VertexLit Blended Particles Only Receive Light On One Side

I'm rather new to Unity, but I'm working on making some fog and smoke effects. I've been using the VertexLit Blended shader for it so far. I need some sort of lit shader because it's a relatively dark environment and I'd like to be able to shine a light on the particles and illuminate them to a lighter grey. The current problem I'm running into is the fact that the particles only seem to receive light from one side. The other side receives the light just fine, illuminating to lighter greys but the other side has no visible change when light is shone on it. Is there something I'm missing or do I need to make a custom shader for something of this sort? Any help is greatly appreciated.