When I suggest herbal remedies to potential clients I always hear things like "I tried valerian root! I still can't sleep!" or "I take turmeric capsules religiously and my joints still hurt!" Medicinal herbs can't be treated as your everyday plant. They must be harvested at the correct time (depending if you're using the root or aerial parts of the herb), can't be allowed to reach temperatures over 101 degrees fahrenheit, and absolutely must be organic. Even then taking the herb in any form other than a tincture is going to severely limit the intended effects of the herb.
Herbs are plants and as such every cell in the herb is surrounded by a cell wall. This cell wall is very hard for the human body to break down allowing only a small amount (~15%)(1) of the key constituents (all the good stuff) contained in the herbs to be absorbed. Our tinctures are created by using a process called the percolation method to slowly filter alcohol through a dry powdered herb so that the alcohol draws all of the key constituents out of the herb from inside the cell into the alcohol. This new alcohol solution (tincture) contains a high concentration of the key constituents of the herbs and is very easy for the body to absorb.
(1) Scientific article explaining in detail how the human body breaks down cell walls