Any truth to online ads claiming meds, vitamins, exercise/stretching can increase height in adults? how about @ almost 40 yo? some say massage does it

Just say no!: After your growth plates fuse during your teens, no magic combination of meds, vitamins, exercising/stretching will increase height, short of spending prolonged period of time in zero gravity to allow your intervertebral disks to decompress. But that will only gain you 1/2-1", not anything dramatically different. Those folks selling dietary supplements don't have to prove effectiveness or safety.

Not true: Mere quackery, ask your doctor if you feel you have a problem or if you want to start something strange, some of these preparations may contain hormones and are not regulated, best wishes

No: At that age only a tumor that secretes growth hormone usually it's a pituitary tumor I'm not aware of any other that could do that.