Hi Asif. From what I read gynocomestia is most likely a hormonal issue. Would imply your brother will have to up his testosterone levels and decrease estrogen levels. The endocrine system is responsible for hormone balance. There are many different foods that can disrupt the endocrine system so I would start with looking into dietary causes for hormone imbalance.
If a disrupted endocrine system is the cause, MMS may only help if one or several of the endocrine organs have pathogenic issues.
Glypohsate, one of the ingredients in roundup the weed killer, is known to disrupt the endocrine system. Roundup is in the food supply. MMS may help neutralize glyphosate. Other factors may be vaccines and/or medication and xtrogen (xenoestrogen - a synthetic form of estrogen that also is in todays food supply).
I do believe gynocomestia can be reversed, over time, but very unlikely MMS alone will do it. You will have to look into dietary and hormone balancing remedies.
I hope this may help put you on the right track.
How to fix gyno
