Women who drink moderate amounts of beer may be strengthening their bones, according to Spanish researchers. Their study of almost 1,700 women, published in the journal Nutrition, found bone density was better in regular drinkers than non-drinkers. But the team added that plant hormones in the beer rather than the alcohol may be responsible for the effects. Experts urged caution, warning that drinking more than two units of alcohol a day was known to harm bone health. Osteoporosis is a common problem for post-menopausal women, increasing the risk of disabling bone fractures later in life. Further research Scientists have been hunting for supplements which might help women maintain the strength of bones into old age. The study authors, from the University of Extremadura in Caceres, said they did not recommend anyone drank beer to boost bone health, but said that ingredients of beer called phytoestrogens deserved further research. They recruited volunteers with an average age of 48, and used ultrasound to measure the density of bones in their fingers. The results were cross checked against factors such as their weight, age and alcohol use. Women defined as "light" or "moderate" beer drinkers, covering consumption of up to 280 grams of alcohol a week - equivalent to up to five units a day, were found to have superior bone density to non-drinkers. The findings echo those from earlier research projects, including one conducted at St Thomas' Hospital in London, which suggested that drinking an average of eight units a week of alcohol could be beneficial. However, experts were quick to point out that the line between a "healthy" dose of alcohol and a damaging one might be very fine. Health concerns At 35 units a week, the upper limit of the "moderate" alcohol consumption defined by the study is double the recommended maximum for women. Dr Claire Bowring, of the UK's National Osteoporosis Society, said that while the findings mirrored previous studies, it would not be recommending any woman to increase her alcohol consumption as a result. "While low quantities of alcohol may appear to have bone density benefits, higher intakes have been shown to decrease bone strength, with an alcohol intake of more than two units per day actually increasing the risk of breaking a bone. "There are also many other health concerns linked with alcohol which cannot be ignored."