CHRISTIAAN Barnard drank hydrogen peroxide in the 1980s in a desperate bid to cure his painful arthritis, but ditched it after developing chronic stomach pain. Professor Barnard, now retired to a remote farm in South Africa's Richmond area in the Cape, drank the chemical while staying in the US. But after several weeks of daily use, he developed internal bleeding and later discovered his stomach lining had been damaged. Hong Kong police are investigating the use and distribution of hydrogen peroxide as a drinkable cure for a range of illnesses, after the evangelical Church of Zion revealed it was encouraging members to drink it. Professor Barnard has become embroiled in the controversy after a mystery letter surfaced in North America apparently backing the drinking of the chemical. In a letter dated March 1986, which appears to bear his signature, Professor Barnard says hydrogen peroxide 'relieved his arthritis'. The one-paragraph endorsement has appeared in Canadian and US publications advocating the use of the chemical. But this week the professor told the Sunday Morning Post he had not written the letter, denouncing it as a fake. 'Yes, I took hydrogen peroxide at a time when I was suffering from arthritis in the US - but I would never recommend it to anyone,' he said. 'I did not write this letter. 'I suffered damage to my stomach lining as a result of taking it and required medical treatment to correct the problem,' he said. His wife Karin said: 'It was at a time when he was desperate because the arthritis was particularly bad; he would have tried anything.'