“boosting the immune system” is a marketing term, not a medical term. If you care about your health then have a chat to your doctor and ask them for advice. Supplements are unlikely to give you any health benefits, unless you have a specific deficiency.

The psychology and marketing of supplements is very interesting. They’re easy to take (easier than making behavioural change like diet, sleep or exercise). Pills are seen as something that makes you better, even though the supplements would do the same thing in powder form. They cost a lot so they must be good. They are advertised on TV as being a good thing, in association with imagery of doctors and healthy-looking people.

Ostensibly supplements are designed to be harmless, but that’s not always the case. Vitamin B toxicity on the federal gov’s healthdirect site:

B6 toxicity can occur even at recommended doses