A vitamin B complex (that includes different forms of B) might be helpful, but I think you've pretty much covered it. I'm adding black cumin seed to my regimen this week myself.

EDIT: Forgot to mention, in addition to all these, I have inadvertently been taking a few OTC items over the years without realizing that they have probably added to my natural immunity. They are a daily powdered aspirin for aches I get from daily gym workouts (I use BC Arthritis Strength 1,000mg).... Meletonin that I use for a sleep aid.... I have always liked the taste of Tonic Water and have one with dinner every night and it contains Quinine...

PLUS!! (and this is very important) eat a healthy diet. Low sugar and salt, leafy green vegetables, fish 2x a week, salads, and healthy protein like tuna, chicken, beef, chick peas, etc.

Good luck, anon.

A vitamin B complex (that includes different forms of B) might be helpful, but I think you've pretty much covered it. I'm adding black cumin seed to my regimen this week myself.