The Pros and Cons of Turmeric

**Michael Greger** (0:00)
Doesn't it seem like when it comes to nutrition there are more opinions than facts to go around?
Every day we hear new theories about diets and supplements and best foods to eat. Well, my role is to take the mystery out of good nutrition and look at the science. Welcome to episode 500 of the Nutrition Facts Podcast. In our first story we look at dozens of human trials that reveal where turmeric delivers and where it doesn't. With our former Senior Research Scientist, Dr. Christine Dennis.

**Christine Dennis** (0:33)
The number of clinical trials on turmeric, not in rats or petri dishes, but with actual people, continues to climb, dozens a year, and most were randomized double-blind placebo controlled, the gold standard for clinical trials. There have been so many trials published that there are now umbrella reviews on turmeric. You've heard of systematic reviews and meta-analyses, pooling multiple studies together. Well, an umbrella review can be like a systematic review and meta-analysis of systematic reviews and meta-analyses, meaning pooling multiple meta-analyses together, placing them at the very top of the hierarchy of evidence pyramid. Dr. Greger has covered the benefits of the turmeric pigment curcumin for knee osteoarthritis, in some cases working as well as or even better than anti-inflammatory drugs and painkillers without their side effects of injuring our gut.
And in the 10 years since, a meta-analysis of 11 meta-analyses on the efficacy of curcumin for relieving osteoarthritis strongly supports that it can relieve pain as well as improve joint mobility and shorten medication use. And more isn't necessarily better. Low dose extracts appear to have similar pain relief effects to high dose extracts. What about other arthritic conditions? A pilot study in 2012 of 45 patients showed promise for rheumatoid arthritis, finding it is actually more effective at alleviating pain compared to the leading drug. And a recent meta-analysis including more than 500 patients found the same. Curcumin was beneficial both for inflammation levels and clinical symptoms.
Curcumin's ability to lower some inflammatory biomarkers like C-reactive protein, a marker of systemic inflammation, extends more broadly to patients with auto-inflammatory conditions, and the stronger effects seem to appear at relatively smaller doses. You may recall that Dr. Greger talked about a 2012 study in pre-diabetic individuals, where 0% of those taking curcumin extract for 9 months progressed to type 2 diabetes, while 16% of those on placebo did. There have been a lot of studies since. 14 systematic reviews and meta-analyses containing 61 individual randomized controlled trials were included in this umbrella review. Fasting blood sugars and HbO1c, a measure of longer-term blood sugar control, both improved, no matter what formulation of turmeric or curcumin was consumed. But the quality of the studies was low, not including important information like their funding sources. And the types of tumor curcumin preparations were wide-ranging. What if we want to know the impact of tumor alone, not a special curcumin formulation that supplement companies can charge us a bunch of money for?
This dose-response meta-analysis breaks it out for us, with tumor resulting in better results than curcumin-only treatments.
Note that benefit was found for a variety of participants, not only those with diabetes.
What about cholesterol? Here's another umbrella review. Although the authors concluded that curcumin could have ameliorating effects, there was only a half-point drop in LDL. Lower doses may work better, but a two-point drop is still nothing to write home about. Turmeric curcumin blocks obesity in mice fed a high-fat diet. What about people? In an umbrella review of 50 randomized controlled trials, curcumin supplementation significantly decreased BMI, body weight, and waist circumference. It was significant statistically, but how much of a difference did it really make? A loss of about a half kilogram or a little more than a pound of body weight. Waist circumference, a measure of abdominal obesity, decreased by about a centimeter and triple the effect in trials with whole turmeric relative to curcumin extracts. So, for those with obesity or type 2 diabetes and wanting to lose weight, the primary prescription is lifestyle modification, and some tumor on the side might be helpful, but may not make that much difference.

**Michael Greger** (4:42)
In our next story, we look at what happens when turmeric is put to the test to reverse DNA damage caused by arsenic exposure. Arsenic is a carcinogenic heavy metal, and the major mechanism of arsenic-related damage appears to be oxidative stress. It's the arsenic-induced accumulation of free radicals that can kill off cells and damage our DNA. And then the double whammy is that it may disrupt our body's ability to repair our DNA once it's damaged. Well, if the damage is oxidation, what about eating an antioxidant-rich food, such as the spice turmeric, which contains an antioxidant pigment known as curcumin?