Amino Acids in Nutrition for Parkinson’s Disease

In the journal Nutrition Reviews, there is a remarkable article about amino acids in nutrition for Parkinson’s disease where we present the author’s arguments, but the question of food supplements is quite complex and multifaceted, and we have a separate article about it

Parkinson’s Disease (PD) is a progressive neurological disorder that causes motor and non-motor symptoms. Treatment typically includes levodopa-based medications that help replenish the lack of dopamine in the brain. However, nutrition, especially the intake of protein and amino acids, can affect the effectiveness of medications and overall health.

There are conflicting opinions regarding protein nutrition and dietary supplements in the form of amino acids for Parkinson’s disease.

On one hand, there is an opinion that protein should be limited because it competes with levodopa medications and reduces their effectiveness. On the other hand, a protein deficiency leads to a decrease in muscle mass, which disrupts balance and makes a person “fragile “, and furthermore, in the body, dopamine is synthesized from amino acids

The authors of the article studied which amino acids compete with levodopa or may be harmful, and which are necessary, thereby Jacob E Earp suggests replenishing amino acids in a balanced manner considering the disease

This article is not a recommendation. You should discuss your condition with a neurologist or dietitian. We provide you with an overview of new research data for your understanding, but each patient has their own characteristics and there may be contraindications!

Why is this important?

Proteins consist of amino acids, which are essential for maintaining the body’s health. However, some amino acids may compete with levodopa for absorption in the intestines and penetration into the brain. This can reduce the effectiveness of treatment. Additionally, people with Parkinson’s disease often experience changes in amino acid proportions, which can lead to a deficiency of some amino acids and excessive accumulation of others. Therefore, it is important to consider these features when planning a diet or intake e supplement

How does protein affect levodopa?

Levodopa belongs to the group of large neutral amino acids ( LNAA), that use the same transport systems for absorption in the intestine and penetration through the blood-brain barrier. If a person with Parkinson’s disease consumes a lot of protein (for example, 160 g per day), it may exacerbate the symptoms of the disease and reduce the effectiveness of levodopa. Studies have shown that reducing protein intake to 7 g per day improves symptoms, but long-term protein restrictions ( <0,8 g/kg of body weight) can be harmful to health.

For people with Parkinson’s disease, a protein redistribution diet may be recommended: reducing protein intake during the day and shifting it to the evening. This allows minimizing the impact of protein on medications during active times of the day. However, such a diet may have side effects, such as muscle mass loss, vitamin deficiencies (for example, B2 и B3) and minerals

The Role of Amino Acids in Parkinson’s Disease

Some amino acids are beneficial for the health of people with Parkinson’s disease, while others may worsen symptoms. Here is a brief overview of key amino acids:

Useful Amino Acids:

• Leucine : Promotes protein synthesis and maintenance of muscle mass. It is recommended to combine with physical activity to enhance the effect.
• Lysine : Important for the health of bones, muscles, and skin. Does not compete with levodopa, so it is safe to add to the diet.
• Tryptophan : Regulates serotonin levels, which helps improve mood, sleep, and cognitive functions. May be beneficial for depression and sleep disorders.
• Arginine : Improves blood circulation and has a neuroprotective effect.
• Glutamate : Participates in the synthesis of the antioxidant glutathione, which protects brain cells from damage.
• Taurine : An antioxidant that stabilizes cell membranes and regulates calcium levels. People with Parkinson’s disease have reduced levels of taurine in plasma and cerebrospinal fluid. Animal studies indicate that taurine may have neuroprotective effects and reduce the risk of dementia. However, additional research is needed to confirm its effectiveness in humans.
• Aspartate : Participates in metabolism and the urea cycle. Aspartate is a neurotransmitter that stimulates NMDA-receptors. In people with Parkinson’s disease, serum aspartate levels are reduced, which may justify its moderate use as a supplement. However, due to the risk of excitotoxicity, further study of the effects of aspartate on people with Parkinson’s disease is required.
• Serine : Necessary for fat metabolism, muscle growth, and immune function. Research shows that serine may improve motor and behavioral symptoms of Parkinson’s disease due to its ability to modulate dopamine and glutamate interactions. However, excessive consumption of serine can be neurotoxic, so its use requires caution.
• Methionine: Involved in metabolism, immune function, and prevention of oxidative damage associated with Parkinson’s disease. Activates antioxidant enzymes and regulates glutathione synthesis. Research shows that methionine may have neuroprotective effects and be beneficial for people with Parkinson’s disease, especially with protein deficiency in the diet. However, excessive methionine intake may increase homocysteine levels, which is associated with damage to dopaminergic and neuronal cells. For safe use, it is recommended to combine methionine with vitamins B6, B9 и B12, that regulate its metabolism

Amino acids that do not require supplementation:

• Histidine : May cause excessive production of free radicals, which enhances brain cell damage.
• Phenylalanine : Competes with levodopa for absorption, which reduces the effectiveness of treatment.
• Threonine : Associated with the formation of Lewy bodies, which play a role in the progression of Parkinson’s disease in people with certain genetic changes [Podoli E, 2010].
• Isoleucine: Involved in maintaining immune function, protein synthesis, and macronutrient metabolism. People with Parkinson’s disease have elevated levels of isoleucine in feces, urine, and saliva, but not in plasma or cerebrospinal fluid, which may indicate impaired absorption. Due to competition of isoleucine with other amino acids and levodopa, its supplements are not recommended.
• Valine Supports mental activity, emotional calm, movement coordination, and protein synthesis. However, valine is a necessary component for the formation of Lewy bodies associated with the progression of Parkinson’s disease. Although there is no direct evidence that valine stimulates this process, its excess may cause insulin resistance—a common comorbidity in Parkinson’s disease. Due to competition with other amino acids and levodopa, as well as the lack of need for supplements, additional valine intake is not recommended.

The table below provides the recommendations of the author of this research article [Jacob E Earp, 2023], however, these recommendations are more general for doctors and should not be applied to oneself without consulting a specialist

The Importance of Vitamins and Microelements

Some vitamins and minerals help amino acids perform their functions in Parkinson’s disease. We have a separate article on the importance of vitamins in Parkinson’s disease.

Taking Amino Acids as Dietary Supplements for Parkinson’s

There are different perspectives on the safety and effectiveness of dietary supplements for Parkinson’s disease. We have outlined our opinion in a separate article here .

Recommendations for Patients:

• Monitor your protein intake with a specialist doctor.
• Keep track of meal and medication times. Take levodopa 30 minutes before meals or 1–2 hours after.
• Discuss with a nutritionist do you have a deficiency of any nutrients, if so, it needs to be addressed as a therapeutic measure
• Pay attention to vitamins. Ensure that your diet is harmoniously rich in vitamins, especially if you are taking levodopa.
• Nowadays, laboratories can conduct tests for vitamin deficiencies, and if something is objectively lacking, it should be compensated with a doctor’s guidance.
• The issue of amino acid supplements remains controversial, You can read our separate article about supplements for Parkinson’s disease

Conclusion

According to Jacob E Earp, 2023, there is currently sufficient evidence to support the inclusion of essential amino acids (leucine, lysine, tryptophan), as well as non-essential amino acids (arginine, glutamate, and taurine), along with the addition of trace elements like copper and vitamins B2, B3, B6, B9 и B12 for the potential enhancement of desired therapeutic effects in Parkinson’s disease, but there is not enough evidence to unequivocally recommend this approach. You can read our stance on dietary supplements in a separate article.

Harmony in nutrition is an important part of treating Parkinson’s disease. It can help minimize medication side effects, improve overall well-being, and slow disease progression. However, any dietary changes should be agreed upon with the attending physician.

Source:

Jacob E Earp, Cristina Colon-Semenza, Dara L LoBuono, Considerations for developing a targeted amino acid supplement for people with Parkinson’s disease that promotes health while accounting for pathophysiology and medication interference, Nutrition Reviews, Volume 81, Issue 8, August 2023, Pages 1063–1076, https://doi.org/10.1093/nutrit/nuad008