Smoking and Mitochondrial function
In order to understand how tobacco may affect mitochondrial function, first it is imperative to have a basic understanding of how the mitochondria work and what their function is.
Structures called mitochondria are located within the cell and are known as the “powerhouse” responsible for generating energy to supply the body's metabolic requirements. The mitochondria's function is to take electrons from the environment and use them to synthesise what is known as Adenosine Triphosphate (ATP), the body's energy source. Through a process called cellular respiration, electrons taken from digested food are shuttled past the mitochondrial membrane with help from specific molecules (via electron chain transport) so that the mitochondria can create ATP. ATP is used to
fuel almost every cellular process in the body and is absolutely essential for all bodily functions, therefore maintaining healthy mitochondrial function is of vital importance.
One of the key players involved in ATP production and mitochondrial health is the enzyme Nicotinamide adenine dinucleotide (NAD). NAD is present in all living cells and is available in two forms: NADH and NAD+. Both forms are essential for proper cellular energy transfer, and insufficient amounts can result in mitochondrial dysfunction. NADH's main function is to transfer electrons to the mitochondria to facilitate ATP synthesis. Once NADH has lost it's electrons, it converts to NAD+.
NAD+ has been shown45 to increase the rate of DNA repair, stress resistance, and regulate cell apoptosis. Furthermore, NAD+ also restores tissue integrity, induces homoeostasis, and increases longevity of the cell46. The cell senses levels of NAD+ as a measure of mitochondrial energy production and rate of metabolism. For this reason, the amount of NAD+ converted actually plays a significant role in regulating the rate of ATP synthesis and cellular metabolism
47. Low levels of NAD+ reduce mitochondrial energy production, decrease the number of mitochondria in the cell48 and contribute significantly to muscular ageing processes
49. Interestingly, NAD+ also has the ability to alter gene expression by “switching off” genes associated with degenerative processes
50.
To follow on, SIRT1 (sirtuin) is a NAD-dependent protein coded for by the SIRT1 gene that cannot function without NAD+. So when NAD+ levels decrease, SIRT1 levels also decrease, and vice versa.
SIRT1 turns out to be one of the single most important enzymes in control of epigenetic expression, metabolism and longevity. Through a process called acetylation, acetyl groups are added to proteins in response to stress, oxidation or inflammation, which causes the proteins to eventually become defective. Sirtuins, however, remove the acetyl groups to allow for those proteins to stay functional for a longer period of time. This gives the body the opportunity to expend less energy recycling, and more energy on other processes. Studies have shown that SIRT1
inhibits MTOR pathway signalling, increases leptin sensitivity51, increases T3 hormone sensitivity52, and also increases the skin' sensitivity to Vitamin D53. SIRT1 also inhibits/ switches off genes associated with inflammation54, blood sugar regulation, and body fat accumulation/storage55.
So, how does this relate to smoking tobacco?
A study56 conducted by Cancer Research in 2012 showed:
SIRT1 activity was the most consistently and significantly up-regulated in smokers compared to non-smokers in all 4 datasets. While SIRT1 was activity correlated to smoking status, SIRT1 pathway activation was not significantly correlated with pack-years among smokers (p > 0.05; Spearman). Therefore, independent of cumulative exposure, SIRT1 activity is consistently up-regulated in smokers. This increase in SIRT1 activity may serve as a protective effect against oxidative stress and DNA damage induced by smoking.
Considering the fact that SIRT1 is anti-inflammatory and can only function in the presence of NAD+,
these findings suggest that NAD+ may also be up-regulated in smokers. An elevated level of NAD+ indicates an increase in mitochondrial functioning and ATP synthesis which are both absolute markers for longevity and overall better quality health! This finding can provide us with valuable insight in to how so many smokers end up leading such long, disease-free lives. For those people who are genetically compatible, consuming tobacco smoking is not a burden on the body. These people do not live to such old-ages despite their smoking habits,
they live so long because of smoking And below are some perfect examples of this:
Most of oldest people in the world... were ALL smokers
Jeanne Louise Calment
French supercentenarian Jeanne Louise Calment was born on February 21st 1875, and on the 4th of August 1997, she was confirmed to have died from natural causes. She lived for a total of 122 years57. Her secret?
Calment smoked from the age of 21 up until the ripe old age of 117 when she finally decided to give up the habit.
Jose Aguinelo dos Santos
Jose Aguinelo dos Santos, a Brazilian man whose parents were African slaves, was born on July 7th 1888. In July 2014, Jose reached his 126th birthday58. Interestingly, Jose has smoked a pack of cigarettes every single day for the past 50 years.
Winnie Langley
Britain's 'oldest smoker', Winnie Langley was born in Croydon in 1907. At her 100th birthday party, Winnie said: “
I have smoked ever since infant school and I have never thought about quitting”. It is thought that she smoked more that
170,000 cigarettes throughout her life59. Sadly, two years later Winnie's life was cut short at the young age of 102.
Emiliano Mercado Del Toro
Born on Auguest 21st 1891 in Puerto Rico, Emiliano smoked for a whole 76 years before giving up at the age of 90. In 2007, Emiliano passed away at age 115 from natural causes60. Another obvious example of how smoking clearly shortens the life-span
Sek Yi
Sek Yi, was a devout buddhist and a martial arts expert who was believed to have been born in 1881. In October 2003, Sek passed away at the age of 122 years old.
Sek attibuted his longevity and that of his 108 year old wife to smoking and prayer. In an interview, Sek said: "When I was young I used to chew betel, but people made fun of me saying I was like a woman, so I took up smoking."61
Batuli Lamichhane
Batuli was born in Nepal in March 1903, which now makes her 112 years old. She is still alive, and has been smoking 30 cigarrettes a day for the past 95 years ever since she was 17. Apparently, Batuli “
claims it’s her daily habit that has helped her outlive almost everyone else in her village – and her own children”62.
Christian Mortensen
Finally, danish-american supercentenarian Christian Mortensen was born on August 16th 1882. Christian passed away on April 25th 1998 at the age of 115 years old. When asked what his secret to a long life was, he said: “
Friends, a good cigar, drinking lots of good water, no alcohol, staying positive and lots of singing will keep you alive for a long time.”63.
List of References can be found
here