Latest revision as of 12:04, 15 May 2006

Red wine may fight deafness

   * 14:00 14 May 2006
   * From New Scientist 
   * Andy Coghlan

MODERATE consumption of red wine or aspirin may delay the onset of age-related deafness and reduce hearing loss caused by loud noise and some antibiotics.

The delicate hairs of the inner ear which are vital for hearing can be damaged by the oxygen free radicals produced by normal cellular processes throughout life and in response to loud noise and exposure to antibiotics. Antioxidants such as resveratrol, which is found in red wine and green tea, or salicylate, the active ingredient of aspirin, help to neutralise these free radicals, so might be expected to protect against some of this damage.

To test this, Jochen Schacht of the University of Michigan Medical School in Ann Arbor and his colleagues used salicylate to try and prevent damage to the hair cells in patients' ears caused by the powerful antibiotic gentamicin. Ironically, gentamicin is often used to treat severe, acute ear infections, although it can damage hair cells in the process. Hearing loss affected just 3 per cent of patients who were given gentamicin plus aspirin for acute ear infections compared with 13 per cent treated with gentamicin plus a placebo. "That's a 75 per cent reduction in toxicity to the ear," says Schacht, who presented his results at an ear conference at University College London last week.

At the same meeting, Matti Anniko of Uppsala University Hospital in Sweden presented results which suggested that an ear condition called Ménière's disease could be treated with a cocktail of three antioxidants: rebamipide, vitamin C and glutathione. Ménière's disease causes vertigo, nausea and balance problems and is linked with oxidative damage to hair cells in the ear. Symptoms improved in people recently diagnosed with the disease after they had been taking the cocktail for up to six months, suggesting that the antioxidants were limiting further damage. The treatment didn't work as well on patients who'd had the condition for many years, however. The antioxidant cocktail is now being tested in four larger trials in which half the patients receive placebos.

Schacht says that there is no direct evidence that consuming more dietary antioxidants - by drinking moderate amounts of red wine, for example - prevents hearing loss in humans. However, rats kept on restricted diets had less age-related hearing loss than rats on normal diets. Since restricting food intake is known to reduce oxidative damage to cells and tissues, this hinted that a similar effect could be achieved by including more antioxidant-rich foods in the diet. "I wouldn't say it is proof for antioxidants," says Schacht. "The jury's still out on that, but it certainly can't hurt to increase the amount of green vegetables, red wine or green tea that you consume."

Red wine's anti-ageing ingredient does it again

IF RED wine holds the key to a longer life, fish are the latest creatures that can drink to it. Those fed resveratrol, a component of red wine already known to prolong the life of yeast, flies and nematode worms, can live up to 60 per cent longer than usual. And if resveratrol works in fish, there is a fair chance that it will prolong the lives of other vertebrates, including humans.

Alessandro Cellerino of the Italian Institute of Neuroscience in Pisa gave three different doses of resveratrol to Nothobranchius furzeri, a fish native to Zimbabwe that lives for an average of 9 weeks. The lowest dose had no effect, but fish on the medium dose lived a third longer, and those on the highest dose lived 60 per cent longer. At 12 weeks, by which time all untreated fish were dead, the fish on the highest dose were still fertile and had the physical and mental agility of a young fish (Current Biology, vol 16, p 296).

Resveratrol also appeared to protect the fish's brain cells against age-related degeneration, suggesting that it could potentially help the elderly stay alert.

"As far as I'm aware, this is the first major demonstration that you can extend lifespan in a vertebrate with a single molecule," says David Sinclair of Harvard Medical School, who in 2003 extended the survival of yeast cells by exposing them to the compound.

Previous studies suggest that resveratrol might slow ageing by preventing chemical damage to DNA in mitochondria, the energy powerhouses of cells. Alternatively, it could stabilise DNA by activating a gene called SIRT1, and so prevent cells and tissues from being sapped of energy and deteriorating to produce the symptoms of old age.

Several companies are now developing resveratrol supplements, but in the meantime the substance can be found in grapes, grape juice and red wine. "It wouldn't hurt to drink one or two glasses of wine a day," says Cellerino.

However, other researchers cautioned against using his results as an excuse to overindulge. Paul Kroon of the Institute of Food Research in Norwich, UK, calculated that the highest dose of resveratrol given to the fish equated to a person drinking 72 bottles of red wine per day. And the compound's effects in humans might be further diluted because around 95 per cent of resveratrol is destroyed by our digestive systems before it makes it into the blood.

From issue 2538 of New Scientist magazine, 11 February 2006, page 14