A large study suggests that people who eat high amounts of ultra-processed foods may be more likely to develop very early warning signs linked to Parkinson’s disease.
These findings add to growing evidence that diet may play an important role in protecting brain health as people age.
The study was carried out by researchers at Fudan University in Shanghai, China, and was published in the medical journal Neurology.
The scientists followed more than 42,000 adults for up to 26 years to examine whether eating large amounts of processed food might be linked to early symptoms connected with Parkinson’s disease.
Parkinson’s disease is a brain disorder that mainly affects movement. It develops slowly over time and is caused by the loss of nerve cells in the brain that help control movement and coordination.
Many people know Parkinson’s for symptoms such as shaking, stiffness, slow movement, and balance problems. However, doctors now understand that changes in the brain often begin many years before these movement symptoms appear.
These early changes are known as prodromal symptoms. They can appear years or even decades before a person is officially diagnosed with Parkinson’s disease. Early signs may include sleep problems, depression, body pain, loss of smell, constipation, anxiety, and changes in color vision.
The researchers wanted to investigate whether diet could influence the appearance of these early warning signs. At the start of the study, none of the participants had Parkinson’s disease. Their average age was around 48 years old.
Over the years, participants regularly completed detailed food questionnaires every two to four years. They recorded what they ate and drank, including how often they consumed certain foods. The scientists focused especially on ultra-processed foods.
Ultra-processed foods are industrially made products that often contain added sugar, salt, unhealthy fats, artificial flavors, preservatives, and other ingredients not commonly used in home cooking. These foods are usually designed to last longer, taste highly appealing, and be quick and convenient to eat.
Examples included packaged snacks, breakfast cereals, sugary drinks, hot dogs, flavored yogurts, packaged sweets, sauces, dairy desserts, and other heavily processed products. In the study, one serving could mean something like a can of soft drink, one hot dog, or a tablespoon of ketchup.
The researchers divided participants into five groups based on how much processed food they ate each day. The group with the highest intake consumed 11 or more servings of ultra-processed food daily. The group with the lowest intake consumed fewer than three servings a day.
The results showed a clear pattern. People in the highest processed food group were about 2.5 times more likely to show at least three early signs of Parkinson’s disease compared with those in the lowest group.
Importantly, the connection remained even after researchers adjusted for other factors that could affect health, including age, exercise levels, smoking, and other lifestyle habits. The processed food diet was linked to almost all of the early Parkinson’s symptoms studied, except constipation.
Dr. Xiang Gao, the lead researcher, explained that healthy eating may play an important role in protecting the brain.
Although the study does not prove that processed foods directly cause Parkinson’s disease, the findings suggest that limiting ultra-processed foods and choosing more natural foods could help reduce the risk of early brain changes.
Scientists are increasingly concerned about ultra-processed foods because previous studies have linked them to many health problems, including obesity, diabetes, heart disease, depression, and memory decline.
Some researchers believe these foods may harm the body through inflammation, changes in gut bacteria, poor nutrition, blood sugar spikes, and damage to blood vessels.
The brain is especially sensitive to long-term inflammation and poor nutrition. Experts believe that diets rich in vegetables, fruits, whole grains, fish, nuts, and healthy fats may help support brain function and reduce the risk of neurological diseases.
At the same time, the researchers caution that the study has limitations. The food information was self-reported, meaning participants may not have remembered or recorded their diets perfectly.
Also, the study only found an association between processed food and early Parkinson’s symptoms. It cannot prove that processed food directly caused these problems.
Still, the study’s large size and long follow-up period make the findings important. Following more than 42,000 people over many years gave researchers a valuable opportunity to examine long-term patterns between diet and brain health.
Parkinson’s disease affects millions of people worldwide, and there is currently no cure. Because of this, scientists are very interested in finding ways to lower risk or slow down the disease before major symptoms begin.
The study adds to growing evidence that lifestyle choices made in middle age may have long-lasting effects on brain health later in life. While more research is needed, experts say eating fewer heavily processed foods and focusing on whole, natural foods may be one simple step people can take to support healthy aging.
Researchers hope future studies will explore exactly how processed foods may affect the brain and whether changing diet habits could delay or prevent Parkinson’s disease in some people.
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