Viral Health Rumors—Fact or Fiction?

False, according to Joshua Grill, PhD, at the Mary S. Easton Center for Alzheimer's Disease Research at UCLA. Risk factors are family history, brain injury, diabetes, heart disease, and, of course, aging.

Earlier this year, a study in the journal Environmental Health suggested that the ubiquitous sweetener high fructose corn syrup (HFCS) contained mercury—at levels high enough to possibly create problems for children and pregnant women. (Mercury can interfere with brain development.) The corn syrup industry's trade association responded, saying that the manufacturing process that introduced mercury into HFCS is no longer used. Hold on, said the Institute for Agriculture and Trade Policy; the process is still in use at four plants around the country. Do you have a headache yet?

Here's our advice: Avoid foods that have large amounts of HFCS (look to see if it's among the first four ingredients), but not because you're worried about mercury. Some products may have traces of the metal, but it's probably not enough to worry about, say some food safety experts. The real problem with HFCS is that we get far too much of it—about 40 pounds a year on average. Get less HFCS and your diet will improve overnight. — Nancy Gottesman

Unlike most e-mail scares, this one has a grain of truth—but there's no need to remodel your kitchen. Radon is a naturally occurring radioactive gas concentrated in soil, water, and rock in various geographic areas, and it can seep into the air we breathe. "All granite emits some radon," says Daniel J. Steck, PhD, a professor of physics at St. John's University in Collegeville, Minnesota, who is conducting research on granite countertops for the Minnesota Radon Project. And radon is the second leading cause of lung cancer, after smoking cigarettes. However, Steck says that countertops emit very low levels of the gas, and the risk to homeowners is tiny. If you're still concerned, you can check air levels with a home test (which costs $15 and up); get information about tests and certified radon technicians in your area at the EPA's Web site, EPA.gov/Radon. — Nancy Gottesman

Keep Reading: The truth about food technology: What's safe, what's not