Even when you donate to a legitimate charity, you have no way of knowing how much of your donation actually goes to the purpose for which it was intended. Sometimes money is eaten away by salary and distribution costs. Also, if you donate to a charity in another country, sometimes the government in that country seizes the food or other items so it doesnt get to the needy citizens.
For those reasons, I only donate money to a church of a recognized, legitimate denomination. More of the money will go to needy people when intentions are good. Church World Service is another organization that seems to provide food and medical help to those in need. Be very, very careful.