Prevention of an incurable disease has been linked to avoiding some common foods

In the study, CNN reports, one serving included 8 ounces of diet or sugar-sweetened soda, one hot dog, one slice of packaged cake, just a tablespoon of ketchup, or 1 ounce of potato chips (a typical small bag of chips weighs 1.5 ounces).

“Our study shows that eating too many processed foods, such as sugary drinks and packaged snacks, may accelerate the onset of early signs of Parkinson's disease,” said senior study author Dr. Xiang Gao, Distinguished Professor and Dean of the Institute of Nutrition at Fudan University in Shanghai, China.

This latest study is part of a “growing body of evidence that diet may influence the development of Parkinson’s disease,” Gao explains.

While the study found that people who ate more ultra-processed foods tended to report more early symptoms, it did not show a direct increase in the risk of developing Parkinson's itself, said Dr. Daniel van Wamelen, a senior lecturer in clinical neurology at King's College London. He was not involved in the new study.

“The study did not track whether participants were diagnosed with Parkinson’s disease later in life,” van Wamelen said in a statement. “However, having more of these symptoms does indicate a higher risk over time.”

The study analyzed long-term health and diet data from nearly 43,000 participants in the Nurses’ Health Study and the Health Professionals Follow-up Study, two studies in the United States that have collected information on healthy behaviors for decades. The average age of the study participants was 48, and none had Parkinson’s disease when they began the study. All self-reported what they ate every few years — a limitation of the new study, since participants may not have accurately remembered what they ate.

The study looked at ultra-processed foods, including artificially sweetened or sugar-sweetened beverages; condiments, sauces and spreads; packaged sweet snacks or desserts; dairy-based yogurt or desserts; bread and cereal; and packaged savory snacks.

The study found a link between early signs of Parkinson's disease and all types of ultra-processed foods except bread and cereals - a finding that points to an underlying feature of most classes of ultra-processed foods that may explain the results, the study says.

One reason may be that ultra-processed foods tend to be lower in fiber, protein and micronutrients, but contain sugar, salt and saturated or trans fats, the study says. Ultra-processed foods may also affect the balance of microflora in the gut, while additives may increase inflammation, free radicals and neuronal death, the study says.

“With a sample size of over 42,800 participants and a long follow-up period of up to 26 years, this study is not only powerful but also methodologically rigorous,” write the authors of an editorial published alongside the study.

The editorial was co-authored by Dr. Nikolaos Skarmeas, an assistant professor of clinical neurology at Columbia University in New York City, and nutritionist Maria Maraki, an associate professor of sports medicine and exercise biology at the National and Kapodistrian University of Athens in Greece. Neither was involved in the new study.

“Prevention of neurodegenerative diseases may begin at the dinner table,” they wrote. “Excessive UPF consumption is not only a risk factor for metabolic diseases, but may also accelerate neurodegenerative processes and associated symptoms.”

In a new study published Wednesday in the journal Neurology, researchers looked at the prodromal stage of Parkinson's disease — the early signals that appear years to decades before the tremors, muscle stiffness, slow gait and changes in posture that are the hallmark symptoms of Parkinson's.

According to the Parkinson's Foundation, body pain, constipation, signs of depression, changes in the ability to distinguish smells or colors, and excessive daytime sleepiness can all be early signs of Parkinson's disease.

A highly unusual sleep disorder in which people can move during REM sleep, or rapid eye movement, is also a key early sign, according to research. During REM sleep, the body is typically paralyzed, so it can't wake up and recreate any dreams, CNN continues.

The study found that people who ate about 11 servings of ultra-processed food a day were 2.5 times more likely to show three or more early signs of Parkinson's disease than those who ate only three servings.

Additionally, eating more ultra-processed foods was associated with an increased risk of almost all symptoms except constipation, according to the study. This finding held true even after the researchers accounted for other factors, such as age, physical activity, and smoking, that could have affected the results.

“Parkinson’s disease has no cure,” says Dr. Gao. “In our previous study, based on the same populations used for the current analysis, we found that a healthy diet and physical activity can slow the progression of the disease. Choosing to eat fewer processed foods and more whole, nutritious foods may be a good strategy for maintaining brain health.”