Last updated by Dr Sarah Brewer on
Cinnamon is an aromatic spice derived from the inner bark of a small tree. True cinnamon (Ceylon cinnamon or Sri Lankan cinnamon) comes from Cinnamomum verum (previously known as Cinnamomum zeylanicum) but most commercial cinnamon comes from Cinnamomum cassia, a related species (known as Dutch cinnamon or baker’s cinnamon). Cassia cinnamon has a sweeter, less over-powering flavour but can be bitter when used in excess.
Apart from its use in the kitchen, cinnamon benefits mostly relate to its effects on glucose control and type 2 diabetes. Cassia cinnamon appears to be most effective for medicinal use.
Cinnamon and diabetes
Cinnamon has a long history of use in Chinese medicine for treating metabolic syndrome and type 2 diabetes. Cinnamon appears to work by reducing insulin resistance to improve the uptake of glucose into muscle and fat cells, and to reduce the production of new glucose in the liver.
Cinnamon bark contains unique, antioxidant polyphenols which activate insulin receptors so they respond to insulin hormone more effectively. Several studies show that taking cinnamon extracts can reduce average fasting glucose levels, triglycerides and LDL-cholesterol compared with placebo, without causing adverse effects.
The results from 10 trials, involving 543 patients showed that taking cinnamon at doses of at least 120mg (and up to 6g) per day, for at least 4 weeks, significantly reduced fasting blood glucose levels (by an average of 24.59mg/dL), total cholesterol (by 15.60 mg/dL), ‘bad’ LDL-cholesterol (by 9.42mg/dL) and triglycerides (by 29.59mg/dL) compared with inactive placebo.
At the same time, cinnamon increased levels of ‘good’ HDL-cholesterol (which protects against heart disease) by 1.66mg/dL. In some studies, but not all, cinnamon produced improvements in haemoglobin A1c, which measures how well glucose levels have been controlled over the previous 12 weeks. The most likely explanation is that some studies were of too short a duration to produce a significant response. Even so, the improvements in glucose levels were similar to those seen with some medications used to treat type 2 diabetes (eg sitagliptin) although not as good as those seen with the drug, metformin.
Four studies achieved the American Diabetes Association treatment goals in reducing fasting blood glucose levels and/or HbAlc <7.0 and the researchers concluded that adding cinnamon supplements to standard hypoglycemic medications and other lifestyle therapies had modest effects. However, they added that until larger, more rigorous studies are available, people with diabetes should continue to follow existing recommendations on diet, lifestyle changes, and continue to take their hypoglycaemic drugs.
If you are having difficulty achieving good control of your type 2 diabetes with medicines alone, however, adding in a cinnamon supplement is worth trying if your doctor agrees. If nothing else cinnamon can improve your cholesterol and triglyceride levels.
Cinnamon tea and glucose tolerance
Cinnamon tea is traditionally used to improve glucose levels after eating.
One study also investigated the effect of drinking cinnamon tea on blood glucose levels in 30 adults without diabetes.
The cinnamon tea was made by soaking 60g cinnamon sticks in a litre of water for 24 hours at room temperature, and then heating to 100 degrees for 30 minutes before filtering.
After an overnight fast, volunteers were asked to drink a 100ml dose immediately after 75g glucose solution as part of a glucose tolerance test.
In those drinking the cinnamon tea, there was a significant reduction in glucose levels, even though the volunteers did not have diabetes.
You can see this effect in the graph where the line with square markers (those taking cinnamon) stays below the line with round markers representing the controls (who did not take cinnamon) throughout the two hours of blood glucose testing.
This is important, as the glucose spike occurring after eating can damage artery linings even in people who normally have good glucose control.
If cinnamon blunts the rise in glucose seen after eating in people without diabetes, it may help those with diabetes, too.
If you like the flavour of cinnamon it’s certainly worth drinking cinnamon tea after a meal if you have metabolic syndrome (prediabetes) or type 2 diabetes for the beneficial effects on blood fat levels, too.
Best cinnamon dose
Researchers have found that doses of 3g cinnamon per day produce a significant reduction in insulin secretion, while 1g has no significant effect. The usual recommended dose is therefore 1g three times a day.
Some cinnamon supplements contain concentrated extracts so that a lower dose is required (eg 200mg extracts equivalent to 1000mg cinnamon).
Do not exceed manufacturer’s stated dose as cinnamon is toxic in excess. Select cinnamon extracted from Cinnamomum cassia, as Cinnamomum verum (also known as Cinnamomum zeylanicum) does not appear to be effective.
NB If you have diabetes, always keep a close eye on your glucose control when taking a supplement. Check with your doctor first, and ensure you know how to adjust your medication if needed.
Chromium picolinate supplements can also improve glucose control.
Click here to read my review of Ayurvedic herbal medicines used to treat type 2 diabetes.
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