Not breastfed as child. is there any way to make up for this with vitamins, supplements, etc. as adult? have always had a compromised immune system

Many vits,mushrooms: Sadly you can't totally make up for it but vitamins A, B complex (esp. B6, B12 & folic acid) C, D, E & K all enhance immune function. Bioflavonoids, minerals like zinc,medicinal mushrooms & colostrum can also help. I recommend the book The Road to Immunity by Kenneth Bock MD for comprehensive info on the use of diet, nutrients, herbs, mind-body techniques & other approaches to boosting immunity.

GET OVER IT: BF infants have benefits in lower incidence of various disorders like diabetes but the primary benefit is during the breast feeding period.It has transient (time limited)immune factors that help keep germs from invading the gut,but these are diluted when eating solid foods and gone after weaning.If your system is compromised, have it evaluated.Supplements have little value unless you are deficient