Studies have shown that you'd have to eat a whole lotta seeds to have any risk of poisoning. And in this case, we're not eating the seeds, we're simply cooking them in the mixture to get the added benefits of the natural pectin in the apple core. I'm just going to leave you with this article from Pick Your Own: Cyanide, Arsenic, and Other Toxins in Fruit: Facts, Myths, and Old Wive's Tales. Blender Mom also has a really informative post about how Apple Seeds Are Safe. If you're still not sure, Here's How Many Apple Cores It Would Take to Poison You. Again, for this recipe, we're simply cooking the seeds and cores, then straining them out.