Summertime Series: Summertime Heat
Welcome to our new newsletter series, where we’ll focus on the health challenges of summertime from a clinical perspective.
The health challenges of summer don’t wait around for the first official day of summer, and we hope that this newsletter series proves helpful to you over the coming weeks.
From Thomas Easley, RH
As summer time approaches and temperatures rise, many of us find ourselves grappling with feelings of being overheated. It’s crucial from the outset that we differentiate between the sensation of overheating and the actual physiological state of overheating. The latter can be hazardous, potentially leading to heat strokes and permanent brain damage. This email, however, will focus on the sensation of overheating, not its more dangerous counterpart. The exploration of heat exhaustion and heat stroke will be detailed later in our herbs for summertime series.
Feeling overheated, even with a normal body temperature, is a sensation many people experience. You can ask those who have gone through menopause what feeling hotter while maintaining a normal body temperature feels like. The sensation of heat and cold is mediated by receptors found in our somatosensory system.
The Science Behind Feeling Overheated
The somatosensory system is a remarkable aspect of our nervous system, responsible for detecting a wide range of stimuli such as temperature, pressure, and chemicals. Have you ever wondered how this intricate system converts these stimuli into electrical signals for our brain to comprehend? The answer lies in the unique properties of neurons in the somatosensory system.
These neurons function as individually tuned sensory cells, each specialized in converting specific thermal, mechanical, or chemical stimuli into electrical signals. These signals are then transmitted to the central nervous system, where our brain processes them and generates appropriate responses. Among the key players in this process are the TRP (Transient Receptor Potential) channels, a superfamily of cation channels that act as polymodal molecular sensors.
TRP channels are particularly fascinating because they can detect both temperature changes and various endogenous or exogenous chemicals, including a wide array of plant-derived compounds. But how does this happen?
Image from National Institute for Physiological Sciences.
When plant-derived substances activate TRP channels in the nerve endings of trigeminal or dorsal root ganglion neurons, it leads to the chemesthetic sensations we typically associate with these compounds.
Imagine biting into a chili pepper or a piece of ginger. The sensations of spiciness or pungency are not only due to the taste buds on your tongue (which are packed with sensory chemoreceptors) but also the activation of TRP channels in your somatosensory neurons. These channels respond to the chemical compounds found in these plants, translating them into the familiar sensations we experience.
Our Sensory System and Sour Tastes
Traditional systems of herbal medicine place great emphasis on these sensations or somatic feelings. I believe traditional energetic systems were primarily based on the felt sensations during illness, and in response to herbal medicines. One common energetic pattern in all traditional systems of medicine is that of excessive heat. When we feel hot, we often become agitated, uneasy, and have difficulty relaxing or even sleeping. In many ways, this hot sensation and the resultant stress and irritability can be thought of as a form of sensory processing overwhelm.
In herbal medicine, many cooling remedies chosen for someone experiencing excessive heat are those that affect our sensory system, and impart the sensation of coolness. Most of these cooling remedies have a tart nature to them, often (but not always) due to the presence of organic acids, like citric acid.
When you taste something sour, what you’re actually tasting is acidity. This is typically caused by the presence of hydrogen ions (H+), which come from acids. In the case of sour foods, these are usually citric acid (found in citrus fruits), malic acid (found in apples), or tartaric acid (found in grapes), among others. When these acids contact the taste receptors on your tongue, they cause a reaction that your brain interprets as the sensation of sourness.
This is because taste receptors are proteins that respond to specific chemicals: for sweetness, it’s sugar molecules; for umami, it’s glutamate; for bitterness, it’s a variety of different potential toxins; for saltiness, it’s sodium ions; and for sourness, it’s hydrogen ions.
We taste saltiness because our taste receptors respond to the sodium ions in salt.
The physiological response to the acidic compounds in sour foods is twofold.
- The lowering of pH around our primary cold sensing receptors (TRMP8) with acidic compounds results in a lowered firing threshold – leading to increased sensations of cold.
- When you consume something acidic, your body wants to neutralize that acidity to maintain a stable pH balance. One way it does this is by stimulating your salivary glands to produce more saliva, which is alkaline and helps to neutralize the acid. This increased salivation can give a sensation of refreshment or coolness in the mouth.
I know that sounds complicated, but luckily you don’t need to understand the exact mechanisms to understand the result. For most people, choosing cooling remedies comes intuitively. For instance, on a hot summer day, would you naturally gravitate towards a thick porridge or hearty chili, or would you prefer a tall glass of lemonade or a slice of watermelon? Most would answer lemonade and watermelon – even just thinking about lemonade and watermelon evokes the mental sensation of cooling refreshment to me.
Lemon, Sumac berries and Peach are my favorite cooling remedies!
Lemons and Sumac berries are rich in citric acid, imparting a cooling sensation that’s perfect for transient periods of feeling too hot. Any red sumac berry will work, but please note that the white berry sumac is poisonous. The fresh red berries of sumac, when soaked in water, make a delightfully sour lemon alternative and are a traditional southern remedy for summertime heat.
You don’t have to limit yourself to just lemons and sumac; any tart, acidic fruit makes you feel cooler – just remember that it’s a passing sensation, so sipping a tart drink regularly for hours has more of a cooling effect that eating a piece of tart fruit. I’ll often use an extemporaneous combination of sumac, lemons, limes, and spearmint (which contains menthol that binds directly to TRMP8 receptors and stimulates a cool sensation) to make a big batch of what I call summer chill on days I’m working outside in the heat.
For deeper, more persistent sensations of heat I find Peach to be more effective than sour remedies. Peach fruit and juice are cooling and moistening, offering a combination of sour organic acids and sweet sugars. Peach pit, leaf, and twig also have a mildly sour taste and have traditionally been used as cooling remedies.
While there’s no evidence to suggest that peach lowers body temperature in normal doses, it does affect our nervous system, cellular energy production and vascular system. These effects are probably because peach pit, leaf, and twig contain amygdalin, a cyanogenic glycoside that breaks down and releases minute amounts of cyanide into our body. Before alarm bells ring, note that our body naturally produces cyanide. New research shows that in small, controlled amounts, like that produced by our body, cyanide acts as a gaseous neurotransmitter, affecting our nervous system regulation. That said, consuming excessive amounts of amygdalin can lead to cyanide poisoning, so moderation is key.
I like to use Peach as a fresh pit/leaf/twig tincture 1:2 in 40% alcohol. 5-10 drops is all you need to cool down deep seated heat.
Stay tuned for our next installment in our Summertime series, where we will delve deeper into more health challenges of summertime. Until then, stay cool!