FOR SEVERAL YEARS NOW the potential health benefits of red wine have been all over the news. The latest health findings may not have so many people reaching for their wine glass. According to a report on WebMD, UK researchers found that red and white wines from most European nations carry potentially dangerous doses of at least seven heavy metals.
A single glass of even the most contaminated wine isn’t poisonous. But drinking just one glass of wine a day – a common habit in Europe and the Americas – might be very hazardous indeed, according to research from biomolecular scientist Declan P. Naughton, PhD, and Andrea Petroczi of Kingston University, London. Naughton calculated “target hazard quotients” (THQs) for wines from 15 countries in Europe, South America and the Middle East. The measure was designed by the US Environmental Protection Agency to determine safe levels of frequent, long-term exposure to various chemicals. A THQ over 1 indicates a health risk. Typical wines, Naughton found, have a THQ ranging from 5O to 2OO per glass. Some wines had THQs up to 3OO. By comparison, THQs that have raised concerns about heavy-metal contamination of seafood typically range between 1 and 5.
“I was surprised at this finding, and would be very interested if regulatory authorities and food-safety people will look at this,” Naughton told WebMD. “The wine industry should look at ways to remove these metals from wine, or to find out where the metals come from and prevent this from happening.” The metal ions that accounted for most of the contamination were vanadium, copper and manganese. But four other metals with THQs above 1 also were found: zinc, nickel, chromium, and lead. Some 3O other metal ions were measured in the wines, but THQs could not be calculated because safe daily levels for these metals are not known. All of these oxidating metal ions pose potential problems. But the manganese contamination particularly worries behavioral neurotoxicologist Bernard Weiss, PhD, professor of environmental medicine at the University of Rochester, NY. Weiss was not involved in the Naughton study.
“From the point of view of just one of these metals in wine, manganese, I would be concerned,” Weiss told WebMD. “Any time you see numbers like they have in this study, you begin to scratch your head and wonder about the effects over a long period of ingestion: Not one glass of wine last Tuesday, but a glass a day over a lifetime. Manganese accumulation in the brain, Weiss notes, has been linked to Parkinson’s disease.
Wines from three of the 15 nations studied had safe levels of heavy metals: Italy, Brazil and Argentina. Based on the maximum THQs for wines from each nation, here’s the list of the worst offenders: Hungary, Slovakia, France, Austria, Spain, Germany, Portugal, Greece, Czech Republic, Jordan, Macedonia, and Serbia. Hungary and Slovakia had maximum potential THQ values over 35O. France, Austria, Spain, Germany, and Portugal had maximum potential THQ values over 1OO. Argentinean and Italian wines did not have significant maximum THQ values. “If you buy a bottle of wine, the only thing it tells you on the label is the amount of alcohol. I like the idea of labeling wines with the amounts of heavy metals they contain,” Naughton says. “Many wines don’t have these metals. So let customers vote by choice whether they want the heavy metals.” Where do the heavy metals come from? That’s unknown. Naughton says possible sources include the soil of the vineyards in which the wine grapes are grown, the fungicides sprayed on the grapes, and possible contaminants in the yeasts used to ferment the wine.
Naughton and Petroczi did not directly measure heavy metals in the wines, but calculated THQs from data published in scientific journals. Since there was no data on heavy metals in US wines, they did not include North American wines in their analysis.
Weiss says he’d like to see such data. He’d be interested to see whether national health databases can link health problems to daily wine consumption, and whether wine drinkers have higher concentrations of heavy metals in their bodies than teetotalers do. In their paper, Naughton and Petroczi note that drinking red wine has been linked to health benefits because it contains antioxidant compounds. “However, the finding of hazardous levels of metal ions which can be pro-oxidants leads to a major question mark over the protective benefits of red wine,” they suggest. The findings appeared in the October 29 issue of the open-access chemistry central journal.