He said the study only proved that certain bypass patients redeveloped the disease "and we don't know the reason."
"If bypass patients stop taking multivitamins, it can result in life-threatening malnutrition."
The long-term mortality rate of gastric bypass patients has been shown to be reduced by up to 40%.
Typically, at hospitals in New York State, between 2 and 3 percent of bypass patients die.
Doctors usually encourage bypass patients to sit up in bed soon and dangle their legs over the side.
Cardiac bypass patients are sometimes cooled by chilling their blood.
Other bypass patients, he said, could be suffering from depression brought on by external factors.
The state's death statistics cover bypass patients who die in the hospital during or after surgery.
By comparison, fewer than 4% of bypass patients need the operation again over the same period of time.
She continues to do individual counseling with gastric bypass patients.