The Downside of Curcumin Supplements

Supplement manufacturers often fall into the same reductionist trap as the drug companies. Herbs are assumed to have only one main active ingredient, so, as the thinking goes, if you can isolate and purify it into a pill, you can boost its effects. Curcumin is described as the active ingredient in turmeric, but is it the active ingredient or just an active ingredient? It is just one of many different components—more than 300, in fact—of the whole food spice.

“Only limited studies have compared the potential of turmeric with curcumin.” Some, however, suggest turmeric, the whole food, may work even better—and not just against colon cancer cells. As I discuss in my video Turmeric or Curcumin: Plants vs. Pills, researchers at the Anderson Cancer Center in Texas pitted both curcumin and turmeric against seven different types of human cancer cells in vitro.

The study found that curcumin kicks tush against breast cancer cells, but turmeric, the whole food, kicks even more. In addition to breast cancer, the researchers found that turmeric was more potent compared to curcumin against pancreatic cancer, colon cancer, multiple myeloma, myelogenous leukemia, and colorectal cancer cells, “suggesting that components other than curcumin can also contribute to anti-cancer activities.”

Most clinical studies treating diseases in people have used curcumin supplements, as opposed to turmeric, but none has tried using turmeric components other than curcumin, even though curcumin-free turmeric exhibits anti-inflammatory and anticancer activities.

“Although curcumin is believed to account for most activities of turmeric, research over the past decade has indicated that curcumin-free turmeric”—that is, turmeric with the so-called active ingredient removed—“is as effective as or even more effective than curcumin-containing turmeric.” There are turmerones, for example, in turmeric, which may exhibit both anticancer activities, as well as anti-inflammatory activities, but these turmerones are processed out of curcumin supplements. So, I assumed this review would conclude by stating we should stop giving people curcumin supplements and instead just give them the whole food spice turmeric, but instead the researchers proposed that we make all sorts of different turmeric-derived supplements!


That’s quite a rebut to reductionism. For more on this flawed nutritional philosophy, see my video Reductionism and the Deficiency Mentality.

Similar videos in this vein include:

Interested in learning more about turmeric and cancer? See:

And for more on turmeric and everything else:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Health Benefits of Citrus Zest

New data demonstrating a DNA protective agent present in at least some fruits and vegetables found that the agent was heat sensitive and determined it was not vitamin C. This was confirmed in a study that tried vitamin C directly and found no effect on DNA protection or repair of DNA strand breaks.

If not vitamin C, what could the DNA protective agent be? The carotenoid beta-cryptoxanthin, found primarily in citrus, seems to be at least one candidate, as I discuss in my video Citrus Peels and Cancer: Zest for Life? If you expose cells to a mutagenic chemical, you can cause physical breaks in the strands of DNA. However, in less than an hour, our DNA repair enzymes can weld most of our DNA back together. What happens if we add some of that citrus phytonutrient? We can effectively double the speed at which DNA is repaired. But, this was determined in a petri dish. What about in a person?

In one study, subjects drank a glass of orange juice and their blood was drawn two hours later. The DNA damage induced with an oxidizing chemical dropped, whereas if they had just had something like orange Kool-Aid instead of orange juice, it didn’t help.

So, do people who eat more fruit walk around with less DNA damage? Yes, particularly women. Does this actually translate into lower cancer rates? It appears so: Citrus alone is associated with a 10 percent reduction in odds of breast cancer.

Given to newly diagnosed breast cancer patients, citrus phytonutrients were found to concentrate in breast tissue, though many complained of “citrus burps” due to the concentrated extract they were given. So, researchers evaluated topical application as an alternative dosing strategy, recruiting women to apply orange-flavored massage oil to their breasts daily. This request was met with excellent compliance, but it didn’t work. We actually have to eat, not wear, our food. 

Why not just take carotenoid supplements to boost our DNA repair? Because it doesn’t work. Although dietary supplements did not provoke any alteration in DNA repair, dietary supplementation with carrots did. This suggests that “the whole food may be important in modulating DNA repair processes…”

Though orange juice consumption was found protective against childhood leukemia, it was not found protective against skin cancer. “However, the most striking feature was the protection purported by citrus peel consumption” . Just drinking orange juice may increase the risk of the most serious type of skin cancer. Daily consumption was associated with a 60 percent increase in risk. So, again, better to stick with the whole fruit. We can eat citrus extra-whole by zesting some of the peel into our dishes.


Now you know why my favorite citrus fruit is kumquat—because you can eat the peel and all!

For other foods that may keep our DNA intact, see my Which Fruits and Vegetables Boost DNA Repair? video. Kiwifruit (Kiwifruit and DNA Repair), broccoli (DNA Protection from Broccoli), and spices (Spicing Up DNA Protection) may also fit the bill.

Interested in learning more about citrus? Check out:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Should Cancer Patients Avoid Raw Fruits and Vegetables?

Back in the 1960s, a patient isolator unit was developed for cancer patients undergoing chemotherapy. Because our immune system cells were often caught in the friendly fire, up to 50% of cancer patients died of infections before they could even complete the chemo because their immune systems had become so compromised. So, a bubble boy-like contraption was developed. The patient was shaved, dipped in disinfectant, rinsed off with alcohol, rubbed with antibiotic ointment into every orifice, and placed on a rotating regimen of a dozen of the most powerful antibiotics they had. Procedures were performed through plastic sleeves on the sides of the unit, and everything in and out had to be sterilized and passed through airlocks. So, the patient wasn’t allowed any fresh fruits or vegetables.

People went crazy cooped up in these bubble-like units, with 38% even experiencing hallucinations. Fifteen years later the results were in: it simply didn’t work. People were still dying at the same rate, so the whole thing was scrapped—except the diet. The airlocks and alcohol baths were abandoned, but they continued to make sure no one got to eat a salad.

Neutrophils are white blood cells that serve as our front line of defense. When we’re immunocompromised and don’t have enough neutrophils, we’re called “neutropenic.” So, the chemotherapy patients were put on a so-called neutropenic diet without any fresh fruits and vegetables. The problem is there’s a glaring lack of evidence that such a neutropenic diet actually helps (see my video Is a Neutropenic Diet Necessary for Cancer Patients?).

Ironically, the neutropenic diet is the one remaining component of those patient isolator unit protocols that’s still practiced, yet it has the least evidence supporting its use. Why? The rationale is: there are bacteria in salads, bacteria cause infections, immunocompromised patients are at increased risk for infections, and therefore, no salad. What’s more, they were actually glad there aren’t any studies on this because it could be way too risky to give a cancer patient an apple or something. So, its continued use seems to be based on a ‘‘better safe than sorry’’ philosophy.

The problem is that kids diagnosed with cancer are already low in dietary antioxidants, so the last thing we should do is tell them they can’t have any fresh fruit or veggies. In addition to the lack of clinical evidence for this neutropenic diet, there may be some drawbacks. Restricting fruits and vegetables may even increase the risk of infection and compromise their nutritional status.

So, are neutropenic diets for cancer patients “reasonable prudence” or “clinical superstition”? Starting in the 1990s, there was a resurgence of research when greater importance was placed on the need to “support clinical practice with evidence.”

What a concept!

Three randomized controlled trials were published, and not one supported the neutropenic diet. In the biggest study, an all-cooked diet was compared to one that allowed raw fruits and veggies, and there was no difference in infection and death rates. As a result of the study, the principal investigator at the MD Anderson Cancer Center described how their practice has changed and now everyone is allowed to eat their vegetables—a far cry from “please don’t eat the salads” 31 years earlier. 

Today, neither the Food and Drug Administration, the Centers for Disease Control and Prevention, nor the American Cancer Society support the neutropenic diet. The real danger comes from pathogenic food-poisoning bacteria like Campylobacter, Salmonella, and E. coli. So we still have to keep patients away from risky foods like undercooked eggs, meat, dairy, and sprouts. At this point, though, there really shouldn’t be a debate about whether cancer patients should be on a neutropenic diet. Nevertheless, many institutions still tell cancer patients they shouldn’t eat fresh fruits and veggies. According to the latest survey, more than half of pediatric cancer doctors continue to prescribe these diets, though it’s quite variable even among those at the same institution.

Why are doctors still reluctant to move away from the neutropenic diet? There are several reasons why physicians may be hesitant to incorporate evidence-based medicine into their practices. They may have limited time to review the literature. They’d like to dig deep into studies, but simply don’t have the time to look at the evidence. Hmm, if only there was a website… 🙂

Bone marrow transplants are the final frontier. Sometimes it’s our immune system itself that is cancerous, such as in leukemia or lymphoma. In these cases, the immune system is wiped out on purpose to rebuild it from scratch. So, inherent in the procedure is a profound immunodeficiency for which a neutropenic diet is often recommended. This has also had never been tested—until now.

Not only did it not work, a strict neutropenic diet was actually associated with an increased risk for infection, maybe because you don’t get the good bugs from fruits and vegetables crowding out the bad guys in the gut. So not only was the neutropenic diet found to be unbeneficial; there was a suggestion that it has the potential to be harmful. This wouldn’t be the first time an intervention strategy made good sense theoretically, but, when put to the test, was ultimately ineffective.

Unfortunately, there’s an inertia in medicine that can result in medical practice that is at odds with the available evidence. Sometimes this disconnect can have devastating consequences. See, for example, Evidence-Based Medicine or Evidence-Biased? and The Tomato Effect.

The reason it is so important to straighten out the neutropenic diet myth is that fruits and vegetables may actually improve cancer survival:

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: