Tag Archive for: microbiome

In the late 1800s/early 1900s, there was a desperate need for researchers to develop medications that could kill bacteria. Pneumonia and diarrhea (conditions that seem quite easy to treat today) were killing people left and right. After years of experiments and studies, manufacturers began mass-producing an antibiotic called penicillin in 1944, a medication that they called the “wonder drug”. 

Antibiotics can clear a vast assortment of bacterial infections, ease symptoms, speed up the recovery process, prevent the spread of ailments from one individual to another, etc. It really is no surprise that physicians were thrilled about this medication and began widely prescribing it even if it wasn’t entirely necessary.

Dangers of the “Wonder Drug”

Despite all of the incredibly healing properties of antibiotics, there is also a lot of damage that they can do as well. For instance, in our bodies, the microbiome in the gut is vital to the food digestion process, breaking down toxic chemicals in the body, and assisting with the regulation of the immune system. When a person consumes antibiotics, however, the gut microbiome can be heavily disrupted, which leads to the over- or underproduction of certain chemicals that are an integral part of the immune system. This imbalance can be quite dangerous, and can actually lead to the development of various cancers. 

Study Linking Antibiotic Use to CRC

In 2022, researchers wanted to see if there was a specific link to antibiotic usage (particularly among younger individuals) and the development of colorectal cancer (CRC). Using census data between the years 2000 to 2011, scientists analyzed 7,903 Scottish individuals who had an official CRC diagnosis, and split them into two comparative groups: 

  • 445 early onset individuals (those who had received a diagnosis at under 50 years) 
  • 7,458 regular onset individuals (those who had received a diagnosis at over 50 years)

While comparing both groups, researchers separately analyzed antibiotic usage to see if there was a positive relationship between increased antibiotic usage and CRC development. 

And what did they find?

Antibiotic usage was associated with an estimated 49% higher risk of CRC in the early onset group compared to a 9% higher risk in the regular onset group. However, a statistically-significant link was not confirmed between the two variables, meaning that a causal relationship cannot be established between antibiotic use and development of CRC. 

Though researchers cannot explicitly define antibiotics as being contributors to CRC or other cancers, there is a link between the two. In terms of moving forward, more research must be conducted on this specific relationship, though researchers and physicians recommend the usual: healthy lifestyle choices to prevent CRC, regardless of antibiotic usage. 


Parker Lynch is a Colorectal Cancer Prevention Intern with the Colon Cancer Foundation.

Cases of colorectal cancer (CRC) are increasing among young people at an alarming rate, prompting the recommended age for screening to be lowered to 45 years. While several risk factors for developing CRC have already been identified, a surprising one has recently been linked to bad breath.

A recent study has shed light on a specific oral organism that may be responsible for CRC. Fusobacterium nucleatum (Fn), a bacterium normally found in the human oral cavity and rarely in the lower gastrointestinal tract of healthy individuals, is found in high concentrations in CRC tumors. High levels of Fn within the tumor have been associated with higher rates of recurrence, metastasis, and poor patient prognosis.

The study examined approximately 200 CRC tumors and collected stool samples from 1,246 individuals in a case-control study. Two distinct subspecies of Fn bacteria were identified: Fna C1 and Fna C2. Of these two, Fna C2 was found to dominate the CRC tumors and provide protection against cancer-fighting drugs. This means that patients with high levels of Fna C2 in the gastrointestinal tract have a worse prognosis and do not respond well to treatment, resulting in an increased risk of recurrence. Fna C2 was present in 50% of the CRC tumors analyzed in the study. Interestingly, Fna C2 is able to withstand high levels of stomach acid, allowing it to travel from the oral cavity through the stomach, while Fna C1 is limited to the oral cavity.

Researchers worldwide are only beginning to scratch the surface of understanding cancer and developing effective treatments. However, this study provides valuable insight into the connection between oral health and CRC, potentially leading to the development of antibiotics specifically designed to target these bacteria at an early stage, thereby preventing CRC or improving treatment outcomes. In the meantime, the best approach is to maintain proper oral hygiene and regularly visit the dentist to prevent CRC.


Emmanuel Olaniyan is a Colorectal Cancer Prevention Intern with the Colon Cancer Foundation.

By Emmanuel Olaniyan

Colorectal cancer (CRC) is one of the more common types of cancer and is the third largest cause of cancer-related deaths worldwide. According to the American Cancer Society, 153,020 new cases of CRC are expected to be detected throughout the U.S. in 2023, out of which 52,550 people will die from the disease. Considering these figures, it is important to raise public awareness about CRC in order to decrease the number of CRC-related deaths and new cases.

Several studies have researched the causes of CRC, and age, diet, genetics, and the gut microbiota have all been identified as risk factors in various ways. The gut microbiome, in particular, has been shown to play an important role in a number of diseases, and research has begun to focus heavily on its role in CRC. 

What is the Gut Microbiome?

The human gut microbiota refers to the trillions of microbes, such as bacteria, viruses, fungi, and others present in the human digestive tract. The microbiome is the environment they live in. Most microbes in the body are beneficial, but they may become harmful when out of balance.

The gut microbiota is crucial for the overall functioning of a healthy digestive system because it supports the absorption of energy from digested food, guards against pathogens, controls immunological response, and fortifies biochemical barriers of the intestine. However, when harmful bacteria enter the gastrointestinal tract through eating contaminated food or drinking contaminated water and cause infection, all of these advantageous activities could be disrupted.

Jaeho Kim and Heung Kyu Lee published a study in 2022 that found a strong association between gut microbiota and CRC. They came to the conclusion that the patients with CRC experienced dysbiosis (an imbalance in bacterial composition, changes in bacterial metabolic activities, or changes in bacteria distribution within the gut) more frequently than healthy individuals. Opportunistic infections were discovered to be more prevalent, and intestinal inflammation has been shown to be reduced along with the percentage of bacteria that produce butyrate, which is an essential component of our digestive system that reduces inflammation in the digestive tract, protects the brain and prevents cancer.

How Can We Maintain a Healthy Gut Microbiome?

Maintaining good hygiene and being mindful of the foods we eat can help keep our gut microbiota healthy. Studies have shown that eating more processed foods and a low intake of dietary fiber increase the risk of CRC. For this reason, it is recommended to consume fermented foods like cheese, soy sauce, vinegar, and yogurt as well as meals high in fiber like whole grains. It has been established that the bacteria present in these fermented foods are similar to those linked to gastrointestinal health. 

Finally, a decrease in processed food consumption and antibiotic use lowers the risk of developing CRC caused by gut microbes. 


Emmanuel Olaniyan is a Colorectal Cancer Prevention Intern with the Colon Cancer Foundation.

Image source: OpenClipart-Vectors from Pixabay

By Parker Lynch

According to a study published in Cancer Biology & Medicine, the role of intestinal bacteria in the development of colorectal cancer (CRC) has been receiving a lot of attention in recent years. Various bacteria such as Fusobacterium nucleatum, Escherichia coli, Bacteroides fragilis, Enterococcus faecalis, and Salmonella sp., have been known to cause DNA damage. Additionally, these bacteria also help tumor cells evade the body’s immune response, creating a pro-inflammatory environment. The DNA damage and other hindrances upon one’s immune system and bodily function have been associated with the development and progression of CRC.

These bacteria can be useful biomarkers for CRC. Additionally, progress is being made in developing effective antibacterial therapies, which could prove useful in the treatment of CRC.

Parker Lynch is a Colorectal Cancer Prevention Intern with the Colon Cancer Foundation.

Diet has been recognized as an important modifiable risk factor for colorectal cancer (CRC). In particular, diets consisting of high fats and carbohydrates, such as red and processed meats, are considered high-risk. Now, a large-scale cohort study among U.S. residents has revealed that high consumption of ultra-processed foods might increase CRC risk in men—the third most diagnosed cancer in the U.S.. 

For the past two decades, researchers have witnessed a significant increase in the consumption of ultra-processed foods, industrial ready-to-eat or ready-to-heat products high in refined sugars, refined starch, and trans fats. Ultra-processed foods currently contribute to 57% of the total daily calories consumed by American adults. A growing pool of evidence suggests that ultra-processed foods increase CRC risk by altering the composition and diversity of gut microbiota and increasing the risk of obesity.  Some examples of these foods include bread and rolls, breakfast bars and cereals, hotdogs and other processed meats, packaged sweet snacks and desserts, jams and jellies, and condiments, among other things.

The above-mentioned study analyzed responses from over 200,000 participants—159,907 women from the Nurses’ Health Study (1986-2015) and 46,341 men from the Health Professionals Follow-up Study (1986-2014)—across three large prospective studies in the U.S. that assessed dietary intake. The follow-up period was between 24-28 years. At the time of study enrollment, none of the participants had any cancer diagnoses. Information on dietary intake, demographic characteristics, lifestyle factors, and medical conditions of the participants was obtained through food frequency questionnaires every four years. 

Of the 206,000 participants who were followed for more than 25 years, the research team documented 1,294 cases of CRC among men and 1,922 cases among women. The study findings indicated that those who consumed the highest amount of ultra-processed foods had a 29% higher risk of CRC compared to those with the lowest consumption. However, this was not observed among women. Among women, the risk of CRC was positively associated with higher consumption of ready-to-eat or ready-to-heat mixed dishes. In contrast, higher consumption of yogurt and dairy-based desserts was linked to a reduced risk of CRC among women. 

These findings support the importance of limiting certain types of ultra-processed foods for better health outcomes. Here are some additional resources on diet and lifestyle and how they can influence your colon health and overall wellness:

  1. Healthy Inside and Out: How Diet and Lifestyle Impact Colorectal Cancer
  2. Dietary Mindfulness Can Reduce the Risk of Colorectal Cancer
  3. Diet and Nutrition to Prevent Colon Cancer


Kitty Chiu is a Colorectal Cancer Prevention Intern with the Colon Cancer Foundation.

Image credit: Tim Toomey on Unsplash