Anyone following this channel wants to live a long, long time, right?
Well, today, we’re going to be taking a look at another one of the Hallmarks of Aging.
This time it’s Telomere Attrition.
And this hallmark has been getting a lot of attention by longevity researchers in recent years.
So stay tuned.
I’ve been working for a while now on a series of videos about the Nine Hallmarks of Aging
with a separate video about each hallmark.
Today’s video is part of that series, and it’s on Telomere Attrition.
In this video, we’ll be discussing what telomeres are, what telomere attrition is and what causes it,
and the impact that it can have on aging.
And finally, we’ll take a look at some strategies that you can employ to lengthen your telomere and reduce telomere attrition.
All right, let’s start this talk off by discussing what telomeres are.
And to do that, we need to take a look a the chromosomes.
All chromosomes consist of a single strand of chromatin fiber,
which itself consists of a single strand of DNA coiled around some packaging molecules called histones.
Whenever a cell gets ready to duplicate itself by splitting in two, a process called mitosis,
the DNA is each chromosome unravels itself so that it can be duplicated.
At either end of this long strand of DNA are sections that are each about 8 - 10,000 base pairs long.
They don’t code for anything because they consist of endless repetitions of a single sequence: TTAGGG.
These letters represent 4 molecules called nucleobases, which are the building blocks of DNA.
They stand for thymine, adenine and guanine, with the fourth being cytosine, represented by a C.
These non-coding sections are called the telomeres, and they have three main functions.
The first of these functions is to organize each of our 46 chromosomes in the nucleus of our cells.
The second is to protect the chromosome.
The whole point of the nucleobases are to bond with each other into a long strand that we call DNA.
We get breaks in our DNA all the time,
and we have these repair enzymes that go around looking for these breaks and repairing them,
by finding the two ends of the break and reattaching them, bonding them together.
But the structure of the telomeres makes them impossible to bond to other nucleobases.
Without the telomeres, the end of one chromosome could easily bond with the end of another chromosome,
resulting in some kind of freak chromosome that would cause the cell to die.
So the telomeres prevent the chromosomes from sticking together.
But telomeres have the third function.
Because of the way that cells divide, the very ends of the DNA strands can’t be fully copied during mitosis.
If nothing were done about this, we would lose genetic information from the very first cell division,
and it wouldn’t be long before cell death would occur.
So the telomeres are there to “take one for the team”
by allowing the chromosome to give up some of the DNA that doesn’t code for anything and that can be lost with no damage.
They’re disposable parts of the DNA that’s available to be lost in the replication process.
Think of them like aglets, those plastic protective ends of shoelaces that keep the laces from becoming frayed.
The telomeres protect the DNA and keep our genetic information intact.
Now, there’s an enzyme called telomerase that’s designed to keep cells dividing.
It does this by adding the TTAGGG sequence back to the ends of the telomeres.
But telomerase is only found in very low concentrations in somatic cells,
which are all the cells of our body except germ cells, which are either egg or sperm cells, and stem cells.
High levels of telomerase can be found in both of these types of cells,
so the telomere length is maintained and these types of cells don’t show signs of aging.
But it’s also found in a third type of cell, and that is in cancer cells.
It’s what allows cancer cells to be immortal and to continue replicating endlessly, forming tumors.
So, each time a cell divides, it gives up a little bit of the telomere.
This keeps happening until eventually, the chromosome reaches a critical length and can no longer be replicated.
This usually happens after 50 to 70 cell divisions, and this limit is called the Hayflick Limit.
And this is the definition of Telomere Attrition.
It’s the erosion of the telomeres, causing them to get shorter and shorter.
The shorter a telomere is, the less protective it is.
Once chromosomes reach this critical length, most cells die.
Cells regularly die and are replaced by brand new cells, which are derived from stem cells.
So telomere attrition combined with stem cell exhaustion, which is another hallmark of aging, are major contributors to aging.
Now, I want to talk for a minute about what telomere attrition isn’t.
I can’t tell you how many articles I’ve read that talk about telomere attrition and aging,
and they keep talking about how we all want our telomeres to last for a 100 years or so.
Like, once your telomeres reach their Hayflick Limit, they die and that’s it…we die.
And that’s not it at all. That’s all wrong.
When our cells reach their Hayflick Limit,
they die and are replaced by fresh new cells that come from our supply of stem cells.
And some of our cells reach their Hayflick Limit after just a few months.
Liver cell only live for about 10 to 16 months.
Pancreases cells for about a year. Your fat cell only live for about 8 years.
Skeletal muscle cells and the intestinal cells live for about 10 to 16 years.
They all die and are replaced by stem cells.
So it’s really the exhaustion of stem cells more than it is telomere attrition that causes aging.
And while we’re on the subject, let’s talk for a minute about our brain cells.
I’m sure that you’ve heard that once our brain cells die, that’s it…we don’t get any new ones.
While recent discoveries have demonstrated that that’s not entirely true, it is true for the most part.
But studies have also shown that our brain cells may actually outlive us.
They have transplanted neurons from old, aged mice into the brains of young mice,
and then let those mice live out their natural lifespans.
Upon autopsy, they discovered that the neuron that they transplanted were not only still alive,
but were still young and healthy…they had not aged.
Which means that our brain cells might possibly have a lifespan of 200 years or more.
That’s pretty good news for anyone planning on living to 200, right?
So, let’s take a look at exactly how telomere attrition can impact the aging process.
Once the chromosomes in a cell reach that cells critical length,
most of them die through a process that’s trigger by the critical length called apoptosis,
also known as programmed cell death.
These dead cells are then disposed of by the immune system.
But not all of these cells enter apoptosis. Some of the cells that experience telomere attrition don’t die.
Instead, they become a kind of zombie cell, a cell that supposed to be dead but isn’t.
This type of cell is called a senescent cell, and cellular senescence is yet another hallmark of aging.
These senescent cells have stopped the normal functioning of cells, and enter a phase where they become highly inflammatory,
sending out a chemical signal called SASP, or senescent-associated secretory phenotype.
SASPs can include highly inflammatory cytokines, immune modulators, growth factors and proteases.
And these SASPs can induce neighboring cells to become senescent, in spite of the fact that these cells that have not yet reached their Hayflick Limit.
So, as we get older and our supply of stem cells gets exhausted, dead cells are not replaced by new cells.
And aging immune systems can degrade the disposal of dead cells.
Over time, this means that the supply of healthy, dividing cells can dwindle,
and when combined with the increase in cellular senescence and the decline in stem cell supplies,
this can lead to increasingly poor tissue and organ function.
In other words, we start aging.
And here’s the thing. Telomere attrition is more than simply a natural function of biology.
It can also be caused by poor lifestyle choices.
Stress, a poor diet and a sedentary lifestyle can speed up telomere loss.
The chemical environment that stabilizes telomere lengths over time is one that is low in insulin, inflammation and stress.
A diet high in refined sugar and low in fiber causes a spike in glucose and inflammation,
the opposite of what we need to sustain telomeres.
Oxidative stress, when there are too many free radicals and not enough antioxidants, can also shorten telomeres.
So can smoke, pollution and certain types of foods.
This leads us to some strategies for avoiding the ravages of telomere attrition.
A lot of the current research is looking at finding ways to extend the lengths of telomeres,
although it may make more sense to find ways to replace stem cell stocks and remove senescent cells through the use of senolytics.
This could maintain a supply of healthy young cells,
rather than attempting to keep aged and potentially mutated cells working.
So, the first thing that researchers have looked at is the benefit of making good lifestyle choices.
If a bad diet can shorten telomeres, can a healthy diet extend them?
Well, it looks like it can.
Scientist have found a number of foods that are pro-telomeres. And you know what?
They’re the same foods that I keep talking about.
Stay away from refined sugars and process meats.
In fact, stay away from overly refined and processed food in general.
And eat whole, organic foods that have been raised in sustainable ways and are minimally processed.
Go for a lot of color in your produce.
These colors reflect the flavonoids and carotenoids that are present in the produce and that are great for your telomeres.
Things like leafy greens, tomatoes, berries, carrots and plums.
Beans, nuts and seeds also contain a lot of antioxidants.
Limit omega-6 fatty acids in foods like corn, safflower and sunflower oils.
And get more omega-3 fatty acids from fish oil.
A study out of China found that people who drank 3 cups a day of green tea
had longer telomeres that people that drank only one.
And another study found similar results in coffee drinkers.
But just as important as what we eat is how we eat.
Eating while stressed out can be a double-whammy.
First, it can lead to eating a lot of comfort food, which typically contains high amount of fat and sugar.
But it also dumps a lot of the stress hormone, cortisol into our system.
The combination of comfort foods and cortisol can lead to inflammatory responses and belly fat.
Doing intermittent fasting and eating a ketogenic diet are also methods of eating that can promote longer telomeres over time.
But there’s another great lifestyle choice that you can make that can actually extend the length of your telomeres,
and that’s exercise. In particular, high-intensity interval training.
A study published in March of 2018 in the Journal of Basic Research in Medical Sciences
revealed that 8 weeks of doing HIIT extended the telomere length
and increased telomerase activity in a group of non-athletic students.
Another study of bicycle enthusiasts that were above the age of 60 produced similar results.
What’s significant about these studies is that they measured telomere length at the beginning and at the end of the studies,
and the protocols actually produced longer telomeres at the end than at the beginning.
They actually increased the length of their telomeres.
Another study found that spending time in a hyperbaric chamber could also extend telomere length.
A finally, there’s some research into extending telomere length that looks really promising in the future.
Researchers at the Salk Institute used programming factors similar to the Yamanaka Factors to reset the epigenetic environment in mice.
And they discovered that it also reset the telomeres, making them longer.
So, it may be possible to erase the epigenetic memory of a cell in a way that can make it functionally younger
and repair a large part of it’s damage.
Interestingly enough, this technique is similar to how scientists create, in the lab, a type of stem cell called an induced pluripotent stem cell.
They use Yamanaka Factors to reset the age of the cells by removing epigenetic markers.
So similar techniques could both lengthen telomeres, extending the life of cells,
and restore stem cell levels, allowing these cells to be replaced more readily by new cells when they do die.
If you enjoyed this video and would like to learn more about the Hallmarks of Aging,
then check out this playlist.
That’s it for me, I’m outta here. Catch ya next time.