How Can Antioxidants Be Dangerous?

My 13th book, Best Future You, is out!

Over the next several weeks, I’ll be posting excerpts from the book and blogging frequently about the main concept in the book – which is the idea of harnessing your body’s internal cellular biochemistry to achieve true balance in body, mind, and spirit – and in doing so, help you to become your “Best Future You” in terms of how you look, how you feel, and how you perform on every level.

Chapter 3 – Antioxidants are Killing You – by Making Cellular Stress Worse

How Can Antioxidants Be Dangerous?

There is no denying that a range of national nutrition surveys show clearly and convincingly that nutrient inadequacies are widespread in the United States – and that multivitamin supplements can help to “close the nutrient gap” that so many people are failing to attain through diet alone. There are also several large long-term controlled research trials where relatively low doses of balanced/mixed blends of vitamins/minerals/antioxidants have shown certain potential health benefits.

Scientists have known for many years that high doses of isolated nutrients can actually cause more problems than they prevent. Recent examples are beta-carotene in smokers (leading to more lung cancer) and vitamin C in cancer patients (which protects cancer cells more effectively than it does healthy cells). The “take-away” message from such studies is not that antioxidant vitamins are always “bad” – but rather that synthetic, isolated, high-dose antioxidant supplements are bad.

Consider several recent examples in prominent scientific and medical journals, showing that high-dose antioxidant supplements can lead to higher rates of lung cancer with beta-carotene and vitamin A (New England Journal of Medicine, 1996), higher rates of skin cancer with vitamins C & E and the mineral selenium (Journal of Nutrition, 2007), and higher overall mortality (death) rates from a variety of antioxidant vitamins and minerals.

In 1994 the Alpha-Tocopherol, Beta-Carotene (ATBC) Lung Cancer Prevention Study was published in the Annals of Epidemiology – and the results shocked the nutrition and medical communities. ATBC was a very large clinical study of more than 29,000 male smokers aged 50-69 years old designed to investigate the protective effects of vitamin E and beta-carotene on preventing lung cancer and other cancers. Subjects took 50mg/day of vitamin E (alpha-tocopherol), or 20mg/day of beta-carotene, or a combination of both, or a placebo, for an average of 6 years. Results showed no benefit of vitamin E and a significant 16% increase in lung cancer risk with beta-carotene.

In 1996, results of the Beta-Carotene and Retinal Efficacy Trial (named “CARET”) were published in the New England Journal of Medicine (NEJM). CARET involved more than 18,000 smokers, former smokers, and workers exposed to asbestos to investigate the effects of 30mg/day of beta-carotene plus 25,000IU/day of retinol (vitamin A) on the incidence of lung cancer. After an average of 4 years of supplementation, the risk of developing lung cancer was increased 28% with increased death rates from lung cancer (+46%), cardiovascular disease (+26%), or from any other cause (+17%). The results were so dramatic that the researchers (from some of the top universities and cancer research centers in the country) decided to stop the study almost 2 years earlier than planned.

Since those initial studies in the mid-1990s, there have been thousands of research studies on the positive and negative effects of antioxidant supplements – with most of the largest and longest trials coming to the same conclusion that high-doses of isolated unbalanced synthetic antioxidants are increasing risk for cancer, heart disease, and overall mortality (death rates). For example…

  • The “SU.VI.MAX” study (Journal of Nutrition 2007) followed more than 13,000 subjects taking supplements of vitamin C (120mg), vitamin E (30mg), beta-carotene (6mg), selenium (100mcg), and zinc (20mg) for 8 years – finding a 68% increased risk of all types of skin cancer and a risk of melanoma skin cancer that was more than 4-times higher in the antioxidant users.
  • The Iowa Women’s Health Study (Archives of Internal Medicine, 2011), found increased death rates (mortality) in nearly 39,000 women (average age of 62 years old) among users of antioxidants supplements, including multivitamins (+6%), zinc (+8%), and copper (+45%).
  • The SELECT trial (SELenium and vitamin E Cancer prevention Trial) published in 2011 in the Journal of the American Medical Association (JAMA) followed more than 35,000 men from 427 study sites in the USA, Canada, and Puerto Rico over a period of almost 4 years. Subjects took 200mg/day of selenium, or 400IU/day of vitamin E, or both, or a placebo. Subjects supplemented with selenium alone and the combination of vitamin E plus selenium had an increased prostate cancer risk (9% and 5% higher, respectively), which did not reach statistical significance, but vitamin E users had a significant 17% increase in their development of prostate cancer.
  • More than two-dozen recent studies over the last 4-5 years have additionally shown that high-dose antioxidant supplements can actually block many of the healthy adaptations associated with exercise. Regular physical activity is well-known to improve cardiovascular function, enhance insulin signaling (reducing risk for diabetes), accelerate weight loss, reduce blood pressure and cholesterol levels, and increase maximal oxygen uptake – but high levels of antioxidants such as resveratrol (250mgday for 8 weeks), vitamin C (1,000mg/day for 11 weeks), and vitamin E (235mg for 11 weeks) have been shown to blunt these positive effects.

Again and again, we are finding that unbalanced, synthetic, isolated, high-dose supplements fail to keep us healthy and fail to prevent disease (and may actually cause cellular damage that accelerates the disease process in certain cases). This is especially important because more than half of Americans report taking at least one supplement on a regular basis – that’s a lot of vitamin users.

Thanks for reading – tune in for the next installment about how “CDR Activation is the Future of Cellular Protection

Shawn M Talbott, PhD, CNS, LDN, FACSM, FAIS, FACN
Nutritional Biochemist and Author
801-915-1170 (mobile)


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The Secret of Vigor – How to Overcome Burnout, Restore Biochemical Balance, and Reclaim Your Natural Energy
Killer at Large – Why Obesity is America’s Greatest Threat – an award-winning documentary film exploring the causes and solutions underlying the American obesity epidemic
The Cortisol Connection – Why Stress Makes You Fat and Ruins Your Health (Hunter House)
The Cortisol Connection Diet – The Breakthrough Program to Control Stress and Lose Weight (Hunter House)
Cortisol Control and the Beauty Connection – The All-Natural Inside-Out Approach to Reversing Wrinkles, Preventing Acne, And Improving Skin Tone (Hunter House)
Natural Solutions for Pain-Free Living – Lasting Relief for Flexible Joints, Strong Bones and Ache-Free Muscles (Chronicle Publishers – Currant Books)
The Immune Miracle – The All-Natural Approach for Better Health, Increased Energy and Improved Mood (GLH Nutrition, 2012)
A Guide to Understanding Dietary Supplements – an Outstanding Academic Text of 2004 (Haworth Press)
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