Before being diagnosed with MAC and bronchiecstasis, I was taking nicotinamide mononucleotide (NMN) supplements. It is a natural product, an immune booster by way of DNA repair. Also some evidence of anti-aging AND hair growth. Boby builders have been using it for years. My biochemist daughter researched NMN and its manufacture in depth, recommended MAAC10 brand (for purity), and now our whole family uses it. We all have grown an astonishing new crop of black hair even though we all had medium to light-brown hair when younger. Dose: 50mg per 50 pounds of body weight. I divide dose, first thing in morning, and just before bed on empty stomach. I'm 84 by the way, survivor not only of a serious MAC infection but also of breast and endometrial cancer. I'm convinced NMN has something to do with my still being alive and in surprisingly good health, even without chemo and inhalers and antibiotics (I'm hypersensitive to chemicals). Every body is unique in some respects, so this is NOT a blanket endorsement, but it might be worth it to research on your own.