A Bit about Bitters, Part I

By Erin Holden

From grapefruit to coffee to arugula – lots of plants are bitter. And while some people will cross the street to avoid a bitter veggie, others can’t seem to get enough. Why is this? Join me on a two part journey as I delve into the science and use of one of nature’s most divisive flavors.

The What: How do you define a bitter? If you’re a chemist, they’re structurally unrelated compounds that, well, taste bitter. If you’re an herbalist, bitters are plants that are used for their therapeutic effect on the digestive system. And if you’re a bartender, bitters are aromatic flavoring agents made from various plant parts to enhance the taste of a drink. Based on these definitions it’s easy to see that bitters fulfill many roles in our lives. But why can we taste bitter to begin with?

The Why:Rat poison The main reason plants create bitter compounds boils down to one simple thing: defense. Since plants can’t run and hide from predators, they devised their own chemical defense system – the first instance of chemical warfare, you could say. When an insect bites into, say, a broccoli plant, it gets a mouthful of glucosinolates, sulfur containing compounds that are toxic to insects and rodents, and gross to some people. Plants see us as essentially giant rodents that want to eat them, and create a wide variety of nasty tasting compounds to deter us from doing so. In turn, since some of these compounds not only taste bad but can also kill humans, we evolved taste receptors to detect them, therefore potentially skirting death.

The Where: So, where exactly do we have these taste receptors? I’m sure many of you learned the “flavor map” of the tongue in school, like I did, which outlines where we can detect sweet, sour, salty, and bitter (poor umami got left out on that one). Well I’m here to tell you, that map is bunk! It’s based on the misinterpretation of a graph from 1942, that plotted out areas of relative sensitivity of the tongue to the various flavors. Later on, low areas of sensitivity were mistakenly interpreted as having no sensitivity, leading to the incorrect map we’re all familiar with today. All flavors can be detected across the whole tongue, the back of the roof of the mouth, and the epiglottis. Other research has suggested that while areas of the tongue do show varying levels of sensitivity to the five known flavors, these differences are not significant (Wanjek, 2006).

Taste_buds

Photo Credit: MesserWoland

Having taste receptors on the tongue is no surprise, but you may be surprised to learn bitter receptors have also been found in the brains, airways, gastrointestinal tract, testes, and pancreas of various mammals (including humans). This leads back to WHY? The prevailing hypotheses boil down to the same thing – protection. If our airways are full of bacteria that are producing bitter compounds, our cough response is triggered, so we cough up and expel the offending invader. If an ingested bitter toxin makes its way to our guts, it’ll essentially trip the “abandon ship” alarm, causing our body to purge itself of the potential poison in unpleasant ways.

I’ll stop there with that thought. Keep an eye out for the follow-up, where I’ll talk about the historical uses of bitters, their role in herbal medicine, and mention some specific bitter herbs.

Wanjek, C. 2006. The tongue map: Tasteless myth debunked. Live Science. From Livescience.com. Accessed January 31, 2019. Available from https://www.livescience.com/7113-tongue-map-tasteless-myth-debunked.html on 1/31/2019

Medicinal Disclaimer: It is the policy of The Herb Society of America, Inc. not to advise or recommend herbs for medicinal or health use. This information is intended for educational purposes only and should not be considered as a recommendation or an endorsement of any particular medical or health treatment. Please consult a health care provider before pursuing any herbal treatments.


Erin Holden is the gardener for the National Bonsai and Penjing Museum at the U.S. National Arboretum in Washington, D.C. She is a member of the American Herbalists Guild, United Plant Savers, and a member-at-large of the Herb Society of America.

 

 

 

The Better Part of (Herbal) Wisdom

By Chrissy Moore

Spend any time with me and you’ll learn quickly that I am a “waste not, want not” kind of person, and that includes food. I have been known to push the envelope with expiration dates–tempting fate, if you will–only occasionally experiencing unpleasant consequences. Not that that’s good practice, mind you, but before you cast the first stone, tell me that you have never ever strategically removed that tiny spot of green on that otherwise perfectly good hunk of cheese in your refrigerator! I thought so.

Recently, I was making a pot of soup, the ingredients for which I had purchased the previous weekend in anticipation of the cooking session. When it came time to throw in the fresh spinach, I noticed that some of the leaves looked a bit dodgy, but decided to risk it. Why? Because that’s just what I do in my personal culinary (mis)adventures. What’s the worst that could happen?

Historical advertisement for castor oil laxative

Historical advertisement for castor oil laxative

I didn’t eat the soup that day, but did have a few spoonfuls as part of the tasting/seasoning process. No harm, no foul…well, until later that night. I was starting to feel a wee bit off, but didn’t think much of it until I was going through my nightly ablutions. The gastric distress came on suddenly with little warning, but, admittedly, it wasn’t the worst I had ever experienced. I skated by on that one. Was it the soup? Maybe the spinach was more “mature” than I originally thought. Or maybe it was the seafood I had the previous night at the restaurant. Either way, I wasn’t about to throw out a whole pot of perfectly good soup on circumstantial evidence. So, in the name of science, I made to find out for sure by eating a small amount of soup for dinner the following day and awaited the results.

While lying in bed that night anticipating the tell-tale signs of digestive misgivings, my mind wandered to herbs with strong purgative properties. (Isn’t that what you think about in the middle of the night?) When people tell me something is “natural” or invoke Mother Earth as if she is some benevolent, gentle grandmother, my first reaction is, “Pff! You have seen National Geographic, haven’t you? ‘Mother Earth’ will kill you in a heartbeat!”

Rhamnus_purshiana_-_Köhler–s_Medizinal-Pflanzen-121

Rhamnus purshiana

In that same vein, purgative herbs, such as Rhamnus purshiana (cascara), if not used properly, can produce severe side effects. Castor oil, extracted from the seeds of Ricinus communis, is another purgative remedy known for its unpleasant, though highly-effective laxative properties. As with cascara, castor oil can cause harmful side effects if not used properly. When contemplating herbal remedies, you should always keep in mind–and remind others who may try to sweet-talk you with herbal accolades–that “natural” doesn’t necessarily mean safe or gentle. The proper respect should always be paid to herbs, no matter their use, and it is always the better part of wisdom to consult a professional before tinkering with herbs’ powerful properties.

The same wisdom should probably be applied to dodgy soup, too.

Medicinal Disclaimer: It is the policy of The Herb Society of America, Inc. not to advise or recommend herbs for medicinal or health use. This information is intended for educational purposes only and should not be considered as a recommendation or an endorsement of any particular medical or health treatment. Please consult a health care provider before pursuing any herbal treatments.


Chrissy Moore is the curator of the National Herb Garden at the U.S. National Arboretum in Washington, D.C.  She is a member of the Potomac Unit of The Herb Society of America and is an International Society of Arboriculture certified arborist.