[Home | Ester-C® Vitamin C is one of the most widely used vitamin supplements. It first gained attention long ago when sailors discovered that eating limes with vitamin C reduced scurvy. Today, it is best known for its ability to support the immune system and fight off free radicals or unpaired atoms and out-of-control cells, with studies showing fewer reports of decreased wellness and improved immune health.* Promising new research suggests it may even play a role in antioxidant support and promoting heart health.*]