Learning about the human body is perhaps one of the most fascinating topics. Perhaps I am biased, as I love all things biology related, but your body is probably the most important system that you should learn about, to best live out this lifetime. I cannot imagine not wanting to know how it works and what makes it tick.

Well, thanks to a recent email from Akemi Gaines of Yes-To-Me, we will have a chance to delve in deeper today into one very fascinating area that deals with our body. This is the area of how our body deals with old cells, nutrients and whether it has some sort of recycling system of its own.

Akemi’s questions and comments about the body’s own waste disposal system were so intriguing that I will break it down here into a few parts and address each part separately. In addition, this will also become part 3 of the “Health and Nutrition Myths” series.

Hence, if you always wanted to know what happens to old cells and how our body cycles nutrients, deals with them and why we constantly have to keep eating, come along for the ride as we explore these depths of the human body.

Health and Nutrition Myths, Questions and Answers

“We are taught we need to eat to get necessary nutrition and energy. I see the need to renew. But what happens to the old chunk of cells that get replaced with the new? Some cells like the skin cells get pushed out, but I guess most of them go into the bloodstream to be excreted in urine or stool. Our blood stream is both the feeding system of nutrition and the sewage.”

What happens to old cells, depends on what cells they are. As for our blood being both the feeding system and the sewage system, that is right on. Both helpful and harmful compounds travel via the blood. However, some people’s blood is much more “dirty” than others.

When it comes to skin cells, most of them actually get sloughed off externally. It is estimated that every minute of the day we lose about 30,000 to 40,000 dead skin cells off the surface of our skin. New ones grow underneath and thus make our new skin.

Old or diseased blood cells for example are most commonly destroyed by the spleen. They can also be removed through the liver and kidneys, and their byproducts are eliminated in the urine.

Most of the cells that pass through in the stool are intestinal cells. These last only a few days, and like skin cells get sloughed off. Since they are located internally, they mix in with our food wastes and pass out in our stool.

Many of our cells actually get eaten by other cells, namely ones from our immune system, as they release a signal to be eaten. This is also referred to as a “programmed cell death” or “cell suicide”. Formally, it is known as apoptosis. This is a pretty complex process, but generally speaking a cell will decide to do this based on many signals that it exchanges between its environment and itself.

“Now this old cell that is getting dumped. It’s no longer good as a cell, but when it’s broken down to molecular level, it’s a chunk of amino acids and lipids. Just like any amino acids and lipids. Can’t we then recycle these amino acids and lipids?”

Generally speaking yes. Our bodies have actually a pretty good recycling system. An individual may recycle and exchange 70% of their cells for new ones each and every year. However, not all is as smooth and simple as we would like to believe.

There are small organs that make up each of our cells called organelles. One of these organelles is called the lysosome. Lysosomes are like mini digesting factories, in that they use their own enzymes within them to recycle the cell’s own organic material. This is known as autophagy and it goes hand in hand usually with the process of apoptosis, described above.  Any wastes then get transported via the blood to areas (organs) which can expel them out of the body.

In this process a lysosome engulfs another organelle or small packet of cell contents. The enzymes take apart the substance and the organic pieces are returned for further use by that cell or another one. This way many cells can actually continually renew themselves. It has been said that a human liver cell recycles half of its macromolecules each week. Macromolecules include things like carbohydrates, fats and proteins.

Now theoretically that is what happens, but to this day scientists don’t yet know all the details of these processes. Also, there are apparently many substances that are indigestible to the lysosome. These can cause problems in cells in the long run.

Practically, I would compare this process to recycling an old car. Sure we can use some of the pieces of an old car to make a new car, some pieces will need to be repaired of course. Others however, will not be able to be used at all, as they had too much wear and tear on them or got used up altogether.

In this sense, our bodies do try to reuse and recycle many of their own components, but some proteins or carbohydrates for example get turned into whole new chemical components, which the body will have to dispose of, and will not be able to reuse again.

“I read Aubrey de Grey’s “Seven Causes of Aging and Death” – which are: undesirable mutation / slowdown of DNA, proteins, etc., and the accumulation of junk in and around the cells. I understand the need to get rid of the old cells, but when cells break down, the building blocks on the molecular level are just that — an amino acid is an amino acid, whether we get it from foods or it’s our own old cell recycled. Food is someone else’s old cells (whether they are animal or plant based.) So the problem is we don’t have such recycling system in our body?”

Aubrey de Grey is definitely a wonderful reference to bring into this topic. I remember I saw his TED talk video a few months ago and he really got me intrigued about a few things when it comes to longevity. I personally believe that these bodies of ours can last much longer than a mere 60-80 years, out of which as much as 2/3rds are usually spent in some kind of pain or discomfort. (I included that TED talk video below.)

Our cells cannot use everything that they contain and thus recycle everything, just as when we eat and go to the bathroom, we cannot reuse those wastes. They are just that – wastes.

Hence, our food coming in and making us up, is like a large scale version of nutrients coming into cells and making them up. While many nutrients can be used again, as I explained in the answer above, others are either used up, indigestible or just plain junk.

Also when we eat, our food is not necessarily the “old cells” of some other species.   It would be old cells if the plant or animal material we are eating is passed its due date, or in the case of the animal, it is actually, physically old.

Similarly, an amino acid is not necessarily kept as that amino acid. According to the teachings of chemistry, sometimes one carbon or hydrogen or any atom extra or less, makes a difference as to what that compound does or how it behaves. Thus what goes into our bodies and what our bodies change that to, are often two very different things.

So while our body does try to capture so much back on a daily basis, mostly through our liver and kidneys, whether they be macromolecules (carbs, fats, proteins) or micromolecules (vitamins, minerals) – it just cannot grab everything back for the reasons explained above. This is why we need to eat regularly to replenish those things that got “used up” or “burned up.”

“So if we can develop an inner recycling system, we wouldn’t need to eat so much?“

As I mentioned above we do have a pretty good recycling system, but there are many parts of ourselves that get used up, chemically changed and thus cannot be used as the ground work for new or more molecules of carbs, proteins or fats. So it does not really mean that we wouldn’t need to eat as much.

For example, we eat macromolecules and micromolecules each day. They get used to build new things, supply us with energy and initiate a whole slew of chemical reactions. The majority of these substances get chemically changed in the body to be the specific part they need to be or work on doing. Once those parts “wear out” – in most cases it is inefficient for the body to change that substance back to being say the original carb, fat or protein we need – or it just plain and simple cannot change them back. A small chemical change, sometimes makes a big difference.

One way to understand this is the idea of burning paper. The molecules that make up the paper are used to be written on. However, once the paper gets burned, one can no longer write on that paper, even though chemically speaking the physical atoms that made up the paper are the same (some left as gas), but re-arranged. In fact, they are so re-arranged that we no longer can treat the ash, the same way as we treat the paper – although chemically they are still very similar.

Therefore, speaking on a purely scientific or medical level, we do need to eat regularly to replenish our body, and all the parts that get used up or worn out. However, one will generally need less food, the less damage is done within the body or the more nutrient dense the food is.

The recycling system that we have is there and is good, but it cannot compensate for the daily usage that we have.

However, if one would consider this topic metaphysically, then we open ourselves up to a whole new level of possibilities that can surpass both food and eating.

Ultimately our bodies are very efficient. Therefore it is more efficient for the body to use the new incoming nutrients, than revert old compounds to what it needs. (This is not the rule for every reaction in our body, but many.) Now say, we take someone who is without food or nutrition for a long period of time, their body will be using more of the “old” stuff to keep them going, but of course at a higher price in the long run.

A Note On Aging and Longevity

According to my own research, understanding and theories on aging, I greatly agree with Aubrey de Grey’s 7 reasons for aging. Out of these 7 reasons he claims that junk that builds up inside and outside of the cells throughout our lives is the biggest contributor to aging.

Thus, if one is interested in longevity, and not even so much for the sake of extending their life, as for having a quality -  perfect health life – then the thought goes that one should focus on “purity” as much as possible.

Here is what I mean. Take for example a processed hamburger versus an organic salad. One of these food choices is filled with much more “junk” – that is, substances that the body cannot use, digest or ones that will actually be toxic – than the other. A diet that is high in such substances is much more indicative of faster aging. Thus for best longevity, the cleaner, or purer the diet, the less junk accumulates in and around our cells.

And this does not only apply to diet. This also applies to the water we drink, the air we breathe and the products we use. It even applies to our thoughts. I don’t mean one has to have “pure” thoughts like religions might like us to believe, but pure or clean with respect to negative or positive. Are your thoughts full of stress and negativity which generates a lot of undesirable chemical reactions, that not only result in cellular damage but also junk in our blood stream – or – are your thoughts happy and coming from a place of low stress, where the body is able to have an optimally working cleaning system.

Finally, this conversation would be incomplete I feel, without mentioning the idea of detox. In the past few decades, various forms of detox have become very popular. While some are all hype and nothing more, the general idea of a detox is very beneficial to our bodies. It allows our bodies to have a properly cleaning system to get rid of a lot of the “junk” that can not only age us, but also lead to various diseases.

One of the easiest detox strategies that each one of us can do is to make sure that there is a 12 hour period of no eating between our last meal of the day and our first meal of the next day. Thus if your last food item came in at 7pm, you do not eat anything again till 7am. This not only allows for proper digestion, but also for our body’s natural cleansing system to kick in. This is also why most healthy people have one or more bowel movements in the morning hours. This is all part of healthy cleaning and elimination.

There are many other and much more rigorous detox systems, but they are beyond the scope of this discussion here. Thus, if you are interested to hear what Aubrey de Grey has to say about his theories and work on prolonging life and postponing aging, I invite you to watch the following video below. It is the lecture that he did for TED.com.

*Main photograph courtesy of Sherri Dwyer
*Burning Paper Photograph courtesy of by hyperscholar

About the author:
Evita Ochel, B.Sc., B.Ed., CHN - is a certified holistic nutritionist, biologist, educator, writer, researcher and speaker in the areas of health, science and holistic wellness. She is a nutritional science expert and her teaching and writing focus on natural, wholesome, plant-based and organic nutrition to achieve optimal health and longevity. Learn more about Evita Ochel or Follow Evita Ochel on Twitter.