Cancer myths are prevalent on the internet, and one of the favorites for the past few years has been turmeric. It has been described as the great secret cancer cure, treatment, and/or prevention. But here’s the thing with these types of claims about cancer — there rarely is much evidence supporting their use clinically.
This article is going to look at what turmeric may do for cancer if anything. You can probably predict that if I’m writing about it, I’m not going to be finding much evidence, but I’ll give it a try.
What is turmeric? What is cancer? So many questions
Let’s start with cancer.
Cancer is a generic word that covers a large set of diseases. Basically, it’s a cell or group of cells that undergo uncontrolled cellular growth and metastasize into other cells and organs. However, cancer is not one disease.
The National Cancer Institute states that there are over 100 types of cancer. Cancer Research UK states that there are over 200 types of cancer. The American Cancer Society lists over 70 types of cancer (although some are more classes of cancer rather than a single type). Wikipedia lists over 180 different cancers.
Nevertheless, each of these cancers has different etiologies (causes), pathophysiologies (development), prognosis, and treatment.
Whenever I read some internet quack claim that there is a cure for cancer, I laugh because I know that they don’t understand the nature of cancer. Maybe someday well into the future, we might have some scientific “ah-ha” moment, and we find a common link between all cancers, but that seems implausible. It is not one disease.
Next up, what is turmeric? It is a flowering plant, Curcuma longa, of the ginger family, Zingiberaceae. The rhizomes of the plant are used in cooking as a flavoring or spice.
Turmeric powder has a warm, bitter, black pepper-like flavor and earthy, mustard-like aroma. It is used widely in Asian dishes.
Curcumin, a bright yellow chemical produced by the turmeric plant, is used as a food additive, but it is the chemical that is often claimed to affect cancer. We’ll see about that.
Does it actually treat cancer?
What do I look for when I want to debunk or support a claim that something treats, cures, or prevents cancer?
I want a credible, published study that demonstrates the effectiveness of a treatment against cancer. That must be a double-blind prospective randomized clinical study.
Furthermore, this means that similar patients in terms of health, fitness, and cancer status are randomly selected by computer to either receive the investigational treatment or not. In cancer studies, it’s not ethical for patients with active cancer to not receive treatment so the best currently available treatment is given to every patient with randomization to the addition of the study medication, in this case, turmeric or curcumin. The control group still gets the current best treatment. This is a real test of whether a new drug or compound has any effect on cancer.
Moreover, double-blind means that neither the patient nor the treating team knows which patient is getting the study drug. No investigator can have significant ownership of the company making the study drug and stock investments need to be disclosed, and they are restricted from participating in the study. This removes as much bias from the results as possible.
Concerning the effectiveness of turmeric (or curcumin) in treating cancer, based on the guidelines above, the answer is a solid and resounding NO.
There are preclinical studies that show that curcumin or turmeric may affect cancer cell cultures or animal models — preclinical studies rarely lead to a science-based medical treatment, probably less than 1% of the time. There’s an old joke in cancer research, “we’ve cured cancer in mice over 10,000 times over the years.”
I have my snarky comment to people who try to take preclinical research and apply it to human medicine — I’ll get excited when you show me a peer-reviewed, published paper that reviews positive phase 3 clinical trial results. In other words, I never hold my breath about this.
That being said, there is no credible clinical evidence that turmeric (or curcumin) is effective in treating, curing, or preventing cancer. Here are some studies that debunk the claims about turmeric and cancer.
- Over the past 50 years, there have been around 120 clinical trials of curcumin. Collectively they have failed to show that curcumin works for any single indication, especially cancer. This one systematic review (at the top of the hierarchy of medical research), pretty much summarizes the fact that turmeric, or curcumin, does not affect cancer.
- A systematic review of eight clinical trials examining turmeric’s effect on prostate cancer showed that half of the studies had no effect, and the other four had minimal effect.
- Another review shows that the clinical effectiveness of curcumin is “weak.”
Why are the clinical trials so bad?
According to Steven Novella at Science-Based Medicine:
One reason is that it has poor bioavailability and pharmacokinetics. It doesn’t matter what a molecule does when you drip it directly on cells in a petri dish. The compound has to have a suite of pharmacological properties in order to be a useful drug. It needs to be sufficiently absorbed, it has to be biologically stable with a decent half-life, it has to reach the target tissue in sufficient concentrations, and it needs to have a therapeutic range where the beneficial clinical effects are significant but the toxic side effects are tolerable (including all of its metabolites).
Curcumin is simply an unstable compound that has terrible pharmacokinetic properties. Its bioavailability is around 1% and its half-life is measured in mere minutes. Sometimes drug company chemists can tweak and alter the structure of potential compounds to give it the properties it needs to be a good drug. This has just not worked out for curcumin.
This is the age-old problem with cancer drugs — how to get the medication to cancer cells without harming other cells. If curcumin works in preclinical studies, and it does seem that it does, the problem moves to how to deliver it effectively. Let’s say you need a concentration in the blood of 1 g/L but only 1% is bioavailable, then if you swallow 10g, you’ll get a blood concentration of less than 0.1 g/L. To get enough in your blood to kill that cancer, you might need to eat 1 kg of curcumin which probably is toxic.
Getting curcumin (or another component of turmeric) to the cancer cells will take some innovative technology that may not be available at this time. And this has to be done safely.
Summary
As I have seen many times, people think that preclinical studies mean that turmeric is a cure for cancer. Unfortunately, there are no clinical trials that have established that, and there seem to be a lot that dispute that claim.
Even if these preclinical studies indicate a potential cancer treatment, swallowing a bunch of curcumin or turmeric is going to be useless in preventing, treating, or curing cancer. You just could not consume enough to have any effect on cancer. This is not a method to self-treat, because it is useless.
If scientists are convinced that curcumin or turmeric affects any of the hundreds of cancers, they will develop a method to target that cancer using some advanced delivery method. And they will do it in a manner that provides the right amount of drug to those cancer cells while not causing general harm to the person.
At this point, there is no evidence that turmeric (or curcumin) supplements or in food will have any effect on cancer. And no, if you think that “well if I consume a little bit that will reduce my risk of cancer,” you’d be wrong. Pharmacological studies will show how much is needed to treat cancer, and it’s clear, based on the pharmacokinetics of curcumin and turmeric, the amount that you could safely consume would be insufficient to kill cancer cells.
Right now, there is just very little evidence that these compounds have any clinical effect on cancer cells. I know people want to consume some simple pill to treat their cancer, but that’s not how it works. Real science requires researchers to figure out if turmeric affects cancer, then figure out how to kill that cancer safely, and then manufacture it. It’s not easy.
One day, if there are clinical trials with a pharmacologically useful form of turmeric that show positive results, then I’ll write about it then. But for the time being, don’t bother. It’s not going to help you.
Citations
- Bagherniya M, Askari G, Alikiaii B, Abbasi S, Soleimani D, Sathyapalan T, Jamialahmadi T, Sahebkar A. Curcumin for the Treatment of Prostate Diseases: A Systematic Review of Controlled Clinical Trials. Adv Exp Med Biol. 2021;1291:345-362. doi: 10.1007/978-3-030-56153-6_20. PMID: 34331700.
- Barcelos KA, Mendonça CR, Noll M, Botelho AF, Francischini CRD, Silva MAM. Antitumor Properties of Curcumin in Breast Cancer Based on Preclinical Studies: A Systematic Review. Cancers (Basel). 2022 Apr 26;14(9):2165. doi: 10.3390/cancers14092165. PMID: 35565294; PMCID: PMC9099919.
- Hassanzadeh K, Buccarello L, Dragotto J, Mohammadi A, Corbo M, Feligioni M. Obstacles against the Marketing of Curcumin as a Drug. Int J Mol Sci. 2020 Sep 10;21(18):6619. doi: 10.3390/ijms21186619. PMID: 32927725; PMCID: PMC7554750.
- Nelson KM, Dahlin JL, Bisson J, Graham J, Pauli GF, Walters MA. The Essential Medicinal Chemistry of Curcumin. J Med Chem. 2017 Mar 9;60(5):1620-1637. doi: 10.1021/acs.jmedchem.6b00975. Epub 2017 Jan 11. PMID: 28074653; PMCID: PMC5346970.
