Tuesday, December 4, 2012

Epigenetics:Why you should care about sleep, physical activity, and what you eat.

Suppose you are sitting on a train, on a bus, on a plane, or on a park bench in between 2 other people.  Look to your left…Look to you right…Look in to your own hands…Now, realize a harsh reality…Two of you are going to die of cancer, diabetes, or heart disease; largely preventable diseases that have a deeper root in the way you live your life than in the genetic hand you were dealt. 

It may come as a surprise to you that you have a hand in preventing these diseases.  Twenty years ago it was thought that you were dealt your “hand” and you had to live with it.  The human genome project was undertaken to identify these genes so that pharmaceutical companies could target them and provide us with personalized therapies for what ailed us.  It was theorized that human complexity was determined by a large number of genes and once we mapped this genome we would be able to use the power of pharmaceutical medicine to completely revolutionize the way we practice medicine.  The fruit fly has about 12,000 genes, a piece of rice…40,000.  With such simple organisms having such a large number of genes, it was assumed that humans would have in excess of 100,000.

When the human genome project finished mapping the human genome, there was a bit of disappointment.  Not only do humans not have more than 100,000 genes, it turns out we barely have 20,000.  In addition, we share about 60% of our genes with the fruit fly.  To add insult to injury, we share 50% with a banana.  So, in the grand scheme of things, we really aren’t that exceptional.  That is, until, you look in to a little part of the DNA sequence that was once referred to as junk DNA.

The human genome project looked at what are called protein-coding genes.  Protein-coding genes make proteins in the body that ultimately make up you.  At the time, it was thought that the rest of the DNA outside of the protein-coding genes was junk and performed no real purpose.  Once it was found that the amount of our protein-coding genes was so low, scientists realized human complexity couldn’t be explained by protein-coding genes.  They decided to take a second look at the junk DNA and, lo and behold, they found something.

The original line of thinking that lead scientists to name this portion of DNA junk was that if a gene doesn’t make anything, it couldn’t have any relevance to human complexity or health.  When they realized the solution couldn’t come from the protein-coding genes, they needed to change their line of thinking.  By looking deeper in to the “junk DNA”, they realized that it wasn’t junk at all.  In fact, the junk DNA is running the show.  While the junk DNA doesn’t make anything, it basically gives the orders to the protein-coding genes to, “Make it happen!”  Rather than making insulin, or cortisol, or forming muscle tissue; the junk DNA acts as a switch and causes a number of genes to be expressed, calling in to action the appropriate gene sequence based on what you tell it to do.  But how do you tell it what to do and how does that impact your health?

There are 3 primary modifiable ways your body communicates with the environment; your diet, your lifestyle, and physical activity.  It is this communication with the environment that tells your body what to do.  In other words, this communication drives evolution by natural selection.  It does this via the hormones you produce in response to this communication.

It is well known that a lack of sleep will cause excess cortisol secretion, one of the primary hormones of your stress response.  Excess cortisol in the long term negatively impacts blood glucose, both by causing your blood glucose to rise directly as well as increasing your appetite for carbohydrate containing foods. This in turn may eventually lead to a malfunction in the hormone insulin, leading to constantly elevated blood glucose and Type 2 Diabetes (T2D).  Type 2 Diabetes is a major factor for many chronic diseases such as heart disease, Alzheimer’s disease, and cancer. 

Most of the recent research on Alzheimer’s disease has identified insulin resistance as a major predisposing factor.  In fact, this relationship is so strong that most researchers are referring to Alzheimer’s disease as Type 3 Diabetes, or insulin resistance of the brain.  Furthermore, a relationship has been established between Alzheimer’s/Dementia and lack of sleep, with sleep troubles being an indicator of future disease progression.  Given the relationship between sleep and cortisol as well as cortisol and insulin resistance it would seem that the answer to a cure for this disease may reside in the switches, not the coding DNA.  In other words your destiny isn’t written for you, a significant amount of it lies in your hands.

When you look at the cellular changes that occur in cancer, insulin and glucose are front and center.  Not only do most cancer cells primarily use glucose for fuel, cancer cells have 6 times more insulin receptors on their cell membranes than healthy cells.  This sounds like a pretty good adaptation to an environment that is high in both glucose and insulin.  Even better, the research on junk DNA identified that most of the thousands of changes seen in cancer don’t happen in the coding DNA, they happen in the switches.  Since they are happening in the switches, we have some control over them.  If you flip the switch on you get problems, if the switch stays off the problems are kept at bay.  This isn’t to say that once you have established cancer that you can reverse or remove it by changing your lifestyle, only that having the gene isn’t necessarily a death sentence provided you do your best to provide the proper information to the switches.  To the best of our knowledge, the best way to do that is get 8 hours of sleep a day, get regular physical activity, and eat a mostly whole foods diet while avoiding processed foods.