1 December 2019

GI News - December 2019

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.

Professor Jennie Brand-Miller, AM, PhD, FAIFST, FNSA
Editor: Philippa Sandall
Scientific Editor/Managing Editor: Alan Barclay, PhD, APD, AN
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Sydney University Glycemic Index Research Service
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Low carb diets. Low fat diets. Owning a dog. Eating leafy greens. Fermented foods. Dairy foods. Eggs. Salt. Sugar. We are bombarded with conflicting messages about food, diet and health in the media and on-line. Universities and research organisations keen to promote their staff and their findings in turn bombard the media with often inflated press releases. How do we work out who or what to believe? In Food for Thought, Dr Alan Barclay explains the different kinds of evidence and how compelling it is, or isn’t.

Evidence pyramid

1. RANDOMISED CONTROLLED TRIALS (RCTS) ARE CONSIDERED THE “GOLD STANDARD”, providing the highest level of evidence, as they can prove that intervention A improves health outcome B, while all other known factors (known as confounders such as age, gender, body mass index, etc.) have been accounted for by the randomisation process. The process of studying people tends to improve their health independent of the intervention itself, because people know that they are being monitored and are more conscious of their health, and are consequently being more careful about what they eat and drink, so having a control group is vital. Only randomised controlled trials are able to show that a particular intervention causes a particular outcome.

2. OBSERVATIONAL STUDIES PROVIDE MEDIUM LEVEL EVIDENCE because scientists are simply observing and measuring people’s behaviour at a point in time, or over a particular time frame, without randomising them to groups and providing different dietary interventions. The best epidemiological evidence comes from large prospective cohort studies where large groups (typically thousands) of people have a medical check-up, their dietary patterns are measured, and they are followed up regularly for long periods of time (e.g., 5–25 years).

Observational studies can’t provide as high a level of evidence as RCTs can as it is not possible to control for all confounders (e.g. people who are already overweight may drink more beverages than those who aren’t, as fluid requirements are proportional to body size, and being overweight is an independent risk factor for developing many chronic diseases), and our tools of observation (e.g. a food frequency questionnaire for measuring a person’s usual food and drink intake) are imperfect. Observational studies are only able to prove that event A is associated with outcome Z. It’s possible that unknown or unmeasured intermediary factors (B, C, D, E, etc) are involved. They are not able to prove that event A causes outcome Z – only RCTs can.

3. ANIMAL STUDIES ONLY PROVIDE LOW LEVELS OF SCIENTIFIC EVIDENCE, however, they can be used to generate hypotheses that can be tested in human populations (either using RCTs or observational studies) and to investigate hypothesised physiological mechanisms in experiments that cannot be ethically conducted in people. They are also used to determine the toxic dose of novel ingredients, like food additives, for example, and results are extrapolated to people using a large safety factor (typically 100 x).

HOW SCIENTISTS REVIEW EVIDENCE: 3 THINGS YOU NEED TO KNOW 1. SYSTEMATIC LITERATURE REVIEWS are based on careful searches of scientific databases (e.g., PubMed, EMBASE, CINAHL, and Cochrane Library) with pre-determined search terms looking for all of the research published on a particular topic over a long period of time (ideally with no time constraints). Once all studies have been identified, researchers then go through each paper’s reference lists to make sure as best as possible that they have not missed any additional evidence. The data from each paper is then extracted and the results summarised in a table. The quality of each study is also rated or graded. Strong conclusions can be drawn from the summarised data.

2. META-ANALYSES can be performed when three or more similarly designed studies on a particular health outcome have been published in scientific journals. The outcome data from each study is entered into specialised software and weighted according to the study size and statistical significance. A final summary statistic is given that indicates whether an intervention is effective, and if so, how effective.

3. SYSTEMATIC LITERATURE REVIEWS AND META-ANALYSES OF RANDOMISED CONTROLLED TRIALS are considered the highest level of evidence. Cochrane reviews are a good example of this method. You can also do systematic reviews and meta-analyses of observational studies. However, because the underlying study design is not as robust as the randomised controlled trials, they are not considered to be as high a level of evidence as a Cochrane review, for example.

If the latest study broadcast in the news is: 

  • A systematic literature review and meta-analysis of randomised controlled trials then the results are worth taking notice of if the people involved are similar to you, and live under similar circumstances. 
  • A systematic literature review and meta-analysis of observational studies then the results are interesting, but a randomised controlled trial in humans that studied the same effect would be necessary to prove that the relationship was causal.
  • A systematic literature review and meta-analysis based on an animal study or in vitro (test-tube) study, then more research in people is needed to prove the hypothesis.
Source: www.dralanbarclay.com


Will leafy green vegetables prevent dementia? Or does living near heavy traffic cause it? ConscienHealth’s Ted Kyle summarises John Ioannidis’ JAMA opinion piece describing our woeful current media diet of questionable science and minor issues, while serious and substantial health concerns get little attention.

Mad scientist
Scientific articles are getting more attention these days in the media. Ioannidis looked at the top 100 papers ranked by how much media attention they received. Altimetric scores were the measure. He found roughly half of the stories dealt with health and lifestyle. But the focus was mostly on trivial issues like coffee’s effect on lifespan. Even if it’s real, it’s not really big. Pointless arguments about fats versus carbs are big too.

Ioannidis says the answer is obvious. Focus on bigger issues, like tobacco and obesity. Those subjects received relatively little attention, he said. He did find one bright spot, though. Exercise is both important for health and amply covered in the media.

Because scientific controversies get so much attention, the public gets many conflicting messages. For example, Ioannidis pointed to recent controversial papers regarding red meat. Media attention, as measured by Altimetric, went sky high on these studies.

This kind of food fight is unhelpful, he writes: “Some expert advocates in these fields have a large number of followers in social media that broadcast their beliefs and attack opponents as being unethical, conflicted individuals. Perhaps this behavior is based on good intentions (e.g., to save lives), but heated advocacy is unsuitable for thoughtful, disinterested scientific exchange. It seems more akin to religious dedication to intolerant sects. Promoting such conflicts in the media offers little public benefit.”

Most of the high-scoring health and lifestyle articles were based on observational research. What’s more, those observational studies attract extreme news coverage. More so than randomized, controlled studies with null results. In other words, once a supposition arises from a weak observational study, even a well-controlled study might not kill it.

Ioannidis says that observational research should be rare in high-impact journals (like JAMA). Instead, they should appear mostly in journals for specialized audiences, with appropriate caveats. Press releases for such studies should fade away.

Sensation has always sold newspapers. And today, it provides great clickbait. But serious health journalists can do better. They would do well to pay attention to Ioannidis.

Read more:


Eating dried fruit is a great snack or natural sweetener in porridge oats or muesli. It not only helps you get those 2 plus serves of fruit a day, it adds to your intake of fibre, antioxidants, prebiotics, vitamins and minerals.

Drying fruit keeps bacteria at bay by reducing water content (from around 90% down to around 5–35%) and concentrating the sugars. Sun drying is still carried out in many parts of the world – Turkish sun-dried apricots, for example, are much sought after. Most fruits (and vegetables) are dried in dehydrators. Processors typically add sulfur dioxide (E220) to ensure they keep their appealing colour and texture and prevent them from oxidising and browning. Organic versions may not have good looks, but they are equally delicious, if not more so. Check out the GI, kilojoules (calories), carbs and fibre of five popular dried fruits.

GI 31
GI 39–45
GI 61
GI 40
GI 49
Read more:


The World Health Organisation classifies traditional dried fruits like apples, apricots, dates, figs, prunes, pears, raisins and sultanas as “fruit”, and like fresh fruit, their natural sugars content is not defined as “free sugars”. In contrast, some dried fruits such as blueberries, cranberries, cherries, strawberries and mangoes are often infused with sugar syrup or fruit juices prior to drying – although these fruits can also be dried without any infusion, which adds to consumer confusion. Candied fruits such as pineapples and papaya have a high added sugar content, but this is generally not mentioned on food labels. Check the nutrition information panel.

There are a number of reasons why sugar and or/sugar syrups are added to dried fruit:

  • It improves palatability to tart fruits (e.g. cranberries) by adding sweetness. 
  • It helps a sweet fruit remain soft throughout its shelf life since sugar and sugar syrups act as natural humectants (a kind of food additive used to reduce moisture loss). 
  • Sugar and or/sugar syrups also have a preservative function by helping to reduce the water activity within the fruit, decreasing microbial growth. 
THE NUTRIENT CONTENT of traditional dried fruits is similar to the fresh fruit equivalent, though more concentrated due to their lower water content. Traditional dried fruits are therefore good sources of dietary fibre and a number of micronutrients including vitamins A, certain B group vitamins, Vitamin K and potassium, but unlike most fresh fruits, they are not good sources of vitamin C which is lost in processing.

Dried fruits are high in a range of dietary fibres and other bioactive compounds with prebiotic effects (e.g. polyphenols), while some dried fruits (e.g., prunes and apricots) also contain high levels of the sugar alcohol sorbitol, which has laxative properties and also increases stool weight.

GUT HEALTH is of major public health importance around the world and low stool weight, delayed gut transit time and alterations in the gut microbiome along with their associated metabolites (e.g. short-chain fatty acids), are key risk factors for common gastrointestinal disorders (e.g. constipation, diverticular disease, colorectal cancers, etc.), all of which can be manipulated via the diet. For example, increased stool weight is one of the major mechanisms underlying the relationship between high intakes of dietary fibre and reduced risk of colorectal cancer.

There are currently a small number of high-quality human studies that show some benefits of traditional dried fruits (e.g. prunes) in some areas of gut health (e.g., stool weight/frequency). Like many areas of research, more studies are warranted to extend our knowledge of the potential beneficial impact for public health, particularly investigating the full range of dried fruits and investigating the relative contribution of dietary fibre and sorbitol to these effects.

DRIED FRUITS AND DENTAL HEALTH There is some concern about the potential impact of dried fruit on dental health, particularly dental caries – where bacteria in dental plaque ferment free sugars resulting in acid production. Free sugars can come from both sugary and starchy foods (certain starches are broken down into the sugar glucose in the mouth by salivary amylase). When the acid level (pH) falls below 5.5 in the mouth, tooth enamel can soften. After repeated insults it can result in the formation of tooth cavities, eventually resulting in dental caries.

For dried fruit to contribute to dental caries, the sugars present in the food matrix need to be solubilised and diffuse into dental plaque. The rate of solubilisation depends on the location of the sugars in the dried fruit matrix (inside or outside the cellular structure), the fruit texture, and the force and frequency of chewing. Other influential factors include plaque thickness, the length of time dried fruit stays in the mouth allowing the sugars to dissolve, and the buffering capacity of saliva (which affects acid levels in the mouth). The different categories of dried fruit may, therefore, behave differently in the mouth.

With a pH of 7, saliva is the tooth’s natural protective mechanism, buffering the effect of oral acids. Following each eating episode, there is a time lapse of approximately 40 minutes before resting oral pH is restored. Therefore, eating less sugary and starchy foods between main meals may help decrease the risk of dental caries.

A recent systematic review addressed the perception that dried fruit adheres to teeth and is detrimental to teeth because of its sugars content. No randomised controlled trials were identified that explored dental caries as an outcome per se, as this would be unethical. One observational study was identified but the intake of dried fruit was too low for any meaningful analysis. One study investigated the effect of whole and juiced fruits and vegetables and whole raisins individually on net demineralisation of enamel compared with positive and negative controls, and found statistically significant net demineralisation with all test foods compared with the negative control, suggesting that raisins were not more detrimental to teeth than fresh fruits or vegetables.

Studies of oral clearance have used different methods and endpoints, and improved techniques for assessment are needed. A recent systematic review found one study that compared subjective perceptions of the stickiness of 21 foods in 315 adults with an objective measure of retention of 9–30g portions of the same foods in 5 young adults. There was a low correlation between perceived stickiness and oral clearance rates (r=0.46) suggesting that most people cannot accurately assess the stickiness of foods. This study also showed low to intermediate retention (based on dry weight retained) for raisins and figs respectively, and intermediate clearance rates (weight retained with time). Another study also measured food retention of 48 snacks and found that dates were ranked 15/48 for carbohydrate retention at 5 minutes, and raisins were ranked 29. This study also suggested that dried fruits do not adhere to teeth more than alternative snacks, such as cookies (biscuits), crackers, apple pie and candies (sweets). A third study that measured the quantity of oral lactic acid production as a marker of oral clearance concluded that foods containing sugars, but no starch, clear the oral cavity more rapidly than starch-containing foods.

It would, therefore, seem prudent to re-evaluate the concept of “sticky” foods and the effect of dried fruits on dental health in general.

DIETARY GUIDELINES encourage us to consume more fruit, with most recommending we aim for a minimum of 2 serves each day including fresh, frozen, canned and traditionally dried fruit. However, few of us do get 2 serves a day; and dried fruit makes up only a small fraction of our total fruit intake. Here are the recommendations for the USA, the UK and Australia. 
  • USA – all forms of fruits, including fresh, canned, dried, and frozen, are recommended as part of a healthy eating pattern and ½ a cup of dried fruit is considered equivalent to 1 cup of fresh fruit. 
  • UK – dried fruit is also considered a healthy option equivalent to fresh, canned or frozen fruits and one serve is based on a portion size of approximately 30g (1oz). However, to reduce the risk of tooth decay, it is recommended that dried fruits are eaten with main meals and not as snacks. 
  • Australia – unlike the USA and UK, dried fruits are not considered an everyday food due to their “stickiness”, and higher energy density. Like the UK, a 30g (1oz) portion is considered an appropriate serve size, but to be consumed only occasionally. High quality scientific evidence does not support current advice in Australia to limit dried fruit consumption. 
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.


Prunes, says dietitan Nicole Senior, are actually dried plums. This probably explains why they are low GI and such a rich source of nutrients and phytochemicals. Calling them dried plums also seems to make them sound so much more attractive, and goes some way to make up for their shortcomings in the looks department. The best plum for prunes is the sweet D’Agen variety, which reduce down to one third of their original moisture content when dried. While plums only last a couple of weeks or two fresh, drying makes them available year round. In these waste-conscious times it’s good to remember that drying fruit is an age-old method for preserving a bountiful and seasonal harvest. They are typically harvested and dried within 24 hours on the farms where they are grown.

Prunes are a good source of vitamins A and C, and contain potassium, calcium and iron. But they are most famous for their effect on the bowels. They get things moving due to their fibre and natural sorbitol content. Both whole prunes and prune juice have provided relief to those suffering from constipation for generations, and are the go-to natural cure recommended by just about everybody. Nowadays of course, we know they are high in FODMAPS (poorly digested carbohydrates) that have adverse effects for many people with IBS (Irritable Bowel Syndrome), but this is a small detail in their otherwise glowing report card.

Prunes are more than their goody-two-shoes reputation: they taste delicious and are marvellously versatile. Traditionally served at breakfast as compote or on top of cereal, they offer so much more than a healthy start to the day. They are compact and travel well making them the perfect snack on-the-go, especially mixed with nuts and particularly those with bitter flavour notes like walnuts and pecans which provide good contrast to the rich sweetness of the prunes. Their sweetness and gooey texture are ideal for making uber-trendy bliss balls (or protein balls), and add richness to cakes, loaves and slices, and especially yummy when partnered with cocoa (see Good Carbs Kitchen). Their slightly tart sweetness and exotic colour make them sensational in crumbles, puddings and tarts. They work well in savoury dishes too and add contrasting sweetness to poultry stuffing, sauces for pork and game meats, tagines, chutneys and cheese platters.
AusFoods, 2019 and The Good Carbs Cookbook (Murdoch Books)



0:15 Prep • 0:25 Cook • 32 Servings • Chocolate treat • Festive fare

200g (7oz) pitted prunes, chopped
1 cup water
75g (2½oz) cocoa powder
¼ cup plain wholemeal spelt flour or plain wholemeal flour
2 teaspoons baking powder
1 cup almond meal
½ cup raw sugar
2 eggs, at room temperature,
⅓ cup sunflower or light olive oil, plus extra for greasing
¼ cup buttermilk
1 teaspoon natural vanilla essence or extract
1 teaspoon icing sugar (optional), to dust

Preheat the oven to 180°C/350°F (160°C/320°F fan-forced). Lightly brush a 16 x 26cm / 7 x 11in (base measurement) slice tin with a little oil to grease and then line with a piece of non-stick baking paper.

Combine the prunes and water in a small saucepan. Bring to a simmer over medium heat, reduce heat to low and simmer for 5 minutes, stirring occasionally, until almost all the water has evaporated and the mixture is pulpy. Transfer to a bowl and set aside to cool to room temperature.

Sift together the cocoa powder, flour and baking powder, returning any husks from the flour to the mixture. Stir in the almond meal and sugar.

In a separate bowl, combine the cooled prune pulp, eggs, oil, buttermilk and vanilla and use a fork to combine evenly. Add to the dry ingredients and use a spatula or large metal spoon to fold together until just combined.

Pour the mixture into the prepared tin and smooth the surface with the back of a spoon. Bake in preheated oven for 25 minutes or until moist crumbs cling to a skewer inserted into the centre. Cool in the tin.

Cut into 32 portions and serve sprinkled with icing sugar, if desired. These brownies will keep in an airtight container at room temperature for up to 4 days.

Per serve 350kJ/ 85 calories; 2g protein; 5g fat (includes 0.8g saturated fat; saturated : unsaturated fat ratio 0.2); 8g available carbs (includes 5.5g sugars and 2.2g starch); 1g fibre

Anneka Manning, BakeClub

Prep: 10 mins • Cook: 30 mins • Serves: 6 • Gluten free • Vegan / Vegetarian

1 medium cauliflower
2 tablespoons olive oil
sea salt flakes
¾ cup raw buckwheat groats, rinsed
⅔ cup medium pitted black olives, roughly chopped
2 tablespoons salted capers, rinsed and drained
3 tablespoons toasted pine nuts
2 tablespoons currants

1 garlic clove, crushed
1 handful parsley, chopped
⅓ cup olive oil
2 tablespoons lemon juice
sea salt flakes and freshly ground pepper

Preheat the oven to 190°C/375°F (fan 170°C/325°F). Line a baking tray with baking paper. • Rinse the cauliflower and cut through the thick core into quarters. Cut each quarter into thick slices and put into a bowl. If you prefer, cut them into large florets. Pour over the oil, sprinkle with a little salt and toss. Arrange the cauliflower on the tray and roast for 20–25 minutes, or until crispy and slightly charred. Set aside to cool.

While the cauliflower is roasting, bring a pot of water to the boil, tip in the buckwheat and simmer for 8–10 minutes, or until al dente. Drain, rinse and leave to cool to room temperature.

Whisk together the dressing ingredients, adding salt and pepper to taste, to make a chunky thick dressing. Watch the amount of salt you use, as both the capers and olives will provide a briny tang.

Put the cauliflower, buckwheat, olives, capers, pine nuts and currants in a bowl. Pour over the dressing and lightly tumble together. Serve at room temperature.

Per serve 1505kJ/ 360 calories; 6g protein; 27g fat (includes 3.5g saturated fat; saturated : unsaturated fat ratio 0.15); 21g available carbs (includes 5.5g sugars and 15.5g starches); 5.5g fibre; 255mg sodium; 505mg potassium; sodium : potassium ratio 0.5.


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


University of Sydney

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