42 | MAY 2016
THE FIT Tim OldsThere are some personal matters one is reticent about putting
into print in a national magazine, but here is one: I take three
sugars in my tea. I will also confess that breakfast cereal for me is
pretty much just a vehicle for cream and sugar.SoI’ve been a little
alarmed bythe recent controversies around sugar and sugar taxes.
Sugarsare carbohydrates with a caloric density of about 16 kJ
per gram. Table sugar (sucrose) is a combination of glucose and
fructose. These sugars have slightly different molecular structures,
and are broken down by different pathways in the body. High-fruc-
tose corn syrup, which is derived from corn and is widely used in
theUS, particularly in soft drinks, is also a mix of glucose and
fructose buthas a slightly different molecular structure to sucrose.
About 20% of calories in theUS adult diet come from simple
sugars, ofwhich two-thirds is in the form of added sugars (table
sugar and sugars added during manufacturing) and the rest from
naturally occurring simple sugars (such as in honey and fruit). In
theUS, aboutone-third of all added sugars come from sugar-
sweetened drinks. The World HealthOrganization suggests that
no more than 10% of total energy intake, and preferably no more
than 5%, should come from simple sugars.
It’s notoriouslydiicult to puttogether reliable data on trends
in diet, but economic and dietary survey data indicate that
consumption of added sugars has been falling for the past 15 years
in theUS and UK, andperhaps Australia.
There are two broad mechanisms proposed as to why sugar
might be harmful for health. The most obvious one is that sugar
provides excess calories, which in turn leads to obesity and obesity-
related diseases. The second is that there is something uniquely bad
about sugar above and beyond the excess calories. The conse-
quences of high-sugar diets, it is argued, are worse than the conse-
quences of equally calorie-excessive high-fat diets.
One version of this latter approach argues that the culprit is fruc-
tose. The fructose hypothesis is based largely on epidemiological
evidence– increases in the use of high-fructose corn syrup mirrored
increases in obesity – and studies in rodents and humans using pure
fructose.
But the fructose hypothesis has been strongly criticised by the
dietary establishment. TheUK’sScientiic Advisory Committee
onNutrition in 2015 concluded that “there isinsuicient evidence
to demonstrate that fructose intake ... leads to adverse health
outcomes independent of any effects related to its presence as a
component of total and free sugars”. The American Medical Asso-
ciation and the Academy of Nutrition and Dietetics agree.
The epidemiological evidence linking fructose intake to obesity
is particularly weak: spurious “ecological” correlations of this sort
are very common. For example, over the period 2000–09, cheese
consumption in theUS was veryhighly correlated with deathscaused by entanglement in bedsheets.Ofmore relevance is a
decline in fructose consumption since 1999 while obesity rates have
continued to increase.
The clinical trial data have also been criticised for using exces-
sive amounts of fructose – sometimes ive times greater than the
averageUS consumption andthree times greater than the amount
of sugar consumed by the top 5% ofUS consumers. Feeding
people only fructose or only glucose alsodoesn’t mimicthe way
we actually eat – we almost always consume a mix of fructose and
glucose.It’s a bitlike feeding someone nothing but bananas for a
week, and concluding that bananas are bad for us.
Finally, trials in which normal sugar intake was replaced with
fructose without changing the total number of calories reported
no effect on weight gain, blood pressure, internal fat or blood
sugar or insulin levels. Therefore it seems that eating fructose in
typical amounts does not lead to adverse health consequences or
increase the risk of heart disease, diabetes or obesity over and
above the effects of increased caloric intake.
Yet it has been suggested thatit’seasier to over-consume sugar,
particularly in liquid form, than other types of food.Sugar may
also bypasssome of the complex mechanisms that tell uswe’ve
had enough.
Butthere’s not a great deal of evidence to support this hypoth-
esis. Sugars trigger satiety in much the same way as other nutrients.
While fructose only results in small increases in insulin (a satiety
signal), other mechanisms kick in so satiety is much the same as
for glucose. Soft drinks suppress appetite to the same extent as
the same number of calories consumed as milk or fruit juice.
It’s possible, however, that calories consumed inliquid form
suppress appetite less than the same amount of calories consumed
in solid form. In particular, thirst may trump hunger, and we may
drink calorie-rich beverages to conquer thirst, the excess calories
being collateral damage.
All thisdoesn’t meanthatit’s OK toeat as much sugar as you
like, or that reducing sugar intake, even through sugar taxes, is
not a good strategy for reducing energy intake and obesity-related
diseases. (I personally thinkit’s worth a go, but don’texpect mira-
cles.) It probably does mean, however, thatthere’s nothing partic-
ularly deadly about sugar (or fructose, or soft drinks) per se, and
that associations between sugar intake and poor health are prob-
ably just a matter of excess calories.
So now I can have a cup of tea, which as I mentioned I take with
just one sugar.Tim Olds leads the Health and Use of Time Group at the Sansom Institute for Health
Research, University of South Australia. He has received funding from Coca-Cola
Corporation for conference travel and accommodation, the National Health and Medical
Research Council, the Australian Research Council, Beyond Blue, SA Health, the Department
of Health and Ageing, the Australian Food and Grocery Council, the Financial Markets for
Children Fund, and Channel 7.Pure, White, But Maybe Not So Deadly
Is there something uniquely unhealthy about sugar above and beyond the excess calories?