Role of Nutrition in Parkinson’s Disease: Neuroprotective Effects Identified, but Definitive Evidence Still Lacking

VBCN - April 2014 Volume 1, No 1 - Parkinson’s Disease
Charles Bankhead

Definitive answers about the role of nutrition in Parkinson’s disease (PD) remain elusive. Epidemiologic data have suggested a beneficial role for nutrition-related factors, including omega-3 fatty acids, tea, caffeine, and wine. Other studies have pointed to potential deleterious effects of certain nutrients, such as milk and other dairy products, according to a new review (Seidl SE, et al. Front Aging Neurosci. 2014;6:36).

“In spite of promising effectiveness of these nutrients in PD, we lack definitive evidence-based answers as a result of limited large prospective randomized controlled studies designed to address these issues,” coauthor Judith A. Potashkin, PhD, MS, Professor of Pharmacology and Molecular Biology, Rosalind Franklin University of Medicine and Science, and colleagues, noted in their review. Epidemiologic studies cannot account for issues such as changing dietary habits and the potential for confounding by nonmotor symptoms of PD, such as dysphagia, constipation, and hyposmia, that can affect nutrition status.

“These factors may remain undetected and therefore not properly reported,” the investigators noted. “Incorporation of these critical factors into clinical practice and epidemiological studies will greatly improve the reliability of studies assessing the role of nutrients in PD.”

Current Evidence
Phytochemicals.The review of potentially beneficial nutrients in PD started with phytochemicals, substances in fruits and vegetables associated with a slowing of age-related functional decline. Several epidemiologic studies have shown inverse associations between PD and the consumption of fruits, vegetables, and fish.

Many fruits and vegetables contain large amounts of antioxidants, another nutrient class associated with a reduced risk for PD. A word of caution came from the investigators of a preclinical study showing that pomegranate juice (a source of antioxidants) exacerbated oxidative stress and neurodegeneration in a PD model (Tapias V, et al. Neurobiol Aging. 2014;35:1162-1176).

B vitamins. Mixed results have also come from studies of riboflavin, because some evidence has suggested beneficial antioxidant effects, whereas others suggested deleterious effects, such as glutathione depletion, mitochondrial DNA mutations, and abnormal iron metabolism.

“Larger placebo controlled blinded studies done over a longer period of time would be beneficial for determining if riboflavin or other related B vitamins are useful supplements for PD patients,” the investigators concluded.

Omega-3 fatty acids. Substantial experimental evidence points to neuroprotective effects of omega-3 polyunsaturated fatty acids and some of their constituents, such as DHA. DHA and its precursor, eicosapentaenoic acid, have demonstrated neuroprotective effects in experimental models of PD. However, the only clinical evidence has come from a study showing that omega-3 supplementation was associated with a reduced prevalence of depression in patients with PD.

Isoflavone genistein. Studies of preclinical models of PD have demonstrated neuroprotective effects of the soy-derived isoflavone genistein. Several reports have documented favorable effects on dopaminergic-­mediated activities associated with neuroprotection.

Caffeine. Animal models have provided a wealth of evidence pointing to neuroprotective effects of caffeine, including inhibition of dopaminergic neuron degradation, dopaminergic-­mediated motor dysfunction, and dopaminergic toxicity. Estrogen may counter the neuroprotective effects of caffeine, according to epidemiologic evidence that postmenopausal women receiving estrogen replacement therapy are at an increased risk for PD compared with women not using such therapy.

Tea. Observational and preclinical studies have produced results consistent with a neuroprotective effect of tea, including green and black tea. Both types of tea are rich in polyphenols, which have antioxidant properties and have demonstrated neuroprotective properties in laboratory experiments.

“Tea consumption seems to be a promising lifestyle choice that may slow age-related deficits and neurodegenerative diseases,” the authors said. “Given the evidence from preclinical studies, green tea polyphenols are currently being tested as a treatment for de novo PD patients.”

Alcohol. Data are mixed for the putative neuroprotection afforded by alcohol. Case-control and cohort studies have suggested an inverse association between alcohol consumption and PD, although evidence suggests a deleterious effect of heavy alcohol intake. Other epidemiologic studies have found no association between alcohol and PD.

Conflicting data aside, the red wine constituents resveratrol and quercetin have accumulated preclinical evidence of neuroprotective effects that could reduce the risk for PD.

Other nutrients. A number of other nutrients have questionable or controversial associations with PD, according to the investigators, including dietary fat; meat; carbohydrates; and vitamins C, D, and E.

Negative effects. The list of nutrients associated with adverse implications for PD is limited mostly to milk and other dairy products. The consumption of milk and other dairy products has been linked to an increased risk for PD. The association is stronger in men than in women. Dopaminergic neurotoxins have been postulated as the milk and dairy constituents most likely to initiate or increase neurodegeneration. However, new evidence shows the neuroprotective role of vitamin D, which is often added to milk.

Practical Implications
Despite the unsettled role of nutrition in PD, clinical guidance includes recommendations involving diet and nutrition, Dr Potashkin and colleague Hope T. Bilyk, MS, RD, LDN, Assistant Professor of Nutrition, Rosalind Franklin University of Medicine and Science, told Value-Based Care in Neurology. Patients with PD are advised to maintain ideal body weight by consuming adequate energy from nutrient-rich foods, have periodic assessments of nutrition and swallowing, ensure adequate intake of essential macro- and micronutrients, consume fiber-rich foods to reduce constipation, maintain adequate fluid intake for hydration, and adhere to nutrition recommendations related to interactions with medications.

“As the disease advances, it is necessary to have frequent nutritional and swallowing assessments done,” said Dr Potashkin. “Many factors, such as depression, cognitive issues, malnutrition, sarcopenia, and impaired immune function, can play a major adverse role in the nutritional status and overall health of the patient, resulting in a geriatric failure to thrive.”

Patients who avoid milk but consume yogurt or other dairy products should make sure that these are fortified with vitamin D, which does not occur naturally in dairy products, Dr Potashkin and Ms Bilyk added.

Related Items
Loss of Independence Common Even in Early-Stage Parkinson’s Disease
Charles Bankhead
VBCN - November 2016 Volume 3, No 3 published on November 22, 2016 in Parkinson’s Disease
One-Fourth of Eligible Patients with Stroke Still Not Receiving Thrombolytic Therapy
Charles Bankhead
VBCN - November 2016 Volume 3, No 3 published on November 22, 2016 in Stroke
Timing of Epilepsy Onset Influences Type of Cognitive Impairment and Memory Deficits
Charles Bankhead
VBCN - November 2016 Volume 3, No 3 published on November 22, 2016 in Epilepsy/Seizures
Characteristics of “Superutilizers” Among Patients with Schizophrenia
Charles Bankhead
VBCN - November 2016 Volume 3, No 3 published on November 22, 2016 in Schizophrenia
More Evidence of Increased Mortality Risk in Patients with Rheumatoid Arthritis
Charles Bankhead
VBCR - October 2016, Vol 5, No 5 published on November 2, 2016 in Rheumatoid Arthritis
Creatine Boosts Muscle in Rheumatoid Arthritis, but Not Strength or Function
Charles Bankhead
VBCR - August 2016, Vol 5, No 4 published on August 25, 2016 in Rheumatoid Arthritis
Mixed Cost Results with Repository Corticotropin Injection Therapy for Patients with SLE
Charles Bankhead
VBCR - August 2016, Vol 5, No 4 published on August 25, 2016 in Lupus
Magnetic Stimulation Decreases "Freezing" Episodes in Parkinson's Disease, Improves Patient Outcomes
Chase Doyle
VBCN - July 2016 Volume 3, No 2 published on July 25, 2016 in Parkinson’s Disease
Mutation Testing Encouraged for All Patients with Ovarian Cancer
Charles Bankhead
VBCC - June 2016, Vol 7, No 5 published on June 17, 2016 in Personalized Medicine
Chemotherapy Use in Breast Cancer Declines with Gene-Based Assay
Charles Bankhead
VBCC - June 2016, Vol 7, No 5 published on June 17, 2016 in Value in Oncology
Last modified: May 21, 2015
  • Rheumatology Practice Management
  • American Health & Drug Benefits
  • Value-Based Cancer Care
  • Value-Based Care in Myeloma
  • Value-Based Care in Neurology