Goji berries are a plant and anyone trying to live a Paleo lifestyle should be sure to eat lots of plants. Much like other berries in the plant kingdom, goji berries are stocked with plenty of nutrients, most notably calcium, potassium, and vitamin C, as well as numerous phytochemicals.
Science v. the Internet
Goji berries are one of those foods that have been touted by the internet as a superfood to a ridiculous extent. It is highly unlikely, for example, that adding a single fruit to your diet could be responsible for adding two decades to your life. Claims that certain foods can cure cancer are also skeptical, but one published study has shown that goji berries are effective at stemming cancer activity by causing cell death and interfering with cancer cell proliferation.
Paleo and Autoimmune Protocol
Despite their numerous health benefits, goji berries are a member of the nightshade family, so anyone who is sensitive to nightshades should stay away from these berries as well. Although many of us can have all the goji berries and tomatoes we want without a problem, this particular type of plant can cause inflammation and digestive issues in certain individuals. The best way to determine sensitivity is to completely eliminate all nightshades from your diet for at least a month. When you reintroduce them, take careful note of the effect they have on your body. If you feel sick afterwards, you might be better off avoiding them altogether.
If nightshades are safe for you, Mark Sisson did list goji berries as a smart fuel on his blog, although he recommends being wary of outlandish internet claims.