Leafy green vegetables, vitamin C tablets, aerobics classes—we all know these very sensible things are good for us and will help us live longer, healthier lives. Our mothers, our doctors, our TV sets continually tell us so. Well, now you can add sex to the list: As several different studies have shown, having an active sex life is not only fun but also good for your health. "I have always believed that keeping your sexual organs healthy helps to stimulate your creativity and concentration and reduces stress," says Ava Cadell, Ph.D., a clinical sex therapist. "But now more and more studies are actually documenting the health aspects of an active sex life."

Remember though, sex is only good for you if it's safe sex. All the benefits mentioned below can easily be erased by an STD.


#1 Immunity Booster

Are you prone to catching colds and influenza? Science says your sex life may help you build immunity to the common cold. According to researchers at Wilkes University in Wilkes-Barre, Pennsylvania, couples who have sex once or twice a week have increased levels of the chemical immunoglobulin A, which protects the body against infections like colds and stomach bugs.


#2 Fountain of Youth

Researchers in Great Britain as well as doctors at the University of Chicago have found that men (only male subjects were studied) who have regular sex live longer. When Michael F. Roizen, M.D., a professor of medicine at the University of Chicago Medical School, and his group of researchers combed over existing studies that looked at men and mortality, they found a correlation between orgasms and death (or delaying death, to be more specific). "The average fifty- to sixty-year-old male has about one orgasm a week," says Dr. Roizen. "Those who had an additional orgasm per week—totaling two a week—lived 1.6 years longer than those who had one per week." And it turns out sex might even keep you younger looking. Researchers at Royal Edinburgh Hospital in Scotland found that randy couples who make love at least three times a week appeared 10 years younger than those who had sex twice a week or less.


#3 Magical Cure

If sex can make you live longer, it would naturally follow that it can help fight off disease. And it does, says Dr. Roizen. His research has concluded that men who have more orgasms are less likely to suffer disability from accidents; are less likely to suffer from heart disease, strokes, or memory loss; and are less likely to die of an infectious disease. No word yet on whether orgasms do the same for women.


#4 Orgasmic Aspirin

Forget using the old headache excuse. Sex, research has shown, is a natural painkiller. During sex, the brain releases endorphins (feel-good chemicals), which ease pain. Studies from Rutgers University have suggested that sex can relieve both headaches and arthritis. And an informal study at Southern Illinois University showed that migraine sufferers who had sex mid-headache experienced some relief from their pain.


#5 PMS Be Gone!

When a woman is cranky, crabby, and ready to kill, a roll in the hay is the last thing on her mind. But, notes Cadell, "Many studies have shown that during sex, women's bodies release the chemical oxytocin, which can help regulate hormone estrogen levels." And since fluctuating hormonal levels may cause PMS stress, sexual intercourse may soothe the symptoms of PMS.


#6 The Happy Pill

People have known for thousands of years that sex makes you feel tingly, energized, mellow, and rejuvenated. Ancient writings about Tantric sex are based in the idea that sexual energy, when harnessed, can be healing and invigorating. And now researchers are backing that up. "That feeling of mellow drowsiness that follows sex is in part due to the rush of blood to all body parts and the release of oxytocin," says Cadell. "The increased circulation and the happy chemical can make you swoon with joy—and also snap your brain into mental-alert mode."


#7 Calorie Burner

The average person burns anywhere from 60 to 155 calories an hour during sex (Health and Fitness Instructors Handbook), and you exercise lots of muscles. Okay, it's not an hour in the gym, but isn't it so much nicer?


#8 Is Celibacy Bad for You?

With all these studies heralding the healthfulness of having sex, you might think that anyone in a dry spell is doomed. Not so, says Dr. Roizen. Many of these studies looked at monogamous couples having intercourse, he notes. "No one has studied whether orgasm through masturbation can have the equivalent effect." Hmm, now there's a study I think we could find numerous volunteers for.