Friends of the National Institute of Dental and Craniofacial Research

Here is a monk's bit of advice: When the urge to spit is unrelenting, it is best to aim downward and not behind oneself to avoid accidentally besmirching one's guardian angel. That seems quite reasonable, given the disrespect that spitting enjoys.

Looking beyond the realm of good manners, biomedical researchers are finding that this bodily secretion offers a mouthful of promising science. Last month, some of these scientists presented their newest work at the Gordon Research Conference and Symposium on Salivary Glands and Saliva in Ventura, Calif.

Lawrence Tabak is the director of the National Institute of Dental and Craniofacial Research, part of the National Institutes of Health. He is also a diabetic, and has pricked his finger more often than he would like to count. He envisions a device so small that it could be integrated into a tooth and would use saliva to monitor his blood sugar level. What sounds perhaps like science fiction is actually a research program involving several universities around the country to develop lab-on-a-chip technology for saliva diagnostic tests.

Got something to hide? Then watch where you spit. Your saliva is a giveaway to all sorts of information on drugs, hormones, disease and more. While a National Institutes of Health initiative aims to expand saliva tests, they already can:

Detect drug use. Lab tests in use by law enforcement agencies and medical institutions can detect alcohol, nicotine and drugs, legal and otherwise. Saliva tests for nicotine and drugs establish only the presence of the drug; alcohol tests also reveal alcohol levels, and are about as accurate as blood tests.
Reveal fertility. MaybeMOM, a home-use salivary ovulation test, in January became the only such product to win clearance from the Food and Drug Administration. The tests, which detect spikes in estrogen, are quick, easy to administer and -- because they are reusable -- cheaper than urine tests. A blood test may be more accurate for women with high estrogen levels; it's also better for checking testosterone, progesterone and other hormone levels.
Monitor chronic disease. Celiac disease, marked by the inability to digest wheat or gluten, can be detected and tracked via saliva, as can hepatitis C. A salivary glucose test under study could help diabetics monitor blood sugar with perhaps fewer daily needlesticks.
Diagnose infection. A salivary test for antibodies to Helicobacter pylori, the bacteria implicated in peptic ulcer and gastric cancer, offers an alternative to blood sampling. Another success, Orasure, is the only oral test approved by the Food and Drug Administration for HIV antibodies. Experts call the lab test 99 percent accurate in testing for HIV-1. It doesn't test for HIV-2.
Assess risk of contaminants. Traces of lead and pesticides turn up in saliva. Tests in development hold promise to rapidly identify individuals in large populations who need treatment. Details: www.pnl.gov.