Transcript – Mark Mattson: Why Fasting Bolsters Brain Power – a TED Talk
Mark Mattson – Professor of Neuroscience, The Johns Hopkins University
Thanks, Brian. I’m at the National Institute on Aging. And as many of you know, as people are getting older and there have been advances in cancer research, cardiovascular disease research. Many people who would have died in their 50s and 60s from those diseases are living into the danger zone for Alzheimer’s and Parkinson’s diseases.
It’s projected that by 2050, the number of people with Alzheimer’s disease will triple from what it is today – 5 million today would be 15 million by 2050.
In my lab, we use a number of different animal models that are relevant to age-related neurodegenerative disorders. We have mice that accumulate amyloid in their brain as they get older and they have learning and memory problems. We have mice that have damage to dopamine producing neurons that control body movements, that’s miles of Parkinson’s disease and we also have miles of stroke which is again another major problem and cause of death.
Well it’s been known for a long time that one way to extend the life span of laboratory animals is simply to reduce their energy intake. And in rats and mice one can increase their life span by 30% or 40%.
We started looking at the effects of energy restriction on the brain in the context of age-related neurodegenerative disorders and found that we could slow down the, for example, abnormal accumulation about amyloid or the degeneration of dopamine neurons in the Alzheimer’s and Parkinson’s mile by reducing energy intake.
Now there’s a number of ways you can reduce energy intake. You can simply eat less at each meal or you can do what we call intermittent fasting. So reduce the frequency of the meals.
Effects of fasting on Brain
And what I’m going to tell you today is that fasting does good things for the brain. In the animals we have insight into a lot of the neurochemical changes that are occurring in the brain that we think explain why fasting is good for the brain.
But I’m going to start out and talk a little bit about anecdotal evidence that fasting is good for the brain and also an evolutionary perspective on why fasting might be good for the brain.
Okay. So everybody knows that in certain religions, people will fast periodically down through history. Many famous brain people — famous people with good brain have fasted regularly.
Up in the top here is a quote from Plato. He fasts for greater physical and mental efficiency.
“I fast for greater physical and mental efficiency.” – Plato
There’s some quotes there, including one from about 6,000 years ago from an Egyptian pyramid inscription that says;
“Humans live on one-quarter of what they eat; on the other three quarters lived their doctor”. – Egyptian pyramid encryption, 3800 BC
“Fasting is the greatest remedy – the physician within.” – Philippus Paracelsus (one of the three fathers of Western medicine)
“A little starvation can really do more for the average sick man than can the best medicines and the best doctors.” – Mark Twain
And in this country as you know, being overweight is a big problem. It’s not only a risk factor for cardiovascular disease and diabetes, certain cancers but emerging evidence suggests that it’s also a risk factor for age-related cognitive impairment and possibly Alzheimer’s disease.
In the lower right there is a reference to a book written over a hundred years ago by Upton Sinclair. Many of you may know Upton Sinclair is the author of The Jungle, a book on the meat-packing industry.
But he also wrote and published a book that you can find the full text online, it’s the Fasting Cure and in that book he interviews 250 people who had some ailment and went on a fast for various lengths of time and except in a handful of cases their health condition improved.
Okay. Before I focus on the brain, which will be the main part of my talk, I just want to point out that there’s evidence not just from animals but from humans that fasting is good for the body. It will reduce inflammation. It will reduce oxidative stress in organ systems throughout the body. And one thing that happens when you fast that does not happen when you eat three meals a day is that your energy metabolism shifts so that you start burning fats.
Every time you eat a meal, the energy goes into your liver and is stored in the form of glycogen. And that’s always tapped into first. And it takes about 10 to 12 hours before you deplete the glycogen stores in your liver.
Okay. So if you eat three meals a day, you never deplete the glycogen stores in your liver, although if you exercise you can. But once you deplete the glycogen stores in your liver, then you start burning fats and you produce what are called ketone bodies.