1. Multivitamins do more harm than good. A 20-year study found that women who took multivitamins were 2.4 percent more likely to die of any cause in that period than those who didn't. Folic acid, magnesium, and zinc seemed to shorten subjects' lives, and the more iron women took, the more lethal its effects. Study author Jaakko Mursu says nature built us to get nutrients from whole foods, so the solution is simple: Eat "as many vegetables and as much fruit as you can" and you'll get all the vitamins you need.

2. Liposuction won't make you skinnier, and it's hazardous to your health. Researchers used full-body scans to track the fat distribution in women who had the procedure on their lower abdomens and thighs. Those regions stayed slimmer afterward, but the same amount of fat quickly appeared in their upper abdomens, shoulders, and triceps. "The brain senses a loss of fat and restores it," says study author Robert Eckel. Because liposuction destroys the structures that house fat cells beneath the skin, the fat often reappears deeper in the body, where it can cause heart disease.

3. Household appliances may cause asthma. Pregnant women with the highest exposure to low-frequency electromagnetic fields, or EMFs — which are generated by microwave ovens, vacuum cleaners, hair dryers, and other common electrical devices — were three times as likely to give birth to a child who later developed asthma as those with the lowest exposure, a Kaiser Permanente study found. "The problem with EMF is that you can't see, smell it, you can't touch it," says study author De-Kun Li. But you should strive to "avoid those sources that we know about," especially if you're expecting.

4. Staring at a screen before bed ruins your sleep. A National Sleep Foundation study found that 95 percent of Americans gaze at some kind of light-emitting electronic device — be it a smartphone, tablet, computer, or TV — less than an hour before bed, which keeps the brain from releasing the sleep-inducing hormone melatonin. Young people, the heaviest gadget users, are the drowsiest, and their habit "may have serious consequences" for their health, says study author Lauren Hale. Sleep deprivation causes 100,000 car wrecks and 1,550 traffic deaths per year.

5. Cheering for a losing team could cost you your life. When the Los Angeles Rams lost the Super Bowl in 1980, a new analysis shows, cardiac deaths in L.A. County spiked 15 percent for men and 27 percent for women over the following two weeks. The Rams' victory in the big game four years later had no impact on local health. Many fans see their team as "a family member," says study author Robert Kloner, and become emotionally stressed when it's in trouble. A high-stakes game can increase a passionate fan's pulse rate, raise blood pressure, and potentially "trigger a cardiac event."

6. Commuting can wreck your marriage. A Swedish study found that couples are 40 percent more likely to split up if one partner has a daily commute longer than 45 minutes each way. Millions of Americans endure the known perils of rush hour — like back pain, stress, and obesity — to enjoy life in the suburbs. But that choice "can also be a strain on your relationship," says study author Erika Sandow. A common source of discord is male commuters leaving their wives with a disproportionate share of housekeeping duties.

7. City living, though, can drive you crazy. German researchers scanned the brains of people who live in an urban setting and found that they had more trouble processing everyday stressors than rural folk did. The bigger the urban area a person lived in, the harder his or her amygdala — the region that handles anxiety — had to work to deal with criticism from the researchers. The stress of urban life "might cause these abnormalities," says psychiatrist Andreas Meyer-Lindenberg. "If everyone were born in the country, there would be 30 percent fewer people with schizophrenia."