Semen, also sometimes known as cum, (incorrectly as) sperm, or even boner milk, is as mysterious as dark matter. You heard tons of myths growing up: Being in a hot tub where someone has ejaculated can get you pregnant, Mountain Dew can make you sterile, and so much more.
But how much of this is true and how much of it is gross old wives' tale? I spoke with Abraham Morgentaler, M.D., FACS, the author of The Truth About Men and Sex, associate professor of urology at Harvard Medical School, and the founder of Men's Health Boston, to differentiate seminal fact from fiction.
1. Semen is not the Navy SEAL of bodily fluids.
"Unlike some germs, sperm are not particularly hardy," says Dr. Morgentaler. "They are designed to be deposited very close to where they need to go to create a pregnancy, and quickly die when exposed to heat, cold, changes in pH, drying, and even exposure to plain old water, let alone water treated with chemicals such as in a hot tub." So don't worry about going near hot tubs you think might have semen in them. I mean, you should worry. You should definitely worry. In fact, you should probably rethink your life choices if you find yourself in that situation. But you won't get pregnant. "Stories about sperm impregnating a woman from a hot tub or toilet seat are just that—stories," Dr. Morgentaler assures.
2. Actually, do stay away from hot tub sex though.
"Male fertility can be somewhat delicate. For this reason I tell my male patients interested in fertility to 'live clean and stay cool,'" says Dr. Morgentaler. The "live clean" part refers to drug use—Dr. Morgentaler cites evidence that marijuana, alcohol, and smoking (among other drugs) have been shown to reduce male fertility. The "stay cool" part is literal: Men who soak in hot tubs regularly can have lower sperm counts. ("Showers are alright, by the way," says Dr. Morgentaler.)
But a lot of rumors about what will damage a guy's cum are untrue. "It is safe to use the microwave, exercise, and drink Mountain Dew," says Dr. Morgentaler. So basically, it's OK for a guy to take a shower while chugging Mountain Dew.
3. No, swallowing is not especially good for you.
"Semen does contain protein, as well as sugars that act as an energy source that allows the sperm to swim. However, I don't think we'll be seeing post-workout protein shakes based on semen anytime soon," says Dr. Morgentaler. So, there's no reason to swallow or get a facial other than it's really, really, really, really (really) hot.
4. Eating a bunch of pineapple probably won't make it taste any better.
"Some foods clearly make urine smell differently. The best example is asparagus," says Dr. Morgentaler. "However I'm not aware of any good scientific evidence that foods alter the taste of semen." So don't pressure your partner into eating pineapple or avoiding asparagus right before sex. But Dr. Morgentaler does suggest that "maybe it's time for a placebo-controlled trial?" *Raises hand.*
5. If you're trying to conceive, the struggle will be real if he's on prescription drugs for a large prostate.
"The majority of fluid in the semen comes from a pair of glands called the seminal vesicles, with most of the remainder coming from the prostate," says Dr. Morgentaler. "The volume of ejaculated fluid will be reduced when a man is dehydrated and if he has ejaculated within the previous few hours." Some medications also reduce the amount of fluid, particularly those used to treat symptoms of an enlarged prostate (e.g. frequent or slow urination). And low levels of testosterone can reduce fertility, as well as the amount of semen. Of course, if you're worried about his semen, ask him to see a doctor.
This article originally appeared on Cosmopolitan.com. Minor edits have been made by the Cosmo.ph editors.