UPDATE 3-U.S. to give Syrian rebels medical, food aid, not arms

* Shift would help fighters with non-lethal assistance * Likely to disappoint Syrian opposition, who want arms * Western nations to discuss military, humanitarian aid * Syrian refugee exodus may reach 1 million next month-UNHCR (Adds details from communique, background) ROME, Feb 28 (Reuters) - The United States will sendnon-lethal aid directly to Syrian rebels for the first time,Secretary of ...