Global restaurant chain McDonald's is to begin reducing the use of antibiotics in its chicken products. It will focus on removing those antibiotics that can have an impact on human health, but keep those necessary for poultry welfare.Many poultry producers in US give their birds antibiotics to make them grow faster. But overuse of the drugs could lead to them becoming less effective in treating illness and disease in humans.The changes come in response to growing consumer demand for food made with natural ingredients only.Last month, Swiss food giant Nestle announced that it would be removing all artificial flavours and colours from its chocolate products in the US.