Tolerance to herbs?

Can you build up a tolerance to herbs and begin to need more to get the same results? If so, what is the best way to prevent this?

Also, a manicurist recently commented on how healthy and strong my nails are. Is this more about hydration (maybe from my fish oil supplementation and wearing gloves when I do dishes), or about vitamins (I do take b-complex twice a day)? Or, perhaps, something else?

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