Often, neuropathies affect the feet first, and then travel up the legs. Once the knees become affected, the hands soon follow. This painful condition typically affects people who are older or taller compared to younger, shorter people. Though this pattern is typical of nearly all cases of neuropathy, researchers have not been able to explain why.
Lead author, Ahmet Hoke, M.D. Ph.D., and colleagues suspected that the reason might be found in mitochondria, the parts of cell that generate energy. Mitochondria for most cells in the body have a relatively quick turnover, replacing themselves about every month. However, those in nerve cells often live much longer to accommodate the sometimes long journey where a cells starts growing to where it ends. The nerve cells that supply the feet are about 3 to 4 feet long in a person of average height. The mitochondria in these nerve cells can take about two to three years to travel from where the nerve originates near the spine to where it ends up in the foot.
To explore whether the aging process during this trek might affect mitochondria and lead to neuropathy, Hoke and his fellow researchers investigated nerve samples taken during autopsies from 11 people who had HIV-associated neuropathy, 13 who had HIV but no neuropathy, and 11 HIV-negative people who had no signs of neuropathy at their deaths. The researchers took two matched samples from each person; one from where the nerves originated near the spine and one from where the nerves ended near the foot.
Through careful analysis of mitochondrial DNA, the researchers found that for the nerve endings at the ankle, there was a 30-fold increase in a type of mutation that deleted a piece of this DNA compared to mitochondrial DNA from near the spine. The difference in the same deleted mutation between the matched samples in people without neuropathy was about threefold.
Hoke explains that as mitochondria travel from the spine to the feet, their DNA accumulates mutations with age. These older mitochondria might be more vulnerable to assaults that come with disease compared to younger mitochondria near the spine, leading older mitochondria to suffer dysfunction first. The finding also explains why people who are older or taller are more susceptible to neuropathies, according to Hoke. He concludes that this discovery could lead to mitochondria-specific ways to treat this condition.
Currently, there are several ways to naturally optimize mitochondrial function:
• Exercise: Those who exercise have more mitochondria present in their cells. Even in older people, the more you exercise, the more mitochondria you have, and the better they work.
• Avoid Toxins: Mitochondria are especially sensitive to toxins. Environmental toxins such as carbon monoxide, cadmium and mercury are harmful in addition to recreational drugs like tobacco and alcohol.
• Take In Nutrients: Antioxidents help reduce the rate of damage to mitrochondrial DNA. Other nutrients that support mitochondrial function include niacin, riboflavin, magnesium, iron, copper, and zinc.
• Enjoy a Glass of Wine: The grape skin extract known as resveratrol has been shown to protect and improve mitochondrial function.