Bytox's patch formulation brings other complications. “My message for the public is ‘buyer beware.’ The evidence for nutrient absorption through the skin barrier is very limited, and many of the health-related claims are unsubstantiated. The companies need to provide proof for the claims,” JoAnn Manson, a physician, chief of preventive medicine at Brigham and Women’s Hospital and Harvard professor, said in an article in The Washington Post . “I would ask the companies to ‘show me the data’ — show me evidence that absorption is effective and blood levels of these vitamins and minerals increase appropriately.”