The common spice cinnamon describes the dried inner bark of several species from the genus Cinnamomum (most commonly C. zeylanicum and C. cassia). As a spice, both its smell and taste are easily recognizable. Medicinally, it has been used as a carminative, stomachic, and antiseptic.
Cinnamon oils as well as powders are available. Bark preparations from both species are "Approved" by the German Commission E for the gastrointestinal complaints described above.
As a spice, cinnamon may be added to many formulations. Very often, cinnamon is used to settle the stomach or in a formulation specifically for yeast or other chronic intestinal complaints.
More recently, cinnamon has been recognized as having anti-fungal and anti-microbial activity.
Another kitchen medicinal remedy uses cinnamon. Bring 4 cups of water to a boil, add 8-10 broken sticks of cinnamon, reduce heat to low and simmer for five minutes; remove and steep, covered, for 45 minutes. Use as a foot bath. Cinnamon effectively combats both yeast and fungal infections.
New Scientist reported in November, 2003 a study that found just half a teaspoon of cinnamon a day significantly reduces blood sugar levels in diabetics. The effect, which can be produced even by soaking a cinnamon stick tea before drinking, could also benefit millions of non-diabetics who have blood sugar problem but are unaware of it.
The discovery was initially made by accident by Dr. Richard A. Anderson, lead scientist at the at the US Department of Agriculture's Human Nutrition Research Center in Beltsville, Maryland. "We were looking at the effects of common foods on blood sugar," he told New Scientist. One was the American favorite, apple pie, which is usually spiced with cinnamon. "We expected it to be bad. But it helped," he says.
Dr. Anderson explained that his research shows that a compound in cinnamon called methylhydroxy chalcone polymer (MHCP) makes fat cells more responsive to insulin by activating an enzyme that causes insulin to bind to cells and inhibiting the enzyme that blocks this process.
It seems that cinnamon may help lower blood sugar levels and thereby combat diabetes by imitating the effects of insulin and increasing glucose transport into cells [J Am Coll Nutr. 2001 Aug;20(4): pp.327-36]. It can also lower blood sugar levels by increasing insulin sensitivity, making insulin more efficient at moving glucose into cells.
One study of seven men showed taking cinnamon increased insulin sensitivity immediately after consumption, with the effect lasting at least 12 hours [Diabetes Obes Metab. 2007 Nov;9(6): pp.895-901]. In another study, eight men demonstrated increases in insulin sensitivity following two weeks of supplementing with cinnamon [Eur J Appl Physiol. 2009 Apr;105(6):969-76].
A review of 543 people with type 2 diabetes found that taking cinnamon was associated with an average fasting blood sugar level decrease of over 24 mg/dL (1.33 mmol/L) [Ann Fam Med. 2013 Sep; 11(5): 452-459].
Further studies have found that cinnamon can help reduce harmful after-meal blood sugar spikes. The mechanism is not clear, but is thought that cinnamon either slows stomach emptying and/or blocks digestive enzymes in the small intestine that break down carbohydrates.