Early Parkinson’s Disease Symptoms Linked to Ultra-Processed Foods

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On May 14, 2025

A new study has found that people who eat a lot of ultra-processed foods, like sugary sodas and packaged snacks, are more likely to have very early signs of Parkinson’s disease when compared with those who eat very few of these foods.

Very early signs of Parkinson’s disease include:

Rapid eye movement sleep behavior disorder, where people physically act out their dreams while asleep
Constipation
Depressive symptoms
Body pain
Impaired color vision
Excessive daytime sleepiness
Reduced ability to smell

“Eating a healthy diet is crucial, as it has been associated with a lower risk of neurodegenerative diseases and the dietary choices we make today can significantly influence our brain health in the future,” said study author Xiang Gao, MD, PhD, of the Institute of Nutrition at Fudan University in Shanghai, China, in a statement.

Diet Is a Modifiable Factor That May Affect Parkinson’s Risk

An estimated 1.1 million people in the United States are living with Parkinson’s disease, a progressive brain disorder characterized by tremors, slowness of movement, limb stiffness, and gait and balance problems.

While there is no cure for Parkinson’s, some medications, therapies, exercises, and lifestyle changes (including following a healthy diet) may help slow the progression of symptoms.

Conversely, the new study supports earlier research linking Western-style diets high in processed foods and red meat to increased Parkinson’s risk.

Diets High in Ultra-Processed Foods More Than Doubled the Risk of Early Parkinson’s Signs

For the new analysis, scientists set out to see whether ultra-processed foods might influence the odds of having very early signs of Parkinson’s.

These signs, called prodromal symptoms, mark the earliest stage of neurodegeneration, and can appear years or even decades before the start of more commonly recognized Parkinson’s symptoms, such as tremors.

This research included more than 40,000 adults who were 48 years old on average. None of the subjects had Parkinson’s disease at the beginning of the study.

During follow-up of up to 26 years, participants had regular medical exams and completed health questionnaires that helped determine if they had early signs of Parkinson’s. Participants also filled out a food diary every two to four years, listing what they ate and how often.

Dr. Gao and his team identified many different types of ultra-processed foods including:

Sauces, spreads, and condiments
Packaged sweet snacks or desserts
Artificially or sugar-sweetened beverages
Animal-based foods, such as hot dogs
Yogurt or dairy-based desserts
Packaged savory snacks

One serving was equivalent to a single can of soda, 1 ounce of potato chips, one slice of packaged cake, a single hot dog, or 1 tablespoon of ketchup.

After calculating how many ultra-processed foods participants ate on average per day, the scientists separated individuals into five groups. The group with the highest consumption of ultra-processed food ate 11 or more servings per day on average, while the group with the lowest consumption ate an average of fewer than three servings per day.

The results, published this month in Neurology, showed that participants in the highest-intake group had a 2.5 times higher likelihood of having three or more early signs of Parkinson’s disease compared to those in the lowest-intake group.

Eating more ultra-processed foods was associated with a greater risk for nearly all the early symptoms except constipation.

The study authors stress that the results only show an association — they don’t prove that ultra-processed foods cause Parkinson’s.

While the findings were based on a large number of participants, researchers note that the subjects self-reported which foods they ate and how much, which may not be accurate.

Eat Right for Better Brain Health

Jessica Ng, MD, an assistant professor of adult neurology at Stanford Medicine in California, regards these findings as further evidence that diet can make a difference in Parkinson’s disease risk.

“I think this study can change the way doctors should counsel patients on dietary changes,” says Dr. Ng, who was not involved in the research. “It is not just about what we should be eating, but what we should not be eating that matters, too.”

To support brain health, Ng advises her patients to follow a Mediterranean diet or MIND diet, and to limit the intake of ultra-processed foods.

Ultra-Processed Foods May Increase Inflammation in the Body

There are many possible reasons as to why ultra-processed foods may increase the risk of Parkinson’s, according to Ng. These include the use of food additives and chemicals that may lead to oxidative stress — a molecular imbalance that can lead to cell damage.

Oxidative stress, she says, can trigger an inflammatory response that may harm the gut microbiome or decrease production of dopamine.

Dopamine is a neurotransmitter that plays a vital role in regulating movement. Reduced dopamine can result in motor symptom irregularities such as those seen with Parkinson’s, including tremors, rigidity, and slow movement.