Many people believe that antioxidants like vitamin C are good for their health. These substances are often found in fruits and vegetables, and they’re also sold in supplement form.
Antioxidants are known for fighting off harmful molecules in the body, called free radicals, which can damage cells. Because of this, many assume that taking extra antioxidants can help prevent diseases like cancer.
But a new study from scientists at Karolinska Institutet in Sweden has found something surprising: antioxidants might actually help certain cancer tumors grow and spread. The team, led by Professor Martin Bergö, discovered that these substances could make lung cancer worse instead of better.
The researchers found that antioxidants can activate a protein in the body called BACH1. This protein plays an important role in helping tumors grow. It does this by starting a process called angiogenesis, which means the tumor builds new blood vessels. These vessels bring nutrients and oxygen to the tumor, helping it get bigger and even spread to other parts of the body.
In simple terms, the more antioxidants you take—especially in supplement form—the more likely it is that BACH1 becomes active, which gives the tumor more support to grow.
“More antioxidants mean more fuel for the tumor,” explained Professor Bergö. “While the antioxidants in food are not a concern, taking large amounts in supplements might be dangerous, especially for people who are at risk of developing cancer.”
The study focused mainly on lung cancer, but the researchers also looked at samples from breast and kidney cancers. They noticed the same thing in these tumors: higher levels of BACH1 activity were linked to more blood vessel growth.
These tumors also responded better to cancer treatments that are designed to stop blood vessels from forming. This might help explain why some cancer treatments haven’t worked as well as expected in the past—because they didn’t focus on proteins like BACH1.
One of the researchers, Ting Wang, said that targeting BACH1 could make treatments that block blood vessel growth more successful. “If a tumor has a lot of BACH1, then those treatments could be more effective,” she said.
The research team now plans to study how oxygen levels and free radicals influence BACH1, and whether the same effects happen in other types of cancer. Their goal is to better understand how this protein works and how to create more targeted, effective treatments.
This doesn’t mean that antioxidants are always bad. Fruits and vegetables are still healthy and important parts of a good diet. But the findings suggest that we should be more cautious with antioxidant supplements, especially for people who already have cancer or are at higher risk.
The study was published in the Journal of Clinical Investigation and adds to a growing body of research showing that what we assume is healthy may not always be helpful in every situation. So, the next time you think about taking high doses of vitamin C or other antioxidant pills, it might be a good idea to talk to a doctor—especially if you’re concerned about cancer.
Science is still learning how our bodies react to different substances, and this study reminds us that more isn’t always better.
If you care about cancer, please read studies about vitamin D and bowel cancer, and a cautionary note about peanuts and cancer.
For more health information, please see recent studies about the link between ultra-processed foods and cancer, and everyday foods to ward off pancreatic cancer.
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