How are water-soluble vitamins absorbed by the body?

Water-soluble vitamins are packed into the watery portions of the foods you eat. They are absorbed directly into the bloodstream as food is broken down during digestion or as a supplement dissolves. Because much of your body consists of water, many of the water-soluble vitamins circulate easily in your body. (One exception is vitamin B6, which is mostly stored in muscle tissue.) Your kidneys continuously regulate levels of water-soluble vitamins, shunting excesses out of the body in your urine.

Contrary to popular belief, some water-soluble vitamins can stay in the body for long periods of time. You probably have several years' supply of vitamin B12 in your liver. And even folic acid and vitamin C stores can last more than a couple of days. Generally, though, water-soluble vitamins should be replenished every few days.