Professors Brian Wharton and Ian Booth, from the Institutes of Child Health in London and Birmingham, warned that in people with vitamin B12 deficiency, consumption of folic acid may mask a condition called megaloblastic anaemia - which if not picked up can lead to degeneration of the spinal cord.

BBC: Caution urged over folic acid

Frequent heartburn or acid reflux are symptoms of a condition called GERD, or gastroesophageal reflux disease, which occurs when a sphincter muscle in the lower esophagus stops working properly.

WSJ: New Surgical Option for Heartburn

For instance, Dannenberg says, Celebrex is being tested in human trials to prevent Barrett's Esophagus, a pre-malignant condition associated with some cases of serious acid reflux (otherwise known as heartburn) that reach up into the esophagus.

FORBES: Magazine Article

Gout, a condition in which the buildup of uric acid in the joints causes pain and swelling, is treated with alopurinol, a drug that prevents the uric acid buildup and has been available in the United States since 1964.

FORBES: Regeneron Announces Strong Results In Gout Study

Gout is a particularly painful condition, consisting of a build-up of uric acid crystals (or urates) in the joints.

FORBES: Gout & About: A Slow Walk Through the Northern Quarter

Doctors can sometimes see the cancer coming years earlier when acid reflux causes cells in the esophagus to mutate to become more like stomach tissue, a condition called Barrett's esophagus.

WSJ: Esophageal Therapy You Can Stomach