Can caffeine kill? How it impacts animals, plants, and the environment.
What is it?
In its pure form, caffeine is an extremely bitter, and to humans, very addictive, powder. Its’ addictive qualities are so strong (and sweeteners/flavorings so greatly improve its taste) that it is, in fact, the most popularly consumed stimulant of the central nervous system in the world (4).
This caffeine-consuming trend is not limited to adults, nor to coffee; up to 98% of youth drink at least one daily caffeinated beverage and more than 30% drink over two (4). These beverages include tea, hot chocolate, sodas, and energy drinks.
Because caffeine is a substance used by the young and old in every country and on every continent its effects affect billions.
In order to better understand these effects we must examine first where and why caffeine exists. We must observe its impact in nature on animals, plants and the environment that reveal the potential ways in which it can change, even destroy, life.
Then, we must consider how it relates specifically to us, at the many pathways it impacts in our bodies once we ingest it, and what these alterations may mean to our health and well-being.
For instance, it makes us more mentally alert; why? It makes us more physically energized; how? And what other aspects of our welfare are improved upon or jeopardized by these same changes?
The debate is ongoing as to whether caffeine is good or bad. It has been linked to and associated with several different things, but often the details of this association are left blank or explained ambiguously.
Without a logical explanation, and one that is backed by science, caffeine’s healthful or harmful impacts remain questionable. So what can be proven; what are the facts? Let’s start with caffeine’s origins and branch out in our analysis from there.
Where does it come from?
Caffeine can either be produced synthetically in a laboratory using petroleum-derived substances or else be extracted from one of the over 60 plants in which it naturally occurs, including the yerba mate, guarana, and ilex guayusa species and, of course, the coffee bean, tea leaf, kola nut, and cocoa bean (7).
Alarmingly to some, regulations do not require companies to specify from which caffeine source their products are derived, only that it is a present ingredient (7). You just may be sipping a little petroleum by-product in your morning java; presently, there's no way for you to really know for sure.
Caffeine in Nature: Animals Harmed
In its natural plant-produced form caffeine functions as a pesticide and inhibits enzymes in herbivorous insects’ nervous systems, triggering paralysis and death in the more susceptible bugs (1,2). Others show enduring reproductive harm (1, 2).
Interestingly, before dying, adult and larval insects develop unusual, unnatural behaviors; for example, the larvae of mosquitoes may lose the ability to swim up to the water’s surface and drown following caffeine exposure (1).
Similar disorientation was observed in experiments with spiders fed caffeine-laced flies, a meal after which the arachnids were incapable of creating symmetrical webs (9).
Caffeine’s potential lethality extends to more than just creepy-crawly insects: When given the option slugs purposefully avoid caffeine dipped roughage and snails exposed to 0.5% caffeine solutions die within days (8). To find out how it kills snails, scientists monitored their heart rate: hearts beat faster at low caffeine concentrations, but at concentrations of 0.1% and above, the caffeine triggered a deadly erratic and slowed pulse (8).
Larger forms of life succumb to the power of caffeine as well. By spraying caffeinated water on coqui frogs, the Hawaiian Department of Agriculture planned to perform mass amphibicide on the nuisance species with drug-induced heart attacks, forever silencing the amphibians’ loud, shriek-like calls (1, 5, 22). Luckily for the frogs, a lack of public support prevented the plan’s actual implementation (22,23).
A post-mortem analysis of another larger animal--a wild parrot--following a 20 gram caffeine-laced meal of dark chocolate showed irreparable damage of its liver, kidneys, and brain neurons (10). A German Shepherd displayed symptoms of overheating, an elevated heart rate, and agitated behavior before dying after it was believed to have consumed a caffeine pill (for dogs the lethal dose is 140 mg caffeine per kilogram body weight) (11).
Them vs Us
While researching the effects of a drug on other animals may prove useful, it is not directly indicative of the human experience; most of these animals have a recognized-as-inferior ability to metabolize caffeine compared to humans (13). While the average person may experience some related symptoms after caffeine ingestion, such as an increase in pulse, these are typically not considered serious or life-threatening.
Where this information could come most in handy is when humans are unusually sensitive to, allergic to, or else over-consuming caffeine so that its ingestion is considered toxic; in this case it may, and has been documented to, negatively impact brain neurons and alter behavior (as in spiders), dramatically change heart and respiratory rates (as in dogs), damage the digestive system (as in parrots), impair the reproductive system (as in insects), and, at times, kill.
Caffeine in Nature: Animals Show Benefits
Lest this analysis be considered one-sided we must also observe the arguably beneficial impacts caffeine has on some animals. For example, its ability to keep its consumer awake and alert, expanding their period of productivity, is a positive effect that has been observed in the chicken.
This is showcased in a study that analyzed the feathers of birds on corporate poultry farms and revealed that the chickens to which they belonged were consuming caffeine (12).
Further inquiry exposed why there were coffee by-product and powdered tea additives in their feed: to discourage sleep and promote alert birds intent on eating for longer periods of time, leading to a plumper product (12).
Chickens are not the only animals to experience a caffeinated pick-me-up; horses display exceptional endurance, jumping ability, and speed after the administration of caffeine, as well as reductions in mental and physical fatigue (17,18). In fact, its ability to stimulate the horse central nervous system and thereby improve performance has rendered caffeine a class 2 and likely result-altering substance by racing authorities, banning its use in competitions (16).
Owners of racing pigeons are similarly forbidden from artificially stimulating bird competitors’ nervous systems, increasing their heart rates, or elevating their blood pressure, landing caffeine on a list of prohibited drugs for organized events (19).
Violations of these guidelines are met with serious consequences; the owner of the winner in the 2008 All American Futurity horse race at Ruidoso Downs found his one million dollar prize in jeopardy when caffeine was found in his horse’s urine and racing pigeon owners are similarly mandated to forfeit all prizes and honors upon the confirmation of a tainted sample from their entrant (16).
The bee experiences post-caffeinating enhancements as well. Unbeknownst to most, the nectar of citrus flowers such as the grapefruit and lemon contains caffeine (14). Studies on bees show that they are statistically much more likely to identify (and stick out their tongues in hopes of getting a taste of) the odor of caffeinated nectar than other nectar types, suggesting a caffeine-influenced improvement in memory (15).
Researchers believe the bee’s brain neurons respond more strongly to stimuli following exposure to caffeine, enhancing their recollection of the encounter and enabling them to later return to the same location in search of more (15). Not only helpful to the bees that can now easily revisit key food sources, the drugged nectar benefits its plants as well and ensures a loyal pollinating force, enabling plants to produce additional fruits or seeds and successfully propagate the next generation (15).
Caffeine in Nature: the Environment
Once produced, caffeine disperses into the environment, where it impacts other plants as well as animals.
Such dispersal is sometimes deadly: researchers applied a 2% caffeine solution to the material surrounding orchid plants and analyzed its effect on the local snail population; only 5% survived (8). Although artificially applied to the substrate in this instance, this phenomenon happens on its own in nature.
For example, in a different but related experiment, scientists who studied the soil around coffee seedlings discovered that it contained elevated levels of caffeine built up from deteriorating leaves and berries on the ground (3, 20). Interestingly, caffeinated soil was found to function not only as a deterrent to approaching would-be assassins, like snails, but also as a protectant of the plant and its immediate surroundings by having antibacterial and antifungal properties (20).
Scientists believe the caffeine has an additional role as well and that, when present in soil, it suppresses the seed germination of weeds (3,20). This would increase the odds of survival for the coffee seedlings as it eliminates the possibility of additional plants growing nearby that would compete for available resources.
However, despite its protection against predators, whether insect, fungal, or bacterial, and despite its ability to prevent weeds and competing growth, caffeinated soil eventually destroys the very plants which produce it and at first thrive because of its production (20).
With the accumulation of degraded leaves and fruits, caffeine in the soil reaches toxic levels, mandating the relocation of coffee plantations to new grounds every ten to twenty-five years or else the death of each and every plant (20).
Caffeine in Agriculture: the Environment
As already described, the Hawaiian government wanted to spray caffeine on frogs as a form of pest control.
However, the permit that had legalized caffeine-based pesticide use and development was suspended after the EPA, spurred by an angry public, stated a need for more information on how non-targeted insects and animals would be affected should the plan be carried out (22).
Groups in protest claimed that caffeine is a known mutagen of bacterial, plant, animal, and human cells and as the EPA itself acknowledged, spraying concentrated mixtures of it into the environment could harm not only insects and animals but also people if it somehow entered into the groundwater supply (22). In a quest to kill an amphibian, the US Department of Agriculture could have poisoned a host of other life forms, from insect to human.
However, the utilization of caffeine as a repellent may still occur. Because most commercially available snail and slug poisons contain ingredients considered dangerous for human consumption and caffeine is labeled a “generally recognized as safe” substance by the FDA, a caffeine-based formula could easily be marketed to farmers and consumers as a natural, organic pest control and applied to cash crops (25).
Furthermore, adding coffee byproducts to soils has been shown to improve the germination of sugar beets and promote growth in cabbage and soybeans and, in Uganda, the application of coffee husk mulch greatly improved banana production (21,26).
Overall impacts of these practices, should they become mainstream, remain unknown.
A Pause to Reflect
One might wonder about the safety of potentially-caffeine-rich honey (from caffeinated bees), poultry (from caffeinated birds), and produce (from caffeinated plants), all which can be considered “organic”, being consumed in addition to the two, three, four, or more caffeinated beverages some individuals drink daily.
On that note, one might wonder too why the synthetically derived caffeine made from petroleum byproducts doesn’t need special labeling and its effects are virtually unknown when this may be the source that some of us are routinely consuming.
Food for thought.