What is a Chinese restaurant headache?

Also in this week's column:

• Do lie detector tests really work?
• Is long life related to where you live?
• What cultures don't share Western economic values?

What is a Chinese restaurant headache?

This is the unfortunate name for one of the symptoms of the allergic reaction to monosodium glutamate (MSG). MSG can induce a headache in people who are allergic to it.

The association with Chinese restaurants comes from the fact that MSG is often an ingredient in Chinese food. According to the Mayo Clinic in Rochester, Minnesota, such a headache typically begins within 30 minutes of consuming MSG and consists of dull and constant pain that may be at the front of both sides of the head.

The clinic adds: "The headache typically goes away within 72 hours after eating a food containing MSG."

What is a brain freeze?

Asked by Michael Friesen of Singapore

The "brain freeze" is another name for "the ice cream headache". The causes of this condition are eating ice cream quickly or gulping a cold drink too quickly. Inhaling very cold air can cause a "brain freeze" too.

This particular form of headache is intensely painful. The pain is in the form of sharp, stabbing pain in the forehead, temples, and around the eyes. The pain peaks at about 30 seconds or less after it begins. It is almost always gone in less than two minutes.

Cold material moving across your palate and the back of the throat is what brings on this type of headache. One possible mechanism is that this temporarily alters blood flow in the brain, causing the brief headache.

According to the Mayo Clinic, one of the few good things about an ice cream headache is that it's often gone in the time it would take you to say its medical name - "headache attributed to ingestion or inhalation of a cold stimulus". The clinic adds: "You may be more susceptible to these if you're prone to migraines."

Stephen Juan, Ph.D. is an anthropologist at the University of Sydney. Email your Odd Body questions to s.juan@edfac.usyd.edu.au