It’s the Holy Grail for medicine: how to stop or even reverse aging. With teams of scientists the world over frantically trying to figure out what may cause it, studying everything from nematode worms to naked mole-rats, it seems that a team from Japan might have taken a step forward.

Defects in mitochondria, called “the powerhouse of the cell,” as they produce the cells' energy, have long been associated with causing aging-related characteristics such as hair and weight loss, curvature of the spine and osteoporosis. One of the most popular current theories on why we age is called “the mitochondrial theory of aging.” It’s been thought that accumulated mutations in the DNA found in mitochondria are the reason behind this.

But researchers from the University of Tsukuba in Japan have been able to demonstrate that this might not be the case. They suggest that the defects are not due to mutations in the DNA after all, but that external factors might be driving them. They looked at how the mitochondria were working in cell lines derived from young people, and compared them with cell lines derived from older people. What they found was fascinating. There were no observable differences in the number of mitochondrial DNA mutations between the older and younger cells. Their results are published in Science Reports.

This led the scientists to suggest that perhaps it was so-called “epigenetic” factors, such as the addition of certain proteins to the mitochondrial DNA, which might be creating the defects that cause the signs of aging. If this were the case - the researchers purposed - then “resetting” the cell lines to stem cells would correct and remove these epigenetic factors. When they tested this with the cell lines from the older people, this is exactly what they found. Quite amazingly, it seemed to turn the “old” cells back into “young” ones.

When they looked further into the sections of DNA that might be influenced by these epigenetic factors, their results pointed to two regions that control the production of a particular amino acid. The amino acid in question is called glycine. What’s more, when they then bathed the cell line derived from a 97-year-old in glycine for ten days, it restored the mitochondria’s ability to produce energy and reversed some age related defects.

Whilst this research was only conducted with cell lines in the lab, the researchers are keen to investigate further whether the same epigenetic factors contribute towards aging in humans, and whether the same processes could be used to either halt or reverse it.