This news release summarizes an 18-month study of 40 healthy adults to determine whether oral curcumin — the active substance in the spice turmeric — has cognitive benefits. While it does provide some details on the study design and results, it is incomplete in several important areas. For example, is a 28% improvement in cognitive test results clinically important or simply statistically significant? This should have been explained.
The release did not speak to the costs of the supplement used although it appears to be commercially available. Furthermore, there are harms and conflicts of interest that should have been explored further.
Curcumin has been investigated as a potential therapy for a wide range of conditions. Because ingested curcumin is poorly absorbed and rapidly metabolized, its bioavailability has been brought into question. This study, according to the published article, used a more bioavailable form of curcumin called Theracurmin.
Curcumin has shown some promising anti-inflammatory and anti-oxidant effects but most of these studies have been in mice.
Given the wide range of health claims being made regarding curcumin, we believe that news releases and stories about this substance need to be cautious and pay close attention to study design and limitations.
There’s no discussion of costs in the news release. A quick google search for Theracurmin capsules reveals that — at the dosages used in the study — a month’s supply would cost somewhere between $75-$100 dollars.
The news release mentions these benefits in the 21 subjects who took curcumin: “significant improvements in their memory and attention abilities (ie. ‘improved 28 percent over the 18 months’) … mild improvements in mood …and their PET scans showed significantly less amyloid and tau signals in the amygdala and hypothalamus” when compared to the 19 subjects in the placebo group.
We are told that standardized tests were used but not where the improvements were seen or how widespread the improvements were seen. Nor are we given context to answer “28 percent of what”? We’re also given no context to understand what reduced amyloid and tau signals mean (nor what “significantly less” means), only that “the amygdala and hypothalamus are regions of the brain that control several memory and emotional functions.”
The release notes that four volunteers taking the curcumin supplement experienced abdominal pain and nausea — a potential harm of turmeric use. But the published study notes that six volunteers dropped out of the study due to “gastrointestinal distress.” This should have been noted in the release as well.
As we have reported before in our reviews related to health claims made about curcumin, the active ingredient of tumeric:
Neither turmeric nor curcumin has been extensively studied in clinical trials, but animal studies have shown that chronic use could lead to stomach ulcers. In addition, the American Herbal Products Association classifies turmeric as a menstrual stimulant. Turmeric should be avoided in patients with bleeding disorders and bile duct obstruction.
Experts believe tumeric is generally safe, although the quality of the available clinical studies is questionable.
The release describes the study as “double-blind, placebo-controlled study involved 40 adults between the ages of 50 and 90 years who had mild memory complaints. Participants were randomly assigned to receive either a placebo or 90 milligrams of curcumin twice daily for 18 months.”
Limitations of the study, not directly addressed in the release, are that the changes observed in the amygdala and hypothalamus of the curcumin group are highly subjective and have no established causal relationship with memory or mood. Also, this is an extremely small sample size and the authors did not correct for the multiple comparisons they made. (Learn more about the problems with multiple comparisons in research studies here.)
The study authors noted in the published paper that the volunteers were not representative of the general population; they were “motivated, educated, physically healthy subjects concerned about age-related memory problems,” authors wrote.
Finally, curcumin levels were measured in the blood only; just how much crosses the blood-brain barrier and is actually bioavailable to brain cells is unknown.
To its credit the release does note that researchers will be following up with larger studies.
The news release lists funders and notes that “Theravalues Corp. provided the curcumin and placebos for the trial, as well as funds for the laboratory testing and for [lead author] Small’s travel to present preliminary findings at the 2017 Alzheimer’s Association International Conference.”
What isn’t mentioned is that UCLA owns the patent for the amyloid and tau labelling method used in the study, and that the lead author — as well as three of the co-authors — invented the method and have a financial interest in the company that sells it (TauMark, LLC). The lead author has financial relationships with a dozen biomedical companies besides Theravalues and TauMark.
There is no discussion of other therapies used in addressing memory or mood problems.
Theracurmin is available from several sources not mentioned in the news release. The initial comments in the release give the reader the erroneous impression that eating Indian food is equal to the form used in the study. (We also discuss this under Unjustified Language.)
The lead sentence of the news release — “Lovers of Indian food, give yourselves a second helping …” — implies that the alleged benefits of curcumin might be achieved through diet alone, thus making availability a no-brainer. But the dosages used in the study (which we’re not told are about three times the commonly recommended dose) require oral supplements, which certainly are widely available in health stores and online, but at a much greater cost than the kitchen spice.
The release notes that previous studies have examined whether curcumin affects memory and mood, that “curcumin has previously been shown to have anti-inflammatory and antioxidant properties in lab studies” and that regions with diets rich in curcumin tend to have a lower prevalence of Alzheimer’s disease.
The release’s first sentence says that people should consume more Indian food for health benefits, but the study measured the effects of “an easily absorbed curcumin supplement” — not traditional Indian meals.