Februari 21, 2017
vaughan sort of mentioned my main declarationsof interest with respect to working for the gi foundation. i am a board memberand a consultant to that organization and most of my work involves reformulation offood basically trying to make foods better and also i thought i should mention that ihave received in the past honorarium for presenting a webinar for coca-cola. i thought i wanted to start first of all talkingabout diabetes. i want do that for a number reasons.first of all my grandfather had type 2
diabetes so i'm at risk of it and my wife has type 1diabetes and therefore my children are at risk of it, and of course it's one of the most commonconditions affecting australians today. about one in four australian adults has either diabetes or pre-diabetes so it'squite a useful point of reference for us all. and i particularly like these guidelinesthat come from the american diabetes association
that really help to put i guess what iwould consider long-term goals of what we call medicalnutrition therapy because once you have diabetes you basically have it for life.you can go into remission if you have some extreme weight loss through lapbanding for example but generally speaking it is a conditionfor life so people have changed their eating habits.therefore i think the american diabetes associationguidelines are very pragmatic and first of all i think when people have diabetes they thin it's just about the blood sugar levels - the blood glucose -but it's much more than that. as well as
having issues with blood glucose management, peoplewith diabetes often quite usually have issues withblood fat, so blood cholesterol and triglycerides and also blood pressure is often anissue for them as well so it's what we call the metabolic syndromein the three tend to go together. and most people with diabetesunfortunately die of cardiovascular diseases and that's a consequence of the high bloodglucose, the high blood fat
and the high blood pressure, so heart diseaseand stroke in particular. so obviously we've got to work withthem to develop an eating pattern that will help themto reduce the risk of those common complications. it's a simple as that. but what i really likeabout these guidelines is the practical side of it because irecognize that food is more than just nutrients. it's not just about good nutrition. wehave all been eating since well obviously the daywe were weaned. anyway, we've been
eating a variety of foods that are particular to ourculture that our mums and dads and brothers andsisters like to enjoy. and of course we're often not diagnoseddiabetes until we're in our mid forties and by that time you know decades ofhaving these personal and cultural preferences ingrained into us. and some people are willing to change. ifthey are it might need to be done fairly slowly and carefully because itdoes have to be for the rest of their lives it's not just about cutting outsomething and she'll be alright. you've really got to workwith the person if they're going to be long-term
changes and i really like the fourthpoint and i think this is often overlooked in alot of the discussions and debate about what we should eat. food is not just about nutrients. we doeat for pleasure. it's a main reason for a lot of ourcelebrations whether it's easter that's coming up, birthdays,christmasses, all sorts of events revolve around eating food and we do consider it to be one of thepleasures of life so we should really only be limiting
foods and nutrients where there is verygood scientific evidence to do so particularly in people with diabetes that have tolive with the condition for the rest of their lives. we mustn't follow each fad as it comes along. nowi said i'll go into a little bit of the scientific background. there's probablytwo main areas that i think i need to focus on and that's really the kinds of studiesthat we used to assess the evidence if you like and the goldstandard is the randomized control trial
in humans. we basically can provecausality with this particular study design we know that intervention a affects healthoutcome b and because you randomize people and controlfor all known factors you know you really are provingcause-and-effect. for example here two groups of people are fed two different diets andhealth status is measured over a period of a few weeks to several years and thenyou can see what effect that particular diet hason their health and of course the control group is viable
if you just go on, make a change, and don't havesomething to compare it with you don't really know whether the changes happeneddue to other reasons. the other kind of study that is verycommon are what we call observational studies.a lot of these come out of the united states because they were first created there if you like particularly in harvard.very large groups of people and i'm talking about tens may be hundreds of thousandsof people are followed up after having a medicalcheck-up and we assess their dietary intake patterns
five but up to twenty years so some of theharvard health studies have been going for about twenty years now. now unfortunately there not quite as good asthe randomized controlled trials because we can't control all of the complex confounders that are in ourlives from smoking, drinking, food, medicationuse race, et cetera. there are all these otherfactors that we cannot completely control for and the tools that we use to measurethese
personal attributes like the foodfrequency questionnaire are by no means perfect and lastly i think we need take intoaccount the the results that come out of these studies,what we call the relative risk. it's the ratio of the probability of an eventoccurring in an individual and at summed over the group and you see these relative risks, youknow a 25 percent increase in risk is something you'll often hear in thenews and i'll go through a few of these this afternoon but when you look at theoverall body of evidence
it needs to be much higher than that. it needs to be three or fourtimes the risk, so three or four hundred percent increase before we can really start to see thatresults are significant and 20 or higher is considered to be enough to provecausality and to give you a good example of that you probably have all heard aboutcigarette smoking and lung cancer. the relative risk for that is about 25times. it's huge and that's why you know whenthose studies were done and everybody said well we really need to start thinking aboutreducing smoking.
unfortunately in food and nutrition it'susually a small fraction of those relative risks in the sorts ofstudies that we're looking at. so i hope that's a given you a good grounding tothe basics because i'm now going to be talking a lot about those kind oftrials but before i do i thought we needed to talk about whatcarbohydrate foods are because you'll here tonight you probably all know whatthey are but when you do surveys of the average australian they don'talways know. there is very poor food literacy inaustralia in general and probably in the world now. so thecommon carbohydrate foods
yes fruits and vegetables but also milk andyoghurt. it's the lactose in those. legumes, beans, peas, lentils,chickpeas, grains, rice, quinoa, rye, wheat, pastas, breads and crisp breads, most of your breakfast cereals, savoury snacks,and by these i mean chips and corn chips, potato chips and all those sort of other savoury kinds of snacksmade out of puff starchy grains, hot chips or french fries, soft drinks, juice, increasingly thingslike iced tea,
confectionery, lollies, chocolate and all thoseother sweet things and also of course tabletop sweetenersthat we've been using for a long time. so all of these are carbohydrate-containing foodsand we mustn't lose sight of the fact that you know we do eat foods, we don't eat ingredients. theone exception probably is table top sugar that is an ingredient and a sort offood as well, but most of us don't spoon that out of a bag into our mouth despite what the tv commercialsshow you.
now as far as the the chemical structureis concerned there are three main types ofcarbohydrate and you're probably all very familiar withthe term sugars which actually describes mono ordisaccharides and mono 1 di-2-saccharide is sweet. it's as simpleas that and if we look at a classicmonosaccharide we've got glucose which is the basis in fact of a lot of other things as well sostarch is just chaines of glucose and
starch, i think a lot of people arefamiliar with, it's the thing that you stick on your shirt to iron the collars but we eat it as well and it's where there's nine or more ofthese little sugars strung together and there is this little group in themiddle that everybody seems to forget about what we call oligo or small or little, few saccharides and they're between three to nine. okay and as i'll show you later the only oneof course that wevlist on the nutrition
panel is sugars. now starch as i've just shown you there is apolysaccharide with 10 degrees of polymerisation. the term complexcarbohydrate was used up into the late 90's and occasionally you stillhear it used but the wh0 actually recommended back in the late 90's thatwe didn't use it anymore and just because it's a starch, it hascomplex carbohydrate doesn't mean it's low gi. i'm going to go through what low gi means in a minute. refined grains not the sameas starch because you get starch in things
like potato for example and other tumorous vegetablesand starches are found in both refined andunrefined foods so they're not automatically good choices just because it's a starch.similarly the flip side sugars are mono and dissacharides but they're also a kind of sugar called a polyol. i probablyshould flip back and yep i've got it up there so these polyols which you may see on food labels, erythritol,glycerol, lactitol, maltitol,
mannitol, sorbitol, xylitol, are common sugarreplacers for example stevia which is very popularat the moment is actually mostly erythretol with a dash of the steviol extractto give it a bit of flavour but it's mostly erythretol. the term thesimple sugar is really meaningless. it was sort of used togive a counterbalance to complex carbohydrate but sugars are simple and doesn't mean they're good or bad.sugars aren't all high gi. it's another common myth thatyou will read and hear about and i'll
go into that in detail in a minute.of course sugars are found in both refined and unrefined foods as well. this is the australia new zealandfood authority's, or fsanz as it's now known, definition of dietary fibre. it is fairlycomplex. you can all read that there i'm sure. the bottom lineis it's mostly found in plants. it's the part of plants that your body can't digest but the bacteria in yourbowel generally can but there are a few other things likelignin's that are found
elsewhere that also are hard to digest by thebody that are captured in that definition as well. whole grains you'll see on labels everywhere today this is again the food standardsaustralia new zealand definition. it's the intact grain or the dehulled, ground, milled, cracked, or flaked grain where theconstituents - the endosperm, the germ and the bran -are present in such proportions that represent the typical ratio of thosefractions occurring in the whole cereal and includes wholemeal. now what thatactually tells you
reading between the lines is that youcan have a highly refined whole grain refined down to a finewhite powder with granules smaller than sugar and if you put the endosperm, germ, and bran back together you can still call it a whole grain cereal. and that's what a lot ofthe whole grain breads and breakfast cereals that you see in the supermarket are that. they're refined down to fine white flour thenthey're reassembled and they're called whole grain. as you'll see in a minute that does havesome implications for their
effect on your blood glucose andyour health as well but that's perfectly legal. that's part of the food standards codeand the last definition we need to look at is what is 'available carbohydrate' and itscalculated by summing average quantity of the available sugars so those sugars thati've shown you and starch and oligosaccharides glycogen and maltodextrins so that isthe best way of determining how much available carbohydrate there is in a food
and i'll tell you later what happens inmost foods cases. moving on to the glycemic index andglycemic load now who is familiar with glycemic index or gi?just about everybody, that's great. it sounds complicated but it's reallynot that complicated. so now we're just looking at equalquantities of available carbohydrates based on that definition i just showed you. its 50 grams of available carbohydrate. it's fedto at least 10 people. we measure their blood glucose levelsbasically every 15 minutes over a couple of hours
for each person, sum them together. you plot the area under the curve with acomputer program and the gi value you get is actually justa percentage. it's as simple as that. and these are real data from sydney uni giresearch service sugars and you can see the difference betweenthe low gi breads and there are a few medium and high and and they're quite realdifferences. we've done this for the major foodgroups and of course australia has the best gi database in the world i might add. the rankings - i think most people aregenerally familiar with what low gi is
and it's 55 or less, 55 percent less. the standards is glucosewhich has a gi of 100 so it's basically telling you that a low gi food will have about half theeffects on your blood glucose levels as pure glucose. seventy or above is high and of course everything that'sleft in between is medium gi. what's probably less well-known is the definition of the whole daydietary gi because we don't generally eat foods, we eat meals and of course those meals arepart of
our dietary patterns so the definitionsthat we've come up with looking at what studies have beendone around the world including some in australia that lowgi diet is 45 or less, high is sixty and above, and moderate's in between. now australia'saverage gi's about 57 so we're right at the top end of that moderaterange. us - the gi's about sixty-two so it's quite a bithigher than ours. common low gi foods, i might say more traditional foods, darei,
but not always the case, so foods thatwe don't eat a lot but perhaps our grandparents would recognize. i don't think too many people eat barleyanymore for example, lots of legumes, beans, lentils, chickpeas, old-fashioned pastas, specialtybreads. there are a few around. i probably shouldn't mentionbrand names but thick, dense, wholegrain breads where you canactually see you know lots and lots of whole grainsin it, around about 20 percent grain is a good guide.
not the ones you get from oftenlocal breadshops where you can count the number of grains in one slice, you know, probably about 5wholegrains in the whole slice. you know really dense ones and also atraditional sourdough and if you've every been to san francisco andhad a real sourdough, you know what it tastes like, very different from the artificial sourdoughs that we get in our local supermarkets that have had a bit of vinegar and a bitof citric acid added in to give it a bit of bite but they're not real sourdoughsreal soughdoughs take about two to, sometimes three or four days to fermentand rise
and that has a big impact on the organicacids and also the gluten matrix that's formed in the bread, and they generally have lowgi values as well. most mueslis do, most fruits, really the onlyexceptions are the tropical fruits and milk and yogurt. now the high gi foods,unfortunately most potatoes that we consume, particularly the ones that been bred for industrial purposes arehigh gi. most of your low sugar breakfast cerealslike cornflakes and rice bubbles, anything that's puffed and cooked underhigh temperatures and pressures, wholemeal or white bread unfortunatelydoesn't make a big difference
because of what i said before, highlyrefined white flours that have been re- assembled. unfortunately it means theirblood sugar raising potential is still very very high. crisp breads and crackers, so ricecakes and you know those little, can't mention brandnames, little rice crackery things that you have savoury. they're all very high glycemic index. they mightbe low fat and they've certainly trumped that in their marketing but they're like a a blood glucose tolerance test ina bag.
rice, unfortunately, most of the ricesthat we eat, but not all the rices in the world, are highgi. most of the ones we've chosen and also, and i've put this one here becausethis one is very popular at the moment, rice syrups, touted as being low gi andeverything else. we looked at the sugars in there and thought no, it's not, there's no way, so we didsome gi testing on it earlier this year. its gi's actually ninety-eight. it'salmost like pure glucose. now just to emphasize that there's quite a lot ofvariability within a class, so i said on average the potatoes were quite highgi,
and russet burbank, you may be interestedto know, is what we use for making chips so your french fries in your fast foodrestaurant is made out of russet burbank. it's not just thefat that's the problem. it's very highly refined starch that's going tobump your blood sugars right up. some of these other ones you're probably lessfamiliar with, but there are some lower gi varieties andcarisma is the only one that's available commercially in australia at the moment but we think there areactually probably lots of low gi potatoes out there in the world and wethink there are probably lots of low gi rices for
that matter because there's lots of different varieties of thoseas well but we've chosen over the last 100 years in our industrialisation of the food supply.we've selected certain varieties for certain reasons and often cases they've been of high givarieties, the ones that might be good commerciallybut not good for our health. and lastly, again to illustrate thedifference, so sugars a lot of people think all sugars are high gi,they're not. certainly maltose,
again you see this one often touted asbeing healthy but it's really just glucose, dextrose and glucose are the same and its gi of 100. sucrose isn't high gi.it's not low either, it's on the high end, its medium 65 andlactose in milk and fructose from fruit, are the only truly low gi sugars, butthere is a five-fold difference between the common varieties. so glycemic load - has anybody heard ofglycemic load at all? a couple - good. glycemic load is relatively simple. it was developed by
the people at harvard to take intoaccount the amount of carbohydrate in the serve so we don't all eat 50 grams of carbohydrate. 50 grams of carbohydrate isabout three slices of bread. so of course we don't all eat threeslices bread at one point in time. might eat a piece of fruit which is about15 grams of carbohydrate and if you simply multiply the gi value bythe amount of carbohydrate in the serve you get the glycemic load, in thiscase an apple is 6. we have come up with some criteria forwhat's low, medium and high which you can see, under ten is low, 20 and above is high
and what's left in between is medium andagain there's been lots research looking at what's a low gl diet and very recently, last year geoff livesey fromthe uk did a systematic literature review andmeta-analyses of all the observational studies. i'll go into some of that a bit more in aminute. and he came up with this figure of less than ninety five units of gl a day for a typical adult diet. now you'veprobably seen the 8700 campaign in australia on your menu boardsand what-have-you which is roughly 2,000
calories and that's why in the united stateswhere they use calories it's 8400. carbohydrate recommendations. so what australia based its on in its nutrition reference values werebasically from these two organizations, from the us's institute of medicine and from the worldhealth organization. so ours are just a combination of these twoorganizations' recommendations, which sort of makes sense. the us says between 45 and 65percent of calories or kilojoules from
from carbohydrates. the wh0 says much higher, looking at fifty-five percentor more and in fact part of the reasons for that isbecause some countries like some of the asian countries where rice isthe staple they can have up to ninety percent of their calories from carbohydrate and as probably most of youknow that you know places like japan have very long lives. theyhave a very long lifespan, probably the longest in theworld. it is quite compatible but that's part of an eating pattern imight add and that's what we've got to
be careful about. with respect to sugars the iom, and i'll explain why in a minute, has said lessthan 25 percent whereas the who has said less than 10. i'll go into detail on that in a minute. and australian ofcourse went in between, 10 to 25 percent. so the scientific rationale for the 45 to65 percent of total kilojoules is base on the institute ofmedicine's recommendations, at the low end, at the 45percent of calories, it's quite hard to meet
your fibre recommendations and particularly in the united sites they don'teat a lot of dietary fibre as it is, so going below that it's hard to get enoughdietary fibre. if you get too high at the other end youstart raising blood fats such as triglycerides and itcan also lower the hdl or the good cholesterol so it tends tohave some negative effects in particular if they're high gi which i'll go into in a minute. but we must keep in mind when looking at these that glucose is theonly energy source for our red blood
cells. it's the preferred energy source forour brains, nervous system, and other important things like the placentaand the foetus so glucose from carbohydrates is absolutely anessential nutrient. and a high-carbohydrate diet can help lower ldl cholesterol if it ishigh in whole grains that have a lower gi and also if they're high in certain kinds of fibrelike soluble fibres like beta-glucans.
and they also tend to be good sources ofthe b group vitamins and often c and e and minerals like magnesium andpotassium, polyphenols which you find in a whole range of foods. and they can also be a good source of dietary fibreif the carbohydrate hasn't been refined. we must keep in mind. now we focus an awful lot on the sugar in our assessment of food and our discussionsto date. i think it's important to compare it topure starch because we do eat pure starch.
if you've every made gravy or you cook various recipes,you would have used corn starch, right i'm sure, most people have some in your cupboard.we certainly do. and if you look them nutritionally they're actually not verydifferent what so ever. amount of manic kilojoulesbecause they're roughly the same amount of carbohydrate. of course one's high in sugars, the other'shigh in starches. they both have next to no dietary fibrebecause they're highly refined. they have roughly the same glycemicindex.
not much have anything else becausethey're so highly refined. so there's not really that much differencebetween a highly refined sugar like sucrose or a highly refined starch like corn starch. i think weoverlook that fact. and this is a prospective cohort study.this is one of the health professional studies that i wastalking about before. 120 odd thousand men and women in the unites states, followed up from86 to 2006, so thirty years and they looked at what factors in the diets of these americans were most stronglyassociated with the
weight gain in that nation and maybesurprising, maybe not, potato chips were actually the most strongest associated food with weight gain net population, and then potatoesnow i guess it's probably because mostly they're eating deep fried and chipped or french fries as theycall them in the states. and then third issue it's sugar sweetened beverages yetyou probably hear more about sugar sweetened beverages than the other two. and a course on the flip side eating moreveggies and
whole grains and fruits and yoghurtwas negatively associated with weight. now a lot of you would be aware of the sugar recommendations. they've certainly been in themedia lately. i mentioned the iom's 25 percent of kilojoules. if you go beyond 25 percent ofkilojoules it's hard to get enough vitamins and minerals in your diet and enough dietary fibre, so that's why that'scapped and the us they looked at a whole range of foods, not all the nutrients but they worked out frommodeling
that about 25 percent energy was enough.beyond that you're starting to dilute nutrients and become deficient in vitamins and minerals. you might not beaware that the 10 percent at the who recommends is actually based on dentalcaries or tooth decay and it's been shown looking at populationsaround the world, if you go about 15 kilograms per persona year or roughly 40 grams per person per day then you start to get moreand more tooth decay and of course tooth decay is a major health problem even in australia today. it costs about 10percent of the health budget apparently
in a lot of parts of the world so it isa serious problem, no question about it. so the who concluded, excuse me, that between 40 to 55 grams perperson or round about six to ten percent of energy should be ok for most adults dependingon where you live in the world of course. and these were released last week and i thinkthey're a little but misrepresented by the media who has actually recommended that westill stick with this ten percent of
total energy but they're also suggesting that weconsider going basically a step back to that lower-level but theydo note and i think this was overlooked mostly in the media, that this is acondition recommendation. they noted that there's uncertaintyabout a number of factors, the quality of the evidence the balance of the benefitsversus the harms and burdens, values and preferences, and resource useso they concluded this means that there isa need for substantial debate and i hope we have it
and involve the stakeholders before thisrecommendation can be adopted as policy. in other words, this is what we think, have a thinkabout it, see how it applies to your nation, what can be achieved, is it necessary,do you have fluoridated food supplies and everything else? does it work for you? moving on, and i thought i should mention first of allthat it's not just sugars of course that cause tooth decay i think we tend to think yepsugars rot our teeth,
sure it does, we forget that refinedstarches can also be used as a fuel by bacteria in ourmouth. a lot of the modern refined starchesactually almost dissolve in your mouth and turn into glucose and bacteria can use that as a fuel. andthis is from out dietary guidelines. these are two quotes from australian dietary guidelinespublished last year. it mentions quite clearly that addedsugars and refined starches are an issue for tooth decay. yet again,this doesn't seem to get a lot of publicity. you don't seem to talk a lotabout it a lot as a community. we tend to focus
on sugars and ignore the starches. who reviewed the effect of sugars and should sugar-sweetened beverages,well in overweight and obesity back in 2013 by some new zealand colleagues acrossthe ditch and they looked at thirty clinicaltrials and 38 cohort studies. basically they found if you reduceyour intake of sugars, you reduce body weight and if youincrease your intake of sugars you increase body weight
roughly proportionally. in other words,calories in, calories out. it's just another source of calories andthis was really emphasized by the fact substituting other kinds ofcarbohydrates, starches and maltodextrins made no difference whatsoever so thisreview basically says that there's no difference between sugars and starchesand other forms of carbohydrate when it comes to weight. if you ate too muchof any of them it would like to put on weight. if you the less you will lose it. simple as that. the sugar-sweetened beverage story,certainly getting a lot of publicity.
there's been at least 20 systematicliterature reviews, and i should define that term, systematic literaturereviews are when you go search databases and find everysingle study that's been published in an area, you put in certain search terms and then youextract the papers and you check through the reference lists and you getrid of the ones that aren't relevant and what you're left withis good quality evidence and then you pull that evidence together, sometimes statistically, and what you haveat the end of that is
is the highest quality evidence andthat's what's done by who and many other groups. so using that technique and i might add that the different systematic reviews use differentmethods and that's okay. there are different ways of looking at things. they don't all have tobe the same. some of them included observational studies, others onlyrandomized controlled trials and as you recall from my introductioncertainly randomized control trials are more powerful if you like. overall those systematic reviews that includeboth systematic reviews
include observations studies and randomisedcontrol trials do conclude that sugar-sweetened beverages lead toweight gain. those that only include randomized controltrials are not quite so clear. the results are moreequivocal. and of course they've all been publishedover the period of about the last ten years and the more recent ones are getting betterquality evidence. i think the weight of evidence is suggesting that it probably is a significant factor.that's certainly the way the evidence is shaping up at the moment.
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