With deteriorating health, particularly brain health, occurring at a global level, this course introduces you to methods for maximizing your brain's fitness through nutrition, exercise, meditation, and sleep. We'll debunk popular myths about prescribed practices for overall health and then uncover studies from the last few decades revealing practical routines and interventions that are proven to help improve the brain. You'll also get a glimpse at the brain's structure and common brain functions, as well as a "prescription" each week of tips for improving your brain's health.
What Happens When We Eat
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From the course by Emory University
Biohacking Your Brain's Health
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From the lesson
Nutrition and the Brain
In this first week, you'll get a simple primer on the brain before diving into the history of nutrition and landmark studies on certain diets that can improve brain health.
Meet the Instructors
Karima Benameur, MDAssistant Professor
Department of Neurology, School of Medicine
Okay, so back to the drawing board.
If it's not the fat, then what is it?
Protein has remained the same for several decades, so
let's look at the next macro-nutrient group, carbohydrates.
As we discussed previously, people starting eating less fat and
more carbohydrates in the form of cereals after the introduction of the food pyramid
in the 1970s.
More startlingly is the higher consumption of high fructose corn syrup.
Completely unknown prior to 1980, we now make 17.5 billion
pounds of it and consume 66 pounds per person every year.
It's a more potent form of sugar that increases appetite,
promotes obesity, and leads to diabetes and an inflamed brain.
It is the main form of sweetener in all processed food
from soft drinks to turkey slices.
Recall what happens when you eat a mixed meal made up of protein,
carbohydrates, and fat.
Proteins get broken down into amino acids, they're building blocks, carbohydrates
into sugar or glucose, and fats are turned into their building blocks, fatty acids.
These get broken down further into acetyl CoA which is a universal currency of
energetic substrate in the cell.
Acetyl CoA then gets processed into the Kreb's cycle,
also called the citric acid cycle to make ATP or
the pure form of energy that can be used by the cell for various functions.
When all goes well, the consumption of carbohydrates into a lesser degree protein
results in the secretion of insulin by your pancreas.
Insulin is an important hormone widely known for its effect on glucose, but
it has many more function.
Insulin secretion act as an energy switch.
It tells your body that it is in a fed state and
needs to use the readily available energy source coming from food for
its immediate needs and to store energy.
Insulin makes different cells in your body take up that glucose by binding to its
special receptors.
Most of the sugar is taken up by the muscle cells,
but other cells also take up that sugar, like the liver, the fat, and other organs.
It also tells your fat stores to stop releasing fatty acids for
energy since you already have readily available glucose to use.
It inhibits what we call lipolysis or the breakdown of fat.
It tells your liver to stock up on sugar in the form of glycogen.
In addition to its role in uptake of sugars,
insulin also has a role in retention in sodium and hence water by the kidneys.
All of this happens in normal conditions.
Insulin and its receptor work like a key and lock model.
Insulin fits in the lock or its receptor, this opens specialized channels for
sugars to get in the cell.
In the past, we thought that the lock was defective and that insulin couldn't open
those channels in the cell, which caused sugar to float around in the blood
outside the cell and basically caused high sugar that resulted in diabetes.
We now know that this is not the case.
Insulin and it's receptor are functioning just fine,
but there is too much sugar in the cell because too much is being
eaten in the form of carbohydrates or too often a combination of both.
So insulin is working hard to cram all that glucose in the cell but
the cell is just too full.
The pancreas senses all the glucose floating around and starts pumping out
more and more insulin which elevates the amount of insulin in the blood.
The body's trying to use up all that energy so it stores it as glycogen in
the liver and muscles and start storing it as fact or what is called de novo
lipogenesis, meaning that the carbs you're eating are turning into fat.
The fat cells starts storing fat and get bigger and bigger.
They don't multiply to accommodate that excess fat.
Once the fat cells get too big,
fat starts depositing in other organs outside of the fat tissue.
We call this ectopic fat deposition, and
it starts in your liver, which is what causes fatty liver,
a very dangerous condition that can lead to liver failure if not addressed.
It also deposits in your blood vessels and elsewhere.
This growing fat mass causes the immune system to activate.
This is the inflammatory response and that is what is behind the inflammation and
clogging of your blood vessels.
That balance between your vessels constricting and dilating is also lost and
the inflamed blood vessels start signaling your platelets to come and
heal the inflammation.
And this is how plaque starts forming in the blood vessels.
This is insulin resistance.
It is what happens, 10 or
even 20 years before your body even shows any signs of diabetes.
And once diabetes developed, you are already behind.
Until the 1970's we thought the brain was the one organ in the body not
sensitive to insulin.
It turns out insulin is not only essential for metabolism in the brain but
it has other roles including promoting the formation of U cells or neurogenesis.
It inhibits apoptosis or neuronal cell death,
it plays a key role in the balance between long term potentiation and
depression which are important mechanisms in learning and memory.
It modulates inflammatory responses in the glial cells and it promotes dilation
of blood vessels in the brain that causes enhanced cerebral profusion.
Ultimately, insulin is a critical hormone in the brain.
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