There is strong scientific support for the use of specified supplements by particular groups of people (e.g., pregnant women; elderly people; people who neither obtain enough vitamin D from the diet nor have adequate sun exposure). However, too frequently, former Visiting Professor Patrick Holford recommends extensive supplemention with products for which there is no substantial scientific or clinical support. Indeed, despite his persona as a “man of science”, Holford professes a belief in “magic supplements” (Myth 6): for him, one of these magical substances is chromium.
One recent example of Holford’s belief in magic rather than science is his recent formulation of Cinnachrome, to support his GL Diet. Holford claims that it is “specifically designed to support natural blood sugar balance”. Cinnachrome sounds delightful, like something that could be used to spice an apple pie, but there is little to indicate that it might be that useful. Holford writes:
Cinnachrome contains a combination of chromium and cinnamon, nutrients which have shown to be useful for anyone needing to pay particular attention to their blood sugar levels. Chromium polynicotinate is a natural form of chromium that provides two major ingredients of the glucose tolerance factor – chromium and niacin (nicotinic acid). Cinnulin PF is a concentrate extract of Cinnamon. The combination of chromium with cinnamon makes this powerful, natural formula ideally suited to all those following a low GL diet.
Overview of the Case for Chromium and Cinnamon
Unlike the case for too many of Holford’s recommendations, there are some trials (albeit of variable quality) on which to base an assessment. However, unaccountably, for a product that he recommends to the interested population for “natural blood sugar balance”, the studies that he cites mostly concern diabetics or rodents. In addition, it is not always clear that there is any correlation between the substance that has been evaluated in trials and that which is included in his formulation.
The cautious reader might be more wary than Holford about whether such studies can be generalised to the wider population. There are more recent studies that Holford does not cite. These studies report that cinnamon does not have a beneficial effect on the blood glucose or cholesterol levels of people with Diabetes Type I or II; this result holds true even for sub-groups. For chromium, the studies are too variable in quality and the results to draw a definitive conclusion but the research findings show that there is no clear evidence to support chromium supplementation for diabetics: there is no ready support for the notion that chromium has an role in “natural blood sugar” management. Far less is there any support for the notion of it as magical.
A number of researchers have investigated whether chromium supplementation has a beneficial effect for glucose or lipid metabolism: most of these studies or trials have involved people with Type 2 diabetes. A systematic review of the relevant randomised controlled chromium supplementation trials by Balk et al concludes that:
[n]o significant effect of chromium on lipid or glucose metabolism was found in people without diabetes.
The authors do add that:
[t]he evidence was limited by poor study quality, heterogeneity in methodology and results, and a lack of consensus on assessment of chromium status.
There was some interesting correspondence that followed-up the review by Balk et al. Kleefstra et al commented on the inclusion of a study that involved a large number of people in China . The study in China skewed the results substantially because of the relatively large number of people in the trial when compared to other trials that were included. The disproportionate numbers of participants influenced the apparent effect size for chromium. Holford assigns undue significance to this study in his case for chromium although it is deprecated by a number of researchers for reasons that are mostly understood and accepted.
Kleefstra et al discuss the apparent consistency in various studies and argue that it may be more productive to look at outcomes for different groups rather than all diabetics. They highlight apparent differences between:
Western and non-Western patients, as it seems that the beneficial effects on A1C are for the most part found in studies in non-Western countries.
(A1C is the test that gives a longer-term, better insight into blood sugar control than the snapshot of the fasting blood glucose test.) Kleefstra et al argued that
chromium has no (relevant) effect on A1C, especially not in Western patients with type 2 diabetes.
Consequently, they expressed the belief that future trials should concentrate on assessing the impact of chromium supplementation on those who are known to be chromium deficient rather than all diabetics. They acknowledged the lack of consensus for a test to establish chromium deficiency.
A subanalysis of the chromium picolinate trials excluding Anderson et al. , because of its quality and its large effect, produced a smaller, though still statistically significant, summary estimate of the effect of chromium supplementation on A1C (–0.3% [95% CI –0.5 to –0.1]). However, such an approach toward meta-analysis is arguably arbitrary.
They restate their position that, “available trials on chromium supplementation are of poor quality and have heterogeneous results” which is not a good reason for including them. They go on to acknowledge again that:
[t]he overall poor quality of the evidence clearly limits any conclusions that are drawn about the effect of chromium supplementation.
They conclude by agreeing that there is a need for a consistent and reliable test to establish a individual’s chromium status and that:
well-conducted trials in clearly defined populations (preferably with an indicator of chromium status) are needed before definitive conclusions can be made about the value of chromium supplementation.
There is considerable dispute about the efficacy and appropriateness of chromium supplementation for the general population of diabetics. There is no consensus or groundswell of support for Holford’s optimism that:
chromium has been shown to dramatically decrease the need for medication in many diabetics and in some cases eliminate the need for drugs completely.
This extravagant claim is made under the heading: Chromium as an alternative to diabetic drugs. The reference for this claim is Rabinovitz et al who reported a small study of elderly people with Type II diabetes in rehabilitation following a stroke or hip fracture. It is only a 3 week study, and it involves a 1500 Kcal diet which might itself have an impact on blood glucose levels for this pool of participants. (We have commented previously on the studies that Holford cites to support the case for chromium supplementation.)
It is self-evident that Holford’s overview of the clinical evidence does not support the use of chromium to modify glucose metabolism in people without diabetes; more generally, as from Balk et al’s recent review and the subsequent discussion, the studies in this area are notoriously poor and may compromise their usefulness for any population that is considering supplemental chromium for the regulation of blood sugar management.
It is worthwhile mentioning that these trials involve different forms of chromium which may have a different bio-availability than the chromium polynicotinate in Holford’s formulation. Chromium polynicotinate has been the subject of even less research than other forms (we comment futher on the quality of research on chromium elsewhere).
When discussing the evidence for “cinnamon – your blood sugar’s best friend” Holford relies upon animal studies and studies in people with Type 2 diabetes however, these may be of limited relevance to people who are not diabetic. In addition, it should be added that the more of extravagant interpretations of the trials that have been published are not always clear about whether the investigators have used common cinnamon or cassia cinnamon.
In Blevin et al’s study of people with diabetes, cinnamon supplementation did not improve diabetic control in a western population . Interestingly, Blevin et al comment that there were significant baseline differences between their study population and that in a previous trial (Khan et al) that had reported benefits. Participants in the Khan study had much higher fasting glucose and triglyceride levels, and they were using different anti-diabetic medications and combinations of them. The participants in the US trial seem to have much better control of biomarkers such as glucose and triglyceride levels. It should be noted that Blevin et al recruited people with type 2 diabetes, based on criteria from the American Diabetes Association. However, the Khan study had people with biomarkers that were considerably higher than those used for the definition, diagnosis and classification of diabetes Type II in the UK so it is reasonable to say that the Khan participants would also differ from diabetics in the UK.
In the absence of positive research findings for the benefits of cinnamon, such difference might suggest that there is even less evidence to support the use of cinnamon in people who do not have dysregulated glucose metabolism or whose diabetes is currently managed with non-insulin medications.
We conclude that the effects of cinnamon differ by population. Studies should be conducted to determine how specific variables (diet, ethnicity, BMI, glucose levels, cinnamon dose, and concurrent medication) affect cinnamon responsiveness. Until then, cinnamon cannot be generally recommended for treatment of type 2 diabetes in an American population. [pg. 2237]
Referring to the Khan trial, Blevins et al remark:
These findings led to widespread cinnamon use, although no study had yet evaluated the effects of cinnamon in Western diabetic populations with likely differences in diet, BMI, baseline glucose levels, and prescribed medication.
It will probably not be too surprising to learn that Holford offers an over-enthusiastic interpretation of the results of the Khan trial which seems to have influenced his formulation of Cinnachrome and his recommendations.
All responded to the cinnamon within weeks, with blood sugar levels 20 per cent lower on average than those of a control group. Some of the volunteers taking cinnamon even achieved normal blood sugar levels. Tellingly, blood sugar started creeping up again after the diabetics stopped taking cinnamon. The biggest improvements were seen with the highest dosage. However, it has been suggested that at very high levels cinnamon could actually lead to hypoglycemia by being over-effective[1]. Therefore, I recommend 1 gram a day, roughly half a teaspoon. Reports suggest that improvements can be seen after just 20 days[1].
Several of those claims have no support in the Khan paper if you consult Table 1— Effects of cinnamon on glucose levels in people with type 2 diabetes. According to the data:
- there is no indication that any of the groups achieved a desirable fasting blood glucose level which would be a value of 7mmol/l if you follow the WHO criteria, as recommended by Diabetes UK
- it is untrue that the “biggest improvements were seen with the biggest dosage”. Khan et al wrote:
At the levels tested, there was no evidence of a dose response because the response to all three levels of cinnamon was similar… After the subjects no longer consumed the cinnamon for 20 days, glucose levels were significantly lower only in the group consuming the lowest level of cinnamon. Glucose values in the three placebo groups were not significantly different at any of the time points. [Emphasis added.]
- despite having combed through the Khan paper several times, we are at a loss as to the source of the claims for over-effectiveness or hypoglycaemia.
Baker et al have performed an analysis of the 5 prospective RCTs (which typically provide a better quality of evidence than other types of study): Effect of cinnamon on glucose control and lipid parameters. In summary, a meta-analysis of several trials shows that cinnamon does not have a beneficial effect on the blood glucose or cholesterol levels of people with Diabetes Type I or II; this result holds true even for sub-groups.
Baker et al conducted a systematic literature search for all placebo-controlled, RCTs of cinnamon and its effects on A1C, fasting blood sugars or lipid parameters for diabetics. Unsurprisingly, and despite the intense marketing of cinnamon’s supposedly remarkable properties, they discovered only 5 suitable clinical trials, involving a total of 282 diabetics. The trials lasted a median of 3 months. Although this duration was not enough for the full effects on A1C to manifest, if a clinical benefit truly existed, it was long enough to have observed notable changes in A1C over this time or a positive trend, had one existed.
Instead, A1C levels increased to a greater extent with cinnamon than with placebo in our meta-analysis, thus reducing our confidence in cinnamon’s impact on long-term glycemic control.
None of the trials reported significant changes in the usual critical biomarkers for diabetics such as A1c; the fasting blood glucose levels (FBG); or the breakdown of cholesterol levels. The results held true for both diabetes Type I and Type II; they were also true for all of the sub-groups analyses that looked to identify any group of people for whom there might be some benefit. The authors conclude:
In this meta-analysis of five randomized placebo controlled trials, patients with type 1 or type 2 diabetes receiving cinnamon did not demonstrate statistically or clinically significant changes in A1C, FBG, or lipid parameters in comparison with subjects receiving placebo… Cinnamon does not appear to improve A1C, FBG, or lipid parameters in patients with type 1 or type 2 diabetes.
Baker at al address the issue of the Khan results that are out of line with the results from the other trials.
We cannot determine the reason for differences between the Khan study and the others. Ethnicity or cultural dietary differences, dose, lack of verification of double blinding, or chance resulting from small sample size in the Khan study could explain the disparate findings.
Baker et al express some appropriate reservations about the statistical power of their meta-analysis because of the small number of published studies and trial participants. However, it might be argued that the same rigorous standard should apply to establishing the level of scientific support for a supplement before its availability on the market. The authors also caution that:
[e]ven if the beneficial changes observed in some of [the] end points were found to be statistically significant, their clinical significance could still be debated.
There have been some studies on cinnamon (not necessarily RCTs or placebo-controlled) but few on continuous rather than experimental use and even fewer involving healthy people rather than those with Type 2 diabetes. E.g., Hlebowicz et al investigated healthy subjects: Effect of cinnamon on postprandial blood glucose, gastric emptying, and satiety in healthy subjects . The results indicate that cinammon supplementation delayed gastric emptying but did not affect satiety; the quantities involved were 6g of cinnamon for a 300g serving of rice pudding. There was a reduction in the blood sugar response after eating this meal; however, it would be disproportionately optimistic to construct an argument for general use of a supplement based on this limited experiment that involved 14 people.
There is no substantial evidence to support chromium supplementation for the people with Type 2 diabetes, far less the general population. Cinnamon may have its uses as a spice but it is premature at best to recommend it for use by either the general population or people with Type 2 diabetes. It is difficult to understand why Holford would argue that there is scientific support for his Cinnachrome formulation. Given the dearth of scientific or clinical evidence, it is unfortunate that he continues to market this as a product to “support natural blood sugar balance” whether or not somebody is on a low GL diet or actually diabetic.
Unlike Holford, Holford Watch feels unable to pronounce on the magical properties of supplements, however, our strongest feeling is that Holford fails to make any sort of case for such a claim.
 Balk EM, Tatsioni A, Lichtenstein AH, Lau J, Pittas AG. Effect of chromium supplementation on glucose metabolism and lipids: a systematic review of randomized controlled trials. Diabetes Care. 2007 Aug;30(8):2154-63.
 Kleefstra N, Houweling ST, Bilo HJ Effect of chromium supplementation on glucose metabolism and lipids: a systematic review of randomized controlled trials. (Letter) Diabetes Care. 2007 Sep;30(9):e102.
 Anderson RA, Cheng N, Bryden NA, Polansky MM, Cheng N, Chi J, Feng J. Elevated intakes of supplemental chromium improve glucose and insulin variables in individuals with type 2 diabetes. Diabetes. 1997 Nov;46(11):1786-91.
 Balk E, Lichtenstein A, Pittas AG. Effect of chromium supplementation on glucose metabolism and lipids: a systematic review of randomized controlled trials. (Authors’ Response) Diabetes Care 2007 Sep 30(9):e103.
 Rabinovitz H, Friedensohn A, Leibovitz A, Gabay G, Rocas C, Habot B: Effect of chromium supplementation on blood glucose and lipid levels in type 2 diabetes mellitus elderly patients. Int J Vitam Nutr Res. 2004;74:178–182.
 Blevins SM, Leyva MJ, Brown J, Wright J, Scofield RH, Aston CE. Effect of cinnamon on glucose and lipid levels in non insulin-dependent type 2 diabetes. Diabetes Care. 2007 Sep;30(9):2236-7.
 Khan A, Safdar M, Ali Khan MM, Khattak KN, Anderson RA. Cinnamon improves glucose and lipids of people with type 2 diabetes. Diabetes Care. 2003 Dec;26(12):3215-8.
 Baker WL, Gutierrez-Williams G, White CM, Kluger J, Coleman CI. Effect of cinnamon on glucose control and lipid parameters. Diabetes Care. 2008 Jan;31(1):41-3.
 Hlebowicz J, Darwiche G, Björgell O, Almér LO. Effect of cinnamon on postprandial blood glucose, gastric emptying, and satiety in healthy subjects. Am J Clin Nutr. 2007 Jun;85(6):1552-6.