I just eat the seeds from whatever "normal-sized serving" of fruit I happen to have--up to once or twice a week; five or six apple or pear seeds, or a peach or apricot pit. At best is may be some sort of "preventative" (like fruit in general), and at worst it's just adding a little variety to my nutrition.
I'll peel the apple seed, or break (hammer) open the pit and eat the seed. Wrap a paper towel around the slimey pits so the hammer doesn't slide off (and that also keeps pit-shards from flying up into someone's eye); which is why apple seeds are nice--so easy to just peel. Chew it up well, and it kinda numbs the mouth a bit. After chewing up the seed, I usually mix that pulp with a bite of the fruit, to help wash the numbness down.
...it's been 30 years, but if I recall correctly:
Laetrile, naturally found in many non-citrus fruit seeds, is a natural chemical that contains cyanide. The laetrile releases its cyanide when the laetrile is metabolized by a cell. The idea is that when the laetrile is broken down by a cell, the released cyanide helps to kill the cell. Since cancer cells metabolize faster than regular cells, it's hoped they will be killed preferentially over normal cells. I think the idea may also be that normal cells are somehow protected against laetrile, so laetrile would release its cyanide mostly in cancer cells.
