Dr. Sidney Valentine Haas was born in Chicago in 1870, but lived in New York City since he was six years old. He attended the public schools in New York City and subsequently attended City College. After he graduated from college he attended New York University Medical School, earned his M.D., and took graduated studies at Columbia's College of Physicians and Surgeons. At Columbia, Dr. Haas came in contact with some of the finest teachers of that generation, including Dr. Emmett Holt, a remarkable pediatrician, who influenced Dr. Haas to enter the field of pediatrics. Dr. Haas interned at Mount Sinai Hospital and became a well-known New York pediatrician, as well as the attending hysician and consultant at some of the city's largest hospitals. Since that time he also became famous as one of the most original thinkers in modern pediatrics. He authored many important papers on a variety of subjects, but his outstanding contribution was on the subject of an effective dietary treatment for celiac disease.

For over fifty years, research had shown that the elimination of carbohydrates brought about dramatic improvement in the condition known as celiac disease today. However, there was a need for some tolerable carbohydrate in the diet of these children. Dr. Haas was interested in learning if some form of carbohydrate could be added to the diet to hasten recovery and provide a more varied and nutritious diet. He had noted reports throughout the years whereby children with severe diarrhea had done very well on banana flour (made of 70% ripe banana) and plantain meal. He soon discovered that celiacs could tolerate this carbohydrate and, more than that, the banana could be fed in large quantities with beneficial effects. He further experimented with carbohydrate containing fruits and some vegetables and found that they, too, could be tolerated and celiac patients could regain health on a far more varied diet than just protein and fat.

During the next few years, Dr. Haas treated over 600 cases of celiac disease with his Specific Carbohydrate Diet, maintaining his patients on it for at lease twelve months, and found that the prognosis of celiac disease was excellent. "There is complete recovery with no relapses, no deaths, no crisis, no pulmonary involvement and no stunting of growth."

In 1951, Dr. Haas, together with his son, Dr, Merrill P. Haas, published The Management of Celiac Disease, the most comprehensive medical text that had ever been written on celiac disease. With 670 references to published research, the book described celiac disease more completely than had ever been done before.

Dr. Haas died on November 30, 1964, at the age of 94. His obituary was printed in all leading New York City newspapers, including The New York Times, and in Time magazine, he was described as a "pioneer in pediatrics," and an "honored pediatrician."