The most effective tool for life-long wellness is understanding why and how your body ages. Here Miranda, one of our resident nutrition and physiologist, breaks down the latest research in aging science.
Last Updated: August 1, 2019
Do you remember the first time you woke up on a wet, cold, rainy day and your joints ached?
Was your reaction the same as mine? A horrified whisper of, “And so it begins.” Then an overly dramatic cry of, “Whhhyyyyy?!”
No? That was just me?
Okay, perhaps the details of your reaction were a bit different. The general sentiment behind it was pretty similar to what I experienced, though, right?
A mixture of a sense of inevitability, mild dread, and a nagging question: why? Why do I have to get older? Why does my body have to age?
Now, neither you nor I meant that question literally when we asked it in our moment of despair. It was more just an expression of frustration at the seemingly inevitable.
Other people, though, do ask that question literally. Why does the human body age?
Aging is clearly a real, physical thing. Young bodies both look and function differently than older bodies. Something has to be different between the two. What is it? Where does it come from and why?
Aging science researchers have put a lot of work into trying to find answers.
And they have made great progress towards helping us understand both the why and how of human aging.
This is exciting news because aging-knowledge is aging-power. It is the ultimate tool for life-long wellness!
The more you know about aging, the more effectively you can make decisions about how to protect your health, long-term.
Why Do You Age?
So, why do we age?
Well, based on the current research, there are two answers to that question: the short answer and the several-billion-year-long answer.
I think we’d better stick to the short one for now!
The simplest, shortest answer for why humans age is: over time, the cells of your body stop being able to do their jobs.
At first glance, that probably doesn’t seem like rocket science. But in a lot of ways, it’s a game-changer for how we think about aging.
For a long time, it seemed reasonable to think aging might be the inevitable destiny of cells — something cells were designed to do. It was suspected that cells were born with programming that forced them to age. (Think of it similarly to how lighting the fuse of a bomb forces the bomb to explode.)
Discovering, instead, that aging is actually body-wide malfunctioning cells changes the whole dynamic. It means that aging is not programmed into your cells.
Something forces your cells to stop working properly and then you age. And the two things scientists think are responsible are:
- Unhealthy DNA
- Unhealthy Proteins
Let’s tackle these one at a time.
Unhealthy DNA and Poor Cell Function
Typically, when you think of unhealthy DNA, you think of genetic disorders — diseases caused by inheriting unhealthy DNA from your parents.
That’s not the kind of unhealthy DNA involved in cell dysfunction in aging, though. (At least not usually, though there are some inherited genes that can indirectly influence how you age.)
The type of unhealthy DNA that causes aging is DNA that was healthy when you were born but became unhealthy later.
How can some of the healthy DNA in your body you inherited from your parents suddenly become unhealthy?
It becomes mutated.
How DNA Becomes Mutated
There are two main ways your DNA can become mutated:
- your cells make mistakes when they divide
- your DNA comes into contact with a mutagen
Cell Division Mistakes
One of the most common ways healthy DNA can be made unhealthy is by mistakes when your cells divide.
Every time one of your cells divides into two cells (which is how you grow, heal wounds, and replace dying cells), all of your DNA — the entire 2 meters of it — has to be copied perfectly.
That’s billions and billions of DNA bases that have to be put together in the absolute perfect order. Unfortunately, sometimes, your cells make mistakes.
And when they do, your DNA is no longer the perfect, healthy code it should be.
Contact with Mutagens
Another common way healthy DNA becomes unhealthy is by coming into contact with mutagens.
Mutagens make your DNA unhealthy by either breaking the strands apart or causing them to bind together in weird ways they shouldn’t. Both of these are bad news for your DNA.
And, unfortunately, mutagens are really common.
Plus, your body creates its own type of mutagens called reactive oxygen species when it breaks down food for energy.
Figure 1: How mutagens damage your DNA Some mutagens make your DNA bind to itself incorrectly (left). Others break your DNA apart (right). Modified from DNA UV Mutation by Mikhail Ryazanov, which is in the public domain.
Mutated DNA Staying in Your Cells Leads to Poor Cell Function
Luckily, most mutated DNA is repaired by a group of proteins called DNA repair enzymes.
DNA repair enzymes act like DNA-doctors. They examine the DNA, diagnose what’s different than in healthy DNA, and then (try to) fix it.
Sometimes, though, the enzymes don’t fix the problem, either because:
- the DNA is too damaged to be fixed or
- the DNA repair enzymes can’t find the problem
If either of these things happens, your unhealthy DNA stays in your cells.
Since your DNA tells your cells everything they need to do to function, having this unhealthy DNA in your cells long-term messes up how they work.
Unhealthy Proteins and Poor Cell Function
Proteins often get boxed-in to their role of helping your muscles function properly.
But proteins have many, many more jobs in the body than just letting you do a push-up! In fact, proteins are responsible for a ton of jobs in each of your body’s cells.
- help build all cell structures
- breakdown and recycle damaged cells
- chop up and burn food for fuel
- package extra food for storage
- carry molecules and building blocks between parts of the cell
- transport messages between areas of the cell
- coordinate cell growth
- organize cell division
- carry out cell suicide
- protect healthy DNA
- repair unhealthy DNA
- tell your DNA when to turn on or turn off a gene
In addition to all these super important jobs within each cell, proteins are also responsible for carrying signals between cells.
When proteins carry signals between cells, they serve as extremely important messengers. They let cells know:
- when their neighbor needs help
- when the organ a cell is a part of is in danger
- what other organs in your body are doing
- when there is an infection anywhere in your body
Basically, healthy proteins let your body function as one unit, not as billions of single cells sitting around in one spot!
How Proteins Become Unhealthy
How do proteins, with all their important jobs, suddenly stop working?
Well, typically, they either:
- are bent out of shape by other molecules in your body or
- are made incorrectly from mutated DNA
Again, let’s look at these one at a time!
Damage from Reactive Molecules
The most important property of a protein is its shape. Everything about how a protein work depends on how it’s folded up!
Unfortunately, that shape is easy fairly easy to mess up.
If a protein in your body comes across a reactive molecule (like glucose or one of those nasty reactive oxygen species I mentioned above), they can become physically attached to one another or the reactive molecule can break the protein apart.
Either of these, of course, changes the shape of the protein and it no longer works.
Made from Mutated DNA
Your DNA code gives exact instructions for how each and every protein in your body should be made. If your DNA becomes damaged, it can lead to your cells making proteins in the completely wrong shape from the get-go!
These proteins can’t do their jobs any better than those damaged by reactive molecules!
Unhealthy Proteins Staying in Your Cells Leads to Poor Cell Function
Luckily, just like with your DNA, your cell has ways to replace unhealthy proteins — your proteasomes and your autophagosomes. These complexes break down unhealthy proteins completely so they can be rebuilt from scratch.
But sometimes your proteasomes and autophagosomes can’t keep up with the number of unhealthy proteins (or they, themselves, stop working properly) and unhealthy proteins build up in your cells.
And I think you can imagine how having unhealthy proteins — proteins that don’t have the right shapes to do their jobs — can keep cells from functioning normally.
Proteins are responsible for basically every function of a cell! If they aren’t working correctly, your cells aren’t either.
What Happens to Your Organs When You Age?
Okay, so we’ve been through how changes in your DNA and your proteins make individual cells not work. But how does that lead to changes in your organs and your whole body — the parts of aging you see and feel every day?
Well, similarly to how each of your cells needs healthy DNA and proteins to function properly, each of your organs needs healthy cells to do their jobs.
Each of your organs is, of course, made up of thousands and thousands of cells which have to work together for the organ to be able to work. That means that having one or two of the cells not working perfectly, doesn’t make that much of a difference.
At some point, though, if too many of your cells have unhealthy DNA and/or proteins and aren’t working, the function of your whole organ suffers.
The symptoms you feel in your body when your organ stop working properly depend on which organ it is. A general comparison of healthy-organ and aged-organ functions are summarized in Table 1 (click on the organ name to learn more).
Table 1: Effects of aging on Each Organ
Preventing Aging: From Theory to Anti-Aging Strategies
Recognizing that all the complicated symptoms of aging simply comes from cells that aren’t working properly begs the question: can you stop it?
If you could keep your DNA from becoming unhealthy and prevent your proteins from becoming unhealthy, could you keep the aging process from happening?
Researchers admit that there is theoretically no reason that we couldn’t.
Practically, though, it looks like coming up with effective tools for life-long wellness that stop aging is pretty impossible.
Aging is Not Completely Preventable
Yep. It seems we can’t stop aging completely.
And the reason for this is statistics.
You have so many cells and mutagens and chemicals that can react with proteins are everywhere. You cannot protect all of your cells, all of the time, from all of them.
Based on the number of damaging molecules you come into contact with and the number of cells you have, scientists now think that, just based on a pure statistics, humans can’t really live longer than between about 115 and 125 years. Let’s split the difference and call it about 120 years.
This actually is remarkably close to the oldest ages people have actually been found to live to, with the absolute oldest ever recorded being 122 years.
Theoretical Life Expectancy vs. Current Life Expectancy
While in some ways that is discouraging news (we do likely have to age, after all), there is a serious silver lining to this cloud. 120 years is much, much longer than the current life expectancies for most people around the world!
As of 2015, the average life expectancy worldwide was just 71.4 years: around 74 for women and 70 for men. Of course, those numbers include very poor countries like Burundi (life expectancy: 55) and active war zones like Syria (life expectancy: 61).
If you look at higher income areas, like Europe or North America, the numbers are a bit higher than the world average (78 and 77, respectively), but not by that much and not for everyone in those countries. In very poor areas within the United States, for example, the average life expectancy is down near that of Syria — in the 60s!
Curious about your personal life expectancy? Check out this cool calculator.
Regardless of where you look, though, life expectancy is nowhere near 120.
Even taking the numbers for the most well-off countries, like Norway or the Netherlands, you’re still a full 40 years short of how long scientists think humans can live.
40 years is a long time. That’s a ton of extra vacations. A ton of extra time playing with grandkids! Heck, 40 extra years means meeting a ton more grandkids — we’re talking possibly up to your great-great-great grandkids!
Is there anything we can do to tweak how we age to add (at least some of) those 40 extra years to our lives? And is there any way to make sure those extra years are healthy years? It looks like there probably are!
Ways to Live Longer and Healthier: Tools for Life-Long Wellness
Now, longevity research is a pretty young field of study. There are tons of researchers still working out!
But even based on the data we already have, it’s absolutely clear that (in addition to the unchangeable genes you were born with) how long you live, and how healthy you over your lifespan, depend on at least five key modifiable factors.
That means there are at least five areas of your life that you can influence that can change how long and how healthily you live!
These factors are:
1. Your Exercise Routine
Study after study shows that physical activity, particularly training programs that help you build endurance and muscle, can help boost longevity!
2. Your Diet
The research couldn’t be clearer on this! The foods you choose to eat every day can have a huge impact on how your body ages.
Food rich in compounds that slow DNA and protein damage slow aging, while foods that contain compounds that damage your cells have the opposite effect.
By filling your plate with more cell-protective foods than cell-damaging foods, you can create a seriously anti-aging diet!
3. Your Environment
As we touched on above, there are all kinds of things in you come into contact with every day that can act as mutagens and damage your DNA and cause you to age: cigarette smoke, air pollution, sunlight, pesticides, industrial chemicals. Mutagens are everywhere!
But not everywhere equally.
You’re exposed to:
- less cigarette smoke if you don’t smoke
- less air pollution if you don’t live in a big city
- fewer UV-rays if you wear sunscreen
- fewer pesticides if you buy organic food
- less industrial chemicals if you wear all the protective gear you should at your job
4. Your Supplement Routine
Certain molecules have been shown to help protect your cells from DNA damage, including some found in green tea, turmeric, and even bacteria!
Getting decent doses of these molecules in your diet every day (a feat made easier by taking concentrated anti-aging supplements!) may be able to help reduce cell damage and slow the aging process!
5. Your Attitude
Believe it or not, the way you see the world, the things you believe, and your personality change how you age! Research consistently links an optimistic worldview with a longer life.
Just cultivating a happy, healthy relationship with yourself and the world around you may make a big difference in how long and healthily you live!
Take Home Message
Aging is a complex process that stems from unhealthy DNA and unhealthy proteins keeping your cells from functioning properly. Unfortunately, you can’t stop this process completely.
However, you can make decisions and take actions that directly influence how close you get to your maximum lifespan and how healthy you are while you’re getting there!