High quality supplements have higher levels of bioavailability than cheaper, mass produced supplements. Good quality supplements are likely to disintegrate and dissolve more rapidly, enabling digestion to begin earlier. As a test, professional standard supplements should dissolve in a glass of water within 20-30 minutes.
There is a further hurdle to bioavailablity. Nutrients in food and supplements should enter the blood stream via the small intestine. However, stomach acid and some enzymes in the stomach can damage or even destroy certain nutrients. Supplement ingredients need to be wrapped in a special delivery system to provide a protective layer against stomach acids.
Enteric coating is used on many drugs to allow them to effectively reach the small intestine where the alkaline environment allows the tablet to release their vital contents. As a guideline, tablets and supplements with an enteric coating do not have to be taken with meals, whereas non-enteric coated tablets do. As enteric coating is expensive and few people know that it is necessary for bioavailability, manufacturers skip this procedure, particularly on cheaper brands of supplements. Some supplements contain ingredients which are not susceptible to stomach acid, so an enteric coating is not always necessary.