What should my friend with a broken foot do to speed healing?

Speedy recovery. Factors that may speed your friend’s recovery include: immobilization, elevation, good nutrition, follow the physicians’ instructions and tell them not to smoke. Bone healing usually takes 4-8 weeks depending on the type of fracture. Each person has a different healing potential depending on age and overall health.
Depends. This depends on the type of fracture and where on the foot and how it was originally treated. Sometimes vitamins with calcium will help.
Fracture. Doing all the hings already stated will help . After that is is dependent on the bone , type of fracture , displaced or not , etc. There are a lot of factors so there is no generic answer. Have the friend ask this question to his treating physician as that person has seen the x rays and knows best .
Broken foot. Follow the instructions of your orthopedic surgeon, some can be walked on, others no weight bearing. Eat a good diet, including the building blocks of bone, vitamin d and c, calcium and protein.