Most of us probably wish we were taller. Height is associated with attractiveness. Taller people are perceived to be better leaders. Being taller also enhances the experience of watching movies. However, one advantage that height does not seem to provide is lifespan.
Of course, if you are tall, that does not mean you are doomed to live a short life. Proper diet and exercise will lead to a healthier life, but research does show an inverse correlation between height and lifespan. While no causative factor has been specifically identified, the general hypothesis explaining the phenomena is damage by free radical oxygen.
Our cells are pretty amazing. Most of our cells have a special organelle (the cell equivalent of an organ) called the mitochondria. This organelle is largely responsible for harnessing energy from food and converting it into usable biological energy: ATP. High-energy electrons from food molecules (glucose, proteins, lipids, etc.) are used to drive a proton pump that generates ATP. Once the energy has been used up from the electrons, they are captured by oxygen and hydrogen ions to produce water.
The whole process is pretty miraculous, and it is what allows our cells to become much bigger than bacterial cells, which do not have mitochondria. However, there is a catch. Occasionally, a single electron is transferred to the oxygen instead of two. This creates a molecule known as a free radical. Free radicals have an unpaired outer electron, and as a result, they are highly reactive. Free radicals are known to damage DNA, and the accumulation of free radicals over time can have a serious impact on our body.
The most notorious disease caused by DNA mutations is cancer. Our DNA contains genes that regulate how long our cells live and how often they proliferate. If these genes are mutated, it may cause a cell to live longer than it is supposed to and multiply more than it is supposed to. Damage to enzymes or cells on a small scale usually pose no problem. Our DNA contains instructions to fix that damage. DNA damage is serious because there are no instructions left to repair it.
Taller people have higher metabolism because they have more cells. More cells mean more mitochondria, and more mitochondria mean more destructive free radical oxygen species. There are some things that we can do to counter free radical oxygen. Anti-oxidants are thought to react with free radical oxygen thereby preventing it from reacting with DNA. In several animal studies, it has been shown that restricting calories increases lifespan. The hypothesis is that fewer molecules are processed by mitochondria, and therefore fewer radical oxygen species are produced. However, restricting calories too much can have other negative health consequences. Nothing fits the phrase “the grass is greener on the other side” better than our height.
