One of my friend's mother is about to undergo some treatment in Magnetic field therapy for Osteoarthritis and he is trying to verify if this is useful as claimed or if this has any harmful effects. The website of their institution claims that

In Yuri Gagarin’s historic flight to space, he returned in near critical condition after only one hour and forty-eight minutes in space. Clearly, there was some vital element missing in space that we receive on earth. Yuri had plenty of food, water and oxygen and since the flight was less than 2 hours, he only needed oxygen. The critical missing element appears to be the earth’s magnetic field. Since that first flight, pulsed magnetic devices have been used in every space suit and space station. Further studies have been done on earth (zero field studies) with both laboratory animals and human subjects.

Did he really ended up in critical condition as it is claimed? Was it verified that such condition was due to the missing magnetic field?