1 December 2007

News Briefs

Cuppa tea anyone?
‘There is no trouble so great or grave that cannot be much diminished by a nice cup of tea’ so the saying goes. Now it looks like that very same cuppa may help quell blood glucose spikes. A one gram cup of black tea may have the potential to stimulate an insulin response and reduce blood glucose levels, report Judith Bryans and colleagues from King's College London and the University of Central Lancashire in the Journal of the American College of Nutrition. Their findings suggest that black tea could blunt blood glucose spikes, keeping the body's blood glucose levels relatively steady throughout the day. They recruited 16 healthy volunteers for a randomised, crossover study and assigned them 75 grams of glucose in either 250 ml of water (control), 250 ml of water plus 0.052 g of caffeine (positive control) or 250 ml of water plus 1.0 gram (1½ teaspoons) of instant black tea. For the first hour after drinking the beverages the glucose concentrations did not differ much at all among the volunteers. However, after two hours tea drinkers’ glucose levels were significantly reduced compared with the controls. Tea drinking also showed elevated insulin concentrations at 1½ hours compared to the controls – the likely reason for the observed decrease in blood glucose levels. In a cautious conclusion the researchers point out that: ‘the physiological effects … were relatively small and were achieved under test conditions. Under normal tea drinking conditions before or after food, the presence of other phenolic compounds could potentially alter, or even enhance, the effects seen in our study.’
Journal of the American College of Nutrition, 26 (5), 2007

[TEA]

Veggie fibre does it
If you want to reduce your risk of diabetes, eat a low GI diet and tuck into your veggies (especially legumes) say University of Sydney researchers writing in the November edition of Diabetes Care. The study which tracked more than 2,100 Australians over 10 years found that veggie fibre offers more protection against diabetes than fruit or cereal fibre reducing the risk of developing type 2 diabetes by 24%. Diets high in fruit or cereal fibre weren’t nearly as beneficial. In a separate analysis of people aged less than 70 years, diets with a high GI increased their risk of developing type 2 diabetes by 75%, compared with those eating a low GI diet.

Talking to GI News, the study leader, Alan Barclay, said: ‘vegetables, and legumes in particular, were probably delivering the best results because they were an ideal source of intact or natural fibre. Legumes like beans, lentils and chickpeas and vegetables like sweet corn, carrots and peas are eaten whole with their dietary fibre intact, which means they actually encapsulate the carbohydrate in the food. They therefore slow down the rate of digestion and absorption and have good flow-on glycemic effects on blood glucose. Cereal fibre was not so effective because it is now often added to products, rather than eaten in a natural form. And while fresh fruit fibre is often eaten intact, people probably just did not get enough from the fruit they eat to show a benefit.’
Diabetes Care, Vol 30, No 11, November 2007

[FIBRE TABLE]
Source: Ontario Beans

What about fibre and GI?
Dietary fibre is not one chemical constituent like fat and protein. It is composed of many different sorts of molecules and can be divided into soluble and insoluble types. The effect of fibre on a food’s GI depends on the type of fibre. Soluble fibres are the gel, gum and often jelly-like components of foods like oats, legumes and apples. Soluble fibre can lower your body’s glycemic response to a food by slowing down the time it takes for food to pass through the stomach and small intestine. Insoluble fibres are dry and bran-like and often referred to as roughage. All cereal grains and products made from them that retain the outer coat of the grain are sources of insoluble fibre. But not all foods containing insoluble fibre are low GI. Why? Insoluble fibres will only lower the GI of a food when they exist in their intact, original form, for example in whole grains of wheat. Here they act as a physical barrier, delaying access of digestive enzymes and water to the starch within the cereal grain.

Why do some high fibre foods have a low GI and not others?
Many processed grain foods that are rich in fibre such as wholemeal bread have a high GI. Why? It all comes down to the physical state of the fibre and the starch in the food. When wheat fibre has been finely divided as it is in wholemeal bread or breakfast cereals, it does little for either constipation or blood glucose levels. That’s why we say to choose your carbs carefully, and if your favourite wholegrain food has a high or moderate GI, combine it with a low GI food to reduce the glycemic load of your meal or snack.

[HIGH FIBRE]

The jury’s still out on cinnamon
Lab research has suggested that cinnamon (Cinnamomum cassia) may make body cells more sensitive to insulin. Some small studies have also shown that cassia cinnamon can reduce the blood glucose rise after eating. But it's too soon to recommend people with diabetes tuck into this spice and think it will steady their blood glucose levels naturally, according to researchers from University of Oklahoma in September Diabetes Care. In this latest study, 43 adults with type 2 diabetes were randomly given either cinnamon capsules or a placebo every day for three months. The cinnamon group took two capsules a day, each of which contained 500 milligrams of the spice. The placebo group took capsules containing wheat flour. In the end, there were no significant differences in glucose, cholesterol, A1C or insulin levels according to the researchers led by Dr Steve M. Blevins.

The reason for the conflicting findings from this and earlier studies may have to do with differences in the study groups according to Blevins and his colleagues. Most of the volunteers in the current study, for example, were on various diabetes drugs; in Khan’s 2003 study that found cinnamon reduced blood glucose levels, none of the participants were on any of these drugs. The researchers conclude that we need more studies to see whether factors such as diet, ethnicity, BMI, glucose levels, cinnamon dose and concurrent medication might affect cinnamon responsiveness. ‘Until then,’ they conclude, ‘cinnamon cannot be generally recommended for treatment of type 2 diabetes in an American population.’
Diabetes Care 30:2236-2237, 2007

[CASSIA]

10 comments:

Anonymous said...

Regarding the use of cinnamon to reduce glucose levels, I use 1/4 to 1/2 teaspoon of cinnamon when I have eaten an "illegal" food, i.e., cookies, cake, pie, white bread, fries, etc. I know I should not eat those foods, but sometimes I do. A 1/2 teaspoon of cinnamon works wonders in reducing blood glucose levels almost immediately.
If I take my medication, Metformin, and then test 1 or 2 hours later and the glucose is still high I take 1/4 tsp. The glucose is reduced. So far, I have not gotten into the trouble of my glucose going too low.

Anonymous said...

I take 1000 mg twice a day in capsule form. I find that while it wasn't a drastic reduction it did reduce my glucose level. I don't particulary watch the carbs I ingest and while my glucose runs between 150 and 210 after fasting overnight my A1C is always within the acceptable range. I also take glipizide twice a day and Metformin once daily.

Cath said...

Cassia and cinnamon are actually quite different spices, and as I recall, the study was actually done on cassia, not true cinnamon.

The American spice commonly called cinnamon is usually actually cassia. This is also known as "Bakers cinnamon". However, the picture shown here at GI news is of "true" cinnamon quills, not cassia at all. That is NOT the relevant spice.

So beware! If you have whole spices, you can look at the pictures on wikipedia to see the difference. Cinnamon quills have many layters, cassia is more solid. Also, cassia has more of a "hot" flavour to it.

Anonymous said...

Re: soluble fiber slowing down the time for food to pass through the stomach/small intestine... I am confused about the semantics of this sentence. Does soluble fiber accelerate or impede transit time?

Anonymous said...

>>>Cinnamon quills have many layters, cassia is more solid.

Thanks for pointing this out. The picture now reflects the more thick-barked cassia.

GI Group said...

Soluble fibre slows down transit time.

Anonymous said...

Re tea - I'm not convinced that I want extra insulin sloshing around. I'm pretty sure that as a T2 diabetic my current problem is insulin resistance, not production. What I need is a drink that reduces insulin resistance, or speeds up glucose transport into cells. Any suggestions?

GI Group said...

When you are thirsty the best drink is water and most of us don't drink enough of the stuff. It's free and has no kilojoules. If you want something hot, why note check out some of the delicious herbal and fruit/berry teas around.

Anonymous said...

My understanding from the research I've read is that the daily cinnamon dose has to be in the 3-4 gram range (3,000-4,000 mg). That's six-eight 500 mg capsules. At lower doses, the cinnamon doesn't reach efficacy on helping control BG levels.

GI Group said...

We have written about cinnamon a few times in GI News (use our Google search facility to check out the previous stories.). In the most recent (December 2007) we reported on a study published in Diabetes Care (30:2236-2237, 2007) that came to the conclusion that the jury’s still out on whether cinnamon (Cinnamomum cassia) makes the body cells more sensitive to insulin. Here’s a summary:
“Some small studies have shown that cassia cinnamon can reduce the blood glucose rise after eating. But it's too soon to recommend people with diabetes tuck into this spice and think it will steady their blood glucose levels naturally, according to researchers from University of Oklahoma in September Diabetes Care. In this latest study, 43 adults with type 2 diabetes were randomly given either cinnamon capsules or a placebo every day for three months. The cinnamon group took two capsules a day, each of which contained 500 milligrams of the spice. The placebo group took capsules containing wheat flour. In the end, there were no significant differences in glucose, cholesterol, A1C or insulin levels according to the researchers led by Dr Steve M. Blevins.

The reason for the conflicting findings from this and earlier studies may have to do with differences in the study groups according to Blevins and his colleagues. Most of the volunteers in the current study, for example, were on various diabetes drugs; in Khan’s 2003 study that found cinnamon reduced blood glucose levels, none of the participants were on any of these drugs. The researchers conclude that we need more studies to see whether factors such as diet, ethnicity, BMI, glucose levels, cinnamon dose and concurrent medication might affect cinnamon responsiveness. Until then, they write, cinnamon cannot be generally recommended for treatment of type 2 diabetes in an American population.”
– Diabetes Care