Do Antioxidants Prevent Heart Disease and Cancer

Do you take antioxidants to prevent heart disease and cancer? 

Millions of people do. Antioxidants such as Vitamin C, Vitamin E, selenium, beta-carotene, coenzyme Q-10, among several others, are among the most common supplements I see on my patient’s medication records. The typical reasons for taking antioxidants are promoting health, slow aging, and preventing heart disease and cancer.

But do they really work?



The Antioxidant Story

The story of antioxidants makes a lot of sense. Our normal metabolism creates potentially dangerous substances called free radicals. We can also be exposed to free radicals from toxins like cigarette smoke, excessive sun exposure, and pollution.

The problem with free radicals is that they can cause cell damage (called oxidative stress), leading to health problems like heart disease, dementia, diabetes, and cancer.

Antioxidants are potentially helpful because they have been shown in laboratory studies to neutralize free radicals. Also, many healthy foods like vegetables, fruits, nuts, and berries are high in antioxidants. This information led to the idea that antioxidant supplements could help prevent heart disease and cancer.


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Early in my medical career, the antioxidant idea was trendy among physicians based on some early observational studies that were promising. During my Mayo Clinic training, I was blessed to have some of the brightest physicians in medicine as teachers. And several of them regularly recommended antioxidants to their patients, such as Vitamin E, Vitamin C, Coenzyme Q-10, and resveratrol.

However, physicians know that observational studies are not strong science. They can be wrong because there are too many variables that can change the outcome that aren’t controlled. We have also learned many times that logical ideas about how the body works don’t always prove correct in real life.

Therefore, to truly test the idea that antioxidants promoted better health, we needed well-designed research studies to know for sure.

The results were a surprise to many.


Antioxidant Research

Dozens of randomized trials looking at the antioxidants have now been completed. A few examples include:

  • A study of over 14,000 male physicians found no difference in prostate cancer or other cancers in those taking vitamin C and E.
  • A study of over 35,000 men showed selenium had no effect and vitamin E increased prostate cancer.
  • A study of over 39,000 women showed no effect on heart disease or cancer in those taking vitamin E.
  • A study of over 8,000 women showed no difference in developing diabetes in those taking vitamin C, vitamin E, and beta-carotene.
  • A study of over 29,000 male smokers showed no difference in lung cancer with Vitamin E but an INCREASE in lung cancer in those taking beta-carotene.




Are antioxidants effective in preventing heart disease?

Despite the promise, higher-quality studies have not shown any benefit to taking antioxidant supplements, and in some cases, they have resulted in harm.

The full story of antioxidants is not known yet. Although the evidence is solid that vitamin C, vitamin E, and beta-carotene do NOT improve health outcomes (and in the case of beta-carotene and vitamin E, maybe increase risk), there are still several unknowns about antioxidants.

Would other antioxidants be effective? Are we giving the right dose to the right people?

Until we have those answers, here is my advice for my patients about antioxidants:

  • Get your antioxidants from real food. There is magic in real food we can’t create in a pill.
  • Be wary of health claims for antioxidant supplements. Be especially wary when the claims come from those who financially benefit from you taking supplements.
  • There are proven ways to dramatically lower your heart disease and cancer risk. They just don’t come in a pill. The remarkable health-promoting benefits of regular physical activity, eating nutritious food, getting adequate sleep, avoiding toxins such as tobacco and excess alcohol are proven.

If you are taking antioxidant supplements or considering it, I recommend talking to your doctor to understand the risks and benefits for you.

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