Although very unlikely, it's possible for a retirement IRA account to lose value over time. But this is much more likely to happen if you invest money in single company stock.
To help prevent this, it's important that you diversify your investments where possible. Invest in more than one company - different industries, locations, and sizes - and choose both bonds and stocks.
This way, when one part of your investment doesn't perform, the rest can help keep your overall portfolio on track.