Herbs can be classified based on the continuum hot-warm-neutral-cool-cold. These classes broadly correspond to the physiologic and experiential effects of the herbs. This classification system has been validated by modern science.
A selection of culinary herbs and spices.
Does Your Herb Have a Temperature?
A tremendous range of plants are used in natural healthcare, from culinary herbs and spices like parsley or garlic, to fruits and vegetables such as jujubes, broccoli, or fennel, to obscure species from the far-flung corners of the earth. From the standpoint of natural healthcare, any plant that conveys health benefits can be considered an “herb.”
You’re probably familiar with many of these “herbs,” but you’ve probably never thought about whether they have a “temperature.” In fact, however, many herbal healthcare traditions classify herbs on a temperature continuum:
Hot – Warm – Neutral – Cool - Cold
These categories help to classify herbs in terms of their effect on the body, both experientially and physiologically.
You’ve probably experienced the fact that chili peppers and horseradish are HOT! “Hot” herbs like this are highly stimulating; they raise body temperature, open pores, cause sweating, and if eaten to excess can…get the GI tract moving a bit too fast. Dry ginger and black pepper are additional hot herbs.
Their cousins the “warm” herbs are gently stimulating. They often improve digestion and the circulation of blood and lymph. Examples of warm herbs include allspice, cardamom, nutmeg, and cloves, as well as walnuts, garlic, and safflower. There’s a good reason our ancestors included these in their cooking! Many of these are classic “comfort food” flavors; their gentle warming effect makes us feel cozy and safe. They also improve nutrition by facilitating the digestion, uptake, and circulation of nutrients.
In the middle of the spectrum we have herbs considered “neutral,” having neither a warming nor a cooling effect. Examples include sesame, cannabis/hemp seeds, and barley sprouts.
On the other side of the spectrum, the “cool” herbs are calming and refreshing. Mint is a classic example, but lavender is also cooling, as are cilantro, chrysanthemum, watermelon and violets. These cool herbs soothe the body and calm the mind. They are often mildly anti-inflammatory. From a culinary standpoint, these are the flavors we crave on a hot day.
Last but not least we have the “cold” herbs. Cold herbs are often quite bitter, and they have a powerful anti-inflammatory effect on the body. They lower body temperature, close the pores, and diminish the activity of the GI tract. Bitter melon, andrographis, skullcap, and gardenia are examples of cold herbs. Because they have such a powerful ability to shut down various physiologic processes, it can be unwise to consume large amounts of cold herbs over the long term; for example, it may interfere with proper digestion.
Interestingly, although the classification of herbs by temperature dates back centuries, it has now been validated by modern science. For example, a study1 in 2011 showed that mice would seek a warmer or cooler environment depending on whether they had been fed colder or warmer herbs. Another study2 in 2019 discovered that eating hot or cold herbs would produce quantifiable differences in photon (light) emissions from the body!
It should be noted, however, that “temperature” is a highly simplistic way of thinking about the health effects of herbs. The classification of where any herb falls on the spectrum can be controversial, and may depend on the part of the plant used or the manner in which it has been processed. For example, cinnamon bark is “hot” while cinnamon twig is “warm”; similarly, dry ginger is “hot” while fresh ginger is “warm.” Some herbs even combine hot/warm and cool/cold effects together. In addition, from a formulation standpoint, it would be incorrect to assume that combining hot herbs with cold herbs will produce a neutral formula; on the contrary, the effect of the formula will be much more complex than that.
Cinnamon and ginger are two herbs that can be classified both as hot or warm, depending on the plant part or the preparation.
Nevertheless, “temperature” is a fascinating and useful way to think about herbs and their health benefits. The fact that this system developed centuries ago by multiple cultures around the world has now been validated by modern science proves, yet again, the wisdom of our ancestors and the deep knowledge they developed about the plants they lived with.
Please note: The above is a highly simplified overview of herbal “temperature.” For a deeper understanding, we suggest this article from the Institute for Traditional Medicine.
REFERENCES
- Study on the cold and hot properties of medicinal herbs by thermotropism in mice behavior. Zhao et al, J. Ethnopharmacol., 2011 Feb 16; 133(3):980-5.
- Characterization of the hot and cold medicinal properties of traditional Chinese herbs by spontaneous photon emission ratio of mice. Zhou et al, J. Ethnopharmacol., 2019 Oct 28; 243:112108.
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