Fenugreek, primarily, but the zapper helps, too. The zapper does seem to inhibit or break down fenugreek, though. For feces odor, the zapper helps most there.
You don't need much fenugreek. If you take a lot, you'll smell like curry. Even a little will change your smell, but not undesirably, in my opinion. Fenugreek is powerful enough for me that I don't even need any kind of deodorant besides fenugreek. I'm still waiting for someone to be convinced by this enough to try it, since I'm the only one in the world I know who uses fenugreek for deodorant. It's really a powerful herb.
I used to use those crystal rock things made of mineral salts until I discovered that the minerals they're made out of are entirely a mineral compound that includes aluminum. I thought they were supposed to be aluminum-free. They're not aluminum-compound-free. So, I had to find something else. I was coincidentally taking fenugreek (for no apparent reason that I remember other than that it might be healthy) about the time I stopped, and eventually discovered this. At first, I thought it was zinc taking away the smell, but it was fenugreek.
I'm not sure how fenugreek gets into your skin so thoroughly from eating it, but it sure does. It was a miracle for me.