Of course I wanted an A, but it is what it is. This was my FINAL paper for school, so I am happy! It is a boring read for some, but it explores how bitters affect the body and are beneficial to health. It didn’t help that the instructor wrote one of the books required for class AND I was an independent study student with one other student. I was INTIMIDATED! Please take a look.
This paper explores the pharmacology, pharmacokinetics, and energetics, of the bitter taste by examining how herbal phytochemicals act throughout the body from mouth taste and feel, to effects on the gut. This paper summarizes research which provides insight on how bitters affect receptors, organs, and even human perception of the bitter taste.
Keywords: Bitters, receptors, gastrointestinal
The bitter taste is one of the strongest, and for many people, the most undesirable of all flavors picked up by human taste buds. In earlier times, the bitter flavor was often associated with toxins and therefore rejected as a means of survival. Most animal species have an aversion to the bitter taste (Chandrashekar, 2000). Since the research of bitters has expanded, we have learned that bitters could in fact be poisonous, but may also provide a wealth of health benefits. Bitters affect many parts of the body, not just taste buds. How bitters are perceived by the body provides researchers some indication of how they work.
Even though the TAS2R’s are on the tongue, receptor response apart from taste is worth a look. There are 25 taste 2 receptors that have been identified in humans. These are known as TAS2R. These receptors are located in the mouth and make up a specific family within the larger family of G protein-coupled receptors. Even though there are only 25, humans can perceive thousands of compounds as bitter (Meyerhof, 2010). In one study by Meyerof, which was conducted to determine the receptive ranges of human TAS2R taste receptors, researchers used 58 natural bitter compounds which consisted of edible, medicinal, and poisonous plants. These plants contained a range of natural constituents including alkaloids, flavonoids, glycosides, and terpenoids. They also used 46 synthetic bitter compounds which consisted of health, cosmetic, and body care items containing ammonium salts, phenolics, and heterocyclics (Meyerof, 2010).
All of the compounds, both natural and synthetic were administered in different concentrations to the 25 TAS2R receptors. The cells were loaded with calcium indicator and fluorescence emissions in order to record results. Many bitter compounds activated more than one TAS2R receptor. For example, diphenidol stimulated 15 different receptors and caffeine most notably in coffee, stimulated 5 different receptors. Almost half of the compounds administered activated only one receptor, while 19 substances activated four or more receptors. There was an obvious difference between natural and synthetic compounds with 14 natural compounds activating four or more receptors while only five synthetic compounds activated four or more (Myerof, 2010).
Since the bitter taste is often associated with toxins, the body’s natural response is to rid itself of the perceived poison. In a 2011 study, there was a link between plant derived bitter compounds in the mouth, and nausea. The study states that nausea in pregnancy is a positive response because it helps to protect the fetus from poisoning. Nausea then, can help protect others from possible toxicity associated with the ingestion of bitter compounds (Peyrot des Gachons, 2011). The bitter taste begins when the compound enters the mouth where the ligand binds to the 72R G protein coupled receptor (Mennella, 2013).
In the study, 63 healthy people sampled intensely bitter but non-toxic sucrose octoacetate solution. Of those, 20 percent reported being strongly nauseated and 45 percent were mildly nauseated. In order to determine if the nausea was contributed directly to the bitter solution, a different group of subjects tested a similarly intensely bitter solution, this time of quinine hydrocholoride, a natural alkaloid. The same proportion of participants were either intensely or mildly nauseated (Peyrot des Gachons, 2011). This proves that even the taste of bitter can produce strong reactions in the body.
Since many medicinal herbs and pharmaceutical preparations taste bitter, the strong physical reaction can be a problem with attempting to dose patients, especially children. The bitter taste of medicines and herbs are often indication of its pharmacological activity (Mennella et al., 2013) with the more bitter being the most potent.
There is evidence that T2R receptors play a role in the upper and lower airways. In the airways, T2Rs are involved in neurogenic inflammation, the local release of inflammatory mediators (Rosa, 2013) and bacterial clearance. (Devillier, 2015). First, T2R receptors recognize many natural and synthetic compounds which are bitter such as caffeine, chloroquine, and erythromycin. Additionally, T2R’s have effects on the lungs by increasing the beating frequency of cilia on epithelial cells and inducing bronchial and smooth muscle to relax. This may have positive effects on diseases that affect the lungs, such as asthma (Devillier, 2015). The ciliary beating transports mucus which is possibly contains debris to the upper and lower respiratory passages to be cleared by expectoration, sneezing, or swallowing (Lee, 2016). Additionally, sense of smell can play a role in detecting poisons. Inhalation of certain toxins activate T2R receptors causing a change in respiration because of irritation (Finger, 2011). This is another way the body’s innate survival mechanisms play a role to preserve life and health.
Pathogen derived triggers in the respiratory tract include those that humans reported as bitter tasting based on observation. Additional testing determined that in vitro stimulation of human lower airway cultures with bitter tasting compounds increased ciliary beat frequency (Lee, 2016).
“Molecular sensing by gastrointestinal (GI) cells plays a critical role in the control of multiple fundamental functions including digestion, regulation of caloric intake, pancreatic insulin secretion and metabolism, as well as protection from ingested harmful drugs and toxins (Rozengurt, 2007). Rozengurt and his team conducted a study to investigate molecular sensing by the GI tract. There is evidence of similarities between molecular pathways that facilitate taste may also trigger chemical sensing by the GI tract. I believe the chemical “sensing” is just part of what the GI tract was made to do. The bitter taste stimulates the gut to release digestive hormones. This is especially helpful to people suffering from lack of appetite due to illness and effects of treatment for disease such as chemotherapy. Bitters also help the liver detoxify the body by increasing the flow of bile (Hoffman, 2003) and therefore increasing the elimination of toxins.
There are a number of bitter herbs, which through taste then ingestion stimulate the gut into action. They can aid the digestive system in releasing digestive juices, stimulating appetite, regulating pancreatic hormones, even repairing damaged areas of the gut wall (Hoffman, 2003). Some major bitter constituents are monoterpenes, sesquiterpenes (Ganora, 2009), and secoiridoids (Pengelly, 2004).
One of my favorite monoterpenes is Plantago major. Plantain as it is commonly called, is used for all manner of problems including externally and in the GI tract. Plantago major is an anti-inflammatory, and has laxative effects, which along with the tannins it contains make it beneficial to the GI tract by helping to normalize digestive function. Chamomile, both Roman and German, contain sesquiterpenes in their volatile oils. The oils contain bitter principles such as flavonoids, coumarins, and polysaccharides. Chamomile is a milder bitter tonic and helps alleviate gas, bloating, and sluggish bowels (Skenderi, 2003). Gentiana Lutea, commonly called Gentian is intensely bitter. It contains gentiopicrin which is a secoiridoid (Pengelly, 2004). Its bitterness works as a tonic in the GI tract and it has laxative, diuretic, and anti-inflammatory effects. It aids in relieving heartburn, flatulence, minor cramps, and sluggish bowels (Skenderi, 2003). One of the best ways to incorporate bitters is through diet. Nature provides many early spring greens such as dandelion leaves, to help rid the body of the stagnation and toxins built up by rich foods over the winter season. Because of the taste, these foods are often eaten in moderation which is how it should be. The digestive systems’ reaction to bitter is another check and balance. Bitters work to rid the body of possible toxins by stimulating the digestive process. As the process takes place, blood from the digestive organs flow through the liver where the substances in the blood are processed to be used by the body, or filtered from the blood for elimination.
The bitter taste is such an important aspect of human eating and human health. The taste alone sends signals to the body to beware of toxins. This same flavor causes the body to begin to work to rid potential poisons, by stimulating the digestive system to begin secreting gastric juices and the liver to begin bile production. As blood flows from the digestive organs, it is cleaned and detoxified by the liver. In the end, many bitters though tough to swallow, are actually good for you because they stimulate the digestive system and liver to quickly clear toxins, and by keeping those organs active, bitters keep our bodies healthy.
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Hi, welcome to my humble abode! I’m Charlena, wife, mother of two, pet mommy, full-time worker, sporadic crafter, former floral designer, trial and error gardener, future chicken owner, and wanna be farmer. I have a Master’s degree in Therapeutic Herbalism. In between my disjointed, seemingly unrelated posts, I hope to share some of what I’ve learned. Thanks for stopping by!