At some point during my many years of working in an office, I developed the habit of making a cup of peppermint tea as soon as I got to work every morning.  I’m less consistent when I’m between jobs (as I am now) so I’m not necessarily sitting down at the computer every morning–but peppermint tea is still a frequent beverage for me.

Aside from seeing occasional recommendations of peppermint in healthy-living articles, I haven’t done any research on it until today.  These have been my personal reasons for the peppermint habit:

• It’s not coffee.  I always drink coffee with breakfast, so I don’t really need more caffeine on arrival at the office just an hour or two later, but
• It’s hot.  From autumn through spring, I tend to get cold when I’m sitting basically still (even if I’m balancing on an exercise ball at my desk), and in the summer, offices are air-conditioned to a temperature that’s often too chilly for me.  I need to keep my hands warm for efficient typing!
• It’s hydrating.  Water is your active ingredient, as my father says: Having enough water in your body helps you stay alert, digest your food properly, recover from exercise, and all kinds of good stuff.  I’m always thirsty when I wake up and drink some water right away, but later in the morning it’s easy to get the idea that I feel sluggish because I need more caffeine–when, really, what I need is more water!  This was especially important when making milk.
• It’s peppy.  The flavor of peppermint seems to make me feel more energetic and clear-headed, perhaps literally, as the minty steam penetrates my sinuses.
• It freshens breath–at least somewhat.  If I ate onions or something for breakfast, it’s really best to brush my teeth or chew xylitol gum to remove the odor as well as camouflaging it!  But peppermint tea helps to give me mildly minty breath that doesn’t smell like stale coffee, anyway!

So, my anecdotal experience suggests that a daily cup of peppermint tea is good for me.  What does science say?

Disclaimer: I am not a doctor. My profession is data management for research studies, so I’ve read a lot of scientific papers (and written some) and I know how a research study should be properly conducted. I’ve done my best to report accurately on scientific findings about peppermint tea that I read online, but I am not qualified to give official medical advice.

One of my biggest questions was whether my preference for peppermint tea, over “mint” tea blends that also contain spearmint, is just a matter of flavor or actually relates to beneficial properties unique to peppermint.  Mentha piperita is the scientific name of peppermint, while Mentha spicata is spearmint.

It appears that peppermint does have special benefits, especially where kidney health is concerned.  This study comparing rats who drank water, peppermint tea, and spearmint tea found that spearmint causes nephrotoxic changes (kidney damage) but peppermint does not.

However, peppermint tea decreases iron absorption more than spearmint tea, and both have some effect on the body’s ability to utilize iron.

There’s evidence that peppermint enhances mental peppiness, compared to chamomile tea or plain water.  People who drank peppermint tea experienced short-term increases in long-term memory, speed of memory, and alertness.

Peppermint tea can prevent respiratory tract infections or decrease their severity by killing a common type of respiratory bacteria.  (Note that although “chlamydia” is in the name of the bacteria, this study is about infections of the nose, throat, and lungs–not the sexually transmitted disease called chlamydia.)

Peppermint also kills E. coli O157:H7, the nasty food-poisoning bacteria that cause serious intestinal and kidney damage and can even be fatal.  The research study looked at peppermint oil in the lab, not peppermint tea in human or animal bodies, but the authors suggest that drinking both peppermint and green tea (they found that they work well together against E. coli) could protect people from the worst effects of an E. coli infection.

Laboratory study of peppermint shows that it’s effective against a variety of pathogenic bacteria.  That suggests (but doesn’t prove) that peppermint tea may help you fight off illnesses.

I had no idea that mint affects sex hormones!  Across studies, the basic effect seems to be that mint decreases levels of testosterone and increases levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH).  This means mint is fine for cis women and for transgendered people trying to reduce their testosterone, but it might be a problem for cis men, pubescent boys, or trans people trying to increase testosterone.  However, because FSH and LH are not just for women–they also have roles in sperm production and supporting testosterone production–mint could be a good thing for men hoping to become fathers if they’re not struggling with low testosterone.  Here are some specific findings about mint and sex hormones:

• This study explains the hormonal effects in male rats drinking large amounts of peppermint or spearmint tea.  It emphasizes that mint tea in normal amounts is likely to be safe for men.
• Peppermint reduces symptoms and effects of polycystic ovary syndrome (PCOS) in rats whose PCOS was artificially induced.  The effects were very comprehensive, and the authors seem to think peppermint is promising for humans whose PCOS occurs spontaneously.
• Spearmint tea helps to normalize the hormone levels of women with excessive facial/body hair and women with PCOS.  (These studies didn’t test peppermint.)

Before you panic about emasculating effects of mint, think about dosage!  Even a daily cup of peppermint tea probably won’t make a big difference; the spearmint tea studies used two cups per day.  Drinking mint tea less often, eating a sprig of mint whenever you walk through your garden, using mint toothpaste, or taking peppermint antacid tablets probably won’t make anyone impotent.  But if you’re struggling with low testosterone, it might be worthwhile to go mint-free for a while and see if that helps.

This study suggests that peppermint isn’t so good for people with gastrointestinal reflux, bile duct, or gall bladder problems.  (I don’t have all the details on this because only the abstract of the article is available.)

Gastrointestinal reflux is not the same thing as gastroesophageal reflux disease (GERD), also called “acid reflux” or “heartburn,” a very common digestive problem that affects some people only at certain stages of life, like pregnancy.  This study found that expectant mothers using peppermint experienced relief from GERD symptoms.

Peppermint oil reduces symptoms of irritable bowel syndrome by more than half!  It’s unclear whether peppermint tea would be strong enough to help.

You might want to skip peppermint tea while taking a cyclosporine antibiotic because peppermint oil reduces absorption of cyclosporine.

Overall, a lot of what I found on peppermint in research articles was along the lines of, “many patients reported helpful effects” or, “many midwives recommend that patients try” or, “shows promise as an alternative therapy”–not real hard science documenting the effects of peppermint tea.  That’s a bit frustrating.  On the other hand, the fact that peppermint tea has been “generally regarded as safe” and casually recommended for centuries, without any serious side effects coming to light, suggests that for most people, it’s harmless even if it’s not helpful for your particular health issues.

I recently investigated the science behind another herbal tea I’ve been drinking for years: Rooibos.  Check out what I learned about caffeine-free “red tea” in my article at Kitchen Stewardship!

Happy steamy sipping!  Visit Hearth & Soul for more cozy tips!