Longevity: The Rate of Living Theory

What happens when our regular metabolism burns energy for life? Well, some of that energy escapes and does damage to DNA decreasing our longevity. Some of the damaged cells naturally end their life cycle and die. In their place come new ones from the division.

The higher the metabolism, the higher the damage, and the higher the division.

Every time a cell divide it clips the telomere in half. A telomere is a small area of repeated nucleotide sequences at each end of a chromosome.

The purpose of the telomere is to keep the end of the chromosome from deterioration or fusion with other neighboring chromosomes. During chromosome duplication, the enzymes that duplicate DNA can maintain their duplication unit at the end of a chromosome. What happens is that in each duplication, the end of the chromosome is shortened. After too many divisions telomeres are gone, and there are no more divisions only death. It is a process called aging.

We can slow this process down and increase our longevity by slowing oxidative damage with high levels of antioxidants in the diet, and we can slow it down by increasing energy efficiency. The problem is that nothing in nature is 100% effective. Some of the oxygen in our cells escapes in the form of free radicals and do their oxidation elsewhere.

Oxidative stress happens when an oxygen molecule splits into single atoms with unpaired electrons. These aggressive molecules are called free radicals. They are so aggressive that they will attack the nearest stable molecule trying to steal its electron particle. When the attacked particle is left with no electron, it will become the free radical itself. The process is going to create a chain reaction. Once the process is started, the final result is the disruption of a living cell.

Free radicals are created as a part of normal metabolism.

Four different mechanisms produce endogenous (your body creates them) free radicals. The production of free radicals cannot be entirely stopped. It is surprisingly amusing to me that oxygen, an element indispensable for life is also responsible for our death.

It is not plausible to directly measure the number of free radicals in the body. The more fuel we burn, the faster we burn out.

Have you ever asked yourself how many heartbeats a common man has in their life?

It turns out each animal gets around a billion beats. Smaller animals have higher metabolic rates, and their heart is beating faster. When we calculate the number of beats for different sizes of different species of animals the magic number is one billion. Horses, rabbits, cats, pigs, elephants, whales, it does not matter, it is always one billion. Other than small dogs. They got the short end of the stick. In contrast, humans and chickens are champions in that we get more than double the usual natural number. Around 2.21 billion for us and 2.17 billion beats for chickens. The quicker your metabolism is the faster you will oxidase and the shorter your longevity.

It is called the rate of living theory. Max Rubner first proposed the concept in 1908. He observed that larger animals always outlived smaller ones and that the larger animals had slower metabolisms. A further affirmation was given to these observations by the discovery of Max Kleiber’s law in 1932. Kleiber assumed that basal metabolic rate could correctly be predicted by taking 3/4 the power of body weight.

This theory is colloquially known as the mouse-to-elephant curve. Support for this theory has been reinforced by studies linking a lower basal metabolic rate (evident with a lowered heartbeat) to increased life expectancy. Grand Tortoise can live up to 150 years. Hummingbirds have the highest metabolism of any homoeothermic animal. Their hearts beat at over 1263 beats per minute. At night, they enter a stupor, a form of deep sleep. In a stupor, their heart rate drops to 50 beats a minute to conserve energy. The average lifespan of a wild hummingbird is 3-10 years.

One species that stick out for longevity are Macaws. Birds in general average some 2 to 3 times the longevity of mammals. There are specific avian groups that are even longer-lived than this overall average. Why and how nobody knows. The interesting fact is that oxygen consumption in a unit of time in bird cells can go as high as 2.5 times that of mammals. If we combine this fact of high metabolic rate and oxygen consumption with the long lives of birds, we have unsolved scientific phenomena. If we calculate the numbers, we can see that some long-lived avian cells may be able to live as much as 20 times longer than some of the short-lived mammals such as mice, and five times that of regular long-lived mammals such as humans. If we find out how and what the secret is, we could possibly have five times life expectancy. Birds have evolved some protection against free radical damage. They have evolved some effective mechanisms for protection from the buildup of free radicals. The circumstances of those protective measures so far remain elusive. Longevity is a big topic in today’s scientific research.

Studies within those sectors of oxidative free radical protection have so far been restricted, and the evidence has been moderately conflicting. It will be significant in pharmaceutics, it already is. Universal strong antioxidant and calorie restriction pill, all we can eat and still have the benefits. There are multiple substances that undergo experiments within the pharmaceutical industry, for example, one substance is called Compound SRT1720. SRT1720 mimics dietary restriction, lessening many of the harmful effects of the high-fat diet and obesity with no signs of toxicity even after 80 weeks of treatment. We cannot buy this stuff yet.

What we can do is a dietary intervention in order to optimize our antioxidant intake. What we can have at present is something in the form of strong universal antioxidants like Astaxanthin, Curcumin, or MegaHydrate and increase our dietary intake of antioxidants from food. There is extensive research that is already available and optimizing our ORAC dietary intake levels is recommended to anyone especially in people that have some sort of inflammation and as a prevention from chronic diseases like cancer, aging, diabetes, cardiovascular disease, liver and kidney problems, neurodegenerative disorders (Neha et al., 2019).

There is no more debate on the list in the scientific field anymore about antioxidant intake. More research had to be done, especially to see if the high rate of dietary antioxidants had an adverse effect on immune cells that use the release of oxygen free radicals like macrophages. There is also evidence that antioxidants like beta-carotene can harm us if not taken in a whole food way. In the future, there will probably be much more research done in this area.

In one study that I will mention (Flanary et al., 2005) they analyzed one type of bristlecone pine, Pinus longaeva. It is the oldest known living eukaryotic organism, with the oldest on record turning 4780 years old in 2015. In this study, researchers did a detailed investigation of telomere length and telomerase activity. Telomerase is a ribonucleoprotein enzyme that adds a species-dependent telomere repeat sequence to the end of telomeres. It lengthens the telomeres. Some cells, not all of them can maintain telomere length by the action of this enzyme, thus keeping themselves from death. The conclusions of the research confirm the assumption that:

“Both increased telomere length and telomerase activity may directly/indirectly contribute to the increased life-span and longevity evident in long-lived pine trees (2000-5000 year life-spans).”

(Flanary et al., 2005)

In the future, we will have some t-pill maybe, but until that time we need to correct our lifestyle. Periodical fasting can be one way. It will help us as much as exercise and as much as a good diet.

However, who will actually do this? Ascetic monks. On a population scale, it is not sustainable, and actually, on a population scale, we see reverse action. For us, it is all about how to overcome our metabolism and calorie adaptation so that we can eat more, lose weight more quickly, and have six-pack abs and French fries at the same time. Many people describe dieting to be a 50% physiological battle and a 50% psychological battle, and they are not far off from the mark unless you can deal with the intensive food cravings you face. Most people on a diet are running a calorie deficit of around 500 calories below maintenance. After metabolic adaptation takes place, we can see how fast weight loss would go. Moreover, just around the corner are birthday parties, holidays, and of course, cheat meals. Eating for pleasure is nothing new.

References:

1. Lints, F A. “The rate of living theory revisited.” Gerontology vol. 35,1 (1989): 36-57. doi:10.1159/000212998
2. Brys, Kristel et al. “Testing the rate-of-living/oxidative damage theory of aging in the nematode model Caenorhabditis elegans.” Experimental gerontology vol. 42,9 (2007): 845-51. doi:10.1016/j.exger.2007.02.004
3. Neha, Kumari et al. “Medicinal prospects of antioxidants: A review.” European journal of medicinal chemistry vol. 178 (2019): 687-704. doi:10.1016/j.ejmech.2019.06.010
4. Flanary, Barry E, and Gunther Kletetschka. “Analysis of telomere length and telomerase activity in tree species of various life-spans, and with age in the bristlecone pine Pinus longaeva.” Biogerontology vol. 6,2 (2005): 101-11. doi:10.1007/s10522-005-3484-4