Monday, August 9, 2010

Cinnamon and Vitamin-D

I don't usually blog on treatments for type-1 diabetes, but these two come up every now and then, and so I looked up the clinical trials for Cinnamon and also for Vitamin-D:

Studies of Cinnamon

Every now and then I hear about cinnamon helping diabetics, so I did a search for studies done on humans that gave cinnamon to people with type-1 diabetes.  There was only one.  You can read the whole paper here:
The clinical trial record is here:
Here is the important bits from the abstract (numbers removed):
RESULTS— There were no significant differences in final A1C, change in A1C, total daily insulin intake, or number of hypoglycemic episodes between the cinnamon and placebo arms.
CONCLUSIONS— Cinnamon is not effective for improving glycemic control in adolescents with type 1 diabetes.
I don't have any discussion to add to this.  One study is one study, and this one is clearly negative.

Status of Vitamin-D
There is sometimes discussion of Vitamin-D as a possible type-1 prevention or cure.  So I looked for human trials of vitamin D in people with type-1 diabetes.  I found six (listed below); two are complete, two are still recruiting, one was only looking a vascular side-effects and the last was the ongoing Haller cord blood study (where they also gave vitamin D and Omega-3s).  Below are quotes from the abstracts of the completed studies:
RESULTS: No significant differences were observed between calcitriol [vitamin-D] and nicotinamide groups in respect of baseline/stimulated C-peptide or HbA1c 1 year after diagnosis, but the insulin dose at 3 and 6 months was significantly reduced in the calcitriol [vitamin-D] group. CONCLUSIONS: At the dosage used, calcitriol [vitamin-D] has a modest effect on residual pancreatic beta-cell function and only temporarily reduces the insulin dose.
RESULTS: Safety assessment showed values in the normal range in nearly all patients, regardless of whether they received 1,25(OH)(2)D(3) [vitamin-D3] or placebo. No differences in AUC C-peptide, peak C-peptide, and fasting C-peptide after a mixed-meal tolerance test between the treatment and placebo groups were observed at 9 and 18 months after study entry, with approximately 40% loss for each parameter over the 18-month period. A1C and daily insulin requirement were similar between treatment and placebo groups throughout the study follow-up period. CONCLUSIONS: Treatment with 1,25(OH)(2)D(3) [vitamin-D3]at a daily dose of 0.25 microg was safe but did not reduce loss of beta-cell function.
So basically, one study found slight benefit and the other one found no benefit.

It is important to remember that both of these studies involved giving vitamin-D to people who already had type-1 diabetes.  Neither of these studies address the question of preventing type-1 diabetes by raising the overall level of vitamin-D prior to diagnosis.  That question is complex, and deserves it's own blog posting.  (If I have time.)  As a quick summary, I think it is fair to say that people who live nearer the equator are less likely to get type-1 diabetes than people who live nearer the poles.  Some have attributed this to the higher levels of sunlight and vitamin-D in those places, but there are many differences between people who live near the equator as compared to the poles: genetics are different, poverty is different, lifestyle is different, diet is different, etc.  So I don't find these sorts of population based studies very convincing.   A few studies which compare different populations within the same country do support the idea that vitamin-D lowers the rates of type-1 diabetes, but there are also studies that don't support this idea.   I don't think the correct answer is obvious at this time.

In general, I think it is a big mistake to compare populations in different countries (no matter what is being studied).  It is often a classic "apples vs. oranges" comparison mistake.  In the Americas (for example), this argument boils down to the idea that Canadians and Americans have a much higher type-1 diabetes rate than Mexicans.  However, there are many huge differences between Mexico and the other two countries, and to focus on vitamin-D as the cause requires more data than just the country vs. country comparison.  On the other hand, across the Atlantic the comparison boils down to high rates of type-1 diabetes in Europe compared to low rates in Africa.  Again: these are very different places!  Therefore, I do not think that comparing type-1 rates in different countries will ever provide enough support to the idea that vitamin-D has an impact on these rates.  I would limit my research to comparisons of similar populations within one country (or possibly in similar countries such as Canada vs. USA or different Nordic countries). 

Here are abstracts for the two that are complete:

Here are the clinical trial records (first two are complete, rest still recruiting):

Joshua Levy
All the views expressed here are those of Joshua Levy, and nothing here is official JDRF or JDCA news, views, policies or opinions. 

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