Started taking vitamins in my 40is as I got cold after cold after cold. This did make a difference I still got colds but nowhere near as frequently.
I am diabetic type11 and not sure what effect this has although it is kept in check. I am pretty healthy generally but if I catch a cold, I am floored. I am just getting over a cold where I coughed for a couple of days so severely that my ribs hurt and were constantly wheezing and sniffing and blowing etc.etc. This has now passed and its a stuffed up head and coughing occasionally.
I take multi vit, cod liver oil, vit E, probiotic, vit D, B12.
I do not have arthritis thankfully and put that down to the cod liver oil. I suffer a bit with IBS and the probiotic settled that down nicely. Metformin which I take for my diabetes depletes your Vit B12 so that's why I take that.
I have just ordered Beta glucan and astragalus which are supposed to improve your immune system.