Microbes in your food can help or hinder your body’s defenses against cancer – how diet influences the conflict between cell ‘cooperators’ and ‘cheaters’

The microbes living in your food can affect your risk of cancer. While some help your body fight cancer, others help tumors evolve and grow.

Gut microbes can influence your cancer risk by changing how your cells behave. Many cancer-protective microbes support normal, cooperative behavior of cells. Meanwhile, cancer-inducing microbes undermine cellular cooperation and increase your risk of cancer 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 the ways the cells in your body interact with each other and either increase or decrease your risk of cancer.

Cancer is a breakdown of cell cooperation

Every human body is a symphony of multicellular cooperation. Thirty trillion cells cooperate and coordinate with each other to make us viable multicellular organisms.

For multicellular cooperation to work, cells must engage in behaviors that serve the collective. 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 effectively. If genetic mutations interfere with these proper behaviors, they can lead to the breakdown of cellular cooperation and the emergence of cancer.

The food in your diet affects the composition of your gut microbiome.

Cancer cells can be thought of as cellular cheaters because they do not follow the rules of cooperative behavior. They mutate uncontrollably, evade cell death and take up excessive resources at the expense of the other cells. As these cheater cells replicate, cancer in the body begins to grow.

Cancer is fundamentally a problem of having multiple cells living together in one organism. As such, it has been around since the origins of multicellular life. This means that cancer suppression mechanisms have been evolving for hundreds of millions of years to help keep would-be cancer cells in check. Cells monitor themselves for mutations and induce cell death, also known as apoptosis, when necessary. Cells also monitor their neighbors for evidence of abnormal behavior, sending signals to aberrant cells to induce apoptosis. In addition, the body’s immune system monitors tissues for cancer cells to destroy them.

Cells that are able to evade detection, avoid apoptosis and replicate quickly have an evolutionary advantage within the body over cells that behave normally. This process within the body, called somatic evolution, is what leads cancer cells to grow and make people sick.