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:

Vitamin C Pills Put to the Test for Cancer

Vitamin C “is no stranger to controversy, as evidenced by the fact that over 40 years lapsed” from the time citrus fruits were shown to cure scurvy in the 1700s and the widespread implementation of eating citrus to save lives. Is it possible we’re in the midst of a similar 40-year lag with research in the mid-1970s purporting to show that terminal cancer patients treated with vitamin C lived 4 times longer and sometimes 20 times longer? I explore this in my video Vitamin C Supplements for Terminal Cancer Patients.

Researchers at the venerable Mayo Clinic decided to put vitamin C to the test, and they failed to show any benefit. The survival curves for both groups of patients were essentially identical. In fact, the one success story, a man with end-stage pancreatic cancer who had shown no response to any previous attempts at chemotherapy but started improving and was still alive five years later, was one of the patients who got the sugar pill placebos. It was official: Vitamin C didn’t work. “The apparently positive results reported…almost certainly resulted” from systematic bias in terms of which historic controls were chosen to compare with the treatment group, read the accompanying National Cancer Institute editorial.

Linus Pauling disagreed, arguing that the prior chemotherapy in nearly all the Mayo Clinic study patients may have negated the effect of the vitamin C. If the vitamin C works by boosting your immune system but your immune system is first destroyed by chemo, the thinking goes, no wonder it didn’t work. In the original vitamin C study that showed remarkable benefit, only 4 out of the 100 patients had ever received chemo. The Mayo Clinic researchers were skeptical, but “Pauling had a legendary reputation for being right about all sorts of things,” so “one might perhaps do worse than rely at least partly on Pauling’s awesome intuition.” Thus, a second, randomized, double-blind, placebo-controlled study was performed on patients with advanced cancer, but, this time, those who had no prior chemotherapy.

Again, it was a spectacular failure.

Researchers found no measurable response. The cancer in the vitamin C group progressed just as rapidly, and the patients on the placebo sugar pills lived just as long. In fact, if anything, the sugar pill group lived longer. At two years, everyone in the vitamin C group had died, but there were still a few survivors in the placebo group who lived at least past three years. The researchers concluded that “high-dose vitamin C therapy is not effective against advanced malignant disease, regardless of whether the patient has had any prior chemotherapy.”

Because the Mayo studies were taken as definitive, the medical community concluded that vitamin C was useless. However, in the Mayo Clinic studies, they gave the vitamin C orally in supplements, not intravenously. In retrospect, the route of administration may have been key.

In the original study, Pauling and his researchers started out infusing 10 grams of vitamin C a day intravenously, whereas in both of the Mayo studies designed to replicate the protocol, the researchers just gave people vitamin C supplements to take orally. Patients were sent home to swallow 20 capsules a day. They got the same dose, but 10 grams given orally is not the same thing as 10 grams given intravenously. They can’t be blamed for their ignorance, though. This fact wasn’t discovered until decades later.

It turns out vitamin C concentration in our bloodstream is tightly controlled, such that if you try to swallow more than you’d get eating five servings of fruits and vegetables, your body cuts down on the absorption in the intestine. For example, if you go from eating 200 mg to eating about ten times more (2,500 mg), the level in your bloodstream only goes up 3 mg per liter or quart of blood. “In contrast, because intravenous injection bypasses the intestinal absorption system,” it can result in super high blood concentrations—as in 100 to 200 times the level you can achieve taking vitamin C orally. Maybe that explains why the original studies seemed so promising but the follow-up studies were so disappointing. This raises the controversial question of the re-evaluation of vitamin C in cancer treatment. Researchers responded to the challenge and took up the mantle, and I discuss this in my video The Role of Vitamin C in the Treatment of Terminal Cancer.


To learn more about the history of vitamin C and cancer, see Intravenous Vitamin C for Terminal Cancer Patients.

To learn more about vitamin C, see Do Vitamin C Supplements Prevent Colds But Cause Kidney Stones? and What Is the Optimal Vitamin C Intake?.

Can eating citrus protect against cancer? Find out in Citrus Peels and Cancer: Zest for Life?.

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:

How to Lose Weight Eating More Food

What happens if you add fruit to your regular diet, eating three apples or pears as between-meal-snacks every day? I explore this in my video Eating More to Weigh Less, which I titled as a nod to Dr. Dean Ornish’s smash bestseller.

Fruit is low in calories, but it does have some. It isn’t calorie-free. So, if you add food—even healthy food—to people’s diets, won’t they gain weight? No, subjects who ate three apples or pears every day added on top of their regular diet lost a couple of pounds. Was that reduction because of all that fiber since our gut bacteria can create anti-obesity compounds from fiber? (See my Beans and the Second Meal Effect video for more on this.) Good question. That’s why, in addition to the fruit groups, the researchers had a cookie group!

Subjects ate either three apples, three pears, or three cookies with enough oats in them to have about the same amount of fiber as the fruit. Despite the fiber, adding cookies to one’s diet did not lead to weight loss. The researchers thought the weight-reducing secret of fruit was its low energy density, meaning you get a lot of food for just a few calories, so it fills you up.

“Energy density is a relatively new concept that has been identified as an important factor in body weight control in adults and in children and adolescents…Energy density is defined as the amount of energy [calories] per unit weight of a food or beverage….” Water, for example, provides a significant amount of weight without adding calories. Fiber, too. “Thus, foods high in water and/or fiber are generally lower in energy density. On the other hand, because dietary fat provides the greatest amount of energy per gram [calories per unit weight], foods high in fat are generally high in energy density.”

The CDC offers some examples. High energy density foods are like bacon, which have a lot of calories in a small package. A medium energy density food is like a bagel, and low energy density foods are typified by fruits and vegetables. In general, the lower the better, but there are two exceptions: Soda is so heavy that by energy density it looks less harmful than it is, and nuts have so much fat that they appear less healthy than they are.

Otherwise, though, the science “supports a relationship between energy density and body weight…such that consuming diets lower in energy density may be an effective strategy for managing body weight.” This is because people tend to eat a consistent weight of food. So, when there are fewer calories per pound, caloric intake is reduced.

A small drop in energy density can lead to a small drop in weight, and the greater the decrease in energy density, the greater the weight loss.

“Energy density can be reduced in a variety of ways such as the addition of vegetables and fruits to recipes or by lowering the fat or sugar content.” Indeed, that’s how we evolved—eating predominantly low energy density foods such as fruits, vegetables, plants, and tubers (starch-filled roots like sweet potatoes). The first study emphasizing how fruits and vegetables could affect energy density and food intake was conducted more than 30 years ago.

Researchers were able to cut people’s caloric intake nearly in half—from 3,000 calories a day down to 1,570—without cutting portions. They simply substituted high energy dense foods with less calorie dense foods. That means subjects ate lots of fruits, vegetables, whole grains, and beans, compared to having high-energy density meals with lots of meat and sugar. They ate nearly half the calories, but they reported enjoying the meals just as much.

Researchers tried this in Hawaii by putting people on a traditional Hawaiian diet with all the plant foods they could eat. The subjects lost an average of 17 pounds in just 21 days, resulting in better cholesterol, triglycerides, blood sugars, and blood pressure. Caloric intake dropped 40 percent, but not by eating less food. In fact, they lost 17 pounds in 21 days while eating more food—four pounds of food a day. But, because plants tend to be so calorically dilute, one can stuff oneself without seeing the same kind of weight gain.

“The energy density of foods is of interest for weight management not only because it allows people to eat satisfying portions while limiting calories, but also because reductions in energy density are associated with improved diet quality.” For example, lower energy dense diets are associated with lower risk of pancreatic cancer.

Lower energy-dense diets tend to be of healthier foods, so we get the best of both worlds.


I talk more about the energy density concept in The Ice Diet and Nutrient-Dense Approach to Weight Management. Are There Foods with Negative Calories? Find out in my video!

The amazing Hawaii study was done by Dr. Terry Shintani. Find out more about the natural human diet in What’s the “Natural” Human Diet?.

Doesn’t fruit have a lot of sugar in it? Check out my videos:

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: