This course is multidisciplinary in nature, and aims to equip the global audience of interested lay people, people with chronic disease, public health researchers, health clinicians, students, administrators, and researchers to reflect on the overall impact of the burden of chronic disease . It shows how all chronic diseases (obesity, diabetes, cardiovascular disease, chronic obstructive pulmonary disease, and cancer) are related by a set of common causes, and that such diseases should be tackled, not individually, but as part of a complex system, with interrelated contributing factors. These factors are genetic, environmental, psychological, economic, social, developmental, and media related. The Charles Perkins Centre at the University of Sydney is a unique interdisciplinary education and research hub which seeks solutions to chronic disease through a complex systems approach. Academics in many disciplines (in Science and Medicine, but also in Architecture, Humanities, Law etc) work in a collaborative fashion to produce novel solutions to the problems of chronic disease. All contributors and participants in this course are members of the Charles Perkins Centre and will speak from the unique interdisciplinary perspective that this Centre affords. The course will describe a complex systems approach as the most productive way to ease the burden of chronic disease. It then describes these diseases in detail, their risk factors, and the environmental and biological factors that have led to the current epidemic of obesity, diabetes and cardiovascular disease. Finally, the solutions – and more importantly the process for finding solutions- is the subject of the last module. No one approach by itself can ever be the answer, and certainly not a simple diet and exercise approach. The entire course consists of 5 content modules, plus an extra module for completing assignments and discussions, and takes about 6 weeks to complete. Completion certificates are issued on the basis of participation in all 6 modules. What you'll learn: - How the Charles Perkins Centre recruits interdisciplinary teams to ease the burden of chronic disease - How a complex systems approach is necessary to provide solutions to a complex problem - The fundamentals of chronic disease research and where it is heading - The biggest risk factors for chronic disease and their global incidence - The biological, genetic, social, regulatory, and other influences that have inflated these risk factors - How to provide solutions globally for the reduction of chronic disease
Our biology
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From the course by The University of Sydney
Easing the burden of obesity, diabetes and cardiovascular disease
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From the lesson
Module 4 - How did we get here?
This module will provide an overview of the main factors in our biology, our environment, our food production systems, and our human psychology that have made us susceptible to the chronic disease health crisis.
Meet the Instructors
Stephen SimpsonAcademic Director and Professor, School of Life and Environmental Sciences
Charles Perkins Centre
To understand how we got ourselves to the position
where we're eating diets that make us unhealthy,
we need to step back in time and think about the history,
prehistory and evolution of our species.
This enables us to get a view from outside of the world that we've come to regard as
normal and see from a broader perspective just how abnormal it really is.
So let's start by thinking about the environments where our ancestors evolved.
This is important because it's those environments to
which our physiology and behavior are adapted.
For this reason, knowing how
our ancestors lived can help to understand what nutrition we need,
what's gone wrong with our modern diet and how it
is that we've come to put our immense cultural power,
science, agriculture and technology to the disservice of making ourselves unhealthy.
This isn't rocket science.
We use the same simple logic every day.
For example, we pay special attention to whether
our vehicles are designed to run on diesel or unleaded petrol.
We do this because if we get it wrong the car won't work or could even be damaged.
The evolutionary approach to human health is similar,
except in this case we think about our bodies being adapted rather than designed.
But this amounts to the same thing.
Adaptation is the evolutionary process through which
biological things are designed to do what they do.
And just as filling a diesel car with petrol results in problems,
so too does filling our bodies with diets they are not designed to eat.
So how did our prehistoric ancestors eat?
Without grocery stores, restaurants,
packaged foods or even farms,
they lived by hunting animals and gathering wild plants.
Knowing this doesn't in itself help very much because we
can't revert to hunter/gatherer diets even if we wanted to.
There are far too many of us and
the natural environment is already way too depleted to support this.
But what we can do is use our knowledge of
the nutritional composition of foods that were hunted and gathered
to help understand how the nutritional balance of
our diets has changed compared with hunter/gatherer diets.
If we do this, we see a number of ways in which
prehistoric diets differed from modern diets.
Among the most important of these is that foods with
high levels of fats and especially the carbohydrates,
sugar and starch were scarce compared with
the protein-rich foods such as meat from wild animals.
And most of the foods that did contain sugar,
starch or oil such as wild fruits,
vegetables and nuts also contain high levels of fiber which dilutes these nutrients.
Hunter/gatherer diets were therefore high in
protein relative to fats and carbs compared with
modern diets and also had high concentrations of
other nutrients including fiber, vitamins and minerals.
To succeed in such environments where easy energy from fats and carbs were scarce,
humans evolved a fondness for sweet and fatty foods with little energy-diluting fiber.
This liking motivated us to make the most of high energy foods,
if the opportunity arose;
to eat lots of ripe fruits,
honey or fatty parts of animals wherever possible.
We also evolved the physiology to efficiently store energy
as body fat and an aversion for unnecessarily using those stores.
In other words, a tendency for laziness.
A biology that targeted the intake and storage of
energy and avoided unnecessarily using it was beneficial
in our ancestral environments because it helped to ensure that we had
the fuel reserves to survive and reproduce even during lean periods.
And we had little need to evolve mechanisms that limit
the accumulation of harmful levels of
body fat because the environment took good care of that.
Fats and carbs were too scarce and the daily demands
for physical activity too high for obesity to be a risk.
So what's changed?
Our greatest asset as a species,
our capacity for sophisticated culture is from
a dietary perspective also our greatest downfall.
Nutritionally, we're victims of our own success.
Complex cultures enabled humans to indulge their fondness for
energy-dense food and reduced physical activity through altering our environment.
So first came agriculture,
which massively increased the availability of carbohydrates in the form of grains and
domesticated fruits and of fats from farmed animals and some fruits and seeds.
Agriculture also provided domesticated working animals such as
horses and oxen which could save us energy by laboring for us.
Then came industrialization and the technology to concentrate fats and energy producing
carbohydrates in bulk by removing them from fiber and
other substances that dilute their concentration in foods.
This changed the nature of the meals we eat because it enables us to easily alter
their composition using isolated nutrients such as starch, fats and sugars.
Industrialization also provided further opportunity to reduce
physical activity through mechanized transport and other labor-saving technologies.
With time, a new kind of food was developed which had never been
eaten by our ancestors or any other species called ultra processed foods.
These are manufactured mainly from industrial ingredients such as refined sugars, starch,
fats and salt rather than from whole foods and are high
in energy and low in non-energetic nutrients and fiber.
Examples include crisps, ice cream,
donuts, pizza and biscuits.
Industrially produced processed foods are designed and
engineered to serve one purpose and that is high sales.
To achieve this, they're made to be tasty,
cheap and convenient and we've taken the bait.
Within a few generations,
processed foods have become a new human staple,
adding to our diets intakes of salt, fat,
sugar and starch, never before experienced in our history and depriving us of the fiber,
vitamins and minerals to which our bodies are adapted.
Finally, globalization including the digital revolution
has ensured that these cultural changes are spread rapidly across the world,
together with their travel companions,
obesity, diabetes and heart disease.
Through agriculture, industrialization and
globalization we've created a world in which the availability,
quality and distribution of foods is no longer determined
mainly by ecology or what's available naturally in our environments,
but rather by technology and economics.
Foods are now farmed,
processed and manufactured to compete for consumer dollars
and many do this by catering for basic human preferences such as
sweetness and fattiness regardless of the consequences for our health.
So unlike our ancestral environments where
tastiness was a good guide to healthiness, for example,
eating energy-rich foods helped avoid life-threatening energy shortages,
now the link between tastiness and health is much more tenuous.
Eating has become less about nutrition and health and more about
pleasure and profit and this poses significant risks to health.
Some people believe that problems with modern diets will
be solved if we eat like our ancestors did and this is
exactly what many people are attempting to do through
popular high protein diets like the paleo diet.
But is this a good idea? It is and it isn't.
The benefit is that like most popular diets,
paleo type diets eliminate
highly processed carb-rich foods and in
this way deal with one of the main causes of obesity.
Unfortunately, they also introduce health problems of their own.
If we remove sugars and starch from our diets then we will need
to replace them with something else and this something
else turns out to be fat and protein.
Fat, particularly saturated animal
fats of which there is plenty in the paleo type diets and
industrially engineered trans fats are associated
with increased risk of heart disease and stroke.
And new evidence suggests that too much dietary protein,
particularly animal derived protein also of which there is plenty in these diets
accelerates the onset of aging and associated diseases including some cancers.
There are several explanations for why
paleo type diets are no longer the best option for humans,
of which I'll mention one.
That is that evolution did not stop with the transition to agriculture,
but our species continued to adapt in important ways to
the increased levels of carbohydrate that farming made available.
For example, in most animals the ability to digest lactose,
which is the carbohydrate in milk,
is lost after weaning.
But human populations with a history of dairy farming have
evolved the ability to digest lactose throughout their lifetimes.
There are also genes involved in
starch digestion that have evolved in humans since the origin of agriculture.
We should therefore think of ourselves as partly adapted to
hunter/gatherer diets and partly to agricultural diets and in other respects,
we still have adaptations reflecting
our pre-human ancestry as primates foraging in trees.
We therefore have a complex combination of
nutritional adaptations derived from various stages in
our evolutionary history and it's challenging to decide
based on that which diets modern humans are adapted to.
A simpler way of approaching the issue is to ask what we are
not adapted to and the answer to this is clear - highly processed foods.
Compared with agriculture to which we been exposed for hundreds of generations,
ultra processed foods have formed a significant part of our diet only for
the past two generations - the same period that obesity became a problem.
This is not nearly enough time for us to adapt to these strange foods.
Practically, what all of this means is that we should
eat diets that have moderate levels of protein,
fat and carbohydrates and that these nutrients should be
obtained mostly from minimally processed whole fresh foods.
This will help us avoid dangerous excesses of any one of these nutrients and
at the same time ensure that we have enough vitamins, minerals and fiber.
An added benefit of this approach to eating is that it's
exactly what most dietary guidelines and professional dietitians recommend.
There's therefore a wealth of information to help you follow it and
also scientific evidence confirming its benefits.
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