Antibacterial Activity of Roasted Coffee Beans and Caffeine

Updated on July 30, 2017
AliciaC profile image

Linda Crampton is a teacher with an honors degree in biology. She enjoys exploring nutrition as well as the culture and history of food.

Roasted coffee beans seem to have many health benefits.
Roasted coffee beans seem to have many health benefits. | Source

A Potentially Healthy Beverage

Coffee is the beverage of choice for many people, who love its rich taste and aroma and its stimulating effect. The drink has been linked to a number of important health benefits. A new one may soon be added to the list. Researchers have found that under certain conditions roasted coffee beans and caffeine kill or hinder disease-causing bacteria.

Until quite recently, coffee wasn’t considered to be a health food. Coffee drinking was even considered to be a bad habit due to the drawbacks that some people experience. These include restlessness, irritability, inability to sleep, heartburn, stained teeth, and withdrawal symptoms when a person tries to stop drinking coffee. Now researchers are finding that coffee seems to have a variety of health benefits, including reducing the risk of type 2 diabetes, gallstones, liver cancer, Parkinson's disease, and Alzheimer's disease. Antibacterial action could be another great benefit of drinking coffee.

Most research into the antibacterial activities of roasted coffee beans has focused on effects in the mouth and the digestive tract.

This is a stained slide of Streptococcus mutans, the main cause of tooth decay. The bacterium consists of single cells, but the cells may join to form chains.
This is a stained slide of Streptococcus mutans, the main cause of tooth decay. The bacterium consists of single cells, but the cells may join to form chains. | Source

Bacteria in the Mouth

Coffee may prevent the adhesion of Streptococcus mutans to teeth. This bacterium is the leading cause of tooth decay and forms a community called a biofilm on the surface of the teeth. The bacteria in a biofilm are surrounded by a protective coating of polysaccharides. Bacterial biofilms form in other places in the body, too. In the mouth, the film is also known as plaque.

The bacteria in the oral biofilm feed on fermentable carbohydrates that enter and remain in the mouth. As they break down the food they produce acid, which softens and destroys tooth enamel. Saliva has a limited ability to prevent the damage by washing the acid away, neutralizing it, and killing bacteria by enzyme action. Once plaque has formed it must be removed by tooth brushing and dental floss. Once it hardens into tartar (also called calculus), a dental hygienist or dentist has to remove it.

These beautiful red berries are the fruit of a variety of coffee arabica.
These beautiful red berries are the fruit of a variety of coffee arabica. | Source

The seeds inside the red coffee berries, or coffee cherries as they are sometimes known, are pale green. They become yellow after being dried in the sun. When they're roasted they turn brown and become the familiar coffee "beans" that we buy in stores.

Green coffee beans seem to fight bacteria, but most of the relevant research has been done with roasted coffee.
Green coffee beans seem to fight bacteria, but most of the relevant research has been done with roasted coffee. | Source

Coffee and Oral Health

One team of researchers tested different kinds of coffee to see if they could prevent Steptococcus mutans from adhering to simulated teeth. The researchers used hydroxyapatite beads that were coated with saliva in their experiment. Hydroxyapatite is the chief substance in tooth enamel.

The researchers found that both green and roasted coffee prevented the bacteria from sticking to the teeth. Some isolated coffee compounds had the same effect. The scientists think that certain chemicals in coffee bind to the tooth enamel, preventing the bacteria from attaching.

Another group of scientists tested green, roasted, caffeinated, and decaffeinated forms of Arabica coffee (Coffea arabica) and Robusta coffee (Coffea canephora), as well as isolated coffee compounds. They found that specific coffee compounds acting together were bacteriostatic. They didn't kill the bacteria but prevented them from growing and reproducing. The caffeinated coffees did a better job at hindering bacteria than the decaffeinated coffees and the lighter roasts of coffee did a better job than the darker ones. In addition, the researchers found that the caffeinated Robusta coffee prevented bacterial attachment and biofilm formation.

The discoveries described above are very interesting and could be very important as well. Results in a living body may not be the same as those obtained in lab equipment, however.

Coffee is healthiest for teeth without milk or cream, although it can stain teeth.
Coffee is healthiest for teeth without milk or cream, although it can stain teeth. | Source

Black Coffee Without Milk, Cream, or Sugar

It's probably important that coffee is drunk black, without any additives, if a person hopes to experience oral health benefits. Milk and sugar can be harmful to teeth. Sweet or milky coffee drunk slowly is especially dangerous, since the saliva doesn't get a chance to repair any damage to the tooth enamel before it encounters another onslaught of harmful fluid.

One dentist has noticed an increase in tooth decay in people who spend hours in front of a computer screen, slowly sipping sweetened, milky coffee as they work. Even milky coffee without added table sugar (sucrose) can damage tooth enamel if it's drunk over a long period of time, since milk contains other types of sugars. This is the reason for baby bottle syndrome, also called baby bottle tooth decay, which can occur in babies who suck on a bottle of milk for a long time.

Escherichia coli, or E. coli, lives in our large intestine and is helpful. Some strains of E. coli are harmful, however.
Escherichia coli, or E. coli, lives in our large intestine and is helpful. Some strains of E. coli are harmful, however. | Source

Research suggests that coffee may fight some of the harmful bacteria in our digestive tract without harming helpful ones.

Bacteria in the Digestive Tract

Strange as it may sound, the human body contains around ten times more bacteria than human cells. The bacterial population is often referred to as our microbiome. The bacteria in the microbiome live on our skin and inside internal passageways that connect to the outside world, including the respiratory tract and the digestive tract. The greatest number of bacteria reside in our large intestine.

Researchers are discovering that the bacteria in our large intestine have important effects on our lives, many of them beneficial. Depending on the species, they help to digest food, produce vitamins that we need, fight dangerous microbes, reduce inflammation, and boost immunity. They may also help to lower cholesterol and fight obesity. Some researchers say that since the intestinal microbiome is so important it should be thought of as an organ in our body.

The Large Intestine

The greatest number of bacteria in our body live in our large intestine, or colon.
The greatest number of bacteria in our body live in our large intestine, or colon. | Source

Coffee and Intestinal Health

In the lab, coffee has been found to fight Salmonella enterica, a bacterium that causes serious gastrointestinal problems. It also fights other harmful bacteria sometimes found in our digestive tracts, including Serratia marcescens and harmful forms of Escherichia coli. Further research needs to be performed to determine whether these effects are the same inside our intestine.

A small study of sixteen people found that moderate coffee consumption (3 cups a day for 3 weeks) didn't kill the healthy bacteria in the subjects' large intestines and actually promoted the activity of Bifobacteria. Bifobacteria are believed to have beneficial effects on human health. Their role in the intestine isn't known for certain, but they may digest polysaccharides and reduce the numbers of unfriendly bacteria in the gut. Their metabolic activities produce a variety of chemicals, some of which may boost our immune system. Understanding the role of our resident Bifobacteria and their companions is a very important pursuit.

Coffee in Moderation Is Healthy

Researchers have shown that roasted coffee has many other benefits besides fighting bacteria. It's a very interesting beverage.

Moderate Coffee Consumption for Health

The antibacterial effect of roasted coffee on bacteria that infect humans has been confirmed by multiple researchers. The coffee has been tested on bacteria in lab equipment, however. It may have the same effect in our mouths and gastrointestinal tracts, but this isn't known for certain until human tests are performed.

The consensus of most researchers seems to be that moderate consumption of coffee is fine for someone who enjoys the drink and may provide important health benefits, but excess coffee intake should be avoided. The links between coffee and health are exciting, but some caution is needed when drinking coffee. As the video above shows, a survey of a large number of people showed that moderate coffee consumption (2 cups a day) reduced the risk of heart disease, whereas heavy consumption (6 or more cups a day) actually increased the risk of heart disease.

Coffee beans contain many different chemicals. There seem to be several compounds responsible for coffee's antibacterial effects. Their identities and mechanisms of action need to be clarified. Hopefully researchers will soon learn more about these compounds so that they can be extracted, enabling people who dislike coffee or who experience unpleasant results when drinking it to benefit from its protective effects.

References

Questions & Answers

    © 2012 Linda Crampton

    Comments

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      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Thanks, mwilliams66. I knew what you meant!

      • mwilliams66 profile image

        mwilliams66 

        6 years ago from Left Coast, USA

        *referring to myself

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Thank you very much for all the votes, mwilliams66! I appreciate your visit and the comment.

      • mwilliams66 profile image

        mwilliams66 

        6 years ago from Left Coast, USA

        Often referring to as a coffee addict, I am quite happy to hear of it's many benefits.I had recently started drinking coffee with a little milk as I thought it would be better for my gut. After reading your article I think I'll start drinking it black again.

        Voted up, useful, interesting and awesome.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Thank you very much for the comment and the votes, Natashalh. It is great that coffee has some health benefits as well as being nice to drink!

      • Natashalh profile image

        Natasha 

        6 years ago from Hawaii

        This is fascinating information! I love drinking black coffee. Now, when people bug me about it, I can point out some additional healthy benefits. Voted up, useful, and awesome

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Hi, Rolly. It's nice to meet you! Thank you for the comment. I've seen the coffee that you mention in lots of stores here, but I haven't tried it yet. I'm going to, though, now that I'm becoming more interested in coffee drinking. I like the fact that it's both fair trade and organic.

      • Rolly A Chabot profile image

        Rolly A Chabot 

        6 years ago from Alberta Canada

        Hi AliciaC... great article... I love coffee roasted right in your Province called Kicking Horse in the Invermere Valley. Been a coffee fan for years... well written article and one I have bookmarked... Thanks

        Hugs from Alberta

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Hi, Nell. Thanks for the vote and the share! Coffee does have its drawbacks, but I do like its benefits!

      • Nell Rose profile image

        Nell Rose 

        6 years ago from England

        Hi, I knew my cup of coffee was safe! lol! to be honest I love it so much I ignored the bad publicity anyway, but this is great! now I can drink it in moderation and not keep worrying about how bad it is, voted up and shared! nell

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Thank you very much for the comment and the votes, mary615. I must add things to coffee too to dilute the strong taste!

      • mary615 profile image

        Mary Hyatt 

        6 years ago from Florida

        I only drink a half cup every morning, but I must have sugar and creamer in it. This is an excellent Hub on the subject and you did some good research to write it. I vote this UP, etc.etc.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Hi, Scribenet. I wish I could drink my coffee black as you do, but I have to add milk and some type of sugar substitute or I find the coffee too strong and bitter. Thank you for commenting!

      • Scribenet profile image

        Scribenet 

        6 years ago from Ontario, Canada

        This is good news, not that any other bad news has ever affected my coffee consumption. I drink my coffee black, a habit developed to avoid the extra calories of sugar and milk. I have always suspected the beverage isn't all that bad :) now my teeth can be happy except for staining...lol

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Hi, Peggy. I agree with you about drinking coffee (and tea) despite their potential to stain teeth. At least there are things that can be done about coffee stains on teeth, like rinsing the mouth out after drinking coffee, not spending too long drinking a cup of coffee and getting the teeth cleaned by a dental hygienist. The potential health benefits of coffee and tea are too enticing! Thank you very much for the votes and the share, Peggy.

      • Peggy W profile image

        Peggy Woods 

        6 years ago from Houston, Texas

        Fortunately I like my coffee black. I found it interesting in reading your material that lighter coffee is actually better than the darker roasted types as far as being bacteriostatic. Also that caffeinated coffees tested better with regard to fighting bacteria than non-caffeinated. Who cares about my less than glistening white teeth...hey!...I am fighting bacteria with my cups of coffee. Ha!

        Voting this up, interesting and useful + SHARING.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        I wish very much that coffee ice cream would work, drbj! It would be lovely to find out that the ice cream was healthy! Thanks for the visit and comment.

      • drbj profile image

        drbj and sherry 

        6 years ago from south Florida

        So coffee is now healthy for you. Who knew? Thanks for your research and well-written exposition on the subject, Alicia. Now I am better informed. Although I do not particularly like coffee, I do like the taste of coffee ice cream. Will that work?

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Hi, Danette! Thanks for the comment and the votes - I appreciate them both. Milky and sweet coffee is my favourite type too!

      • Danette Watt profile image

        Danette Watt 

        6 years ago from Illinois

        Well, my first thought was, Yay, now I can not feel guilty about my Starbucks mochas I love. But then you mentioned coffee should not be milky and sweet and slowly sipped in front of the computer. Rats! Actually, like you, I enjoy a cup of tea better and only have that one cup of milky, sweet coffee a day.

        I always appreciate your hubs, Alicia, b/c I always learn something. Voted up and interesting.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Hi, Tom. Thanks for visiting and for the votes! It is good to know that drinking coffee gives us some health benefits.

      • kashmir56 profile image

        Thomas Silvia 

        6 years ago from Massachusetts

        Hi Alicia, great hub and very well written and researched. Glad to hear there are some good benefits to drinking coffee, even though i only have one cup a day.

        Vote up and more !!!

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Hi, Golfgal. I'm drinking my morning coffee too! It is a nice way to start the day. Thanks for the comment.

      • Golfgal profile image

        Golfgal 

        6 years ago from McKinney, Texas

        C-O-F-F-E-E, coffee is good enough for me...remember that song in music class? There are a lot of Starbuck lovers out there that are doing high fives at the moment I am on my second cup right now and I attest I am feeling better already. Thanks for reminding us that are vices today could be benefits tomorrow given enough time in the lab and research. Everything in moderation as your hub states is my philosophy too. Salute.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Hi, GoodLady! It is good that coffee has some health benefits so that we can enjoy the drink and know that we are probably doing our body some good at the same time! Thank you very much for the visit and the comment.

      • GoodLady profile image

        Penelope Hart 

        6 years ago from Rome, Italy

        Finally! I don't have to be SO guilty about loving a couple of cups of coffee in the morning,(well I drink mine with a little rice milk, but that can't count, can it?) or about my not-white teeth. Thank you so much for the justifications (research and findings).

        Great Hub!

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Hi, teaches. Yes, unfortunately I hate black coffee but love it when it’s very milky! We should still be getting some of coffee's health benefits, though. I still enjoy tea more than coffee, but I'm starting to like coffee more and more.

      • teaches12345 profile image

        Dianna Mendez 

        6 years ago

        I am an avid coffee drinker, but use a light creamer in my cup (sorry!). I am all for the health benefits of this drink and the wonderful idea of extracting the compounds that make it unfavorable. Great research on this topic and it provides a bit of hope. Voted up.

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