If you're talking about American-style bacon, and it tastes like bacon, there's no such thing. They're just exploiting labeling rules by selecting very specific nitrite sources. Nitrites are what give bacon (and ham) its flavor.
<strike>This is before we get to the whole premise of avoiding nitrates. Would you eat a beet? That's a serving of industrial bacon's worth of nitrates right there.</strike>
Later
(Actually, super bad example, since the concern is nitrosamines which are formed in the presence of proteins. The point about the illegitimacy of nitrite-free bacon stands!)
<strike>This is before we get to the whole premise of avoiding nitrates. Would you eat a beet? That's a serving of industrial bacon's worth of nitrates right there.</strike>
Later
(Actually, super bad example, since the concern is nitrosamines which are formed in the presence of proteins. The point about the illegitimacy of nitrite-free bacon stands!)