Food As Medicine: Diet’s Role In Parkinson’s Disease

For 15 years, John Duda, MD, National Director of the VA Parkinson’s Disease Research, Education and Clinical Centers, has urged his patients to “keep waiting” for effective treatments to manage both motor and nonmotor symptoms of Parkinson’s disease.

However, Duda, who also serves as director of the Brain Wellness Clinic at the Corporal Michael J. Crescenz VA Medical Center in Philadelphia, recognized the persistent lack of effective drugs to address these symptoms. This prompted him to consider what other evidence-based strategies he could use to support his patients. 

“I recognized that nutritional approaches within a broader program that includes medication review, stress management, social connections, adequate sleep, and physical exercise could make a real difference,” he told Medscape Medical News.

Observational studies have shown an inverse association between dietary patterns and PD risk, age of onset, symptom severity, and mortality rates, particularly with the Mediterranean diet (MeDi) and the MIND diet, which combines elements of MeDi and the Dietary Approaches to Stop Hypertension (DASH) diet. 

For example, a cross-sectional study comparing 167 participants with PD vs 119 controls showed that later age of PD onset correlated with adherence to the MIND diet in women, with a difference of up to 17.4 years (P<.001) between low and high dietary tertiles. 

The MeDi was correlated with later onset in men, with differences of up to 8.4 years (P=.002). In addition, lower rates of PD have been shown in populations following vegetarian and vegan dietary patterns. 

Duda also reviewed the role of dietary interventions in addressing common PD symptoms, such as orthostatic hypotension. He recommended that PD patients with this condition should avoid eating large meals, increase dietary salt intake, increase fluid intake, and decrease alcohol intake.

Malnutrition affects close to 25% of those with PD, which is partially attributable to diminished olfaction. Because the experience of taste is largely driven by a sense of smell, patients may be less interested in eating. Duda recommended increasing herbs, spices, and other flavors in food. High caloric density foods, including nuts, nut butters, and seeds, can boost weight, he said. However, he added, any patient with significant weight loss should consult a nutritionist.

Constipation is one of the most debilitating symptoms of PD, affecting up to 66% of patients. Duda advised increasing fluid intake, exercise, and dietary fiber and use of stool softeners and laxatives. The MeDi may reduce symptoms of constipation and have a beneficial effect on gut microbiota. 

Coffee may be helpful for sleepiness in PD and may also confer neuroprotective, motor, and cognitive benefits. As an adjuvant treatment, caffeine may alter levodopa pharmacokinetics, reduce dyskinesia, improve gait in patients with freezing and may even reduce the risk of developing PD, with a maximum benefit reached at approximately three cups of coffee daily.

Food As Medicine 

Although recent research shows that the drug development pipeline for PD is robust, with a wide variety of approaches being developed and evaluated in phase 1 and 2, investigators note that only a limited number of disease-modifying treatments are transitioning to phase 3.

Duda noted that phytochemicals incorporated into the diet might target some of the same mechanisms that are targets of these drugs in development. 

“Flavonoids have been shown to stabilize alpha-synuclein in vitro,” he said. “Caffeine, curcumin, resveratrol, and eliminating meat and dairy inhibit mTOR [mammalian target of rapamycin], and mTOR inhibition results in increased autophagy that may help clear alpha-synuclein. Genestein, an isoflavone in soybeans, protects dopaminergic neurons by inhibiting microglia activation. Flavonoids inhibit inflammation by inhibiting release of NO [nitric oxide] and pro-inflammatory cytokines,” he noted. 

Ongoing studies of dietary interventions for PD are exploring various areas, including the potential role of the ketogenic diet in protecting the gut microbiome, optimizing protein intake for muscle preservation and sleep, the effects of psyllium and wheat bran on weight and constipation, and the impact of a gluten-free diet.

Practical Tips for Healthy Eating 

[Rebecca Gilbert, MD, PhD, chief mission officer of the American Parkinson Disease Association] emphasized that there are no medications or interventions currently available that can delay a PD diagnosis by up to 17 years, as some dietary patterns have been shown to do, and she noted that it’s not possible to replicate the MeDi diet in a pill. However, she recommended a practical approach to eating that includes a diet low in ultraprocessed foods and high in beneficial nutrients. She encouraged people to shop for “real food” and enjoy a variety of colorful fruits and vegetables.

Duda acknowledged that motivating patients to follow a healthy diet can be difficult. As a result, the focus often shifts to making small adjustments and modifications. For example, he suggested that instead of pairing meat with french fries, people could opt for vegetables or add greens to their meals. Similarly, instead of having eggs and bacon for breakfast, they might choose oatmeal.

Preparing whole-food, plant-based meals may take more time than patients are accustomed to, so Duda suggests that, if possible, patients involve loved ones in both the meal preparation and the meal itself. He explained that a healthy meal can become an opportunity for bonding and that the key is educating them about new meal-related concepts.