It is the fastest growing neurological condition in the world. Around 153,000 people in the UK are currently living with Parkinson’s, with two more diagnosed with the incurable progressive condition every hour. While its symptoms, including tremors and a slowing of movement, begin to appear when the brain can no longer produce enough dopamine, the root cause of this process remains a mystery. Yet a growing body of research now points to a possible origin and even a potential course of action for those looking to protect themselves against the disease.
This summer, a study in the journal Gut analysed the medical records of 24,624 people with Parkinson’s and found that four gut conditions – irritable bowel, constipation, gastroparesis and difficulty swallowing – were associated with a higher risk of the disease. For Becky Jones, of leading research and support charity Parkinson’s UK, this was just the latest in a series of promising studies.
“There’s growing evidence to suggest that the gut might be involved in Parkinson’s,” she says. “Clumps of a protein called alpha-synuclein, known to be associated with Parkinson’s, have been found in the gut of some people with the condition, sometimes before they can be seen in the brain.”
These connections have led some researchers in the field to the Braak hypothesis. “It suggests that, for some people, Parkinson’s might start somewhere other than the brain, such as the gut,” says Jones. “Those clumps of alpha-synuclein protein begin to stick together in the gut, and then travel up the vagus nerve which connects the intestine and the brain. Once in the brain, they start to cause further damage and spread to dopamine-producing cells and other areas in the brain.”
Recent research has further explored the connection between the brain disorder and the gut. In January, Nature Communications published a study showing that 30 per cent of the gut bacteria found in people with Parkinson’s differs from that in neurologically healthy people, while in May, an animal study from the University of Helsinki identified specific strains of bacteria in the gut that may be the cause of Parkinson’s.
Parkinson’s UK is currently supporting research projects delving deeper into both of these connections to the gut. In the meantime, “We don’t yet know what causes Parkinson’s or how people can protect against it,” says Jones. “But keeping a healthy, balanced diet and remaining active is advisable to all.”
Follow the fish
In 2019, a Harvard University study that examined health data from 47,679 participants found that those who followed the healthiest Mediterranean diets, in which fish is prioritised as a protein source, were 30 per cent less likely to develop early Parkinson’s symptoms.
“Dozens of studies show that dietary patterns like the Mediterranean diet reduce the risk of a number of diseases, including Parkinson’s,” says leading microbiome researcher Tim Spector, professor of genetic epidemiology at King’s College London, and founder of ZOE, the personalised health company.
In 2018, Swedish researchers discovered that fish’s potential power to prevent Parkinson’s might be linked to a specific chemical, found in abundance in many species. “Parvalbumin collects up the ‘Parkinson’s protein’ and actually prevents it from aggregating,” explained lead study author Pernilla Wittung-Stafshede. Herring, cod and red snapper are among the fish that contain high quantities of parvalbumin.
Focus on fibre
“Your gut bacteria thrive on fibre,” says Dr Emily Leeming, a registered nutritionist. “But in the UK we are starving our gut bacteria of it. We get just over half the 30g of fibre [a day] that we need for our health.”
Studies have shown that inflammation is linked to certain Parkinson’s symptoms and that people with Parkinson’s have markers of inflammation in their blood and cerebrospinal fluid. When we feed our gut bacteria with fibre, they break it down and produce healthy molecules called short chain fatty acids that have anti-inflammatory effects, explains Leeming. “An easy hack to get enough fibre is to make half your plate of vegetables, and a quarter wholegrains,” she suggests.
Pack in the plant
“While there’s no conclusive evidence on exactly which foods can reduce risk, research on Parkinson’s disease and the gut microbiome is really exciting,” says Dr Federica Amati, medical scientist and nutritionist at Zoe. “Looking after your gut health and gut microbiome with a gut friendly, high-plant-diversity diet is an important strategy to reduce your risk and improve outcomes for those who suffer with it.”
“Increasing our plant intake to 30 plants per week is associated with a diverse gut microbiome,” agrees Spector. In fact, a large-scale UK study appeared to confirm the benefits of a plant-based diet as a protective measure against Parkinson’s when it was published this summer. Using UK Biobank data, it found that healthy plant foods were associated with a 25 per cent lower risk of developing the disease. Unhealthy plant-based foods (like refined grains, sweets, and desserts) did not confer such benefits.
“These results are important to help refine and inform public health messages that consider plant-based diets and provide evidence that simple dietary change has the potential to reduce [Parkinson’s disease] risk,” wrote the researchers.
Colour code your cooking
It is not enough to fill up on your favourite veg, however. “Polyphenols are a group of antioxidants that give fruit and vegetables their colour – from the green in spinach to the red of a tomato,” says Leeming. “Different bacteria prefer different types, so eating the rainbow can make sure they get the food type they like.” If that sounds tricky, “choose the ready mixed options next time you’re shopping, like mixed cans of beans, mixed salad, and fruits of the forest berries,” she suggests.
Find fermented foods
“Six servings of live fermented foods a day is linked to less inflammation and higher microbial diversity,” says Leeming. Six servings can sound intimidating, but, “remember that live fermented foods aren’t only kimchi and kraut but also yoghurt, unpasteurised cheeses and kefir. You can find live ferments in the refrigerated section of the supermarket.”
Be warned however. “Some foods – like sourdough bread – are fermented but the bacteria has died during cooking,” she says, “so while it still has benefits like being easier to digest and having more nutrients available for absorption, it doesn’t contain the live microbes anymore.”
The magic of olive oil
“Extra virgin olive oil has been linked with lower risk of Parkinson’s disease and other neurodegenerative diseases,” says Leeming. “Extra virgin olive is particularly high in polyphenols, a type of antioxidants that your gut bacteria like to feed on and metabolise, and have anti-inflammatory effects.”
A 2022 study of approximately 92,000 men and women in the US showed that – during 28 years of follow-up – those participants who consumed the highest amount of olive oil (greater than 1/2 tablespoon, or 7 grams, each day) had a 29 per cent lower risk of dying from neurodegenerative disease such as Parkinson’s or Alzheimer’s.
Fight back with fruit
In 2021, a study published in Neurology shed light on the power of antioxidant-rich fruits such as oranges, strawberries and kiwis.
“Improving diet is a known way to improve overall health, but the research on exactly how diet affects a person’s risk of Parkinson’s disease has been somewhat mixed,” said study author Essi Hantikainen of Italy’s University of Milano-Bicocca. “Our large study found that vitamin C and vitamin E were each linked to a 32 per cent lower risk of Parkinson’s disease, and we found the association may be even stronger when intake of both vitamin C and E is high.”
Vitamins C and E are antioxidants – nutrients that can reduce or even prevent cell damage and inflammation. So add some vitamin E rich spinach to your fruit smoothie to supercharge your health.