Researchers from the Oregon Health & Science University School of Dentistry are doing their part to banish the needle from your doctor’s office. They find that many of the medically significant proteins present in blood samples can also be found in a more readily accessible bodily fluid: spit.
Phillip Wilmarth and colleagues knew these compounds were in saliva since all mouths—even the most periodontally perfect—leak blood and their proteins at the gum line. The problem was distinguishing these substances from the panoply of other chemicals in the mouth. Using a sensitive analytical technique called liquid chromatography, Wilmarth identified 67 key proteins, more than seven times as many as previous experiments achieved. “This is far short of the 800 to 1,600 proteins identified in blood serum,” he says, “but it has narrowed the gap.”
Spit tests have the potential to be easier, cheaper, and safer than blood analysis. Patients can collect their own sample by licking a strip or spitting in a cup; health-care providers needn’t get near infected blood; and saliva doesn’t require refrigeration. A variety of commercial saliva-based tests have already been spurred by the fact that hormones and drug metabolites also pass through the salivary glands. The Department of Transportation recently approved a test that measures alcohol levels, and several companies sell one that measures a woman’s fertility. For now, however, doctors still understand blood chemistry much better than they do spit, Wilmarth says. “Hopefully, our results will stimulate other researchers and pharmaceutical companies to take saliva more seriously.”