Photo by Steven Jackson

I recently received an email from one of my close relatives asking about my opinion of turmeric supplements. My reaction was OMG, where do I begin?


Here’s what turmeric advocates say

Here is a typical example of a claim about turmeric, this one from an author who is pushing his own product:

Faithful radiant turmeric users
Faithful happy turmeric users

Turmeric: Doctors say spice is a brain health miracle. Red flag alert when I see such headlines, I think to myself: Who are these “doctors”? What are their credentials? Are they researchers? Did they publish what they are advocating in a peer-reviewed journal? Or are they just selling something?

The article goes on to list the “8 incredible health benefits of turmeric.” Amongst them are the following:

1. It boosts cognitive function. A review of the psychological literature shows exactly zero studies to back up this claim.

2. It fights body-wide inflammation. By which I presume they mean inflammatory diseases like rheumatoid arthritis—not a shred of clinical evidence.

3. It supports cardiovascular function. Supports? What does that mean? Does it increase the heart’s pumping strength? Does it improve the cardiac ejection fraction? Or does it inhibit coronary artery plaque formation? No evidence for any of these important cardiovascular parameters.

4. It promotes youthful and radiant skin. Just look around you? Who looks “youthful and radiant?” Chances are you are looking at someone who is chronologically young, not someone who is ingesting turmeric.

5. It supports joint and muscle health. May I suggest a better way? Try exercise, scientific studies show that it works!

6. It boosts detoxification. Presumably, this implies improved liver function. Any physiology student will tell you that the normal liver capacity to handle “toxins” (or metabolites that need to be neutralized and/or removed from the body) is quite large, reaching 400-500% of all metabolic requirements. In actual fact, 3/4 of the liver can be resected without impacting the liver’s ability to “detoxify” the body.

7. It promotes healthy mood balance. So, what is the right balance? Exactly what is included in the “right balance.” And how do you achieve it? Perhaps a glass of wine might be good alternative.

8. It supports natural weight loss. This, plus diet and exercise, work like a charm. In fact, diet and exercise alone do the trick even if you don’t add turmeric to your diet.

If you peel away the layers of these unsubstantiated assertions, you discover that the underlying assumption is that turmeric (and many other nutritional supplements for that matter) have anti-oxidant activity and such activity is “good for you” because it inhibits the injurious effects of free radicals. So let’s set the record straight.


The antioxidant theory is so 20th century

Advocacy for the antioxidant theory was started in 1954 by a Denham Harman. Here is the Wikipedia on the subject:

“In 1954, between his internship and residency in internal medicine, Harman became a research associate at the Donner Laboratory of Medicalphysics at UC Berkeley, where he was able to pursue the puzzle of the cause of aging. After four months of frustration, he hit upon the idea of free radicals as cause of the damage to macromolecules known as “aging“. Although initially other scientists were reluctant to accept his theory, he was finally able to get it published in what is now a much-cited article in the Journal of Gerontology.”

“After years of frustration over his inability to increase maximum lifespan with antioxidant supplements, Harman came to the conclusion that mitochondria were producing, as well as being damaged by free radicals, but that exogenous antioxidants don’t enter the mitochondria. And that it is mitochondria that determine lifespan. He published his ideas on what he called the ‘mitochondrial theory of aging‘ in the April 1972 issue of the Journal of the American Geriatrics Society”.

I will leave it to the people who look into the Sociology of Science to divine why so many subsequent publications found evidence that antioxidants increase longevity. I guess that much of it is due to relying on in vitro experiments, a particularly risky proposition when dealing with complex organisms as mice and humans. Others may be due to poor controls and other design flaws, and some may be due to simple “data fitting.” In any event, the fad started fading in the 1970’s, at least in the scientific literature but not in the popular culture. As one of those supplement-promoting blogs put it, “Without Dr. Denham Harman’s work, it is unlikely that the nutritional supplement industry would exist, or certainly not as we know it today.” But by the 1970’s, “there wasn’t a robust demonstration that feeding animals antioxidants really had an effect on life span.” Michael Ristow and his colleagues published, in the Proceedings of the National Academy of Sciences, an article titled “Antioxidants Prevent Health-Promoting Effects of Physical Exercise in Humans”. That says it all.


The facts about free radicals

Free radicals, when unchecked, can indeed wreak havoc on the cell’s DNA, proteins, and lipid membranes. But fortunately, evolution noticed this way before human scientists and the supplement industry that began exploiting these findings only recently. Free radicals are generated primarily by processing oxygen in the mitochondria, in a process called oxidative phosphorylation. This process has been in all cells since the advent of aerobic life (we are talking 2.3 billions of years ago!). And, of course, evolution provided enzymes (superoxide dismutase and carbonic anhydrase) the ability to work just fine in neutralizing the free radicals generated by oxidative phosphorylation. No need for outside help, thank you.


If it doesn’t hurt you, why not take it anyway?

Because it may really hurt you!

To understand, we have to understand how natural antioxidants in food work. For instance, chocolate has more than 20 antioxidant flavonoids. One is converted into a free radical and becomes reactive, but less reactive than the first. It then reacts with another, and that one is less reactive and so on and so forth, and all of them react with each other, decreasing the damage that would be happening to our lipids, or proteins or DNA. Sort of a molecular cascade where there is a gradient from the strong to the weaker antioxidants, thereby moderating their effect.

If there is only one type of antioxidant present, say in the case of a high-dose vitamin C supplement, then there are no other antioxidants to provide that protective cascade effect. Then you could end up with a bunch of reactive vitamin C, which itself can cause what they call “antioxidant stress”.

Case in point from the vegetable world; a broccoli floret is a presentation of vitamin C and beta-carotene that the body digests and systemically disperses in a manner more natural and evolved than that of the exact same vitamins presented in tablets and capsules.

Your mother knew what she was talking about when she said:eat you broccoli
Your mother knew what she was talking about when she said, eat your broccoli

Ingestion of supplements charges the body with concentrated vitamin doses lacking the beneficial delivery components that broccoli and other vegetables provide in well-received quantities. The generation and buildup of harmful oxidants are thus more likely to occur.

Is it all academic speculation? What about the real world of medicine? In 2007, JAMA published a systematic review and meta-analysis of 68 clinical trials, which concluded that antioxidant supplements do not reduce risk of death. But that’s not the end of it. When the authors limited their review to the trials that are least likely to be affected by bias, namely randomized double-blind, they found that certain antioxidants were linked to an increased risk of death, in some cases up to 16%!

Bottom line? Eat veggies, exercise to heart’s content—and don’t worry about free radicals. The body takes care of them much better than we could ever do.

Featured Photo Credit: Steven Jackson

Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.


  1. […] Turmeric: The Latest Health Fad – Here is a typical example of a claim about turmeric, this one from an author who is pushing … antioxidant theory was started in 1954 by a Denham Harman. Here is the Wikipedia on the subject: Free radicals, when unchecked, can indeed wreak … […]

  2. […] Turmeric: The Latest Health Fad – Here is a typical example of a claim about turmeric, this one from an author who is pushing … antioxidant theory was started in 1954 by a Denham Harman. Here is the Wikipedia on the subject: Free radicals, when unchecked, can indeed wreak … […]

  3. As soon as you assume the value of curcumin comes only from it’s capacity as an “antioxidant” you show your ignorance. And yes many other “antioxidants” have multiple mechanisms of action as does curcumin. Your article shows you still have a lot to learn so why not start with curcumin. Check out the research being done at MD Anderson on curcumin and cancer for example

  4. This is my experience: Cuts arthritic pain by 30-50% with me, is judged safe by various sources IF you use a high quality product such as “Curamin”. Various other brands had no effect with me.


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