Louis Pasteur studied the effect of magnets on plant growth and on fruit enzymes. The magnetic field modifies water structure, changing some of its physical properties. In the body, the magnetic field increases the dilution of oxygen in plasma, transporting more oxygen together with the hemoglobin mechanism. Osteoporosis is caused by the absence of the Earth's magnetic field. Space agencies use magnetotherapy to help their astronauts recover.
Osteoporosis occurs during space flight because of weightlessness.
There is no more stress on the weight-bearing bones of the body when in orbit, and so calcium tends to be absorbed in the bloodstream. The same thing happens on Earth to patients who are in bed for long periods of time, and to people who have to keep one leg suspended or non-weightbearing due to disease or fractures. In 1777, two French medical doctors, Androy and Thouret, gave their approval to magnetotherapy in a session of the Royal Society of Medicine. In the eighteenth century, therapies included unguents, purges, and bleedings. It's so easy . . .