Economics is the key. Most health supplement "formulae", or health supplements, are based on basic biological discoveries that have been made publicly. They require little research and development compared to pharmaceuticals. Manufacturers have little to lose in terms of reputation and class action litigation if they don't incur the costs.
Further fragmentation of the market was caused by the advent of complementary medicine. While standard supplements like vitamins and minerals are well-proven in our natural diets; herbal remedies often lack scientific support. If they did, the compound would be isolated and marketed as such. You can also browse online for more information about supplement manufacturers.
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These two developments almost conspired for the death of omega-3 fish oils. These soft gels, which contain oil purified from deep-sea fish like tuna and hoki, are, as the name implies, a condiment. However, the price is prohibitive. These soft gels fall under the category of dietary supplements. Their main benefit is the treatment of a nutritional deficit, namely omega-3 fatty acids such as DHA or EPA.
Omega-3 deficiencies are now well understood, particularly in terms of chronic inflammation and cardiovascular risk. The next time you go to the store looking for "bottles of pure health", or what the condescending ads seem to suggest, be a discerning buyer.
Only use molecularly extracted fish oils with DHA. They have a faint sea-breeze scent when they are popped. You can even search online for more information about supplement manufacturing companies.