Are A/D converters with +- voltage supplies always bipolar inputs?

Just a basic question: I want to find an A/D converter to sense +- voltage input (I guess it's bipolar). There are many of these A/D converters out there and I'm not sure which one to pick. To stick with the basic requirement of bipolar sensing, I wonder: If I see an A/D converter that requires +- 5V supplies, does that mean the A/D converter can sense +- 5V as well or not necessarily? Thanks!

Keep it simpler - take your AC signal and AC couple it into a single-supply ADC.

@CrossRoads

Can you place a Zener diode of 5.1 V in your cicuit, parallel to analog in to gnd, cathode at analog pin for protection ?

That only provides protection in one direction.

Thanks CrossRoads. My signal is mostly DC. They have low frequency around 0.1-10Hz. BTW I'll be in Boston later today. Too busy with meeting :(