Here is one of many Review Articles:
Supplemental nutrition drinks: help or hype?https://www.health.harvard.edu/staying-healthy/supplemental-nutrition-drinks-help-or-hype
You don't need a doctor's okay to try a nutrition shake, but it's a good idea to ask your doctor if any of the ingredients will interfere with your medications. For example, some drinks contain vitamin K, and sudden changes in vitamin K intake may interfere with the effect of the blood thinner warfarin (Coumadin).
Supplemental nutrition shakes contain more than just healthy ingredients. "You may be getting more sugar than any of the other ingredients," says Stacey Nelson, a dietitian from Harvard-affiliated Massachusetts General Hospital.