How gut bacteria are linked to Parkinson's Disease

“Parkinson’s Disease is the fastest growing neurological condition in the world” ¹

In the papers recently, there was an incredible story of Jo Milne, a woman who can detect Parkinson’s Disease in people using her unusually sensitive sense of smell. Milne noted a musty odour which signalled the disease with high accuracy.² Scientists now believe that what Milne was smelling was a chemical change in skin oil, known as sebum, that is triggered by the disease.

As a result, scientists began focussing on disease-linked molecules found in skin swabs. A test using this information has now been successfully developed, which may contribute to the early detection of the disease in people who aren’t yet showing symptoms.

Parkinson’s disease is a degenerative disorder affecting the brain, characterised by a loss of nerve cells in a part of the brain called the substantia nigra. An accumulation of abnormal alpha-synuclein proteins damages the nerve cells that release dopamine which has a knock-on effect on the function of the central nervous system and overall motor function.³,⁴

Symptoms of Parkinson’s Disease:

Motor symptoms include resting tremor, slow movement, ‘freezing’, joint stiffness, rigidity and gait abnormalities. ⁵
Non-motor symptoms include decreased sense of smell, sleep disorders, speech and swallowing difficulties, depression, and gastrointestinal symptoms (most commonly constipation). ⁶

Researchers have noticed that gastrointestinal symptoms such as constipation occur many years before the onset of motor symptoms and indeed the diagnosis of Parkinson’s Disease. ⁷ As well as environmental and genetic factors ⁸, it is thought that the gut microbiome is involved in the development of Parkinson’s (PD). Inflammation and toxins, caused by gut dysbiosis, are thought to be possible causes of these neural changes and the effect on motor signals.⁹

Alterations in the gut microbiome are thought to cause disturbances in the enteric nervous system (the nervous system of the gut) as well as the central nervous system.¹⁰ Neurotoxins and inflammatory chemicals produced as a result of gut dysbiosis may cause the build-up of these abnormal proteins within the enteric nervous system. ¹¹ The vagus nerve provides a pathway for these toxins to be transmitted from the gut to the central nervous system ¹², ¹³ where they affect the production of dopamine, and cause changes to the immune system and inflammatory response. ¹⁴.

Changes observed in the gut microbiome of patients with Parkinson’s:

Lower levels of short-chain fatty acids (SCFAs) such as butyrate. Butyrate is an important substance produced by commensal bacteria: it has many health benefits including reducing inflammation. Lower levels of SCFAs in PD patients have been linked to poorer cognition, gait issues and postural instability. ¹⁵
Significant changes in the composition of the gut microbiome of Parkinson’s patients with constipation. ¹⁶
An increase in certain gut bacteria (Megasphaera and Akkermansia) and reduced Roseburia have been correlated with motor and cognitive function in people with PD. ¹⁷
Lower levels of Prevotellaceae, Faecalibacterium, and Lachnospiraceae in patients with PD. ¹⁸
Higher levels of Bifidobacteriaceae, Ruminococcacea, Verrucomicrobiaceae and Christensenellaceae. ¹⁹
Increased intestinal permeability due to low levels of SCFSAs which normally support the health of the gut lining. ²⁰

Optimising gut health may improve symptoms and may slow the progression of the disease.²¹ Here are some ways to increase the levels of commensal bacteria in your gut:

Increase dietary fibre (pulses and legumes, nuts and seeds, whole grains, fruit and vegetables, herbs and spices). ²²
Increase antioxidant-rich foods including polyphenols which can cross the blood-brain barrier, soaking up free radicals which contribute to neural inflammation: nuts and spices, green leafy vegetables, beans, spices, and dark chocolate, green and black tea. ²³ ²⁴
Increase fermented food intake: miso and tempeh²⁵, kefir, probiotic yoghurt, kimchi and sauerkraut.
Alleviate constipation associated with PD:
- Gradually increase fibre intake to 30g per day
- Drink plenty of water throughout the day
- Daily consumption of Probiotic Kefir and Complete Prebiotic
- Drink Gut Cleanse Tea

Wondering about the state of your own microbiome? Take a microbiome test, and get a free 30 minute personal consultation from one of our Nutritional Therapists. Read more about our test here.

If you’d like to learn more about the connection between the gut and the brain, read this article by Shann Jones in our Gut Health Express blog!