In 1892, he and his wife privately funded the Nathan Straus Pasteurized Milk Laboratory to provide pasteurized milk to children to combat infant mortality and tuberculosis. In his battles with the disease he opened the Tuberculosis Preventorium for Children at Lakewood Township, New Jersey in 1909. 

Disease in Milk: The Remedy Pasteurization: The Life Work of Nathan Straus records that unclean, unpasteurized milk fed to infants was the chief cause of tuberculosis, typhoid, scarlet fever, diphtheria and other diseases that were the main cause of a 25% infant mortality rate in the U.S. in 1890, 15% in 1903 (but 7% in New York in 1900, where pasteurized milk had already become the norm). Straus is credited as the leading proponent of the pasteurization movement, which eliminated the hundreds of thousands of deaths per year then due to disease-bearing milk.