Richelle Flanagan has been a registered dietitian for the past 19 years, is a wife and mum to two children and has lived with YOPD for six years. Her lived experience has led her to develop My Moves Matter, a digital self-care companion tailored to support and empower women to live well with Parkinson’s. Here she gives advice on what kinds of diet plans people with Parkinson’s should follow.

Richelle Flanagan

How important is diet for people with Parkinson’s?

I think it’s totally underutilised as a way of helping people with Parkinson’s (PwPs). That is from the perspective of both being a dietitian and living with the disease and doing the research myself. I think in some cases people may be being escalated up with Parkinson’s medications before looking at how their symptoms may be improved by certain lifestyle aspects as they do for other chronic diseases.

I have never worked with a chronic disease where diet and nutrition play such a fundamental role regardless of age, gender, ethnicity and Parkinson’s stage. However, we need more research to investigate the effect of diet and nutrition on Parkinson’s in areas such as malnutrition, post-DBS weight gain, bone health, medication influences, executive function, cognition, bowel function and so much more. Diet in Parkinson’s is totally under-researched in comparison to other chronic disease areas such as cardiology, cancer and diabetes.

What sort of diet should a PwP follow? Can it slow progression?

The evidence is beginning to build for the benefit of diet and nutrition not only in helping to manage and reduce Parkinson’s symptoms, but also in potentially slowing progression. Research papers have assessed diet quality in terms of the Mediterranean diet, of which there are several regional variations, including the Greek Mediterranean diet and the MIND – Mediterranean in neurodegenerative delay – diet.

These variations share fundamental characteristics, which are beneficial in the health of people living with Parkinson’s. One key characteristic is the reduction of intake of less healthy foods such as highly processed, high-fat and sugar snacks and baked goods, sugary drinks, processed meals and processed meats high in saturated fat and salt.

Healthy patterns of the diet include eating a largely plant-based diet with plenty of unprocessed cereals, especially whole grains, fruits and vegetables, pulses, nuts, seeds, herbs and spices; olive oil as the main source of fat; moderate consumption of fish and seafood, poultry, eggs and dairy products such as yogurt and a low consumption of red meat. There is some evidence that the MIND diet may have more specific advantages for Parkinson’s due to the additional focus on berries and green leafy vegetables.

A study in 2018 of older PwPs showed that the MIND diet may be associated with slower progression of the condition. The same authors also found that specific nutrients within the PwPs’ diets were associated with slower progression. These include carotenoids, vitamin E and vitamin C, which are found in leafy greens and berries. A 2022 study suggests MIND and Mediterranean diets are associated with fewer patient-reported symptoms over time, with the MIND diet being twice as effective in reducing symptom severity.

There is limited but hopefully growing evidence that the Mediterranean diet may help to slow progression of Parkinson’s. The question remains as to whether this is a direct or indirect result of the diet. For example, the high fibre content may improve Parkinson’s symptoms by reducing constipation, which for many PwPs improves levodopa uptake into the brain and therefore improves symptoms. Or does the diet indirectly improve symptoms by improving the balance of good and bad bacteria in the gut which we know plays a role in Parkinson’s? Or is it the anti-inflammatory phytonutrients in fruit and vegetables that have an effect? There are so many constituents in foods that it is hard to identify which specific element is potentially beneficial. Research shows that it is the synergistic effect of the different elements of food that confers the benefit, i.e., the fibre and the phytonutrients acting together.

There is limited but hopefully growing evidence that the Mediterranean diet may help to slow progression of Parkinson’s

Are there any differences between diets that male and female PwPs should follow, or diets to follow at different ages?

One study showed that higher adherence to the MIND diet was significantly associated with developing Parkinson’s at a later age, especially in women, with an almost 17.5-year difference between those women with the highest adherence to the diet versus the lowest. They found that the Greek Mediterranean diet was more effective than the MIND diet in men, with an almost 8.5-year difference between those men with the highest adherence versus the lowest. The effect size of the MIND diet in women was more than three times that of the men. The tendency for women to adhere more strongly to the MIND diet may have contributed to their lower rates of Parkinson’s.

There are a couple of studies that suggest women with Parkinson’s suffer from more food addiction issues. There is also some evidence indicating that women suffer from more weight loss particularly in the earlier stages of the disease and have higher levels of osteoporosis and higher fracture risk.

What we lack is more sex- and gender-specific research on PwPs. Determining the subtle differences in the metabolic profiles of the different diets and their interplay with sex/gender may help to elucidate elements of what causes Parkinson’s and how we might slow its progression.

What part does weight play in the condition – should you gain or lose weight? Are there any types of diets that aren’t recommended for PwPs?

One longitudinal study in PwPs showed that decreasing BMI was associated with higher (worse) scores over time in both the motor and total Unified Parkinson’s Disease Rating Scale (UPDRS). Another study showed that clinically significant weight loss within the first year of diagnosis was independently associated with dependency, dementia, and death. So yes, weight plays a significant role in Parkinson’s, but many neurologists, GPs, nurses and health professionals neglect this aspect. In fact, when I did a nutrition survey of 82 people for the Dublin branch of the Parkinson’s Association of Ireland, 63 per cent reported that they had lost weight unintentionally since their diagnosis, but almost 60 per cent reported that neither their GP nor their neurologist had ever weighed them. Research has shown that increasing weight and nutritional status – where a PwP is underweight – can improve symptoms and quality of life.

On the other hand, being obese has been shown in one study to be associated with more rapid progression in early-onset PwPs. Obesity can develop due to issues such as impulse control disorder triggered by dopamine agonist medication which can cause people to over-eat. Weight gain has also been seen post-DBS, which some attribute to the reduced energy expended due to the reduction in symptoms after the surgery.

PwPs should aim for an ideal body weight for their height, known as the Body Mass Index within the range of 18-24. Being overweight within the range of 25-29 does not seem to be associated with progression as much as being obese (BMI >30). However, people should try to keep their weight in check, avoiding being underweight (a BMI of <18) or exceeding a BMI of 27.

There are no specific weight-loss diets for Parkinson’s but reducing daily calories and following a Mediterranean-style diet is recommended. Intermittent fasting has been seen to be beneficial for weight loss in the general population and can potentially benefit Parkinson’s symptoms. Eating between the daylight hours of 7am to 7pm is a natural form of overnight fasting. PwPs often report food cravings due to fluctuating dopamine levels which can lead to grazing between meals and late at night. However, filling up on wholegrain and plant-based foods can help to keep you full, cut cravings and reduce constipation – all of which can help improve symptoms.

One weight-loss diet some PwPs try is the ketogenic diet. There are some very small studies that show a benefit for PwPs, however, the diet is complex to follow, and we do not know what the long-term health risks compared to the weight-loss benefits could be. I would recommend getting advice from a dietitian if you are considering a ketogenic diet.

A word of caution is that weight loss can lead to a need to reduce one’s levodopa medication as a lower body weight can lead to greater absorption of the medication which can lead to side effects such as dyskinesia. It is therefore important for PwPs to track their symptoms when losing weight. This also applies to PwPs who lose weight unintentionally, who find that their dyskinesias may worsen due to the higher levodopa absorption – this is particularly true for women with Parkinson’s who absorb levodopa more rapidly than men, as shown in this study.

Next week, Richelle discusses probiotics, protein foods and levodopa absorption, eating dairy and gluten, and reveals what she eats as a PwP. Read part two.