GI News - January 2021

 

GI News is published by the University of Sydney, School of Life and Environmental Sciences and the Charles Perkins Centre, and delivered to the mailboxes of our 97,000 subscribers. Our goal is to help people choose the high-quality carbs that are digested at a rate that our bodies can comfortably accommodate and to share the latest scientific findings on food and diet with a particular focus on carbohydrates, dietary fibres, blood glucose and the glycemic index.

Publisher: Professor Jennie Brand-Miller, AM, PhD, FAIFST, FNSA, PhD
Editor: Alan Barclay, PhD, APD
Contact GI News: glycemic.index@gmail.com

Sydney University Glycemic Index Research Service
Manager: Fiona Atkinson, PhD, APD
Contact: sugirs.manager@sydney.edu.au

Like us on
Follow us on

FOOD FOR THOUGHT

RICE AND RISK OF TYPE 2 DIABETES
Around the world, the prevalence of type 2 diabetes continues to climb. The rate of increase is particularly high in countries such as China and India, the most populous nations on the planet. China and India are also similar in the sense that rice is their staple food. Although there have been changes in lifestyle, nutrition and physical activity, rice remains a favourite food. Indeed, rice provides about 20% of all calories eaten globally. White rice is still preferred over brown rice, but there have also been more subtle changes in milling and polishing that have altered the inherent nutritional properties of rice. 

 A long time ago, I recall reading a magazine article about the many different varieties of rice. Even though I had already devoted 4 years to training in Food Science, I was amazed to learn that ordinary people distinguished between different types of rice, favouring one versus another, depending on the cuisine. To me, at that time, rice was rice! I learned that some people liked Jasmine best - the grains were fluffy and slightly sticky. They clumped together, making them ideal for eating with chopsticks. Other varieties such as Basmati were not at all sticky and individual cooked grains could be picked out one at a time. Basmati was the favourite for curries and other Indian dishes. 

Today, we can find many varieties of rice on supermarket shelves, including short grain, long grain, medium grain, Arborio (ideal for making risottos) and sushi rice (short-grain Japanese rice) for making sushi. There’s also black rice, red rice, wild rice and Doongara (Clever Rice™) – a new variety developed in Australia to compete with Basmati. 

One of the first research projects that I was to carry out as a scientist was on the GI of different rices sold in Australia. We compared 10 different rice products – 3 were commercial rices with different levels of amylose starch, a waxy variety with only 2% amylose, a converted (parboiled) rice, a quick cooking brown rice, puffed rice cakes, rice pasta and rice bran. Amylose starch is a straight-chain molecule that lines itself in rows, making it more difficult to gelatinise than the other form of starch called amylopectin. Higher temperature and more water is needed to cook high amylose varieties of rice. 

The GI values varied, ranging from medium to high on a scale where glucose = 100. The low amylose Pelde variety gave the highest GI (93), while the high amylose rice gave the lowest GI (64). The quick-cooking brown rice also had a very high GI (80), as did the brown rice pasta (92). Interestingly, white rice and brown rice have similar GIs. It was the variety that was important, rather than the grain size, degree of milling or parboiling. 

So here once again, the GI concept turned conventional nutrition wisdom on its head. It was wrong to automatically assume that a brown rice would have a lower GI than white varieties. 

In November 2020, the prestigious journal Diabetes Care, carried a paper and editorial about the link between eating rice in large amounts and the risk of developing type 2 diabetes. The PURE study was an observational study in over 130,000 individuals from 21 countries. On average, people were followed-up for 10 years, during which time just over 6000 developed diabetes. 

The authors found that those who ate more than 450 g per day (that’s around 2.5 cups of cooked rice) were more likely to have a diagnosis than those who consumed less than 150 g per day (less than 1 cup). In scientific wording, their risk was 20% more. 

However, people from South Asia (India) were substantially (60%) more likely to have developed diabetes when rice was eaten in large amounts. People from South East Asia, the Middle East, South America and Africa were also more at risk, but not as much as those from South Asia. Surprisingly, there was no association between the amount of rice consumed in China and the risk of diabetes. 

These mixed findings are difficult to explain on the grounds of differences in GI alone. We know that a diet with a higher GI and glycemic load will increase the risk of type 2 diabetes, but in the PURE study, the lower GI variety (Basmati) is associated with more diabetes than the higher GI variety consumed in China. 

There are other possible explanations, e.g., the presence of toxic elements such as arsenic in rice grown in India. Also, some have interpreted the results of the PURE study as an indicator of a “poverty diet”, rather than nutrition. Most study participants located in low-income countries subsisted almost entirely on carbohydrates, “especially from refined sources.” A “poverty diet”, which is common in poor rural areas, is also typically high in sodium and low in animal products and vegetable oils. In this situation, it is extremely challenging if not impossible to separate the effects of diet from poverty and undernutrition. 

Indeed, the South Asian (Indian) diet is higher in saturated fat (ghee is a popular cooking fat) that increases insulin resistance and the demand for insulin secretion. Over time, insulin resistance worsens, and the beta-cells eventually fail, despite the rices lower GI. Moreover, in China, the alternative to high GI rice is a large range of wheat products (including bread and dumplings) that also have a high GI. 

And finally, as I often say to my students and colleagues, nutrition science is still very young, it’s very complex and we have lots to learn. 

Read more: 

• White Rice Intake and Incident Diabetes: A Study of 132,373 Participants in 21 Countries 
• PURE study makes headlines, but the conclusions are misleading 
• Dietary Glycemic Index and Load and the Risk of Type 2 Diabetes: A Systematic Review and Updated Meta-Analyses of Prospective Cohort Studies 

      
Professor Jennie Brand-Miller holds a Personal Chair in Human Nutrition in the Charles Perkins Centre and the School of Life and Environmental Sciences, at the University of Sydney. She is recognised around the world for her work on carbohydrates and the glycemic index (or GI) of foods, with over 300 scientific publications. Her books about the glycemic index have been bestsellers and made the GI a household word.

WHAT’S NEW?

WHOLEGRAINS AND RISK OF DIABETES
A new study published in the British Medical Journal has found that a higher intake of wholegrains is associated with a lower risk of developing type 2 diabetes. 

 Researchers combined the findings from three large prospective cohort studies – the Nurses’ Health Study, The Nurses’ Health Study 2 and the Health Professionals Follow-Up Study. Together, they included 158,259 women and 36,525 men who did not have type 2 diabetes, cardiovascular disease, or cancer when the studies began. Participants completed a dietary questionnaire at the start of the study and every four years, and another questionnaire to identify newly diagnosed type 2 diabetes and other health conditions every two years. The average follow-up period was 24 years. 

In this study, the researchers looked specifically at intake of total and individual whole grain foods and the risk of type 2 diabetes. 

After adjusting for other lifestyle and dietary factors which might affect diabetes risk, participants with the highest intakes of wholegrains had a 29% lower risk of type 2 diabetes compared to those with the lowest intakes. 

The researchers also looked at specific wholegrains including wholegrain breakfast cereals, wholegrain breads, oatmeal and brown rice. People who ate 1-2 serves of wholegrain cereal or breads per day had around a 20% lower risk of developing diabetes compared to those who ate these foods less than once per month. And those who ate oatmeal or brown rice once or twice per week had a 21% and 12% lower risk, respectively, than those who ate these foods less than once per month. Physical activity, family history of diabetes and smoking status didn’t affect the findings but the association between wholegrain intake and diabetes risk was stronger in those who were lean compared to those carrying excess weight. 

These findings are consistent with previous studies showing a lower risk of type 2 diabetes associated with wholegrain, but not refined grain, intake. When it comes to rice, previous research has found that higher intakes of white rice were associated with an increased risk of type 2 diabetes and it was estimated that replacing 50g (uncooked) per day of white rice with brown rice could reduce diabetes risk by 16%. 

Read more: 

• Hu Y, and colleagues. Intake of whole grain foods and risk of type 2 diabetes: results from three prospective cohort studies. BMJ. 2020. 
• Sun Q, and colleagues. White rice, brown rice, and risk of type 2 diabetes in US men and women. Arch Intern Med. 2010. 
• Aune D, and colleagues Whole grain and refined grain consumption and the risk of type 2 diabetes: a systematic review and dose-response meta-analysis of cohort studies. Eur J Epidemiol. 2013.

    
Kate Marsh is an is an Advanced Accredited Practising Dietitian, Credentialled Diabetes Educator and health and medical writer with a particular interest in plant-based eating and the dietary management of diabetes and polycystic ovary syndrome (PCOS).    
Contact: Via her website www.drkatemarsh.com.au.

PERSPECTIVES: Dr ALAN BARCLAY

RICE: THE GO-TO GRAIN 

English translation: “Have you eaten rice?” 

This popular greeting used throughout East Asia is a reminder that traditionally food was scarce and people were often starving. Rice saved lives, so it’s not surprising that the word for “rice”, “food” and “meal” is one and the same in Chinese—and in many other parts of East Asia, too. 

 Those early farmers who planted the first seeds some 10,000 to 8,000 years ago in Southern China would be gobsmacked at the number of varieties that have evolved (more than 100,000 it is estimated) and at their colours (white, red, black), sizes, shapes, aromas, stickiness and starchiness. And at all the things we make with the grains from flour, noodles, and crackers to syrup, alcohol, oil and puffed breakfast cereals. 

In wok, pot or bowl or on a plate, rice soaks up the flavours from stocks and sauces and partners with meat, chicken, fish, seafood, tofu, vegetables, nuts, or fruit in snacks, soups, salads, sides, pilafs, paellas, risottos, desserts and more. 

WHAT TO LOOK FOR
Nutty-tasting brown rice with just the inedible hull removed is the rice with the serious nutritional wholegrain credentials. This is because it contains all parts of the grain — including the fibrous bran, the nutrient-rich germ and the starch-rich endosperm. Because of this, brown rice has more dietary fibre, antioxidants, vitamins and minerals than white rice. But it tends to be slow cooking. 

However, these days we can buy 2-minute microwave options to help get meals on the table fast. Refined, popular, palatable white rice is still an ok choice, especially when combined with lots of veg. For speedy meals rice noodles are good to have on hand. Look for lower-GI varieties. 

LOWER GI RICES - THE AMYLOSE FACTOR
The starch in raw food is stored in hard, compact granules that our bodies find hard to digest, which is why starchy foods usually need to be cooked. Water and heat expand the starch granules during cooking to different degrees; some actually burst and free the individual starch molecules (this is gelatinisation). Rice is a great grain for getting to know the starches in our foods— amylose and amylopectin. 

• Amylose is like a string of glucose molecules that tend to line up in rows and form tight, compact clumps that are harder to gelatinise and digest. The lower GI rices have a higher proportion of amylose.
• Amylopectin is a string of glucose molecules with lots of branching points, such as you see in some types of seaweed. Amylopectin molecules are larger and more open and the starch tends to be easier to gelatinise and digest. Higher GI rices have a higher proportion of amylopectin. 

Adapted from The Good Carbs Cookbook, by Dr Alan Barclay, Kate McGhie & Philippa Sandall. 

Published by Murdoch Books.

Alan Barclay, PhD is a consultant dietitian and chef (Cert III). He worked for Diabetes Australia (NSW) from 1998–2014 . He is author/co-author of nearly 40 scientific publications, and author/co-author of  The good Carbs Cookbook (Murdoch Books), Reversing Diabetes (Murdoch Books), The Low GI Diet: Managing Type 2 Diabetes (Hachette Australia) and The Ultimate Guide to Sugars and Sweeteners (The Experiment, New York).
Contact: You can follow him on Twitter, LinkedIn or check out his website.

DIABETES CARE

RICE AND THE MANAGEMENT OF DIABETES
Due in part at least to the current popularity of “low carb” diets, people with diabetes are often advised to at the very least severely limit, if not completely avoid rice. This is of course a major issue for people who traditionally eat rice for all of their main meals (breakfast, lunch and dinner), like many people from South and East Asia. For these people, complete avoidance is not really a long-term strategy for success, as it goes against their cultural and personal food preferences. What are the alternatives, if any? 

Portion caution
Cooked rice is indeed a concentrated source of starchy carbohydrate. As can be seen in this month’s “Your GI Shopping Guide”, a quarter of a Cup of most cooked rices provides around one carbohydrate exchange (12-18g carbohydrate per serve). While everyone with diabetes should see a dietitian for personalised advice, as a general guide, the carbohydrate recommendations for main meals for adults are: 

Men 45 – 60 grams of carbohydrate, or 3 – 4 exchanges 

Women 30 – 45 grams of carbohydrate, or 2 – 3 exchanges 

So, if you are going to continue to enjoy rice for breakfast, lunch and dinner, aim to have less than 1 cooked Cup at each meal. Bulk the meal out with non-starchy vegetables (e.g., alfalfa sprouts, asparagus, bean sprouts, bok choy, broccoli, Brussel’s sprouts, cabbage, capsicum, cauliflower, celery, chives, cucumber, eggplant, endive, garlic, green beans, kale, lettuce, leeks, marrow, mushrooms, okra, onions, radish, rocket, shallots, silverbeet, spinach, squash, tomatoes, watercress, and zucchini) and some lean protein (e.g., eggs, lean meat, seafood, skinless poultry or tofu). 

Swap it, don’t stop it
There are literally thousands of varieties of rice grown around the world. We have measured the GI of only a small portion of them. While many varieties have a high GI (>70), not all varieties do. Lower GI varieties are becoming increasingly available in both South and East Asia, to suit the culinary needs of the local population. See this month’s “Your GI Shopping Guide” for some more common examples and ideas. 

Glycemic load counts
The glycemic load (GL) is the amount of available carbohydrate (grams) in a serve of food, multiplied by its GI value (which is a percentage): 

GL = available carbohydrate per serve X GI value ÷ 100. 

Each unit of GL is equivalent to 1 gram of pure glucose – the sugar people measure in their blood with their home blood glucose meter when they have diabetes. So, by choosing the lower GI variety of your favourite rice, and eating it in smaller portions, you can potentially cut the glycemic impact of the rice you eat in half. 

Long-term success
For those people who have enjoyed eating rice for their main meals for most of their life, complete avoidance or severe restriction is not a recipe for long-term success. As the scientific evidence base shows us, many people can adhere to a “low carb” diet for 6 months, but most can’t for 12 months or more. It is therefore arguably better to enjoy a smaller amount of high-quality rice on a regular basis, than to try to avoid it. 

Read more: 

• Diabetes Australia: What should I eat 
• National Diabetes Services Scheme: Carbohydrate counting and diabetes 
• Effect of dietary carbohydrate restriction on glycemic control in adults with diabetes: A systematic review and meta-analysis

Alan Barclay, PhD is a consultant dietitian and chef (Cert III). He worked for Diabetes Australia (NSW) from 1998–2014 . He is author/co-author of more than 30 scientific publications, and author/co-author of  The good Carbs Cookbook (Murdoch Books), Reversing Diabetes (Murdoch Books), The Low GI Diet: Managing Type 2 Diabetes (Hachette Australia) and The Ultimate Guide to Sugars and Sweeteners (The Experiment, New York).
Contact: You can follow him on Twitter, LinkedIn or check out his website.

YOUR GI SHOPPING GUIDE

WHICH RICE?
Preparing this article on the GI of rice turned out to be way more difficult than I anticipated. There are literally hundreds of studies that have looked at the GI of rice and identified virtually as many GI values! I’ve chosen just a few varieties of rice to profile in this month’s shopping guide, and simplified the evidence, but if you would like to read more see the reference below. 

Generally, rice should be considered a medium to high GI food with the potential to contribute a significant glycemic load to our diet. To moderate its glycemic impact you could consider: 

• Species - high amylose rice (think long, firmer grains that expand less during cooking) has lower GI values than high amylopectin varieties (think shorter grain, waxy, sticky or glutinous rice) 
• Preparation technique - shorter cooking times and steaming, rather than boiling, tend to lower GI. Cooling cooked rice by refrigeration increases resistant starch and lowers the GI 
• Accompaniments - eating rice with vinegar (as in sushi) or with pickled foods can lower the GI, as can incorporating soluble fibres such as those from barley and legumes And finally 
• Portion size - a smaller serve will have a lower glycemic load 

   

Arborio, risotto rice, boiled
GI 69
Serving: 1 cup (170g/6oz)

Basmati rice (medium amylose), white, boiled
GI 43-69.
Serving: 1 cup (165g/6oz)

Broken Rice (Thai- cooked in rice cooker)
GI 86
Serving: 1 cup (170g/6oz)

Brown rice, high amylose
GI 50-66
Serving: 1 cup of cooked rice (210g/7.5oz)

Cambodian Fragrant Rice long grain white
GI 62
Serving: 1 cup of cooked rice (200g/7oz)

Glutinous rice, boiled or cooked in rice cooker (low amylose)
GI 75-98
Serving: 1 cup of cooked rice (174g/6oz)

Jasmine rice, white, cooked in rice cooker or boiled
GI 79-109
Serving: 1 cup of cooked rice (200g/7oz)

Low GI, high amylose, white rice, Doongara, Rice Growers Australia
GI 54
Serving: 1 cup of cooked rice (220g/8oz

Red Rice (Sri Lankan, cooked in rice cooker)
GI 59
Serving: 1 cup of cooked rice (170g/6oz)

Read more: 

• Kaur, and colleagues. The glycemic index of rice and rice products: a review, and table of GI values. Critical Reviews in Food Science and Nutrition, 2016. 

• www.glycemicindex.com

 
Kaye Foster-Powell is an Accredited Practising Dietitian who has worked with people with diabetes for 30 years. She was co-author of the original series of international, best-selling books on the glycemic index. She conducts a specialized private practice for people with diabetes in the Blue Mountains, west of Sydney, Australia.  
Contact: Via her website.

GOOD CARBS FOOD FACTS

BLACK RICE
Have you noticed a trend toward black foods, such as bread with charcoal, black seaweed, black sesame and squid ink? Perhaps this is because they are unusual, or because they look great and really ‘pop’ on the plate making for Instagram (black) gold. Black rice is another black food that is enjoying popularity and is now widely available.

 

 Black rice is a variety of regular rice Oryza sativa. In ancient China black rice was known as forbidden rice as only the wealthy could afford it. Now you can buy it in the supermarket, although it is a little more expensive than regular rice. I’ve seen it labelled as a ‘super food’ and while we may not be used to seeing rice labelled this way, it does have something special. The black colour is due the presence of an antioxidant called anthocyanin, which is also found in blue and purple fruits and vegetables such as berries, grapes, plums and cabbage. Besides looking gorgeous, anthocyanins are also good for you because they have antioxidant and anti-inflammatory properties that might help reduce the risk of numerous diseases such as cardiovascular disease, type 2 diabetes and even cancer. This sounds pretty ‘super’ to me, but I think lots of foods are super. It is also a good source of magnesium and a source of B-vitamins thiamine and niacin, and 1 cup of cooked black rice has just over 3g of fibre as most black rice is wholegrain and still has its bran layer. Black rice is naturally gluten free and offers a bit of excitement and variety in a gluten-free diet for those with coeliac disease or gluten intolerance. 

Many rice varieties have a high glycemic index (GI), several have medium GI, but unusually black rice appears to have a low GI. There is only one black rice listed on the GI database, and it is a Chinese black rice porridge that has a GI of 42 (low). With most rices the main determinant of GI is the balance of the two main starches present, amylose and amylopectin. However, in black rice it is likely that the high levels of anthocyanin antioxidant is also slowing down the absorption of the carbohydrate and thus lowering the GI. 

Black rice keeps its shape and is chewier than polished white rice and has a nutty flavour. It also takes longer to cook, around 35 minutes. To save time, try cooking up a big batch, freeze meal-sized portions and take one out as you need it. Black rice is perfect for rice salads, rice bowls, pilafs, risotto, paella, fried rice and as a base for curries and stir-frys and even as a sweet rice pudding dessert. 

  
Source: USDA, 2020

    
Nicole Senior is an Accredited Practising Dietitian, author, consultant, cook and food enthusiast who strives to make sense of nutrition science and delights in making healthy food delicious.    
Contact: You can follow her on Twitter, Facebook, Pinterest, Instagram or check out her website.

GLYCEMIC INDEX FOUNDATION NEWS

 

SWAP IT, DON’T STOP IT

The GI Foundation (Australia) has a handy Swap It tool that you can use to find healthy lower GI alternatives to your favourite foods, like rice. 

Read more: 

• www.gisymbol.com

THE GOOD CARBS KITCHEN

GOLDEN RICE WITH PEAS AND CASHEWS
0:10 Prep • 6 Serves • Side dish • Every day 

 

INGREDIENTS
1½ cups (300 g) basmati rice
1 tablespoon vegetable oil
4 whole cloves
1 small cinnamon stick
4 cardamom pods, bruised
1 teaspoon cumin seeds
1 teaspoon turmeric
1½ cups (235 g) shelled garden peas
3¼ cups (875 ml) hot chicken stock
1 teaspoon salt flakes
1 cup (155 g) raw cashews 

METHOD
Wash the rice several times and drain well. 

Heat the oil in a large sturdy pot, add the cloves, cinnamon, cardamom pods and cumin seeds and gently fry for 1 minute. Add the turmeric and rice and stir over medium heat for about 3 minutes. Add the peas with the hot stock and salt. Bring quickly to the boil, then turn the heat to very low and cover the pot with a tight fitting lid. 

Cook for 25 minutes without lifting the lid. Remove the pot from the heat, take the lid off and stand for 3 minutes to let the stream escape. Remove whole spices at this stage if liked. Add the cashews and fluff the grains lightly with a fork and serve. 

NUTRITION
Per serve 1350kJ/323 calories; 8.9g protein; 17g fat (includes 3g saturated fat; saturated : unsaturated fat ratio 0.2); 31g available carbohydrate (includes 3.5g sugars and 27g starch); 6g fibre; 434mg sodium; 284mg potassium; sodium : potassium ratio 1.5 

RECIPE
Kate McGhie, The Good Carbs Cookbook, Murdoch Books. 

IMAGE
Alan Benson 

RAINBOW STEAMED RICE
1:00–2:00 hr Prep • 0:35 Cook • 4 Servings • Gluten free • Lactose free • Nut free • Main meal 

 

INGREDIENTS
1 cup White rice
2 tablespoons Black rice
¼ Cup Red mung/Azuki beans
1 tablespoon Green mung beans
2 tablespoons Pearl barley
2 tablespoons Red quinoa
¼ Cup Sorghum
Roasted black sesame seeds, to sprinkle 

METHOD
Preparation
Soak the black rice, sorghum, red beans and green mung beans separately for 1-2 hours or overnight. Drain the water. 

Cooking
Put black rice, sorghums, red mung beans, green mung beans, pearl barley and red quinoa in a rice cooker. Do not mix them. Add 2 cups water or according to the rice cooker’s instruction for 2 cups of rice. Choose the function for rice cooking. The time to cook varies depending on the cooker and may take ~35 minutes. When cooked, use the plastic rice spoon to mix all together. Sprinkle black sesame seeds on the top. 

Serve with stir-fries or salads. 

TIPS

• Try plant-based meat for extra protein. Pre-cook the plant-based meat and mix with the rice in the pan for 1-2 minutes.
• For quick and easy meal, can use tin or pre-cooked beans and grains instead raw rice and grains. 

DID YOU KNOW?
This type of rice is popular in Asia. It is very similar to the traditional Korean multigrain rice (Japgokbap/Ogokbap) which also include grains and beans. 

NUTRITION
Per serve 1528 kJ/365 calories; 12.5g protein; 2.5g fat (includes 0.7g saturated fat; saturated: unsaturated fat ratio 0.7); 69g available carbohydrate; 6.7g fibre; 7mg sodium; 400mg potassium; sodium: potassium ratio 0.02  

RECIPE


Shannon Shanshan Lin is an is an Accredited Practising Dietitian and Credentialled Diabetes Educator with a particular research interest in culturally and linguistically and indigenous populations. She has been actively involved in the various committees both national and internationally, including the Australian Diabetes Educators Association, Global Chinese Diabetes Association and Beijing Key Laboratory of Nutrition Intervention for Chronic Disease. Contact: You can contact her via Wechat (ID= shannon033)

COPYRIGHT AND PERMISSION

 

This website and all information, data, documents, pages and images it contains is copyright under the Copyright Act 1968 (Commonwealth of Australia) (as amended) and the copyright laws of all member countries of the Berne Union and the Universal Copyright Convention. Copyright in the website and in material prepared by GI News is owned by University of Sydney, School of Life and Environmental Sciences and the Charles Perkins Centre. Copyright in quotations, images from published works and photo libraries, and materials contributed by third parties including our regular contributors Alan Barclay, Jennie Brand-Miller, Kaye Foster-Powell, Kate Marsh and Nicole Senior is owned by the respective authors or agencies, as credited.

GI News encourages the availability, dissemination and exchange of public information. You may include a link to GI News on your website. You may also copy, distribute, display, download and otherwise freely deal only with material owned by GI News, on the condition that you include the copyright notice “© GI News, University of Sydney” on all uses and prominently credit the source as being GI News and include a link back to ginews.blogspot.com.au. You must, however, obtain permission from GI News if you wish to do the following: 

• charge others for access to the work 
• include all or part of the work in advertising or a product for sale, or 
• modify the work. 

To obtain such permission, please contact glycemic.index@gmail.com

This permission does not extend to material contributed and owned by other parties. We strongly recommend that you refer to the copyright statements at their respective websites and seek their permission before making use of any such material, whether images or text. Please contact GI News if you are in doubt as to the ownership of any material.

Nutritional analysis To analyse Australian foods, beverages, processed products and recipes, we use FoodWorks which contains the AusNut and Nuttab databases. If necessary, this is supplemented with data from www.calorieking.com.au or http://ndb.nal.usda.gov/ndb/search.

Disclaimer GI News endeavours to check the veracity of news stories cited in this free e-newsletter by referring to the primary source, but cannot be held responsible for inaccuracies in the articles so published. GI News provides links to other World Wide Web sites as a convenience to users, but cannot be held responsible for the content or availability of these sites. All recipes that are included within GI News have been analysed however they have not been tested for their glycemic index properties by an accredited laboratory according to the ISO standards.

© ®™ The University of Sydney, Australia

GI News - November 2020

GI News is published online bi-monthly (during 2020) by the University of Sydney, School of Life and Environmental Sciences and the Charles Perkins Centre, and delivered to the mailboxes of our 97,000 subscribers. Our goal is to help people choose the high-quality carbs that are digested at a rate that our bodies can comfortably accommodate and to share the latest scientific findings on food and diet with a particular focus on carbohydrates, dietary fibres, blood glucose and the glycemic index.

Publisher: Professor Jennie Brand-Miller, AM, PhD, FAIFST, FNSA, PhD
Editor: Alan Barclay, PhD, APD
Contact GI News: glycemic.index@gmail.com

Sydney University Glycemic Index Research Service
Manager: Roslyn Muirhead, PhD, APD, AN
Contact: sugirs.manager@sydney.edu.au

Like us on
Follow us on

FOOD FOR THOUGHT

NON-DIGESTIBLE COMPONENTS OF FOOD – SHOULD WE BE EATING MORE? 

Once upon a time, the roughage in food, now called dietary fibre, was regarded as a nuisance, something that might slow the growth of children, just like it did in animals. But in the 1970s two British nutrition scientists, Dennis Burkett and Hugh Trowell, proposed something radical - that dietary fibre might actually be helpful - preventing the development of diseases like type 2 diabetes and colon cancer. In fact, they suggested that nearly every “Western” disease might respond favourably to eating more roughage. 

I can still remember raising my eyebrow while listening to Dennis Burkett’s presentation to Sydney scientists in 1980. He showed us a plate-size ‘cow pat’ next to a match box. In the next slide, he showed a typical human stool of a westerner, a few hard pellets, again next to a match box (If you’d like to see more description of human stools, you’ll love the Bristol stool chart (see below)). Today, 50 years later, we know that dietary fibre increases the water content, volume and weight of faeces, and along with that the ability to alter human metabolism in ways we never thought possible. 

Last year, I was lucky enough to join a group of 40 eminent scientists calling themselves the International Carbohydrate Quality Consortium, who met in Palinuro, Italy, to draw up a consensus statement on what we know and don’t know about dietary fibre. The ensuing paper was published in the journal Nutrients recently (see below). 

There is still some confusion and disagreement about the definition of dietary fibre and how it should be measured. Many of us still use the original definition: carbohydrates (and relatively small amounts of other substances) derived from plants that are not digested by our digestive enzymes or absorbed in our small intestine. Hence, they reach the large intestine where a substantial amount is digested by the microbes in our microbiome. Helpful bacteria produce small organic acids that are absorbed into the body, used for our metabolism, and promote insulin sensitivity. 

However, there is much that is not known about dietary fibre, in part because the structure of the plant cell wall which makes up the majority of our dietary fibre has not been fully explored. Added to this, what occurs during chewing and movement through the digestive tract is not clear. The nature and actions of the microbiome are just beginning to be investigated. 

What do we know? Dietary fibre can alter gut function starting in the mouth and ending where the intestinal tract exits the body (the anus). The actual physiological effects depend critically on the properties of individual plant polysaccharides and oligosaccharides (i.e., types of fibre) and also the structural integrity of cell walls, an important part of the architecture of the plant tissue. These effects may include increasing or decreasing salivation, viscosity of the food as it travels down the gut, stomach emptying rate, extent of nutrient digestion and absorption, transit time, faecal bulking, laxation, fermentation, colonic acidity, microbiota amount and composition, binding of mucus, enzymes, hormones, bile acids and other metabolites, which may also be bioactive. Whew! 

Beyond the gut, the established metabolic effects of specific types of fibre include lowering of blood cholesterol and postprandial (after meal) blood glucose, and fasting blood glucose in people with diabetes. In particular, these effects have been observed with isolated viscous fibres such as psyllium, β-glucans, guar gum, glucomannan and pectic polysaccharides. Another plant isolate, inulin, though not viscous, can lower fasting glucose and insulin and fasting LDL-cholesterol while increasing good cholesterol (HDL) in people with diabetes and to a lesser extent in overweight and obese persons. Some manufactures add inulin to yogurt and other products. 

These observations show that fibre is capable of modifying our metabolism. Moreover, fibre-rich sources of edible plants such as pulses, nuts, barley, oats, some vegetables and fruits have been shown to improve long-term control of established chronic-disease risk factors, like blood fats (i.e., cholesterol and triglycerides), glucose, blood pressure and body weight. Many of these beneficial health effects have been attributed to the presence of fibre in these foods. But a distinction needs to be made between natural sources of dietary fibre and purified or modified forms of fibre. The purified forms may not have the same properties that they did as part of the original food. 

Recommendations from the ICQC: 

• Dietary fibre is an important part of a sustainable, balanced healthy diet. Consumption is below recommended intake levels for optimal health in many parts of the world and may be decreasing. 
• We should eat a total of 14 g /1000 Calories (3.3 g / 1000 kilojoules) of dietary fibre a day, ideally from naturally-occurring fibre. 
• Dietary fibre should be a compulsory part of a food label’s Nutrition facts / information panel. 
• Labelling should distinguish between fibre that is intrinsic to foods and that added as a functional supplement. 

REFERENCES: 

• Burkitt DP and Trowell HC. Refined carbohydrate food and disease. Academic Press, London, 1975. 
• The Bristol stool chart 
• Dietary Fibre Consensus from the International Carbohydrate Quality Consortium 
• Capuano E. The behavior of dietary fiber in the gastrointestinal tract determines its physiological effect. Crit Rev Food Sci Nutr. 2017 

      
Professor Jennie Brand-Miller holds a Personal Chair in Human Nutrition in the Charles Perkins Centre and the School of Life and Environmental Sciences, at the University of Sydney. She is recognised around the world for her work on carbohydrates and the glycemic index (or GI) of foods, with over 300 scientific publications. Her books about the glycemic index have been bestsellers and made the GI a household word.

WHAT’S NEW?

FIBRE AND BODY WEIGHT 

The role of dietary fibre in weight management has been investigated for many decades and is still debated. A recently published systematic review and meta-analysis of randomised controlled trials sheds more light on the subject by specifically investigating the effect of viscous dietary fibres on body weight, waist circumference, body mass index (BMI), and body fat, independent of energy (kilojoule/calorie) reduction. 

 Agar, alginate, β-glucan, guar gum, konjac, viscous fiber blend (konjac, alginate, and xanthan), psyllium and xanthan gum are all common kinds of viscous dietary fibres that are found naturally in foods, are added as ingredients, or can be consumed as fibre supplements, and were included in the systematic review. 

There was a total of 62 trails including 3,877 people, with an average age of 51 years (range 16 – 70 years), and a baseline body mass index (BMI) of 27 (range 19 - 33) kg/m2. Around one fifth (18%) of participants had diabetes and/or the metabolic syndrome and over a third (37%) were at risk of cardiovascular disease (e.g., heart disease or stroke). The main findings were: 

• consuming 8 g (range 0.8 - 36 g) of viscous fibre a day leads to a 0.33 kg decrease in body weight over 8 weeks (range 4-52 weeks), with evidence that the longer people consume the soluble dietary fibre, the more weight they lose. 
• consuming 7 g (range 2.3 - 36 g) of viscous fibre a day leads to a 0.63 cm decrease in waist circumference over 12 weeks (range 4-52 weeks), with evidence that the longer people consume the soluble dietary fibre, the smaller their waist circumference. 
• consuming 6 g (range 1.3 - 36 g) of viscous fibre a day leads to a 0.28 kg/m2 decrease in BMI over 8 weeks (range 4-52 weeks). 
• consuming 9 g (range 3 - 36 g) of viscous fibre a day did not quite lead to a statistically significant decrease (-0.78%, P=0.05) in body fat over 8 weeks (range 4-52 weeks). 

While the reductions in weight, BMI and waist circumference are not huge by any measure, they were all independent of energy (kilojoule/calorie) reduction and are comparable to other popular dietary approaches like the Mediterranean-style diet (0.29 kg reduction in body weight), low-carbohydrate diet (0.48 kg reduction in body weight) and high–dietary pulses (legumes) diet (0.34 kg reduction in body weight). 

Therefore, making sure you include more soluble dietary fibre in your diet may have some added benefits if you are trying to lose weight or get into shape. 

Read more: 

• Can dietary viscous fiber affect body weight independently of an energy-restrictive diet? A systematic review and meta-analysis of randomized controlled trials.

Alan Barclay, PhD is a consultant dietitian and chef (Cert III). He worked for Diabetes Australia (NSW) from 1998–2014 . He is author/co-author of more than 30 scientific publications, and author/co-author of  The good Carbs Cookbook (Murdoch Books), Reversing Diabetes (Murdoch Books), The Low GI Diet: Managing Type 2 Diabetes (Hachette Australia) and The Ultimate Guide to Sugars and Sweeteners (The Experiment, New York).
Contact: You can follow him on Twitter, LinkedIn or check out his website.

PERSPECTIVES: Dr ALAN BARCLAY

FIBRE AND GLYCEMIC INDEX 

There is a common belief that foods that are high in fibre do not raise blood glucose levels as much as those that are low in fibre, and therefore “high fibre” can be used as a surrogate marker for “low GI” when shopping for foods. Is this belief valid? 

Before I can answer this question, it’s important to consider what information about carbohydrates can be found on most food labels around the globe. 

Carbohydrates and food labelling 

As discussed in previous editions of GI News, currently, in most parts of the world, only very basic information about carbohydrate is included on food labels. Unfortunately, Nutrition Facts / Information panels are not mandatory in many parts of the world, and in places where they are, only total (available) carbohydrate (i.e., all maltodextrins, starches and sugars) and total sugars (e.g., all naturally occurring and added sugars) are generally included. 

Dietary fibre, which is a kind of carbohydrate, is not a mandatory component of the Nutrition Facts / Information panel in most countries at present, with the exceptions being Canada and the United States of America (USA). In some nations, it must be included under certain circumstances, like when a fibre claim is made, and in many countries, it can also be included as voluntary information. 

Unfortunately, the GI is not a mandatory component of food labels in any part of the world at present. However, voluntary GI labelling scheme’s do exist in many countries, including Australia, China, India, New Zealand, Singapore, South Africa and the USA. 

Total carbohydrate and blood glucose levels 

People with diabetes – in particular those that use insulin – can use the information about the total amount of available carbohydrate on food labels to help manage their blood glucose levels. Carbohydrate counting – whether using gram (g) amounts, 10 g portions or 15 g exchanges – has been proven in randomised controlled trials to significantly lower glycated haemoglobin (HbA1c), the 3-month average of blood glucose levels, by 0.35% - 0.64% points in people with type 1 diabetes. While it may sound small, lowering HbA1c by 0.5% points may reduce the risk of deaths related to diabetes by around 10%, heart attack by 7%, and microvascular complications (e.g., retinopathy, neuropathy, nephropathy, etc…) by around 18%. 

GI and blood glucose levels 

There is good evidence from randomised controlled trials that choosing mostly low GI foods and meals instead of high GI alternatives lowers HbA1c by 0.5% points in people with diabetes. 

Sugars and blood glucose levels 

Surprising to most, the total amount of sugars in a food or meal is not useful from a blood glucose management perspective, for several reasons: 

• The GI of commonly consumed sugars (naturally occurring and added) ranges from a low of around 20 for the sugar fructose to a high of 105 for the sugar maltose. 
• Commonly added sugars like sucrose, high-fructose corn syrups and most honeys, have GI values in the 60’s and therefore are medium GI. 
• Sugars are not the only kind of carbohydrate that effect blood glucose levels – maltodextrins and starches also raise them, and they are all included as a part of total carbohydrate in Nutrition Facts / Information panels. 

This is why, for people with diabetes, total carbohydrate is a more useful component of Nutrition Facts / Information panels than sugars. 

Dietary fibre and blood glucose levels 

Jason Bao and colleagues recently investigated the effect of 121 different foods and 13 mixed-meals in 1000 kJ (240 Calorie) or 2000 kJ (480 Calorie) portions, respectively, on blood glucose and insulin levels. The foods and meals all had widely differing amounts of carbohydrate, fat, protein and dietary fibre, reflecting what we commonly consume in our regular diets. Consistent with the evidence from clinical trials in people with diabetes that investigated the effect of either total available carbohydrate or GI on blood glucose levels, they found that the foods glycemic load, which is the product of available carbohydrate and GI (GL = GI x available carbohydrate per serve ÷ 100), was the strongest predictor of a foods and meals effect on blood glucose and insulin levels. 

Perhaps surprisingly, for individual foods containing between 0 and 24 grams of fibre and meals containing between 0 and 21 g of fibre, total fibre content was not a predictor of either blood glucose or insulin response for the foods or meals. 

While this may sound surprising, its important to remember that there are a large number of factors that determine a foods GI, including (but not limited to): 

• type and amount of sugars 
• type and amount of starch (i.e., amylose or amylopectin) 
• starch gelatinisation
• acidity (pH)
• polyphenol content 
• type of dietary fibre 

There is evidence that viscous dietary fibres like agar, alginate, β-glucan, guar gum, konjac, pectin, psyllium and xanthan gum do help lower the glycemic index of foods or meals. However, other types of dietary fibre may not have the same effect, particularly when processed. Unfortunately, the type of dietary fibre is not included in mandatory Nutrition Facts / Information panels anywhere in the world at present. 

Therefore, total dietary fibre is not a useful surrogate for GI (or GL) with respect to the effects of individual foods or meals on blood glucose levels. Just because a food or meal is high in fibre does not mean it will have a low GI. 

The GI and GL are the best predictors of a food or meals effect on blood glucose levels 

Therefore, if you want to know how a food will affect your blood glucose levels, look at the amount of total available carbohydrate per serve (based on the amount you will be eating – which is not necessarily the same as what is printed on the pack) and the foods GI. Sydney University’s GI Research Service lists the GI values for hundreds of foods on its website www.glycemicindex.com which can be accessed for free on your PC, tablet or smart phone when shopping. 

Read more: 

• Food and Agriculture Organisation of the United Nations. Food Labelling. 
• Bell and colleagues. Efficacy of carbohydrate counting in type 1 diabetes: a systematic review and meta-analysis. 
• Thomas and Elliott. Low glycaemic index, or low glycaemic load, diets for diabetes mellitus. 
• Stratton and colleagues. Association of glycaemia with macrovascular and microvascular complications of type 2 diabetes (UKPDS 35): prospective observational study. 
• Bao and colleagues. Prediction of postprandial glycemia and insulinemia in lean, young, healthy adults: glycemic load compared with carbohydrate content alone. 
• Jenkins and colleagues. Dietary fibres, fibre analogues, and glucose tolerance: Importance of viscosity. 
• Sydney University’s free on-line GI database.  

Alan Barclay, PhD is a consultant dietitian and chef (Cert III). He worked for Diabetes Australia (NSW) from 1998–2014 . He is author/co-author of more than 30 scientific publications, and author/co-author of  The good Carbs Cookbook (Murdoch Books), Reversing Diabetes (Murdoch Books), The Low GI Diet: Managing Type 2 Diabetes (Hachette Australia) and The Ultimate Guide to Sugars and Sweeteners (The Experiment, New York).
Contact: You can follow him on Twitter, LinkedIn or check out his website.