'Vanilloids' are found in other plants as well. Imitation Vanilla comes from Pine Bark.
Years ago in Canada one version of Cancer remedy consisted of Cloves and Black-Walnut Hulls - both known for anticarcinogenic effects.
One reason for benefit of Cayenne is that it spcifically triggers one of the glands to function properly - Combine with the the other triggers to get all the glands functioning: Yellow Dock, Echinacea, Garlic, Ginseng {the preceding 4 are the 'YEGG Formula' of Jeanne Rose}, Ginger, Horseradish, Goldenseal or Oregon Grape Root.