I don’t have the science to back any of this up, just empirical evidence.
However I gave my hopefully soon daughter-in-law a BOT mattress pad. My son says she LOVES how it helps her aches and pains (she runs 10 miles a day). She has a PHd in Physics so is not an uneducated ignoramus about the scientific method.
Both me and my husband are in our seventies. We have various pains in many joints. The medicines and therapies prescribed by our MDs do not work very well on us. The BOT and Fenwick stuff really helps us, it relieves our pains, when we wrench a joint it seems to help the joint heal a bit quicker than the normal 6 weeks, and we would be living in misery from our age related/body wearing out pains without the far-infrared therapy fabrics.
Without this stuff we both would be either attacking our stomachs with a lot of aspirin or wrecking our livers with the other non-steroidal anti-inflammatory medicines.
The elderly school horse (28 year old Appendix QH with controlled navicular disease) I ride for my lessons agrees with me about all the BOT and Fenwick stuff I put on the horses. Without his BOT and Fenwick boots/wraps I put on him this horse just refuses to extend his walk, will not trot over a pole, and is extremely reluctant to move out at the trot even using my legs, spurs, or popping him with my crop. With them on he will move out without many leg aids and keep going at the speed I want without too much work from me. Lately, after two years of refusing to trot over poles, he has consented to trot over ground poles again under his other rider, and after a few months of refusing to take his right lead (his worst foot) he has started taking the right lead again at the canter.
The elderly Arab-Welsh mare in her late twenties that I ride has arthritis, we just walk around the ring. I can get a decent ride at the walk with no or just a little bit of flinching if she wears her BOT and Fenwick boots/wraps, without them she flinches deeply every step and I cut the ride short. One ride started without the stuff on her lower legs, she gave me a great amount of flinching, her owner then got her various boots, put them on, and I could continue my ride without her flinching deeply every single step. That mare BELIEVES in the efficacy of these products.
Your point about the titanium dioxide being used with all these different products may explain why my body does not want me to use them. Too much heat for too long a time makes the symptoms of my MS MUCH WORSE, as in I start staggering, have difficulty standing, and my already horrendous balance gets a lot worse. The last thing I need to do is slather a mineral that reflects my body heat back onto my body for extended periods of time.
Thank you for listing all the products types that use the titanium dioxide so I can avoid all of them as much as possible. It is so easy to take the therapeutic fabrics off my body when my body says enough, it would be much harder to get the stuff off my skin. This might be the reason why my body does NOT want me to use cosmetics or sun screen, this started maybe 40 years ago when my undiagnosed MS got worse and worse. Come to think of it that was the last time I lived in a room painted white.
Yep, all I have is empirical evidence, and my body is much happier and I can keep elderly lame horses serviceably sound for light riding. These therapeutic fabrics do not cure, they do not help everything, but they can make life a lot less physically painful. Unfortunately they do raise my core body temperature so I cannot wear them as much as I would like to wear them.