What vitamin decreases with Parkinson's? A deeper look into nutrition and neurological health

October 6, 2025 •

4 min read

Studies reveal that up to half of all individuals with Parkinson's disease (PD) treated with levodopa may experience low levels of certain vitamins over time. A critical question is, what vitamin decreases with Parkinson's, and how does this affect health and symptoms? The answer primarily points toward vitamin B12, but other nutrients like vitamin D are also frequently deficient.

Quick Summary

This article explains how deficiencies in specific vitamins, notably B12 and D, are common in people with Parkinson's disease. It covers the link between low vitamin levels and worsening symptoms, the impact of medication, and important dietary strategies for neurological and overall health.

Key Points

Vitamin B12 Deficiency: Low levels of vitamin B12 are frequently found in Parkinson's patients, with long-term levodopa use being a contributing factor.
Homocysteine Elevation: A decrease in B12 can lead to elevated homocysteine, a neurotoxic metabolite linked to faster disease progression.
Vitamin D is Commonly Low: PD patients have a higher prevalence of vitamin D deficiency, which may be tied to reduced sun exposure and is correlated with disease severity.
Symptom Worsening: Deficiencies in both B12 and D are associated with worsened motor symptoms, balance problems, and cognitive decline.
Dietary Strategy Importance: A balanced diet, often structured to manage protein timing around levodopa doses, is a key component of managing nutritional status in PD.
Monitoring is Recommended: Healthcare professionals should monitor B12 and D levels, and consider supplementation based on individual needs and clinical guidelines.
Antioxidants from Food: While not proven to slow progression via supplements, getting antioxidants like vitamins C and E from food is part of a healthy diet often recommended for PD.

Understanding nutritional deficiencies in Parkinson's Disease

Parkinson's disease (PD) is a complex neurodegenerative disorder, and its symptoms extend far beyond motor control. Nutritional status is a vital, yet often overlooked, component of managing the condition. Reduced appetite, difficulty swallowing (dysphagia), and medication side effects can lead to poor nutrient intake and malnutrition. Furthermore, the disease itself, alongside its treatments, can alter how the body absorbs and processes essential vitamins, creating specific deficiencies that can exacerbate symptoms.

The crucial link between Vitamin B12 and Parkinson's

Among the vitamins that decrease with Parkinson's, vitamin B12 is one of the most significant. Several studies have highlighted a high prevalence of B12 deficiency in PD patients, particularly those on long-term levodopa therapy. The reasons for this decline are multi-faceted:

Levodopa's metabolic effect: The metabolism of levodopa, the most common Parkinson's medication, requires methyl groups. This process can place a high demand on the body's methyl-group donors, potentially depleting B12 and folate.
Elevated homocysteine: As B12 levels drop, a metabolic byproduct called homocysteine (Hcy) can build up. High levels of Hcy have been linked to increased oxidative stress and neurotoxicity, which may accelerate the loss of dopamine-producing neurons.
Neurological symptoms: Low B12 status is correlated with worsened walking and balance, peripheral neuropathy (nerve damage causing numbness or tingling), and cognitive decline, all of which are also common PD symptoms.

Vitamin D deficiency and disease progression

Vitamin D is another micronutrient commonly found to be low in people with PD. While part of this can be attributed to reduced outdoor activity and sunlight exposure due to mobility issues, studies show that lower D levels are also independently associated with more severe disease and a higher risk of falls.

Neuroprotective role: Vitamin D is more than just a nutrient; it acts like a hormone with receptors located throughout the brain, including the substantia nigra, the area most affected by PD. It has neuroprotective effects and plays a role in regulating nerve growth factors.
Correlation with severity: Research has found a negative correlation between vitamin D levels and PD severity scores, suggesting that lower levels are linked to more advanced symptoms. Supplementation has shown some promise in trials, with some studies noting improved motor function in deficient patients.

The role of other B vitamins and antioxidants

Beyond B12 and D, other vitamins may also play a role in PD management, although the evidence is less conclusive for supplements.

Vitamin B6: Like B12, low levels of vitamin B6 have been noted in some PD patients, potentially linked to levodopa treatment. Monitoring B6 levels is a prudent recommendation.
Vitamin B3: Early-phase clinical trials are exploring high-dose nicotinamide riboside (a form of B3) for its potential to boost cellular energy and protect nerve cells.
Antioxidant vitamins (C and E): Some studies have associated higher dietary intake of vitamins C and E with a lower risk of developing PD, suggesting a protective effect against the oxidative stress implicated in the disease. However, supplementation with these vitamins has not shown clear benefits in slowing disease progression.

Dietary strategies for optimizing nutrition

For individuals with Parkinson's, a balanced diet is crucial. The following strategies can help mitigate nutritional deficiencies and manage symptoms.

Prioritize a balanced diet: A diet rich in fruits, vegetables, whole grains, nuts, and healthy fats (like the Mediterranean or MIND diet) provides a wide range of essential nutrients and antioxidants.
Manage protein timing with levodopa: For some patients, dietary protein can interfere with the absorption of levodopa medication, leading to motor fluctuations. A strategy known as protein redistribution involves shifting the majority of protein intake to the evening meal, reserving carbohydrate-based meals for earlier in the day to maximize the medication's effectiveness. This should be done under the guidance of a dietitian to prevent malnutrition.
Address potential weight loss and dysphagia: Symptoms like tremors and dyskinesias can increase energy expenditure, while depression and swallowing difficulties can decrease food intake. Eating several small, nutrient-dense meals throughout the day can help maintain weight and nutrient levels. A speech-language pathologist can assist with swallowing difficulties.
Stay hydrated and manage constipation: Constipation is a common non-motor symptom in PD. A high-fiber diet, along with adequate fluid intake (6-8 glasses of water daily), is recommended.

Comparison of key vitamin deficiencies in Parkinson's


Feature	Vitamin B12	Vitamin D
Prevalence	High prevalence, especially in long-term levodopa users.	High prevalence; more common than in the general population.
Mechanism of Deficiency	Can be depleted by metabolic demands of levodopa metabolism.	Reduced sunlight exposure due to immobility is a factor, but not the only one.
Impact on Symptoms	Worsens gait/balance, peripheral neuropathy, and cognitive issues.	Associated with increased fall risk, disease severity, and potentially cognitive/mood issues.
Associated Biomarkers	Elevated homocysteine and methylmalonic acid (MMA).	Measured by serum 25-hydroxyvitamin D levels.
Management	Regular monitoring and supplementation (oral or injections) as guided by a doctor.	Supplementation is often recommended, but efficacy in slowing progression is mixed.

Conclusion

Nutritional management is an essential part of comprehensive Parkinson's care. Deficiencies in vitamins like B12 and D are common and can impact disease progression and symptom severity. While supplements may offer some benefit, a balanced, whole-food diet remains the cornerstone of good nutrition. Patients should work closely with their healthcare team, including a registered dietitian, to monitor vitamin levels, address any deficiencies, and develop an individualized dietary plan. Managing these nutritional aspects can help improve overall well-being and quality of life while navigating the challenges of Parkinson's disease. For more information, the Parkinson's Foundation offers extensive resources on diet and nutrition for managing PD.

Frequently Asked Questions

The vitamin most commonly found to decrease with Parkinson's is vitamin B12, especially in individuals taking the medication levodopa long-term. The metabolism of levodopa can interfere with the body's B12 and folate, leading to a deficiency and a build-up of the neurotoxic compound homocysteine.

Yes, studies show a correlation between low vitamin D levels and increased Parkinson's disease severity, including worse motor symptoms and a higher risk of falls. This may be due to vitamin D's neuroprotective role and its receptors found in areas of the brain affected by the disease.

A healthy diet rich in fruits, vegetables, and whole grains is foundational. A key strategy for some is a protein redistribution diet, where protein is consumed later in the day, to prevent interference with levodopa absorption. Working with a dietitian is recommended to personalize this approach.

While vitamins C and E are antioxidants that combat oxidative stress linked to PD, clinical trials using supplements have not shown a benefit in slowing the disease's progression. Evidence suggests that obtaining these vitamins from a diet rich in fruits and vegetables is more beneficial.

Taking excessive amounts of certain vitamin supplements can have negative effects. For example, high doses of vitamin E have been linked to health risks in other studies. It is crucial to consult a healthcare professional before starting any new supplement regimen.

Parkinson's medications, particularly levodopa, can interfere with the absorption of certain nutrients, most notably vitamin B12. Side effects like nausea can also decrease appetite, leading to overall poor nutritional intake and weight loss.

Yes, PD patients are at a higher risk of malnutrition. Symptoms such as tremors, rigidity, and swallowing difficulties can decrease food intake, while dyskinesias can increase energy expenditure. Monitoring nutritional status is an important part of care.