MD, PhD, FMedSci, FSB, FRCP, FRCPEd

Turmeric (Curcuma longa) is a truly fascinating plant with plenty of therapeutic potential. It belongs to the ginger family, Zingiberaceae and is native to southern Asia. Its main active ingredients are curcumin (diferuloylmethane) and the related compounds, demethoxycurcumin and bis-demethoxycurcumin (curcuminoids) which are secondary metabolites. Turmeric  has been used extensively in Ayurvedic medicine and has a variety of pharmacologic properties including antioxidant, analgesic, anti-inflammatory, and antiseptic activities.

In the often weird world of alternative medicine, turmeric is currently being heavily hyped as the new panacea. Take this website, for instance; it promotes turmeric for just about any ailment known to mankind. Here is a short excerpt to give you a flavour (pun intended, turmeric is, of course, a main ingredient in many curries):

It comes at a surprise to a lot of people that herbs can be highly effective, if not more effective, than conventional medications …

To date, turmeric is one of the top researched plants. It was involved in more than 5,600 peer-reviewed and published biomedical studies. In one research project that extended over a five year period, it was found that turmeric could potentially be used in preventive and therapeutic applications. It was also noted that it has 175 beneficial effects for psychological health…

The 14 Medications it Mimics

Or should we say the 14 medications that mimic turmeric, since turmeric has been around much longer than any chemical prescription drug. Here’s a quick look at some of them:

  • Lipitor: This is a cholesterol drug that is used to reduce inflammation and oxidative stress inside of patients suffering from type 2 diabetes. When the curcuminoid component inside of turmeric is properly prepared, it can offer the same effects (according to a study published in 2008).
  • Prozac: This is an antidepressant that has been overused throughout the past decade. In a study published back in 2011, turmeric was shown to offer beneficial effects that helped to reduce depressive behaviors (using animal models).
  • Aspirin: This is a blood thinner and pain relief drug. In a study done in 1986, it was found that turmeric has similar affects, which makes it a candidate for patients that are susceptible to vascular thrombosis and arthritis.
  • Metformin: This is a drug that treats diabetes. It is used to activate AMPK (to increase uptake of glucose) and helps to suppress the liver’s production of glucose. In a study published in 2009, it was found that curcumin was 500 to 100,000 times more effective at activating AMPK ad ACC.
  • Anti-Inflammatory Drugs: This includes medications like ibuprofen, aspirin and dexamethasone, which are designed to reduce inflammation. Again, in 2004, it was proven that curcumin was an effective alternative option to these chemical drugs.
  • Oxaliplatin: This is a chemotherapy drug. A study done in 2007 showed that curcumin is very similar to the drug, acting as an antiproliferative agent in colorectal cell lines.
  • Corticosteroids: This is a steroid medication, which is used to treat inflammatory eye diseases. In 1999, it was found that curcumin was effective at managing this chronic condition. Then in 2008, curcumin was used in an animal model that proved it could also aid in therapy used to protect patients from lung transplantation-associated injuries by “deactivating” inflammatory genes.

Turmeric Fights Drug-Resistant Cancers… it’s been shown that curcumin can battle against cancers that are resistant to chemotherapy and radiation…

END OF QUOTE

As I said, turmeric is fascinating and promising, but such hype is clearly counter-productive and dangerous. As so often, the reality is much more sobering than the fantasy of uncritical quacks. Research is currently very active and has produced a host of interesting findings. Here are the conclusions (+links) of a few, recent reviews:

Overall, there is early evidence that turmeric/curcumin products and supplements, both oral and topical, may provide therapeutic benefits for skin health. However, currently published studies are limited and further studies will be essential to better evaluate efficacy and the mechanisms involved.

This meta-analysis of RCTs suggested a significant effect of curcumin in lowering circulating TNF-α concentration.

While statistical significant differences in outcomes were reported in a majority of studies, the small magnitude of effect and presence of major study limitations hinder application of these results.

Overall, scientific literature shows that curcumin possesses anti-diabetic effects and mitigates diabetes complications.

The highlighted studies in the review provide evidence of the ability of curcumin to reduce the body’s natural response to cutaneous wounds such as inflammation and oxidation. The recent literature on the wound healing properties of curcumin also provides evidence for its ability to enhance granulation tissue formation, collagen deposition, tissue remodeling and wound contraction. It has become evident that optimizing the topical application of curcumin through altering its formulation is essential to ensure the maximum therapeutical effects of curcumin on skin wounds.

What emerges from a critical reading of the evidence is that turmeric has potential in several different areas. Generally speaking, clinical trials are still thin on the ground, not of sufficient rigor and therefore not conclusive. In other words, it is far too early to state or imply that we all should rush to the next health food store and buy the supplements.

On the contrary, at this stage, I would even warn people not to be seduced by the unprofessional hype and wait until we know more – much more. There might be risks associated with ingesting turmeric at high doses over long periods of time. And there are fundamental open questions about oral intake. One recent review cautioned: …its extremely low oral bioavailability hampers its application as therapeutic agent.

WATCH THIS SPACE!

10 Responses to Turmeric: lots of potential, but beware of the hype

  • The extremely low bioavailability is a common problem associated with phenolic type compounds, although this aspect is usually ignored by the CM researchers who base their amazing claims mostly on results from in vitro type bioassays. These bioassays do not take into account the ADMET properties of these compounds. Massive dosages or micro-encapsulation techniques can be used to overcome the bioavailibility issue but then the risk of toxic effects is also increased. Another problem with the phenolic type compounds is their tendency to be non-selective (in vitro activity against just about everything) indicating that their mechanism of action is to bind to a very common receptor/enzyme – good for marketing purposes but from a scientific point of view an indication of a typical false positive. If after 5600 peer reviewed publications the evidence is still mainly inconclusive, then I would suggest that curcumin is a false positive.

  • Even if a component(s) of turmeric was found to be usefully effective against a disease it would still not justify the selling and consumption of turmeric. Unregulated dosage, mode of delivery and contaminants would make this a dangerous product.

    In a way, I hope that it is not found effective, it may lead to the banning of the spice and I find it so delicious in many dishes.

  • Regarding the downregulation of TNF-alpha by curcumin supplementation that seems to be supported by the meta analysis that Prof. Ernst links to.
    Can someone who understands this tell us whether the downregulation found in theses studies amounts to a clinically useful effect and whether such an effect would not make it inadvisable for those who do not need it i.e. healthy people?
    TNFalpha suppression has serious side effects and is only advisable in severe inflamatory diseases if my understanding is right. https://en.wikipedia.org/wiki/TNF_inhibitor#Side_effects

    • Correct! Any prolonged suppression of TNF-alpha would result in the suppression of signalling pathways of the immune system that not only ‘fight’ infection, but serve in the elimination of foreign cells.

      I probably read at least half the papers on turmeric and curcumin by 2012, if not sooner. I recall telling the owner of a local health food store that just because the spice in capsules was flying off the shelves didn’t mean it was effective at the suggested dosages. He didn’t believe me when I informed him that the only human studies to show any anti-inflammatory activity were poorly conducted preliminary dosing studies in India from years ago, and that the minimum dosage required for even a small effect amount to 15 grams of turmeric; not 350 mg 3 times per day as the label on bottle he showed had claimed. A year later, I dropped by for a second visit when he eagerly told me I was right and the public was being duped. Not long after, curcumin was ‘hot’, but not in just any form. It had to be complexed with something in order to enhance its bioavailability. The catch was that, not unlike the effects of eating too much heavily spiced East Indian food, some enhanced formulations were producing flatulence and diarrhea, so he was trying them out to see which ones ‘worked’ best. No amount of attempting to explain the inherently poor bioavailability of curcumin in practically any formulation, despite prolonged concentrations in the serum, would convince him that the benefits of the products remained questionable.

  • Björn Geir said:

    Can someone who understands this tell us whether the downregulation found in theses studies amounts to a clinically useful effect and whether such an effect would not make it inadvisable for those who do not need it i.e. healthy people?

    But it’s natural so it must be safe! That’ll be £50 please.

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