1 July 2020

GI News - July 2020

GI News

GI News is published online every month 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

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FOOD FOR THOUGHT

MAPPING POSTPRANDIAL RESPONSES SETS THE SCENE FOR TARGETED DIETARY ADVICE 
A new study finds that machine learning can predict differences between people in how they respond to meals If you are managing to stay lean in today’s obesogenic environment (lucky you!), you might suspect that it’s your good genes and/or disciplined adherence to a healthy diet and lifestyle. On the other hand, if you’ve struggled with body fat and dieting for most of your life, you live in hope there’s a specific type of diet (or perhaps better still, a drug) that’s perfect for you… if only you could identify which one. Enter Personalised Nutrition.

Healthy range of foods

In the June issue of the prestigious journal Nature Medicine, Sarah Berry and her colleagues took a major step in that direction. They presented the findings of PREDICT (1), a large-scale study involving ~1000 people, including twins and other adults from the US and UK. Using machine learning, the goal was to use the data to derive ‘algorithms’ (mathematical formulas) that predict a person’s postprandial (after-meal) responses, that is, the rise in glucose, insulin and triglycerides (fats) in the blood after meals of varying composition.

The end-game of this kind of research is the ability to give scientifically valid ‘personalised’ dietary advice based on factors such as age, body mass index (BMI), specific genes, large bowel microbial flora (the “micobiome”) and postprandial responses.

But the findings were not what they expected. They found much more person-to-person variation than was expected, but differences in genes, the gut microbiome and insulin levels explained only a minor proportion of the differences.

By contrast, they were surprised to find a person’s response to the same foods was fairly predictable and reproducible. Food composition and macronutrient (carbohydrate, fat and protein) distribution explained some of the variation in post-meal blood glucose levels, but not in triglyceride levels. And interestingly, blood glucose responses did not predict triglyceride levels; indeed, they warned that advice based just on glucose responses (such as flash glucose monitoring) alone would be misleading.

From our point of view, the associations between the carbohydrate content of meals, post-meal blood glucose levels and other factors were among the most interesting findings. High blood glucose levels after meals are a well-established predictor of type 2 diabetes, the metabolic syndrome, fatty liver, and cardiovascular disease (2).

We have known for a long time that people vary widely in their ‘glucose tolerance’, i.e. the absolute blood glucose response to a carbohydrate challenge. In a lean, active person, the area under the curve (AUC) after a 50 g glucose challenge can be as low as 50 units, but in a sedentary person with a family history of type 2 diabetes, it can be 400 units, an 8-fold difference. Higher AUC means the beta-cells (insulin producing) in the pancreas are working hard. If you have a family history, your pancreas may not have what it takes to do this without becoming dysfunctional over time.

We know that glucose tolerance worsens (measured as higher AUC) with age, increased body weight and sedentary lifestyle. We also know that the background diet is important – low carbohydrate consumption is associated with a higher glycemic response to a glucose challenge. However, it’s reversible - just a day or so of higher carbohydrate intake will improve glucose tolerance.

Is there an optimal diet composition for your body? Is one diet better than another for you but not me? Does human evolution play a role here? Yes! Many different diets can reduce blood glucose responses on a day-to-day basis. Indeed, we have argued that this is one of key mechanisms behind the success of the Mediterranean diet, low GI diets, vegetarian diets based on legumes and lower carbohydrate diets.

Logically, reductions in blood glucose can also be achieved with carefully planned, very-low-carbohydrate diets (50-100 g/day), with parallel improvements in body weight and HbA1c (glycated haemoglobin) in people with type 2 diabetes (3). However, it would be very easy to choose a poor quality very-low-carbohydrate diet and it may be hard to sustain in the longer-term. It may not be as effective (or as easy) as changing the kind (quality) of carbohydrate.

For a given amount of carbohydrate, the glycemic index of a food predicts the degree of glycaemia relative to a standard reference food. Choosing a diet based on low GI foods such as pasta, legumes, most fruit, milk, yogurt and specific types of rice and bread can halve the AUC and reduce HbA1c in individuals with diabetes. Furthermore, meta-analyses of observational studies confirm that diets based on low GI food choices are associated with reduced risk of type 2 diabetes (4) and cardiovascular disease (5). The relative risk reduction is biologically significant, similar to increasing the amount of exercise or dietary fibre.

In our view, the potential of personalised nutritional guidance versus standard advice (national dietary guidelines) to improve weight control is far from proven. In many ways, the findings of PREDICT are important because they challenge so much of the prevailing hype.

REFERENCES:

  1. Berry S, and colleagues. Decoding human postprandial responses to food and their potential for precision nutrition: the PREDICT 1 study
  2. The DECODE group. European Diabetes Epidemiology Group. Glucose tolerance and mortality: comparison of WHO and American Diabetes Association diagnostic criteria
  3. Wycherley TP, and colleagues. Effects of energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets: a meta-analysis of randomized controlled trials
  4. Livesey G, and colleagues. Dietary Glycemic Index and Load and the Risk of Type 2 Diabetes: A Systematic Review and Updated Meta-Analyses of Prospective Cohort Studies
  5. Livesey G, and colleagues. Coronary Heart Disease and Dietary Carbohydrate, Glycemic Index, and Glycemic Load: Dose-Response Meta-analyses of Prospective Cohort Studies

Professor Jennie Brand-Miller       
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?

IS ONE WEIGHT LOSS DIET MORE EFFECTIVE THAN OTHERS? 

If you’re trying to lose weight, there’s no shortage of ‘diets’ and weight loss programs promising impressive results. But is there really one type of diet that is more effective than others?

Person on scales

A new study published in the April edition of the British Medical Journal (BMJ) set out to answer this question. The researchers conducted a systematic review and meta-analysis looking at the effect of different dietary macronutrient patterns and popular diet programs on weight loss and improvement of cardiovascular risk factors in overweight adults. They included 121 randomised controlled trials involving almost 22 000 subjects. The diets included low fat, low carbohydrate and popular named diets such as Atkins, Zone, DASH (Dietary Approaches for Stopping Hypertension) and Ornish.

When they compared these diets to usual or control diets, low fat (such as Ornish), low carbohydrate (such as Atkins and Zone) and moderate macronutrient diets (such as DASH and Mediterranean) all resulted in moderate weight loss at 6 months but not 12 months. The average weight loss at 12 months was 2kgs and any differences between the diets are described as being trivial to small.

At six months, each of these diets also reduced blood pressure and the low fat and moderate macronutrient diets reduced levels of ‘bad’ LDL cholesterol. However, these improvements almost disappeared by 12 months.

The authors conclude that people wanting to make dietary changes to lose weight should choose the diet they prefer. This is an important point. For example, an older study comparing four different diets with different macronutrient ratios (Atkins, Ornish, Zone and Weight Watchers) found that weight loss was similar on all four diets and what predicted success was cutting kilojoules and being able to stick to the diet.

This new study, and previous research comparing different diets for weight loss, show us that there are different ways to achieve the same result – it’s not one size fits all. The key is to find an eating plan you can adopt for the long-term as this is the only way to lose weight and keep it off.

Read more:


Kate Marsh     
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

PUBLIC HEALTH NUTRITION COMPARED TO PERSONALISED DIETARY ADVICE 

Diet-related health conditions like obesity, type 2 diabetes, heart disease and certain cancers (e.g., bowel) are increasing all around the globe and governments are struggling to cope with their economic costs as are individuals with their social, psychological and financial costs.

Strategies for reducing their burden range from public health nutrition at one end of the intervention spectrum, using a systems approach to sustainably re-shape the food and nutrition supply, and at the other, there is personalized dietary advice ideally provided by suitably qualified health professionals like dietitians and nutritionists. While the two are not mutually exclusive, they often do play complimentary roles.

Public Health Nutrition 

The epitome of public health nutrition is the federal government’s Dietary Guidelines that provide advisory statements for the general population (i.e., healthy children, adolescents and adults). They are very similar around the globe. Australia’s most recent version published in 2013 advises people to:

  1. Be physically active and choose amounts of nutritious food and drinks to meet energy needs. 
  2. Drink plenty of water and enjoy a wide variety of nutritious foods from the five food groups every day:
    - plenty of vegetables, including different types and colours, and legumes/beans
    - fruit
    - grain (cereal) foods, mostly wholegrain and/or high fibre varieties, such as breads, cereals, rice, pasta, noodles, polenta, couscous, oats, quinoa and barley
    - lean meats and poultry, fish, eggs, tofu, nuts and seeds, and legumes/beans
    - milk, yoghurt, cheese and/or their alternatives, mostly reduced fat (reduced fat milks are not suitable for children under the age of 2 years). 
  3. Limit intake of foods containing saturated fat, added salt, added sugars and alcohol. 
  4. Encourage, support and promote breastfeeding. 
  5. Care for your food; prepare and store it safely. 

The Guidelines stated aims are to:
  • promote health and wellbeing; 
  • reduce the risk of diet-related conditions, such as high cholesterol, high blood pressure and obesity; and 
  • reduce the risk of chronic diseases such as type 2 diabetes, cardiovascular disease and some types of cancers. 
They are primarily used by health professionals, policy makers, educators, food manufacturers, food retailers and researchers, so they can find ways to help people eat healthy diets.

In theory, Dietary Guidelines apply to all healthy people, as well as those with common health conditions such as being overweight. However, they do not apply to people who need special dietary advice for a medical condition like diabetes or heart disease, or to the frail elderly.

In some countries like the USA, they are updated every 5 years and as such they are based on the most recent and best available scientific evidence. Unfortunately, in others, like Australia, they are not updated on a regular basis and may be scientifically outdated.
A healthy diet
Personalised dietary advice 

Ideally, people with specific diet-related health conditions like obesity, type 2 diabetes, heart disease, cancer, etc… will see a registered/accredited dietitian or nutritionist for personalised dietary advice.

A dietitian/nutritionist assesses your:
  • vital statistics (height, weight, waist circumference, etc…), 
  • biochemistry (blood glucose, insulin, blood proteins, iron status, etc..) and 
  • eating and drinking habits (diet recall, food frequency, etc…), 
to form an overall picture of your nutritional status.

Based on this, they will then work out what area of your diet needs improvement, if any, and what changes can be made based on your own:
  • personal goals (weight loss, weight gain, blood glucose, pressure, cholesterol, etc…), 
  • food preferences, 
  • family situation, 
  • cultural background, and 
  • finances. 
Depending on your needs, a structured menu plan may be provided, tailor-made to your own unique requirements.

Shopping lists, information sheets and other written materials (e.g., booklets) may also be provided, depending on your own personal needs.

Follow-up appointments cover how well you are feeling and how you are managing with your dietary changes, assessment of your vital statistics and biochemistry, and general progress towards your goals, trouble‑shooting and further refinement of your personalised eating plan.

It is easy to see that public health nutrition epitomised by Dietary Guidelines is by necessity very different from personalised nutrition advise provided by a qualified health professional. Unfortunately, sometimes debates about what constitutes a healthy diet get heated and the two are conflated, with some fad diet advocates erroneously believing that dietitians/nutritionists simply advise everyone regardless of their personal circumstances to follow the latest version of the Dietary Guidelines. The reality is that both public health nutrition and personalised dietary advice can help people purchase healthy, affordable foods to ensure they enjoy a sustainable diet that will help them achieve optimal health, whatever their circumstances.

Read more:
 Dr Alan Barclay
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.

DIABETES CARE

INDIVIDUALS FASTING BLOOD GLUCOSE AND INSULIN ARE STRONG PREDICTORS OF THE WEIGHT LOSS RESPONSE TO DIETS WITH DIFFERENT MACRONUTRIENT COMPOSITION IN A LONG-TERM STUDY 

Efforts to identify a single optimal diet for the treatment of overweight and obesity have so far failed.

Scales

Overall, the body of scientific evidence from randomised controlled trials (RCTs) indicate that in order to lose weight, individuals need to consume less energy (kilojoules/calories) than they are expending through their physical activities and basal metabolic rate. Dietary energy can come from a range of different diets with varying macronutrient contents. The macronutrients are carbohydrate, fat, protein and arguably alcohol (although not officially a macronutrient, for some people it is a significant source of energy). One size does not fit all, and the best diet for most people is the one that they can stick to (the one that suits their cultural, religious, familial and personal food preferences, and budget) in the long run.

Due to the high cost of conducting RCTs, most are short-term (conducted over a period of 3-6 months) and few are long-term studies (at least 2 years). Short-term studies often do suggest that one dietary pattern is superior to another, but these results rarely hold true after 12 months in the rare instances that they last that long, and differences usually completely disappear by 2 years as people develop diet fatigue and are no longer able to maintain the disruptions to their family, religious and social lives.

Because they are rare, when a well-designed long-term RCT is conducted, we should pay attention to the results. Back in 2010, a group of American scientists randomised around 300 people to one of two diets and followed them up for 2 years: 

  • One of the diets was low-carbohydrate, which consisted of limited carbohydrate intake (20 g per day for 3 months) in the form of low–glycemic index vegetables with unrestricted consumption of fat and protein. After 3 months, people in the low-carbohydrate diet group increased their carbohydrate intake (5 g per day per week) until a stable and desired weight was achieved. 
  • The other was a reduced energy (1200 to 1800 calories (5000 to 7500 kJ) per day) low-fat diet that provided no more than 30% of calories from fat. 
Weight loss was significant at 1 year (a decrease of approximately 11 kg) and 2 years (7 kg), however, there were no differences in weight, body composition, or bone mineral density between the two different diet groups at any time point.

However, a group of Danish scientists worked with the original American scientists last year, re-analysing the study data according to whether the people in the study had prediabetes (blood glucose between 5.6-6.9 mmol/L) or high fasting blood insulin. After 2 years, participants with prediabetes and high fasting insulin lost 7.2 kg more with the low-fat compared to the low-carbohydrate diet, whereas those with prediabetes and low fasting insulin tended to lose 6.2 kg more on the low-carbohydrate diet than low-fat diet.

This new analysis of a well-designed long-term randomised controlled trial helps explain why there is not one single optimal diet for the treatment of overweight and obesity. Tailor-making dietary advice to suit the specific needs of individuals is the direction we need to be heading in.

Read more:

 Dr Alan Barclay
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 STARCHY SNACK FOODS? 

Spending more time at home means easier access to food, especially unplanned extras, like snacks. Ideally snacks are chosen from core foods - things like a piece of fruit, a handful of nuts, a hard-boiled egg or a slice of wholegrain bread - and make a valuable nutrient contribution to our diet. More popular options like crispy, crunchy crisps and cookies don’t give us much except starchy carbohydrate that add to the glycemic load of the diet. Here we’ve taken a look at how the GI and GL of starchy snack foods compares.

Starchy snack

PWD

Popcorn (commercial microwave popcorn) 
GI 51-67
Serving: 1 small bag (25g/1oz)
Starchy snack

Potato chips/crisps 
GI 51-60
Serving: 1 single serve bag (50g/1 ¾oz)
Starchy snack

Flavoured extruded crispy packaged snack 
GI 74-90
Serving: 1 single serve bag (50g/1 ¾oz)
Starchy snack

Wholegrain rye crackers 
GI 59-74
Serving: 2 large crackers (20g/ ¾oz)
Starchy snack

Plain crackers - white flour based, e.g., Soda cracker or Sao
GI 63-78
Serving: 3 large, or 6 small crackers (20g/ ¾oz)
Starchy snack

Puffed Rice cake 
GI 82-91
Serving: 3 thick or 5 thin rice cakes (30g/1oz)
Starchy snack

Oatmeal biscuit or cookie 
GI 45-55
Serving: 2 cookies (20g/3/4 oz)
Starchy snack

Read more:

 Kaye Foster-Powell     
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

CITRUS 
I know its winter because the citrus trees in my neighbourhood are laden with fruit. The citrus fruit family has something for everyone, whether it be the sweet and juicy orange, the cute and easy to peel mandarin, the gorgeously fragrant lime, the cook’s favourite lemon or bittersweet grapefruit. Then there are the more exotic citrus fruits such as the gigantic pomello (aptly named citrus maxima), the oh-so-hip Japanese yuzu or the gorgeous pot plant and preserve favourite, cumquat. There really is a citrus fruit for everybody but the whole citrus family shares the qualities of intensely exhilarating refreshment and beautifully bright colours.
Citrus
Citrus is famous for its fresh zing, both in your mouth and in the air around you when you peel them. For cooks, their sour astringency makes them ideal to partner with creamy or fatty foods as they ‘slice through’ the richness for an altogether more satisfying taste sensation. This is used to great effect in Asian savoury dishes, in the famous French dish duck a l’orange and my grandma’s specialty lemon butter (or lemon curd). Citrus zest packs amazing flavour. Use a microplane or zester and add zest to baking, sauces and anything with a citrus ingredient to turn up the citrus flavour volume to the max. The sourer the citrus, the better they balance with sweetness, so lemon and lime cakes taste divine and lemon curd is sunshine and happiness on a spoon.

Citrus are also perfect for juicing but limit to small amounts and eat mostly whole fruit to preserve all their nutritional goodness and fibre. If you only drink citrus you juice yourself this puts a natural brake on your intake. And once you’ve experienced the joy of freshly squeezed, it’s hard to go back.

Citrus fruits are a powerhouse of nutrition. They are perhaps best known for their vitamin C content, however this is only part of their good news story. They are packed with natural phytochemicals with a laundry list of health benefits including antioxidant, anti-inflammatory and anti-cancer properties. All this and they are also low GI.

CousCous
Source: AusFoods, 2019

Nicole Senior     
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.

THE GOOD CARBS KITCHEN

QUICK CHICKEN and VEGETABLE SOUP WITH GREMOLATA
0:20 Prep • 4 Serves • Main • Every day

QUICK CHICKEN and VEGETABLE SOUP WITH GREMOLATA

INGREDIENTS 
1 tablespoon olive oil
1 leek, chopped
2 x 400g packets fresh pre-chopped soup vegetables
5 cups reduced-salt chicken stock
2 cups shredded or chopped BBQ chicken
4 small slices rye bread, toasted, to serve

Gremolata
¼ cup chopped flat-leaf parsley
2 tablespoons lemon thyme leaves
1 garlic clove, crushed
3 tablespoons fresh grated Parmesan

METHOD 
Place the olive oil in a large, heavy-based pan on medium-high heat. Add the chopped leek; sauté for 2–3 minutes, or until just softening. Add vegetables; cook, stirring for 1–2 minutes.

Add stock to pan and bring the mixture to the boil. Cover, reduce the heat and simmer for10 minutes. Add chicken, stir to heat through. Add an additional ½–1 cup of water, if the soup needs more liquid. Season with cracked black pepper.

Meanwhile, make gremolata: Combine all the ingredients in a small bowl. Season and mix well.

Divide soup between serving bowls. Top with gremolata and serve with rye toast.

NUTRITION 
Per serve 1691kJ/405 calories; 34g protein; 14.6g fat (includes 4.8g saturated fat; saturated : unsaturated fat ratio 0.5); 28g available carbs (includes 9g sugars and 19g starch); 11.5g fibre; 414mg sodium

RECIPE AND IMAGE
Courtesy of Australian Healthy Food Guide magazine.

Australian Healthy Food Guide

For more healthy recipe inspiration and expert advice, visit healthyfoodguide.com.au

WOOD EAR MUSHROOM and ENOKI MUSHROOMS SALAD 
0:15 Prep • 0:08 Cook • 4 Servings • Entrée • Vegetarian

WOOD EAR MUSHROOM and ENOKI MUSHROOMS SALAD

INGREDIENTS 
½ cup dried wood ear mushrooms
1 cup celery
1 cup enoki mushroom
4 cups water
1 tablespoon soy sauce (salt-reduced or dark soy sauce is preferred)
2 tablespoons Chinese black vinegar
1 teaspoon sesame oil
1 teaspoon ginger
2 teaspoons white sesame seeds (optional)
Oil for cooking (2-3 tablespoons)

METHOD 
Preparation 
Gently rinse the wood ear mushrooms with tap water. Soak with 2 cups of warm water in a big bowl. Rehydrate for 30 minutes or until tender. Prepare the celery by chopping it into small pieces. Remove tough ends of wood ear mushrooms, then chop into bite-sized pieces. Grate the ginger.

Cooking 
Add the water to a pot, and then add the wood ear mushrooms and enoki mushrooms to it. Brining the water to a simmer. Transfer the mushrooms to the dish, and combine with the celery, soy sauce, Chinese black vinegar, ginger, and sesame oil.

Top with white sesame seeds (optional) and serve.

TIPS • For a nut-free and gluten-free dish, use gluten-free soy sauce.

DO YOU KNOW? Dark soy sauce is less salty than the regular soy sauce. Dark soy sauce is darker, thicker and sweeter due to added molasses. It is often used for seasoning and dipping. You can use dark soy sauce to replace regular soy sauce in stir-fries, stews and casseroles.

NUTRITION 
Per serve Energy: 152kJ/36 Calories; 1.8g protein; 2.1g fat (includes 0.3g saturated fat; saturated : unsaturated fat ratio 0.2); 1g available carbs (includes 0.5g sugars and 0.5g starches); 1.2g fibre; 227mg sodium; 252mg potassium; sodium : potassium ratio 0.9.

RECIPE

Shannon Shanshan Lin
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 follow her on.

COPYRIGHT AND PERMISSION

University of Sydney

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: 

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

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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

1 May 2020

GI News - May 2020

GI News

GI News is published online every month 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 Facebook
Follow us on Twitter

FOOD FOR THOUGHT

NUTRITION AND PREGNANCY

There has been a tendency not to study the female body in science and medicine. Only since the 1990s, when it was made law in the US, have scientists been forced to include at least some women in their research (or show cause why not). It’s even worse for pregnancy…pregnant women are routinely excluded from just about any study. Reasons include ‘women’s bodies are too complicated, the menstrual cycle will interfere with results’.

Yet, when it comes to obesity and lifestyle research, women volunteer at twice the rate of men. We live longer lives too so there must be something we do right and it’s worth investigating why and how. We know we have a more active immune system which might serve us well most of the time. There is a hypothesis that because women give birth, the female immune system has evolved around this. But it can turn on us when things go wrong - autoimmune diseases are more common in females.

Pregnancy is interesting from the point of view of obesity research. In the space of 9 months, we gain an average of about 13.5 kg, but many women gain twice that. This is the fastest rate of weight gain in life, faster even than adolescent boys at their peak. And yet, in the first trimester we appear to eat no extra calories, and often consume less than normal because we feel nauseous. And we still don’t know why nausea and vomiting are so common. Luckily, the vast majority of babies turn out perfectly formed despite the lack of (or perhaps in spite of) less than ideal nutritional intake.

Pregant woman

Interestingly, research shows that women don’t eat much more than usual during the last trimester than they did in the first trimester. How can this be when we weigh much more and are gaining weight fast? In 2015, two of my students did some research to find out more. We undertook a systematic review and meta-analysis (the gold standard of research these days) to find studies that had documented food and energy intake from early to late pregnancy (1).

There were only 18 studies over the past 25 years that met strict inclusion criteria (extraordinary, really!). On average women gained 12.0 kg and yet reported only a small increment in energy intake (about 450 kJ, or 100 calories per day) that did not reach statistical significance. This is only half the amount of additional energy that is recommended by health authorities – 1000 kJ per day in the 3rd trimester. In fact, it’s possible that the recommendations do harm, by encouraging women to gain an excessive amount of weight and therefore deliver bigger babies, destined to be overweight children and young adults.

We also know that the extra demands in pregnancy mean that micronutrient requirements also increase. The most important of these are iron, folic acid and iodine, which are particularly critical for brain growth and intellectual development. Human babies are born with brains that are 3 times larger for their weight than our nearest relatives, chimpanzees. Indeed, it’s one of the reasons that childbirth can involve a difficult labour and the decision to use a C-section delivery.

Unfortunately, even with a perfectly healthy diet, it is challenging to reach the target intake of vitamins and minerals for pregnancy. For this reason, pregnant women are routinely recommended to take dietary supplements to ensure they get the amounts needed. Their cost, however, may discourage vulnerable women from buying them. ¬¬¬

This fact makes me rather sad and angry. All of us have the right to start life in the best environment possible. Ideally, the moment of conception takes place in a healthy body, receiving the full quota of micronutrients needed for rapid cell division and differentiation. Women planning pregnancy can be counselled to take dietary supplements immediately. But we also know that half of all pregnancies are not planned. So an embryo might start life on the wrong foot. Nothing obvious, but not optimal for the formation of the first tissues in the brain. The effects may not be known for years and may be quite subtle. For example, we know that sub-clinical iodine deficiency in parts of Australia may be responsible for lower NAPLAN scores in primary school (2).

In my view, this is totally unacceptable situation. In a prosperous, highly developed country, Australian women (and men) have the right to a food supply that serves their needs from day 1 of conception. If the normal food supply and a healthy diet don’t give us what we need, then there is a good argument for fortification of some foods to make it possible. Currently, iodine must be added to some bread, but not all breads, and certainly not to rice, a key staple food for many Australians.

Which brings me back to our opening paragraph. The needs of women in pregnancy should be well studied, not avoided. There is a good argument for making their requirements the standard requirement – the common denominator when we study the nutritional needs of a whole population.

References

  1. Jebeile H, Mijatovic J, Louie JCY, Prvan T, Brand-Miller JC. A systematic review and metaanalysis of energy intake and weight gain in pregnancy. American Journal of Obstetrics and Gynecology 2016. 
  2. Hynes KL, Otahal P, Hay I, Burgess JR. Mild Iodine Deficiency During Pregnancy Is Associated With Reduced Educational Outcomes in the Offspring: 9-Year Follow-up of the Gestational Iodine Cohort. The Journal of Clinical Endocrinology & Metabolism 2013.
Professor Jennie Brand-Miller       
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?

WHAT ROLE DOES DIET HAVE IN THE PREVENTION OF DIABETES AMONG WOMEN WITH PRIOR GESTATIONAL DIABETES? 

According to the International Diabetes Federation, 1 in 6 births in 2019 were affected by gestational diabetes.

Gestational diabetes is a form of diabetes that first occurs during pregnancy and usually goes away after a woman gives birth. However, women who have gestational diabetes during their pregnancy are at higher risk of developing type 2 diabetes in the future. Making lifestyle changes, such as eating a healthy diet and exercising regularly, can help to reduce this risk. Achieving and maintaining a healthy weight is also important.

Pregnant woman

To help determine what type of eating plan might best help women with previous gestational diabetes to reduce their risk of developing type 2 diabetes, a group of Australian researchers recently performed a systematic review of relevant studies, which was published in the January 2020 issue of the Journal of the American Academy of Nutrition and Dietetics. The review included twelve articles from four intervention and four observational studies.

The intervention studies didn’t show any clear benefits of different types of diet although there was a trend towards the beneficial effects of a low-glycemic index diet, a low-carbohydrate diet, and a diet in line with general population dietary guidelines. However, the authors note concerns about the quality of these studies, which were found to have an unclear or high risk of bias.

After adjusting for confounding factors, including body mass index (BMI), the observational studies showed a higher risk of type 2 diabetes and/or impaired glucose tolerance (pre-diabetes) in women who had higher intakes of branched-chain amino acids, total and haem iron, and a diet that was relatively low in carbohydrates and high in animal fat and protein. Women who were consuming diets high in fruit, vegetables, nuts, fish, and legumes but low in red and processed meats and sugar-sweetened beverages, were found to have a lower risk. Amino acids are the building blocks of protein while haem iron is the form of iron found in animal foods.

The authors conclude that there is a lack of high-quality evidence from randomised controlled trials to show what type of diet might be best for reducing the risk of type 2 diabetes in women with previous gestational diabetes. However, findings from observational studies show associations between several nutrients, foods and dietary patterns, which are in line with current dietary recommendations, suggesting that diet may play an important role in the prevention of type 2 diabetes among women with prior GDM. They highlight the need for further, large randomised controlled trials to confirm the benefits of dietary modification for reducing diabetes risk in these women.

In the meantime, eating plenty of fruit and vegetables, more fish and legumes in place of red meat, choosing vegetable fats (such as nuts, seeds, avocado and olive oil) over animal fats and limiting sugar-sweetened beverages is likely to be of benefit and very unlikely to do any harm.

Read more:



Kate Marsh     
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

IT TAKES TWO TO TANGO
It is generally well accepted that a key factor in the health and wellbeing of both the mother and new-born infant is an optimal food and nutrient intake before and during pregnancy. Of course, the nutritional status of prospective fathers is also an important factor in at the very least conception, but it is often overlooked, however.

Couple

Indeed, male infertility is on the rise around the globe, and sub-optimal food and nutrient intake may be part of the problem. Infertility is defined as the failure to achieve a successful pregnancy after 12 months or more of regular unprotected intercourse.

In recent decades, infertility has been recognized by the World Health Organisation as a global public health issue, affecting 15% of all reproductive age couples. In real terms this means that worldwide, 70 million couples experience subfertility or infertility.

Male factors, including decreased semen quality, are thought to be responsible for ~25% of cases of infertility. Some studies suggest that human semen quality has declined in certain geographic regions of the world in recent decades (e.g. Europe and USA). Environmental factors such as air pollution, smoking, stress, chemicals and other toxic agents have all been considered as possibly responsible.

Accumulating evidence from human, animal and in vitro studies indicates that male obesity and some components of the diet may play a pivotal role in modulating spermatogenesis, sperm maturation and fertilizing ability. For example, male obesity has been related to impaired reproductivity because of its effect on the molecular and physical structure of sperm. Diets high in energy (kilojoules/calories), trans-fatty acids, saturated fats and/or cholesterol have been associated with testicular disruption, involving impairments in spermatogenesis potentially affecting male fertility and the offspring.

A recent systematic review and meta-analysis of randomized controlled trials that included 2,900 men aged 18 to 52 years from 11 countries (Australia, England, Germany, Iran, Italy, Kuwait, Netherlands, Saudi Arabia, Scotland, Spain, and the USA) found that supplementation with the following nutrients improved sperm quality and quantity: 

  • Selenium (100–300 μg per day for 3–11 months)
    - Increases sperm concentrations, motility (ability to swim) and improves morphology (shape, which affects sperms ability to fertilize eggs).
    - Selenium is found in seafood, poultry and eggs and, to a lesser extent, muscle meats. 
  • Zinc (66–500 mg per day for 3–6 months)
    - Increases sperm concentrations and sperm motility.
    - Meats, fish and poultry are the major contributors to the diet, but cereals and dairy foods also contribute substantial amounts. 
  • Omega-3 fatty acids (1000 mg per day for 2–8 months)
    - Increase sperm concentrations, sperm counts, motility and improve sperm morphology.
    - Long-chain omega-3 fatty acids are found predominantly in oily fish such as mackerel, herrings, sardines, salmon, tuna and other seafood. 
  • Co-enzyme Q10 (200–300 mg per day for 3–6 months)
    - Increases sperm concentrations, sperm counts and improves sperm morphology.
    - Co-enzyme Q10 is found in many foods but in particular cold-water fish, like tuna, salmon, mackerel, and sardines, vegetable oils and organ meats. 
There is also some evidence from observational studies that provide some additional clues as to what an optimal dietary pattern for male reproductive health may look like. A recent systematic review of observational studies included ~13,000 men aged 18 to 80 years from 18 countries (Argentine, Brazil, Canada, Denmark, Estonia, Finland, France, Germany, Greece, Iran, Italy, Lithuania, the Netherlands, Norway, Poland, Spain, Sweden and the USA). It found that a higher consumption of these foods is associated with improved sperm quality: 
  • Fruits, vegetables and cereals
    - Many are rich in antioxidant vitamins (e.g., vitamin C, A, β-carotene and polyphenols), some minerals with antioxidant properties (e.g., potassium and magnesium), folate and fibre. 
  • Lower fat dairy products
    - Low-fat and skimmed milk consumption is associated with higher circulating levels of insulin-like growth factor 1 and insulin and this may increase sperm motility and concentration. 
  •  Fish, shellfish and seafood - Are rich sources of omega-3 fats. 
On the other hand, it found that a higher consumption of these foods is associated with decreased sperm quality: 
  • Potatoes
    - Most varieties have a high GI and insulinemic response and this has been associated with oxidative stress which has an important effect on semen quality. 
  • Sugar-sweetened beverages
    - Excess consumption of sugar-sweetened beverages (high glycemic load) is associated with weight gain and insulin resistance which could negatively influence semen quality via increased oxidative stress. 
  • Meat and processed meats
    - Some meats are low in omega 3 fatty acids but high in saturated fatty acids, trans-fatty acids and/or cholesterol which are related to decreased fertility parameters in men. 
These nutrients can be obtained from dietary patterns that are in-line with current dietary guidelines for adults. It takes two to tango - optimal nutritional status is also important for men to facilitate conception of healthy children.

Read more
 Dr Alan Barclay
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 or check out his website.

DIABETES CARE

THE ADVANTAGES OF A LOW GLYCEMIC INDEX DIET FOR WOMEN WITH GESTATIONAL DIABETES 
Disorders of blood glucose levels in pregnancy are relatively common. In a representative Australian population about 1-2% of women with pre-existing diabetes become pregnant. This type of diabetes is usually insulin treated type 1 diabetes or type 2 diabetes with various treatments ranging from diet alone, oral hypoglycaemic agents (tablet(s)) to insulin.

However, relatively minor elevations of glucose levels during pregnancy, a condition called gestational diabetes mellitus (GDM) are associated with a range of adverse maternal and fetal outcomes. The most common problems are a large for gestational age baby leading to birthing problems, an increased rate of caesarean section and an increased rate of admissions to a special care nursery. Evidence is now accumulating that problems in childhood may be related to the effects of intrauterine programming linked to high glucose levels in the mother. It is not only the “average” maternal glucose level that is associated but also the fluctuations (usually highs) that can happen in the mother, invariably related to diet.

It is recommended that all women are tested for diabetes in every pregnancy. Conventionally this is around 28 weeks gestation, but early testing is recommended for women with risk factors – a family history of diabetes, previous GDM, high risk ethnic groups, etc...

In Australia, the majority of women diagnosed with GDM are referred to a specialist Diabetes Centre and a see a diabetes educator and a dietitian. The diabetes educator will usually arrange for access to a lancing device (finger pricker) and home blood glucose meter and give instruction on its use. Women are all asked to measure their fasting glucose level, either one or two hours after each of the three major meals. There are strict criteria about the upper range of the glucose levels. If either the fasting level or the after-meal level (post prandial) are exceeded, then it is usual to advise the use of insulin injections. Clearly this is a situation and recommendation that most women would like to avoid.

Pregnant woman

The dietitian has two major roles. The first is to ensure that the overall diet for the pregnancy is suitable and nutritionally sound for both the mother and the developing fetus. The second is to ensure that the glucose targets fasting and after meals are not exceeded. It is here that knowledge and application of a low GI diet is critical.

The dietitian will ensure that the diet contains an adequate amount of low GI carbohydrates and that this is distributed as evenly as possible throughout the day. A common example is to advise women to have two carbohydrate exchanges (15 g each) at the three major meals and to have one exchange with snacks. A 15 g exchange might include a slice of bread, or an apple, or a medium potato. For some women this might involve a redistribution of their daily food intake, especially with the evening meal.

With strict attention to the diet, most women will avoid the need to use insulin to help lower their glucose levels. The low GI diet choices really work. In a major clinical trial, women with GDM were randomised to either a low GI diet or a conventional diet in pregnancy and observed.

Women on a conventional diet were far more likely to meet the criteria to commence on insulin. However, if they were then changed to a low GI diet, about half could avoid having to use insulin.

Low GI dietary advice is not just suitable for women with GDM. While women with GDM are an obvious choice for intervention, normal pregnant women with glucoses in the higher range have more adverse pregnancy outcomes than women in the lower range – hence a low GI diet is suitable and advantageous for all women in every pregnancy.

A low GI diet makes common sense for everybody. It is especially relevant in pregnancy where it has been shown to improve pregnancy outcomes.

Read more:

Bob Moses  
PROFESSOR ROBERT MOSES, OAM is an international authority on diabetes and its treatment. Since opening an endocrinology practice in Wollongong in 1975, his interest and referral base has developed to focus on diabetes and problems that can arise during pregnancy, particularly gestational diabetes.
Contact: Illawarra Health and Medical Research Institute

YOUR GI SHOPPING GUIDE

WHICH BREAD? 

Baking your own bread is suddenly popular so it’s worth taking a closer look at its GI.

If you eat bread most days choosing one with a low GI is critical to keeping the GI of your diet low. Most commercial sandwich breads made with finely milled flour, either wholemeal, whole wheat or white have high GI values around 70-80. Breads with a higher proportion of whole grains, and authentic sourdough, tend to be the lowest GI options. Also, you can influence the glucose response to bread by the foods you eat with it. Legumes, nuts, and acidic foods such as vinaigrette, yoghurt and pickled vegetables have all been shown to lower the meals glucose response.

Bread

And if you’re pregnant or planning pregnancy don’t overlook bread as a valuable source of that all-important nutrient folate – it’s important to the healthy development of babies in early pregnancy. In fact it’s so important that more than 60 countries around the world (including the US, Canada and Australia) have mandatory fortification of wheat flour used in bread making with folic acid. Other types of packaged flour don’t have to be fortified. If they are, you’ll find folic acid in the ingredient list.

PWD

Pumpernickel (rye kernel bread) 
GI 41-56
Serving: 1 thin slice (50g/1¾ oz)
Bread Table

Sourdough rye bread 
GI 48
Serving: 1 large slice (60g/2oz)
Bread Table

Sourdough wheat bread 
GI 54
Serving: 1 large slice (60g/2oz)
Bread Table

Spelt multi-grain bread 
GI 54
Serving: 1 slice (30g/1oz)
Bread Table

Mixed Grain / Multi-Grain bread 
GI 39-68
Serving: 1 slice (30g/1oz)
Bread Table

Fibre-enriched white bread 
GI 52-77
Serving: 1 slice (30g/1oz)
Bread Table

Gluten-free bread (gluten free wheat starch) 
GI 71-80
Serving: 1 slice (40g/1½ oz)
Bread Table  

Read more:

 Kaye Foster-Powell     
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.