A massive new study has found evidence that blood iron levels could play a role in influencing how long you live.
It's always important to take longevity studies with a big grain of salt, but the new research is impressive in its breadth, covering genetic information from well over 1 million people across three public databases. It also focused on three key measures of ageing: lifespan, years lived free of disease (referred to as healthspan), and making it to an extremely old age (AKA longevity).
Throughout the analysis, 10 key regions of the genome were shown to be related to these measures of long life, as were gene sets linked to how the body metabolises iron.
Put simply, having too much iron in the blood appeared to be linked to an increased risk of dying earlier.
"We are very excited by these findings as they strongly suggest that high levels of iron in the blood reduces our healthy years of life, and keeping these levels in check could prevent age-related damage," says data analyst Paul Timmers, from the University of Edinburgh in the UK.
"We speculate that our findings on iron metabolism might also start to explain why very high levels of iron-rich red meat in the diet has been linked to age-related conditions such as heart disease."
While correlation doesn't necessarily mean causation, the researchers used a statistical technique called Mendelian randomisation to reduce bias and attempt to infer causation in the data.
As the researchers note, genetics are thought to have around a 10 percent influence on lifespan and healthspan, and that can make it difficult to pick out the genes involved from all the other factors involved (like your smoking or drinking habits). With that in mind, one of the advantages of this new study is its sheer size and scope.
Five of the genetic markers the researchers found had not previously been highlighted as significant at the genome-wide level. Some, including APOE and FOXO3, have been singled out in the past as being important to the ageing process and human health.
"It is clear from the association of age-related diseases and the well-known ageing loci APOE and FOXO3 that we are capturing the human ageing process to some extent," write the researchers in their published paper.
While we're still in the early stages for investigating this association with iron metabolism, further down the line we could see the development of drugs designed to lower the levels of iron in the blood - which could potentially add extra years to our lives.
Besides genetics, blood iron is mostly controlled by diet and has already been linked to a number of age-related diseases, including Parkinson's and liver disease. It also affects our body's ability to fight off infection as we get older.
We can add this latest study to the growing evidence that 'iron overload', or not being able to break it down properly, can have an influence on how long we're likely to live, as well as how healthy we're likely to be in our later years.
"Our ultimate aim is to discover how ageing is regulated and find ways to increase health during ageing," says Joris Deelen who studies the biology of ageing at the Max Planck Institute for Biology of Ageing in Germany.
"The 10 regions of the genome we have discovered that are linked to lifespan, healthspan, and longevity are all exciting candidates for further studies."
The research has been published in Nature Communications.