Friday June 25 2010
Red wine should be enjoyed in moderation
"Drinking wine could protect your eyes,” The Daily Telegraph reported. It said that resveratrol, a substance found in red wine, could protect blood vessels in the eye being damaged by old age.
The story is based on a small study in mice, investigating whether resveratrol can inhibit the abnormal growth of blood vessels in the eye. Giving the substance to mice with damaged eyes appeared to inhibit the abnormal growth of blood vessels, a condition similar to macular degeneration in humans.
However, while this study is of scientific interest, there is very long way to go before we know if resveratrol can be used to treat human eye disease. This model of eye disease is different to that in humans, and clinical trials would have to test if this compound affects human blood vessels.
It is not advisable or practical to drink more red wine to increase resveratrol intake. These mice were given high doses of the substance and the human equivalent would be more than could be found in several bottles of wine. If it were to be trialled in humans, it would probably be in a pill.
Where did the story come from?
The study was carried out by researchers from the Washington University School of Medicine, St Louis, and the University of Dentistry and Medicine of New Jersey. It was funded by the National Institutes of Health and several charitable foundations and research institutes. It was published in the peer reviewed The American Journal of Pathology.
The Telegraph’s report appears to rely heavily on a press release issued by Washington University. Its main shortcoming is that it does not mention that this was a study in mice and so its findings cannot be directly transferred to humans.
What kind of research was this?
This experimental, animal study aimed to explore the potential effects of resveratrol on the growth of blood vessels in mice. Resveratrol is a natural compound produced by plants. It can be found in red wine due to its presence in the skins of grapes.
Some animal and laboratory studies have suggested the compound may have various benefits for health, including protecting against Alzheimer’s disease, tumours and obesity, and possibly even slowing the ageing process. However, none of these effects have been proven in humans. It is also not known how resveratrol works, but one theory is that its effect may be mediated by particular proteins.
The researchers were interested in the potential effects of resveratrol on the growth of blood vessels, pointing out that the abnormal growth of blood vessels is central to several diseases, including certain types of eye disease.
Only very limited conclusions can be drawn from this type of study. If a compound such as resveratrol were thought to offer promise in the treatment of eye disease, it would have to go through many stages of testing for safety and efficacy in human trials.
What did the research involve?
Common laboratory mice were separated into three groups of five. For the next seven days, the groups were given either a non-active ingredient, a lower dose of resveratrol (22.5 mg per kg of weight) or a higher dose (45mg per kg of weight).
The mice were then anaesthetised before being given laser treatment that encourages the growth of abnormal blood vessels in the choroid layer of the eye. This is the vascular layer of connective tissue between the retina and the outer layer of the eyeball. In humans, it is the part of the eye affected by macular degeneration. Treatment in the groups continued for seven days after the laser injury.
After seven days the mice were killed and their eyes examined in the laboratory. The researchers state that all work was performed in accordance with recognised guidelines and protocols on animal care.
What were the basic results?
The researchers observed a ‘significant reduction’ in the abnormal growth of blood vessels in mice treated with the higher dose of resveratrol. Further laboratory analysis suggested the effect was possibly due to resveratrol activating an enzyme called ‘eukaryotic elongation factor-2 kinase’. This contradicted previous research indicating that resveratrol interacts with proteins called sirtuins.
How did the researchers interpret the results?
The researchers conclude that resveratrol can stop or slow down the abnormal growth of blood vessels in the eye, and is effective at preventing both new blood vessels from developing and eliminating abnormal blood vessels that had begun to develop. They also say the results have unravelled a ‘novel pathway’ by which resveratrol may affect the behaviour of blood vessels. They suggest these findings may have a significant impact on the understanding of diseases caused by blood vessel growth, and that resveratrol could potentially be used to treat these disorders.
This study suggests that high doses of the plant compound resveratrol has an inhibiting effect on abnormal blood vessel growth in the eyes of mice. It also identifies the mechanism by which this might happen. As such, it is of scientific interest. However, researchers would need more testing to see whether resveratrol or a derivative could potentially treat eye diseases in humans. Any treatment would then need to go through many stages of efficacy and safety testing in humans before it was made generally available.
Whatever properties resveratrol may or may not have, it is best to stay within the recommended limits when drinking wine as excessive consumption is known to be harmful to health. Relative to their weight, the doses of resveratrol given to the mice were high, and the human equivalent would be more than would be found in several bottles of wine. This suggests that if this compound were to be trialled in people with eye disease, it would need to be in pill form.