Parkinson’s disease (PD) is a disorder that shows its symptoms gradually, increasing in severity over time. It causes neurons (nerve cells in the brain and nervous system) to break down and die, affecting the function of the nervous system and body parts controlled by nerves. Tremors are often the first symptoms noticed. Other outward signs are stiffness and slowing of movement, lack of arm swinging while walking, slow or slurred speech and little to no facial expression. PD is also associated with pain, mood disorders, sleeping problems, cognitive impairment, reduced sense of smell, constipation and incontinence. Indications of the disease often begin on one side of the body and progress to the other side, although the originally affected side is usually worse affected. Researchers have identified certain gene variations and exposure to some toxins such as industrial chemicals, herbicides and pesticides which appear to increase the risk of PD, however only by a relatively small amount. Medications can ease some symptoms but there is no cure for PD. (1,2)
PD is the fastest growing neurological disorder, affecting around 1% of those over 60 years of age and 3% of those over 80 years of age in industrialized countries. (3) When last estimated in 2013-2014, 0.4% of Canadians were living with diagnosed parkinsonism and the prevalence of PD was 169 times higher in those aged 85 years or above compared to those aged 40 to 44 years. (2)
The data on dietary patterns and risk of PD is scarce. But recent research is pointing to the possibility that certain foods may prove to be linked to lower risks of PD while other foods might raise it. For instance, some investigations suggest that caffeine intake from coffee and tea might reduce PD risk and slow its progression while dairy intake might increase PD risk. Growing evidence on plant-based dietary patterns that are rich in beneficial nutrients like fiber, vitamins and other bioactive compounds has shown their potential for the prevention of many chronic diseases through the reduction of inflammation and oxidative stress and the protection of nerve cells. On the other hand, foods such as refined sugars and refined grains which lack healthful nutrients have been associated with increased risks of several chronic diseases. (3)
Research on food sources and their link to the Risk of Parkinson’s disease
New science published in August 2023 has linked significantly lowered risks of PD when eating a healthy plant-based diet. And, on the other side of the equation, consuming an unhealthy plant-based diet higher in refined grains and sugar-sweetened beverages was associated with higher risk of PD. This study looked at data from 126,283 participants of the UK Biobank Study (an ongoing national health resource in the UK). (3)
Study Methods (3)
A discussion of the methods used in this examination will help in understanding exactly what was scrutinized in this analysis. Diet information was assessed using the Oxford WebQ dietary questionnaire, a method shown to result in reliable data. For this analysis, three dietary patterns were established;
- An overall plant-based diet index (PDI) which assigns plant-sourced foods a positive score and animal-sourced foods (animal fats, dairy, eggs, fish/seafood, poultry, red meat and other miscellaneous animal-based foods) a reverse score
- A healthful plant-based diet index (hPDI) which assigns healthy plant-sourced foods a positive score (whole grains, fruits, vegetables, nuts, legumes, vegetarian protein alternatives and tea/coffee) and less-healthy plant-sourced foods (fruit juices, sweetened beverages, refined grains, potatoes, sweets and desserts) as well as animal-sourced foods (animal fat, dairy, eggs, fish, seafood, meat and miscellaneous animal-sourced foods) a reverse score
- An unhealthful plant-based diet index (uPDI) which assigns positive scores to less healthy plant foods and reverse scores to healthy plant and animal foods
To make this more clear, the study authors sum up these classifications by explaining, “… higher values of PDI reflect a diet rich in plant-based foods regardless of the type; higher scores of hPDI reflect a diet with greater amount of healthy plant-based foods, and finally, higher scores of the uPDI are associated to unhealthy plant-based diets. All of them, however, reflect lower intake of animal-based foods.”
Excluded from this study were;
- Alcoholic beverages – excluded because their associations with health are still unclear
- Margarines – excluded because they have been altered in recent years to avoid trans-fatty acids and their present health effects are unknown.
- Vegetable oils – excluded because they were not considered part of either a healthy plant score or an unhealthy plant score since their influences on health are still uncertain
A special note about potatoes: They can be quite healthy if they are prepared without high fat additives. They were likely placed on the less-healthy plant-sourced foods list for this study because, though they are the most commonly consumed vegetable is places like the USA, they are unfortunately eaten mostly as French fries. (9)
Study Results (3)
Results showed that over the 11.8 years of follow-up in this investigation, 577 participants developed PD. Those who reported the consumption of more healthy plant-based foods lowered their risk of developing PD by the following amounts, after accounting for genetic risk factors;
- Participants eating an overall plant-based diet (PDI) were associated with an 18% lower risk of PD.
- Participants eating the most healthful plant-based diet (hPDI) were associated with a 22% decrease in PD risk.
- Participants eating an unhealthful plant-based diet (uPDI) were associated with a 38% higher risk of PD.
- Participants with higher intakes of vegetables were associated with a 28% lower risk of PD.
- Participants with higher intakes of nuts were associated with a 31% lower risk of PD.
- Participants with higher intakes of tea were associated with a 25% lower risk of PD.
Note that the food-based analyses showed that lower PD risk was particularly linked to;
- Higher intakes of vegetables (especially tomatoes, salad, carrots and cruciferous vegetables (arugula, bok choy, broccoli, Brussels sprouts, cabbage, cauliflower, kale, radish))
- Higher intake of nuts
- Higher intake of tea
Why Would Plant-Sourced Foods Reduce the Risk of Parkinson’s Disease? (3)
Recent research on the gut microbiome has examined the relationship between the types of microbes living in the gut and inflammation, a factor that seems to drive chronic diseases including PD. When the population of unhealthy gut microbes dominates over that of healthy gut microbes in a microbiome, harmful inflammation appears to be the result.
However, a preponderance of healthy gut microbes in the microbiome offers benefits that can reduce inflammation. Healthy microbes promote more efficient function of the mitochondria (the miniature organ systems inside cells that produce energy) which results in fewer harmful byproducts such as reactive oxygen species (free radicals) during energy production and thereby reduced inflammation. In addition, the function of neurons depends on neuropeptides which are produced by a healthy and balanced gut microbiome and the gut itself is positively influenced by a nutritious diet.
Indeed, current literature illustrates the neuroprotective effects of a healthy gut microbiome. For instance, diets high in bioactive compounds such as polyphenols, flavonoids and fiber, all of which are found only in plants, favour beneficial gut microbes over harmful ones and are linked to reduced oxidative stress and inflammation. On the other hand, diets higher in ultra-processed foods have the opposite effect. (4,5,6,7,8)
Take Home Message
These investigations illustrate not only the potential for reduced risk of the development of PD that can be obtained from the consumption of a healthy plant-rich diet but also emphasizes the likely significantly increased risk of PD from eating unhealthy plant-based foods. Though this research is new, it is promising. Additionally, evidence continues to mount demonstrating the healthful effects on a wide range of chronic diseases to be gained from eating a variety of foods sourced from plants.
Final thoughts seem clear. There is no need to wait for more positive scientific outcomes. With no downside to increasing your intake of healthy plant-sourced foods and the growing indications that choosing the right foods might reduce your possibility of developing PD as well as other chronic conditions, now might be the right time to put more plant-based foods on your plate.
SOURCES:
1 https://www.mayoclinic.org/diseases-conditions/parkinsons-disease/symptoms-causes/syc-20376055
3 Tresserra-Rimbau, A., Thompson, A.S., Bondonno, N., Jennings, A., Kühn, T. and Cassidy, A. Plant-Based Dietary Patterns and Parkinson’s Disease: A Prospective Analysis of the UK Biobank. Mov Disord. 2023: https://doi.org/10.1002/mds.29580.
4 Yemula, N., Dietrich, C., Dostal, V., Hornberger, M. Parkinson’s disease and the gut: symptoms, nutrition, and microbiota. J Parkinsons Dis 2021; 11(4): 1491–1505.
5 Romano, S., Savva, G.M., Bedarf, J.R., Charles, I.G., Hildebrand, F., Narbad, A. Meta-analysis of the Parkinson’s disease gut microbiome suggests alterations linked to intestinal inflammation. NPJ Parkinsons Dis 2021; 7(1): 27.
6 Solch, R.J., Aigbogun, J.O., Voyiadjis, A.G., Talkington, G.M., Darensbourg, R.M., O’Connell, S., et al. Mediterranean diet adherence, gut microbiota, and Alzheimer’s or Parkinson’s disease risk: a systematic review. J Neurol Sci 2022; 434:120166.
7 Lubomski, M., Tan, A.H., Lim, S.Y., Holmes, A.J., Davis, R.L., Sue, C.M. Parkinson’s disease and the gastrointestinal microbiome. J Neurol 2020; 267(9): 2507–2523.
8 Martínez, L.E.E., Segura, C.M.R. Effect of ultra-processed diet on gut microbiota and thus its role in neurodegenerative diseases. Nutrition 2020; 1: 71.
9 https://www.ers.usda.gov/data-products/chart-gallery/gallery/chart-detail/?chartId=58340#
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My name is Debra Harley (BScPhm) and I welcome you to my retirement project, this website. Over the course of a life many lessons are learned, altering deeply-rooted ideas and creating new passions.
