The microbes living in your food can affect your risk of cancer. While some help your body fight cancer, others help tumors grow and grow.
Gut microbes can influence your risk of cancer by changing the behavior of your cells. Many cancer-protecting microbes support the normal, cooperative behavior of cells. Meanwhile, carcinogenic microbes undermine cellular cooperation and increase your cancer risk in the process.
We are evolutionary biologists who study how cooperation and conflict occur inside the human body, including the ways cancer can evolve to exploit the body. Our Systematic review examines how diet and the microbiome affect how your body’s cells interact with each other and increase or decrease your risk of cancer.
Cancer is a breakdown of cellular cooperation
Every human body is a symphony of multicellular cooperation. Thirty trillion cells cooperate and coordinate to make us viable multicellular organisms.
For multicellular cooperation to work, cells must adopt behaviors that serve the community. These include controlled cell division, proper cell death, resource sharing, division of labor, and protection of the extracellular environment. Multicellular cooperation is what allows the body to function efficiently. If genetic mutations interfere with these appropriate behaviors, they can lead to the breakdown of cellular cooperation and the emergence of cancers.
Cancer cells can be considered as cell cheats because they don’t follow the rules of cooperative behavior. They mutate uncontrollably, escape cell death and consume excessive resources at the expense of other cells. As these cheat cells replicate, cancer in the body begins to grow.
Cancer is basically a problem of having multiple cells living together in a single organism. As such it has been around from the origins of multicellular life. This means that cancer suppression mechanisms have evolved over hundreds of millions of years to help control potential cancer cells. Cells themselves monitor for mutations and induce cell death, also known as apoptosis, if necessary. Cells also watch their neighbors for signs of abnormal behavior, sending signals to aberrant cells to induce apoptosis. In addition, the body’s immune system monitors tissues for cancer cells in order to destroy them.
Cells that can evade detection, avoid apoptosis, and replicate rapidly have an evolutionary advantage in the body over normally behaving cells. This process in the body, called somatic evolutionis what leads cancer cells to grow and make people sick.
Microbes can help or hinder cellular cooperation
Microbes can influence cancer risk by changing the way cells in the body interact with each other.
Some microbes can protect against cancer helping to maintain a healthy environment in the gut, reducing inflammation and DNA damage, and even directly limiting tumor growth. Cancer-protective microbes like Lactobacillus pentosus, Lactobacillus gasseri and Bifidobacterium bifidum are found in the environment and in different foods, and can live in the intestine. These microbes promote cooperation between cells and limit cheat cell function by strengthening the body’s defenses against cancer. Lactobacillus acidophilusfor example, increases the production of a protein called IL-12 which stimulates immune cells to act against tumors and suppress their growth.
Other microbes can promote cancer by inducing mutations in healthy cells that make it more likely that cell cheats emerge and overpower cooperative cells. Carcinogenic microbes as Enterococcus faecalis, Helicobacter pylori and Papillomavirus are associated with increased tumor burden and cancer progression. They can release toxins that damage DNA, alter gene expression and increase proliferation of tumor cells. Helicobacter pylorifor example, can induce cancer by secreting a protein called Tipα which can enter cells, alter their gene expression and cause gastric cancer.
Healthy food with cancer protective microbes
Because what you eat determines the amount of carcinogenic and preventative microbes in your body, we believe that the microbes we consume and grow are an important part of a healthy diet.
Beneficial microbes are usually found in fermented and plant-based diets, which include foods like vegetables, fruits, yogurt, and whole grains. These foods are high in nutritional value and contain microbes that increase the immune system’s ability to fight cancer and reduce overall inflammation. Fiber-rich foods are prebiotic in that they provide resources that help beneficial microbes thrive and subsequently provide benefits to their hosts. Many cancer-fighting microbes are abundantly present in fermented, fiber-rich foods.
In contrast, harmful microbes can be found in highly processed and meat-based diets. The Western diet, for example, contains an abundance of red and processed meats, fried foods, and foods high in sugar. It has long been known that meat-based diets are linked to a higher prevalence of cancer and that red meat is a carcinogenic. Studies have shown that meat-based diets are associated with cancer-causing microbes, including Fusobacteria and Peptostreptococcus both in humans and in other species.
Microbes can enhance or interfere with the way cells in the body work together to prevent cancer. We believe that deliberately cultivating a microbiome that promotes cooperation between our cells can help reduce the risk of cancer.