While the avocado flesh is nutritious and safe, the seed (pit) contains persin a natural antifungal compound and high levels of tannins. Persin is toxic to certain animals (especially birds and large livestock), though dogs and cats are rarely affected by small amounts. For humans, there is no established safe dosage for consuming the seed. The pit is extremely hard, creating a serious choking hazard and risk of gastrointestinal obstruction if ingested whole or in large fragments. Some trends promote drying and grinding the seed into powder for smoothies, but clinical studies confirming safety are absent. The high tannin content makes the seed unpalatably bitter and may irritate the digestive tract. Until rigorous safety data exists, the seed should be discarded.