How to help without being offending?

My brother is just 28 years old and has really thinning hair. I was teasing him last week about it and he was really annoyed and walked out of the room. We've made up since then. I didn't know it was such a touchy subject since he always, always teases me too about my physical appearance, etc. Anyway, I looked online for possible solutions to his problem. I want to help him since I think it causes him to have a low self-confidence. How do I bring up the subject, of trying possible solutions, without me offending him? Any suggestions? I don't even think he's had any gf's since birth!

 

Unless you want to go for a hair transplant or a wig, the only remaining option in my opinion is to buy some clippers and mow the remaining hairs down to 2 or 3mm. At least, that's the way I went with my thinning hair. All hair grow products or treatments are a waste of money.... I believe the new hype is caffeine-shampoo, come on, save yourself the money and effort, it won't work and you'll spend hours in front of a mirror to see if there are any effects... I never tried any, but I have seen other people trying stuff and they are all bald now. If there would exist something that really works, we would know about it.
I have to say, I didn't regret my decision to cut it down once. In the morning I don't have to tame my hair any more, no fatty pillow from all the hair products that were needed to keep it tamed down during the day, it gets the focus of my thinning scalp (grow a beard to get the focus off even more), it saves you a load of bucks at the barber and on hair products. All I really have to do is cut it once a week. The only downside is that I kinda miss the nice, soothing feeling of having a hairdresser wash your hair
As a sign of compassion you can offer to cut yours down too...