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SOLNA, Sweden — Taking vitamins or dietary supplements could be feeding tumors and promote their growth, scientists warn. Common antioxidants, such as vitamins A, C, selenium, and zinc, can stimulate the growth of blood vessels in cancer when taken in excess. This discovery surprised researchers, as prior studies have shown antioxidants to be protective. While Swedish scientists state that natural levels of antioxidants in food are safe, taking supplements containing additional antioxidants could fuel tumor growth and allow the disease to spread faster.

The study, conducted by a team at the Karolinska Institutet, concludes that vitamin C and other antioxidants promote the formation of new blood vessels within lung cancer tumors. Study authors suggest that this finding could be applicable to all cancers and their spread.

“We’ve found that antioxidants activate a mechanism that causes cancer tumors to form new blood vessels, which is surprising, since it was previously thought that antioxidants have a protective effect,” says study leader Martin Bergö, professor at the Department of Biosciences and Nutrition and vice president of the Karolinska Institutet in Sweden. “The new blood vessels nourish the tumors and can help them grow and spread.”

Antioxidants neutralize free oxygen radicals, which can damage the body and are commonly found in dietary supplements. However, excessively high doses can be harmful.

“There’s no need to fear antioxidants in normal food but most people don’t need additional amounts of them,” Prof. Bergö adds in a statement. “In fact, it can be harmful for cancer patients and people with an elevated cancer risk.”

Vitamins in fruits and vegetables
Vitamins in fruits and veggies (© airborne77 –

The research team found that antioxidants reduce the levels of free oxygen radicals, but when extra amounts are introduced, the drop in free radicals activates a protein called BACH1. This, in turn, induces the formation of new blood vessels, a process known as angiogenesis.

“Many clinical trials have evaluated the efficacy of angiogenesis inhibitors, but the results have not been as successful as anticipated,” says Ting Wang, doctoral student in Professor Bergö’s group at Karolinska Institutet. “Our study opens the door to more effective ways of preventing angiogenesis in tumors; for example, patients whose tumors exhibit high levels of BACH1 might benefit more from anti-angiogenesis therapy than patients with low BACH1 levels.”

Using lung, breast, and kidney tumors, they found that when BACH1 was activated through ingested antioxidants or by overexpression of the BACH1 gene, more new blood vessels were produced. However, these blood vessels were highly sensitive to angiogenesis inhibitors.

“The next step is to examine in detail how levels of oxygen and free radicals can regulate the BACH1 protein, and we will continue to determine the clinical relevance of our results,” Wang concludes. “We’ll also be doing similar studies in other cancer forms such as breast, kidney and skin cancer.”

The study is published in the Journal of Clinical Investigation.

South West News Service writer Jim Leffman contributed to this report.

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  1. Michael Nelson says:

    Don’t believe it until the study has been replicated.

  2. Louis Veazey says:

    Cancer cells MUST have iron to multiply and grow. Rule number #1 in cancer patients taking multivitamins that are not anemic is to take senior multivitamins (They don’t have iron) instead. Women that have gone through menopause don’t need supplemental iron. Most doctors never tell their cancer patients not to supplement their iron or take regular multivitamins with iron. The likely cause of the increase in cancer is not antioxidants, but rather iron in their vitamins and or several MRNA Covid vaccinations and booster shots that severely weaken most folk’s immune systems.

  3. Tom Dockery says:

    My supplements will allow me to be on the White House lawn with President Barron Trump on Tricentennial Day,July 4,2076 at age 126.That will be 10 years after I toss the coin at Super Bowl 100 in 2066.

    1. RT says:

      Inappropriate and tacky. Must you sow seeds if discontent by politicizing everything.

  4. Archie Walks In The World says:

    Just read this article, what I hear: Stop eating oranges, oysters and no more cod-liver.

    Think this site should be re-named, “Cherry Picker Finds.”

  5. Robert W Tucker says:

    This is a complex issue that will not be resolved by retreating generalized views. The evidence is decent that the same antioxidants for which there is abundant evidence of benefit might also confer harm once certain kinds of tumors are established. It is already well known that antioxidants can reduce the effective of certain crude chemotherapies.

    Today, the evidence favoring supplemental antioxidants is greater than the contrary evidence, but that could change.

    Given what we know today, one must place their bets and remain vigilant. My personal bet is on the pro side because of the demonstrated benefits of antioxidants, polyphenols, etc., derived first from abundant consumption of vegetables, fruits, legumes, healthy fats and, second, from data driven supplementation. Everyone’s decision should be personal.