Metformin May Lower Colon Cancer Risk

A low-cost medication, frequently endorsed by podcaster Joe Rogan, might help reduce the risk of colon cancer.

Recent research indicates that metformin—a 20-cent pill designed for managing type 2 diabetes—can decrease the chance of developing this serious disease by as much as 13 percent.

Israeli scientists monitored 31,000 individuals who took metformin for a duration of up to five years.

Those who used the drug for three to five years exhibited a 13 percent lower risk of developing cancer in the sections of the colon most vulnerable to tumors. Meanwhile, taking it for one to three years showed a 10 percent reduction in risk.

The participants were primarily veterans over the age of 50, but researchers believe these findings could extend to broader demographics for colon cancer prevention.

Unmanaged diabetes is a known risk factor for colon cancer, so effectively treating it may lower that risk. However, metformin appears to offer additional benefits, as prior studies have linked it to slower aging and reduced mortality rates.

Joe Rogan, 57, who has not disclosed whether he personally uses metformin, often mentions the medication on his podcast, highlighting its potential longevity benefits with various expert guests.

One of these guests, anti-aging researcher Dr. David Sinclair from Harvard, claimed that metformin could aid in slowing down the aging process. In a discussion with Dr. Sinclair back in 2019, Rogan expressed interest, saying he needed to find a physician willing to prescribe him the drug.

This study was presented at ASCO 2025, one of the largest cancer conferences, held this week in Chicago, Illinois.

While the results are promising, the researchers did not clarify why the medication might offer this protective effect, and they stressed the need for further investigation.

Metformin is a prescription drug approved for type 2 diabetes management. Patients typically take around two pills daily, which can cost around 20 cents each. It is estimated that over 19 million Americans use this medication annually.

Additionally, it is often prescribed off-label for a variety of conditions, including prediabetes and Polycystic Ovary Syndrome, a disorder affecting women with ovarian cysts.

The researchers at The Jusidman Cancer Center in Israel examined patient data from the Veterans Affairs database dating from 1999 to 2020.

They compared metformin users to similar patients who weren’t taking the drug, noting that the latter group generally had poorer health, thus presenting a higher risk for colon cancer.

In the metformin group, most individuals used the medication for at least five years.

The analysis covered tumor location for more than 113,000 participants. Of this number, 13,691 were part of the metformin group—about 9,588, or 70 percent, developed colon cancer on the left side of the colon.

In contrast, roughly 100,000 people made up the non-metformin group, with about 95,000, or 95 percent, developing cancer on the same side of the colon.

The findings were published as an abstract by the American Society of Clinical Oncology and have yet to be fully peer-reviewed. However, previous research has shown similar benefits.

A 2019 study found an eight percent reduction in colorectal cancer linked to metformin use, with a 14 percent decrease in rectal cancer risk. A study from 2024 highlighted changes in HCT116 cells found in colon cancer patients, suggesting that metformin can influence gene expression to suppress colorectal cancer cell growth.

Another recent study indicated that metformin correlates with a significant reduction—around 30 percent—in colon cancer risk, especially among white individuals and those with obesity. Researchers concluded that metformin’s advantages likely extend to populations facing a higher initial risk.