(Undated)  --  A new study ranks Portland among the healthiest cities in America.  Financial website WalletHub.com ranked the 150 biggest cities in the nation, based on choices for health care, food, fitness, and green space, and ranked Portland the fifth-healthiest in the U.S.  Vancouver is in 26th place.  The WalletHub study says San Francisco is the healthiest city in America, with Seattle at number four.