Therefore, after curcumin is ingested in the body, it is difficult for the gastrointestinal tract to absorb, metabolize and quickly remove from the body. Consuming curcumin in foods rich in lecithin, such as eggs, vegetable oil, and buttermilk, may help increase its absorption through the gut. Studies combining curcumin with piperine, the natural ingredient of black pepper, have shown that because piperine slows the metabolism of curcumin, it increases curcumin levels by a factor of 20.