Turmeric has gained much popularity as a natural anti-inflammatory; I regularly see supplements promoted for animals that make wild claims to their health benefits. (Sometimes verging or being blatantly illegal making medicinal claims). So, what’s the evidence? Is this really a useful – or even miracle – product, or not?
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There have been several in vitro (taking place outside a living organism) studies investigating the claim, suggesting the antioxidant, anti-inflammatory and anti-cancer activity of its active ingredient curcumin and other constituents of turmeric. However, owners must be made aware that in vitro studies can never prove a clinical benefit for patients. What we see in laboratory conditions don’t often correlate to what we see when we test on real life specimens!
The National Center for Complementary and Alternative Medicine (NCCAM) stated, ‘There is little reliable evidence to support the use of turmeric for any health condition because few clinical trials have been conducted’.
A lot of focus is on one of its active ingredients called curcumin. However, there are other ingredients and there is some evidence that these possess anti-inflammatory properties. The most studied in terms of medical applications however, are the curcuminoids. Many of the studies that have been done in humans have focused on curcumin and have found that it is poorly absorbed when taken orally, for example stating that poor bioavailability (only a low percentage of the substance entering the body during digestion) reported by some investigators are a major limitation to the therapeutic use of curcumin.
The evidence (or lack of)
Many of the studies that have been done in humans have focused on curcumin. But a major barrier to curcumin’s clinical efficacy is its poor bioavailability; there have been few controlled studies in dogs.
As there is very little evidence in animals, we can first look at reviews of turmeric use in humans; although we also know that human data cannot always be extrapolated to animals either! In one review all potential uses were given the evidence grade of C. Grade C evidence basically means that the evidence available is of poorer quality resulting in the results being unclear, conflicting, or insufficient to draw any conclusions. Even in humans, there is no compelling clinical evidence supporting any use of curcumin or other turmeric compounds.
One study found no objective difference, but there was improvement in subjective indicators; this outcome is particularly important when considering the impact of caregiver placebo, as objectively there was no benefit, but people felt that there was.
What does that mean?
The fact that there was no objective difference, but there were subjectively, means that the human participants may have allowed bias, prejudgement and placebo effect to impact their belief in the treatment. If the patient did indeed not experience any positive effects but the owners believed there was, then this could result in the dog not receiving adequate pain control in a timely fashion.
Does it need to be paired with black pepper?
A common brand of turmeric-based supplement sold in the UK discusses the ingredients turmeric, coconut oil, apple cider vinegar, ceylon cinnamon, black pepper, citric acid and potassium sorbate. The black pepper and coconut oil are cited to aid in ‘bioactive absorption’ of the turmeric, which is understood to have poor absorption, biodistribution, metabolism, and bioavailability. Sounds great, right?
In one study comparing human and rat subjects, the addition of piperine (black pepper), a known inhibitor of hepatic and intestinal glucuronidation, with turmeric, did show a significant increase in bioavailability of turmeric in humans; but the results in rats were much less drastic.
What about the oil?
In relation to coconut oil, curcumin has a low solubility in water, so the addition of oil to the ingredients aims to mitigate this problem. The problem? Evidence that an oil carrier will help bioavailability is somewhat lacking in animal studies, but one review looked at liposomal encapsulation. Liposomes are considered effective drug carriers because of their ability to solubilise hydrophobic compounds. In theory, this could suggest that the use of oil alongside turmeric could aid in increased bioavailability and absorption. However, the evidence base does not yet allow us to draw conclusions as to the in vivo efficacy of this combination. Hopefully future studies will shed further light on the proposed interaction between the specific components in this formulation.
Turmeric does actually contain several potentially useful chemical compounds which have been studied in vitro, in the laboratory, of which the most studied is curcumin. Because of this there is enough in vitro research to suggest some biological effects which might be clinically beneficial. This in vitro research is where most claims for use are made from, so what’s the problem?
The concept that turmeric, or more specifically its compounds, could have therapeutic value is plausible; however there is very little good quality research in humans, never mind our pets. In some pets we may see gastrointestinal upset, and as in humans it can impact blood clotting, especially when used alongside anticoagulants, it might not be fully ‘benign’ in our pets either. But we simply don’t have the evidence to tell us that either. Overall, I would probably be spending my money elsewhere on more evidence-based interventions until I have more firm proof. Will it help? Maybe. Will it harm? Possibly. I will leave you to decide if you want to try it, but I would always ensure you ask your veterinary team first and make sure they are aware you are using it if they are using any other medication in case of unknown drug interactions!