There's been much talk in research circles about cinnamon (Cinnamomum cassia), its possible health benefits and how the popular spice could perhaps help diabetics improve their blood-sugar control.
It's been suggested that chemical compounds in cinnamon called polyphenols might be responsible for the glucose-lowering effect.
Now, Nestle Nutrition Information Africa (NNIA, 2009) has reported on one of the latest studies to investigate the possible role of cinnamon in lowering blood-sugar levels.
Fifteen healthy subjects were either given 1g or 3g of cinnamon, added to rice pudding, after which a number of biochemical markers of insulin and blood-glucose control were monitored.
The Swedish team, lead by Joanna Hlebowicz (2009), found that the insulin response of the subjects was significantly lower after eating rice pudding to which 3g of cinnamon was added.
Most of the other markers were not affected. These included blood-glucose levels, gastric emptying (slower gastric emptying lowers blood-glucose and insulin levels), ghrelin concentrations (a hormone that's linked to appetite control) and satiety.
Hlebowicz and co-authors concluded that consumption of 3g of cinnamon a day may improve people’s control of blood-glucose levels.
Early research with diabetics
In 2006, a Dutch team of scientists at Maastricht University (Vanschoonbeek et al, 2006) studied the effect of using 1.5g of cinnamon per day in post-menopausal women with type 2 diabetes.
In view of findings of animal studies, which showed that cinnamon has strong insulin-like or insulin-potentiating effects, the researchers set out to determine if they could produce the same beneficial effects in diabetic women.
Twenty-five women in their 60s, with average BMIs of about 30 (overweight to obese) and type 2 diabetes mellitus, were either given 1.5g of cinnamon per day or a placebo (dummy medication) for a period of six weeks.
The researchers could find no improvements in insulin sensitivity or glucose tolerance and the blood-fat profiles of the people who had cinnamon also didn't improve. Consequently, the authors warned that “more research on the proposed health benefits of cinnamon supplementation is warranted before health claims should be made”.
Cinnamon in healthy subjects
Solomon and Blannin (2007), from the School of Sport and Exercise Sciences at the University of Birmingham, tested the effect of cinnamon in lean, healthy men. Although this study only used seven subjects, ingestion of 5g cinnamon – either immediately before or 12 hours before an oral glucose test – showed that the spice improved insulin sensitivity and reduced the blood-glucose reactions of the subjects by up to 13%.
These results also showed that the effect of cinnamon on blood glucose appears to be immediate and may last up to 12 hours.
A more recent study undertaken by these two authors (Solomon & Blannin, 2009) – this time with eight healthy male volunteers who ingested 3g of cinnamon or placebo a day for 14 days – also obtained positive results. The men had lower blood-glucose and insulin responses from the start of the study, and by day 14 their insulin sensitivity had also improved.
However, these improvements were lost once cinnamon supplementation was stopped.
Cinnamon and chromium
A paper published by Anderson in 2008 suggested that there are certain compounds that can be used to improve insulin sensitivity and control blood-sugar levels. Two of these compounds are chromium and the polyphenols in cinnamon.
Anderson pointed out that chromium supplementation can improve glucose, insulin and other markers of diabetes, as well as cholesterol levels. Cinnamon reduced average fasting glucose levels by up to 29% and serum cholesterol by as much as 27% in type 2 diabetics who had 1g to 6g of cinnamon a day for a period of 40 days.
This author does admit that not all studies conducted so far have obtained positive results and that there are a number of factors, such as the length of the treatment period, which may play a role.
The bottom line
Is cinnamon really a new and important treatment for diabetics and individuals with raised blood-fat levels, or have studies conducted to date not been rigorous enough to produce clear results?
NNIA (2009) points out that a meta-analysis of the presently available research results “found no significant benefits of cinnamon supplement on glycated haemoglobin (a diabetes marker), fasting blood glucose or other lipid [fat] parameters”.
It's therefore still too early to make recommendations. At this stage, nutrition experts aren't sure whether it's safe to recommend that diabetics or people with metabolic syndrome or raised blood-cholesterol levels should start taking large doses of cinnamon.
Ageless.co.za (Ageless, 2009), a website that generally has a sensible approach to herbal products, warns that cinnamon shouldn't be used by pregnant women or people who have gastric or duodenal ulcers. In addition, the website cautions that the use of cinnamon-containing essential oil may sensitise the skin and cause convulsions if used in large quantities.
My advice to anyone who is contemplating the use of cinnamon in large doses to treat diabetes, insulin resistance, overweight or raised blood-fat levels, is that they should tread cautiously.
Let’s wait until large, well-controlled scientific studies have determined whether cinnamon is a boon and exactly how much people would need to take on a daily basis to improve their blood-sugar, insulin or lipid levels.
It may also not be so easy to take 6g of cinnamon daily and we don’t yet know what side effects can be expected.
In the meantime, use a low-glycaemic-index (GI) diet to keep your blood-sugar and insulin levels under control, and cut down on your fat intake to lower you blood-lipid levels or to lose weight. Enjoy cinnamon with puddings, pancakes and other foods in moderate quantities.
(Dr I.V. van Heerden, DietDoc, March 2009)
Any questions? Ask DietDoc
(Ageless (2009).Cinnamon. www.ageless.co.za ; Anderson RA (2008). Chromium and polyphenols from cinnamon improve insulin sensitivity. Proc Nutr Soc, 67(1):48-63; Hlebowicz J et al (2009). Effects of 1 and 3 g cinnamon on gastric emptying, satiety, and postprandial blood glucose, insulin, glucose-dependent insulinotropic polypeptide, glucagon-like peptide 1, and ghrelin concentrations in healthy subjects. Am J Clin Nutr, 89(3):815-21; NNIA (2009). Cinnamon may improve blood sugar levels. ww.nnia.org/en.nestle-company/2009; Solomon TP, Blannin AK (2007). Effects of short-term cinnamon ingestion on in vivo glucose tolerance. Diabetes Obes Meta, 9(6):895-901; Solomon TP, Blannin AK (2009). Changes in glucose tolerance and insulin sensitivity following 2 weeks of daily cinnamon ingestion in healthy humans. Eur J Appl Physiol, [Epub ahead of printing]; Vanschoonbeek K et al (2006) Cinnamon supplementation does not improve glycemic control in postmenopausal type 2 diabetes patients. J Nutr, 136(4):977-80.)