Re: Side effects of herbs.

 Hv, can you talk a little more about tannins? How exactly do they work?

Tannins are antioxidant, which is why tannin sources are frequently added to antioxidant formulas. But they also bind with various compounds including alkaloids, glycosides and many minerals preventing their absorption.

If they can block the effects of other herbs, can they also prevent the absorption of nutrients?

Yes.

For example, if I take amla with acerola, can the amla's tannins negate the benefits of acerola?

If the amla is standardized for tannins then this could be a problem.  But straight amla powder does not have enough tannins to bind everything since tannins also react with other things such as yeasts binding them as well.  So the real problem is with very high tannin sources.