Intermittent fasting may be most famous as a weight-loss method (or not), but we all know diet can affect more than just our waistlines. In recent years, intermittent fasting has turned out to have quite a few surprising health benefits: studies have suggested that the diet technique may help ward off infections, lower the risk of various cancers and metabolic diseases, and perhaps even extend your lifespan.
A new study published in Nature has revealed another benefit of intermittent fasting: it may be able to help us heal damaged nerves.
“Intermittent fasting has previously been linked by other studies to wound repair and the growth of new neurons – but our study is the first to explain exactly how fasting might help heal nerves,” said Simone Di Giovanni, Professor of Restorative Neuroscience at Imperial College London and lead author of the study, in a statement.
“There is currently no treatment for people with nerve damage beyond surgical reconstruction, which is only effective in a small percentage of cases, prompting us to investigate whether changes in lifestyle could aid recovery,” he explained.
It may sound like a leap – how can fasting repair nerve damage? It all comes down to a gut metabolite known as 3-Indolepropionic acid (IPA). It’s a potent antioxidant with potentially huge implications in the treatment of fatal bacterial infections; it plays an important role in protecting us from diabetes and bowel and liver issues; it can even help us get horny. Best of all, it turns up in our bodies naturally, produced in our guts by the bacteria Clostridium sporogenesis.
It's also a crucial metabolite for regenerating axons. These are the thread-like structures at the ends of nerve cells that send out electrochemical signals to other cells in the body – if your axons get damaged, your nerves can’t communicate with each other properly, which is why neurodegenerative diseases are as debilitating as they are.
But wait: if IPA regenerates nerves, then the question for neurologists isn’t “how do we grow nerves back,” but “how do we get more IPA in our patients” – and that’s exactly what the Imperial researchers figured out. They realized that many of the various known ways to promote nerve regeneration – exercise, environmental enrichment, those kinds of things – have the same knock-on effects as intermittent fasting.
After all, intermittent fasting is well-known to have positive effects on gut biomes, where IPA lives. Could intermittent fasting hold the key to nerve regeneration?
To test the hypothesis, nerve regeneration was assessed in mice whose sciatic nerve – the longest nerve in the body, running from the spine down the leg – had been crushed. Half of these poor rodents were then put on an intermittent fasting diet, with one day eating as normal followed by one day fasting, while the other half were allowed to gorge themselves silly whenever they felt like it.
At ten and thirty days into the experiment, axon regrowth was measured for both groups – and the results were clear. The intermittent fasters’ axons had regrown approximately 50 percent more than the mice with no such dietary restriction.
There were also significantly higher levels of specific metabolites, including IPA, in the blood of diet-restricted mice. Another experiment proved the converse: mice who were given IPA after a nerve injury healed faster and better than those who weren’t.
Of course, there are still quite a few questions left to answer before IPA is touted as a miracle cure for nerve damage. “One of the questions that we haven’t explored fully is that, since IPA lasts in blood for four to six hours in high concentration, would administering it repeatedly throughout the day or adding it to a normal diet help maximize its therapeutic effects?” said Di Giovanni.
Without further research, the team can’t say for sure whether these results will be replicated in humans – though there are reasons to be hopeful.
Either way, it’s an exciting new world out there. “One of our goals now is to systematically investigate the role of bacteria metabolite therapy,” said Di Giovanni.
“[It] opens up a whole new field where we have to wonder: is this the tip of an iceberg? Are there going to be other bacteria or bacteria metabolites that can promote repair?” said Di Giovanni.