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Is Caffeine Bad? Its Effects on Animals, the Environment, and Us

Schatzie has bachelor's degrees in animal science and English and a master's in education.

The impact of caffeine

The impact of caffeine

What Is Caffeine?

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 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 or even destroy life.

Then, we must consider how it relates specifically to us, 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 Caffeine 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 to 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-products 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's 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 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, but the drugged nectar also 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 caffeine also has an additional role 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

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 insects to humans.

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 Moment 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 of 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.



Questions & Answers

Question: What effect does caffeine have on the heart rate of a mammal?

Answer: The heart rate goes up.

© 2013 Schatzie Speaks


Carrissa from Somersworth, NH on November 28, 2019:

This is very good information, thank you!

Kenneth Avery from Hamilton, Alabama on September 13, 2019:

Hi, Schatzie . . .oh my goodness. I was roaming through my followers and I saw your smiling face, and then I saw ME because I came to your site a while ago. I apologize for not returning earlier. I have no excuse except I have had a lot of health issues from 2016 through this year. It is the truth. I still love COFFEE. I drink it with a fiery vengeance.

I am so gad that YOU DO too.

So keep it up.

Love your hubs and writing style.

Write me sometime and let us talk about drinking coffee.

NO joke.

Love your success.


Rhea Dixon on August 27, 2019:

I actually came here because my daughter gives coffee to my grandchildren before school, that concerns me as they are 10yrs old and younger. I have learned quite a bit and I thank you! We have a small farm and plan to order some (a little to start) for insect control to see if it will work for that, keeping it where the animals can't access it of course. Will see how that works out I guess and if it does we will order more. And I will show this to my daughter so she can rethink giving coffee to her children!

Schatzie Speaks (author) on August 05, 2019:

Hi Kenneth,

Thank you so much for taking the time to read and comment.

I'm the same. Even after writing this, I still drink coffee. I feel a few cups of it are okay. Probably the amount I had during college was a bad idea, but I survived, barely!

I am sorry to hear you haven't been feeling well. I hope you feel better, very soon!

Kenneth Avery from Hamilton, Alabama on August 05, 2019:

Schatzie: Fantastic piece. I am not a hypocrite, I drink coffee every day and I think that it does help me with the Fibromyalgia in my bones and somehow the oils in the coffee helps them to move.

Honest. I am so sorry that I have not had time to visit with you due to my health problems, but I am doing THIS one with you.


Write me soon.

lenny on February 08, 2018:

good article and very informative!

thank you!

a on January 08, 2018:

will you add something bout plants

jonnycomelately on November 20, 2015:

Schiatzie, thanks for your research.

Being an avid composter, I must now look into the application of spent coffee grounds to compost and worm farms.....not sure what deleterious effects it might have upon earth worms and other soil biota.

lavenderLove from Philippines on May 16, 2015:

I'm a coffee lover and your article is very educating...!!thanks its very informative.

Kristen Howe from Northeast Ohio on May 05, 2015:

This was an interesting hub about caffeine and how it impacted on animal's health and the planet in general. This was also useful to know what it can do too. Voted up!

Sheila Craan from Florida on March 18, 2015:

Coffee is a staple food people love to drink that helps to stimulate brain cells, just as you mentioned in your article. So, why do manufacturers of food input poison in coffee?

Ashley Vailu'u from Central Texas on March 18, 2015:

Your article is incredibly rich in detail, I had no knowledge of petroleum based synthetic caffeine, or its toxicity to certain insects and amphibians! Being a heavy stimulant, I'm not surprised. I am fairly disturbed however, that this information isn't common knowledge. Thank you for sharing!

Kristen Howe from Northeast Ohio on March 11, 2015:

A real interesting hub about caffeine. I drink mostly tea and caffeine free soda. Voted up!

Sheila Craan from Florida on October 25, 2014:

Whenever I drink a cup of coffee, it could be in the morning as well, it keeps me up all night.

Suzie from Carson City on October 25, 2014:

Schatzie.....This is an excellently researched and written hub. You have certainly shared in-depth info about caffeine, much of which I was not aware. Education is always a good thing. Thank you so much.

Being a serious coffee-lover, I can say that this hasn't scared me into giving it up! Not a chance. LOL

I see that you are one of the old-timers here at HP...6 years! I hope to be here at least that long. By scanning your collection of Hubs/Topics, it's clear to see how you have earned your score of 100. Congratulations on your HP success.....UP+++

Larry Rankin from Oklahoma on May 14, 2014:

Very interesting. I don't know why everything natural must eventually be made synthetic in this society. Hasn't anyone read "The Lorax"?:)

As to natural caffeine and its effects, humans have been consuming it a very long time. I think if you don't have pre-existing health problems, consumed in moderation, (not 32 oz energy drinks) it's not that bad.

That being said, if you can, you are probably better off to avoid it, and it bothers me that they don't card for energy drinks.

victor from India on August 12, 2013:

Highly informative hub.

Good caution to coffee lovers.

Maggie Griess from Ontario, Canada on April 09, 2013:

Interesting...I am also a coffee lover. I thought I had stumbled on the perfect insecticide and use for coffee grounds, but then I read on and found it isn't so healthy in the long run for plants. Guess the bugs are safe for now! Great and thought provoking info! No wonder they can't decide if coffee is good or bad!

Schatzie Speaks (author) on March 20, 2013:


Thanks for reading and for the positive feedback. I used to think an organic meal (esp. a vegetarian one!) was a sure safe bet as far as being contaminant free. But now you have to worry about what could be allowed under "organic" labeling. And because the ultimate effects of consuming caffeinated meat and produce depend on the individual and how much exposure they already have to it from other sources in their lives, there's no easy way to determine how much is too much for the population at large. Maybe it's time to start ordering decaf? ;)

Leah Kennedy-Jangraw from Massachusetts on March 18, 2013:

Great hub. Like the other commenters I had no idea about the effects of caffeine on nature, really interesting stuff. And it definitely does make you wonder if it going to be used as a natural pesticide or in other cases an additive to animals we ultimately consume what effects that will have on our already over-caffeinated human population.

I look forward to reading the next installment.

Schatzie Speaks (author) on March 16, 2013:

Hi Careermommy,

Thanks for stopping by and commenting! Most of the information in here was new to me too and only stumbled upon after hours of research and a little blind luck. I sure have my work cut out for me with the next hub, but I'm looking forward to it. Thanks so much for expressing interest in reading it, that will keep me motivated! :)

Schatzie Speaks (author) on March 16, 2013:

Hi torrilynn!

I'm glad you enjoyed the read. I, too, love coffee...probably a little too much...which is what motivated me to discover its real effects. But I had no idea the amount of information out there...all fascinating, and much too interesting not make into a hub. But it sure does take awhile to sift through it all! Luckily I had my coffee to help me stay focused and on-task! :)

Tirralan Watkins from Los Angeles, CA on March 15, 2013:

Wow, that was a lot of information about caffeine. I had know idea about the facts that you shared with regard nature, animals, etc. I know that I drink it too much, so I'm looking forward to seeing how your hub develps further on how caffeine affects humans.

torrilynn on March 15, 2013:

Schatzie Speaks,

thanks for writing about caffeine

I for one am a coffee lover so this hub immediately

brought me in to enjoy discovering new information

thanks for the facts

Voted up and shared