Many health authorities recommend that adults over 50 years take a daily vitamin B12 supplement, usually in the range of 25100 micrograms per day, and/or consume foods fortified with vitamin B12
Yes, checking blood pressure when lightheaded helps identify orthostatic hypotension
From there, they can invite someone else to join at a discounted rate
Additionally, AHR agonists have been studied for their ability to enhance the immune response against certain pathogens
So there was a couple papers talking about increase included found in the brain
doi:10.1038/s41398-019-0515-5 Paddon-Jones D, Westman E, Mattes RD, Wolfe RR, Astrup A, Westerterp-Plantenga M