Naturally caffeine-free tea
When you drank your cup of tea (or coffee) this morning, did you realize you were drinking a pesticide?
Caffeine, which is the stimulant in coffee and tea that has helped make these drinks so widely popular for centuries, is one of many naturally occurring pesticides. It is found in a wide range of plant species, several of which people consume regularly. This includes tea (Camellia sinensis, family Theaceae), coffee (Coffea spp., family Rubiaceae), cocoa (Theobroma cacao, family Malvaceae), yerba mate (Ilex paraguariensis, family Aquifoliaceae), and guarana (Paullinia cupana, family Sapindaceae). The caffeine in these plants helps to protect them from insects such as butterfly caterpillars. Caffeine can interfere with the insects’ ability to digest food and can cause imbalances in their nervous systems.
Why not for garden pests?
Since caffeine is a naturally occurring insecticide, some gardeners wonder why it isn’t used to protect plants, like other plant-derived organic compounds. For example, pyrethrum is derived from several species of Chrysanthemum (family Asteraceae). And rotenone is found in the seeds and stems of the South American jicama vine (which has a delicious, tuberous root) and several bean species (all in family Fabaceae).
Caffeine is less useful as a pesticide because it can accumulate in the soil. It can build up enough to hinder the growth of the plants it was meant to protect. It is also not selective in its effects, killing both beneficial and harmful insects. Also, caffeine extraction for industrial-level use is generally not cost-effective. One kilogram (2.2 lb) of pure caffeine powder can cost upwards of US $100.
Another well-known pesticide is nicotine, the addictive component in tobacco. Nicotine is not produced just by the tobacco plant, but also occurs in smaller amounts in many other species within the family Solanaceae (nightshades), such as potatoes, tomatoes, eggplants, and peppers. Even though tobacco extracts have been used for centuries as pesticides in home gardens, they are no longer available commercially due to their high toxicity (against plants, pets, and people as well as insects). However, scientists have produced a safer nicotine-free insecticidal tobacco oil by heating tobacco in a vacuum to 500 °C (900 °F).1
Toxins in everything we eat
You may have noticed something in the discussion above. The foods we eat are, surprisingly, ‘full’ of toxic molecules. If you randomly take any naturally occurring chemical in your favourite food, it’s quite likely that it would be toxic in high concentrations. This is why it’s often said, ‘It’s the dose that makes the poison.’2 Caffeine, when consumed in moderate quantities, is a very safe food ingredient, as millions of people across the world, for the past several centuries, can attest.
Caffeine is a stimulant that increases the activity of the brain and nervous system. This is why it is used to help overcome drowsiness. But excess amounts can cause anxiety and palpitations and can make it harder to sleep if consumed late at night. Thus, many prefer at least some of their daily cups of tea or coffee to be decaffeinated.
But removing caffeine from tea or coffee is a complex process. It can be accomplished using solutions of methylene chloride (a potential carcinogen, though much safer than the benzene involved in earlier methods). Ethyl acetate can also be used. This is generally regarded as safe, especially since most organisms produce this compound naturally. The caffeine binds to these chemical agents, leaving most (but not all) of the flavourful molecules behind. Sometimes the flavours and oils extracted in the process can be returned to the tea before the leaves are dried.
Caffeine can also be removed by leaching it from tea leaves under pressure at a temperature of 60 - 70 °C in supercritical3 carbon dioxide or water.
People sometimes find that decaffeinated tea tastes ‘watered down’. This is because the tea does not have its full spectrum of soluble chemicals, which are difficult to reintroduce into the tea leaves. This depends on the decaffeination process used and how much effort was used to preserve the original flavours.
Thus, a naturally occurring caffeine-free tea would likely be appreciated by tea aficionados and could well become a best seller.
A tea plant minus caffeine
A few years ago, The Economist reported that a naturally caffeine-free tea plant had been discovered in Fujian province, China.4 This wild tea plant, called Hongyacha, will require considerable time and effort to breed enough plants to support its commercialization. Tea plants generally require three years to reach maturity. And this particular tea plant will require additional protection, since it has lost some of its natural ability to resist insect infestations.
Another caffeine-free tea plant was already known (the so-called cocoa tea, Camellia ptilophylla), but Hongyacha is interesting for several important reasons. First, a second caffeine-free tea plant gives more economic opportunities for farmers. Second, Hongyacha is a wild variety of the standard tea plant (C. sinensis), meaning we already know much about its cultivation.
The Economist article reports that inspection of Hongyacha’s genetics indicates that the absence of caffeine is the result of a mutation in a gene that codes for the enzyme caffeine synthase, which enables the plant to make caffeine. This means the plant will produce no or minimal caffeine. A similar mutation that causes an absence of the caffeine synthase gene has also been reported in wild coffee.5,6
Another caffeine-free coffee plant, Coffea charrieriana, has a splicing defect in this gene so that theobromine7 is produced instead. Chocolate has this chemical, and it is about five times more toxic (per kg of body weight) to dogs and cats than to humans. This makes it unsafe to give chocolate to your pet, because it may well be fatal.
The Economist claims the Hongyacha tea plant has made an “evolutionary journey towards losing caffeine” (emphases added). As is often the case, mutations which cause defects are referred to in the media and the science literature as evolution. However, in this instance, the genome of the tea plant has lost the ability to produce a protective defence mechanism, so the Hongyacha plant will have greater difficulty surviving in the wild. This is contrary to the evolutionary paradigm, which requires increasing complexity over time.
Also, when God created tea (and coffee) plants, He certainly knew how they might change over time.8 In fact, the design of the caffeine synthesis pathway seems to be such that a plant can undergo many changes with no known detriment to the plant. In the absence of pests, a caffeine-free plant would freely grow in the wild. In other words, God designed a system that can be modified over time, producing abundant diversity with all sorts of interesting economic, medicinal, and other benefits for humans, including sheer enjoyment.
Maybe someday you will be able to enjoy drinking a cup of naturally caffeine-free tea.
References and notes
- American Chemical Society, Tobacco and its evil cousin nicotine are good as a pesticide, 27 Oct 2010, acs.org. Return to text.
- Bergman, J., Understanding poisons from a creationist perspective, J .Creation 11(3):353–360, 1997; creation.com/poison. Return to text.
- At a high enough pressure and temperature, many substances do not have a separate liquid and gas phase. For carbon dioxide, the critical point is reached at 304 K and ~74 atm of pressure. Return to text.
- The Economist, A newly discovered tea plant is caffeine-free, 17 Nov 2018, economist.com. Return to text.
- Raharimalala, E. et al., The absence of the caffeine synthase gene is involved in the naturally decaffeinated status of Coffea humblotiana, a wild species from Comoro archipelago, Scientific Reports 11(1):8119, 2021. Return to text.
- Stoffelen, P. and Noirot, M., A new caffeine-free coffee from Cameroon, Botanical Journal of the Linnean Society 158(1):67–72, 2008. Return to text.
- Theobromine is the same molecule as caffeine, minus one methyl group. Return to text.
- See Carter, R., Species were designed to change, part 1, 1 Jul 2021. Return to text.