardiovascular
The view was based on an evaluation of some 41 articles in the
literature predominantly published from 1995 onwards. In essence,
the article suggested that the literature on any potential effects
of wine-derived phenolic compounds in cardioprotection was inconclusive,
as were, perhaps, certain clinical data relating to the role of
ethanol per se in cardioprotection. The article concludes with
a recommendation for a "large-scale, randomised, clinical end-point
trial of wine intake", and that the AHA "maintains its recommendation
that alcohol use should be an item of discussion between the physician
and patient." The authors of the article are cautious both in
their evaluation of the literature and their subsequent conclusions
and recommendationsthis is proper and prudent, given the known
adverse effects of alcoholic beverages and the propensity for
misuse within certain communities. However, there are some statements,
which are more grey rather than the stated black and white.
Risk factors for cardiovascular disease include: a high body mass
index; a diet high in fats and low in fruits, grains and vegetables;
a lack of exercise; cigarette smoking; an unbalanced plasma cholesterol
concentration; and a high blood pressure. What is quite correct,
as stated by the authors, is that the diet and lifestyle of consumers
of wine is generally related to less risk factors for cardiovascular
disease, than for example, consumers of beer and spirits. That
is, consumers preferring beer usually consume more alcohol, smoke
more, exercise less, and consume more fatty foods and less fish,
fruit and vegetables than do abstainers or consumers of wine.
Consumers of spirits have the least favourable patterns and practices.
Furthermore, wine, in particular, is generally consumed with food,
slowly or over a longer period of time and with regularitynot
episodicwhich would attenuate a high blood alcohol concentration,
prolong any acute plasma antioxidative and antithrombotic effects,
promote any chronic effects and prevent any rebound effects of
the ethanol and phenolic components of the beverage.
A high dietary intake of flavonoids, irrespective of the source
of the flavonoids is associated with a reduced risk from cardiovascular
disease, which is not attenuated by adjustment for dietary and
non-dietary risk factors. However, while tea, fruit and vegetables
provide a significant dietary source of flavonoids, wine, which
is integral to the diet of the Mediterranean countries whose populations
have the lowest risk for cardiovascular disease, contributes significantly
to the daily combined dietary antioxidant capacity of blood plasma.
Furthermore, comparing the character-istic diet of France with
that of the Mediterranean countries, wine consumption appears
to be extremely important in countries, which have a higher intake
of saturated fats and a lower intake of polyunsaturated fats,
such as France.
Most of the earlier evidence of a differential role for wine was
based on in vitro data. In vitro studies have shown that the wine-derived phenolic compounds may
prevent and even reverse the oxidation of LDL. They have also
shown that under certain conditions, the wine-derived phenolic
compounds increase the antioxidant capacity of blood plasma and
serum, and are, collectively and individually, 1020 fold more
anti-oxidative than endogenous vitamin E, where wine does confer
protection against the oxidation of LDL by free radicals in blood
plasma, in particular when the plasma concentration of vitamin
E was being depleted.
A question of considerable concern, however, has been whether
these in vitro data reflect accurately what is happening in the human body.
While approximately 90% of the alcohol component is readily absorbed
across the small intestine into the blood stream, it has only
been relatively recently established from in vivo data that the wine-derived phenolic compounds are absorbed into
the blood stream in sufficient quantity to act as effective anti-oxidants.
Eight in vivo studies have been undertaken to date and the results of these
data are less clear cut than that of the in vitro studies. Six of the eight studies conducted have shown that the wine-derived
phenolic compounds are active antioxidants in vivo. Any inconsistencies in the study results may reflect differences
in study design and duration as well as in the analyses used to
assess antioxidant activity. Indeed, significant antioxidant activity
may only be observed following the medium- to long-term consumption
of wine, although the phenolic compounds are absorbed in significant
amount after the acute or short-term consumption of wine. In addition,
the eighth in vivo study showed that while LDL was significantly protected from
oxidation following the consumption of de-alcoholised red wine,
it was not protected following the consumption of red wine per
se. This implies that any anti-oxidant effects of the wine-derived
phenolic compounds may be counteracted by the pro-oxidant effects
of ethanol, as the hepatic metabolism of ethanol has previously
been postulated to induce the oxidation of lipids, such as LDL.
Thus wine may have a positive role in protecting against ethanol
induced damage and diseases.
In conclusion, the authors are indeed proper and prudent in their
conclusions that the data are inconclusive as to whether wine
is equally or more cardioprotective compared to the other alcoholic
beverages. Research is, however, continuing to make the grey more
black and white, including large-scale, randomised, clinical end-point
trials of wine intake. It is also prudent of the authors to advise
that alcohol consumers consult with their physician, as age, gender
and genetics are all known to influence the effects of alcohol
on human health.
Creina Stockley is Health and Regulatory Manager of the Autralian
Wine Research Institute and member of the AIM Editorial Board