Homocysteine is a non-protein forming amino acid which is associated with Parkinson's disease (+ vascular dementia, heart disease...) in several ways: MTHFR gene mutations raise homocysteine levels in PWP and several articles highlight this fact:
Homocysteine Level and Mechanisms of Injury in Parkinson's Disease as Related to MTHFR, MTR, and MTHFD1 Genes Polymorphisms and L-Dopa Treatment
Meta-analysis supports association of a functional SNP (rs1801133) in the MTHFR gene with Parkinson's disease.
A summary of the above articles are located on the MTHFR SUPPORT/Australia website: mthfrsupport.com.au/conditi...
In addition to possible MTHFR gene mutations raising homocysteine levels there is the (near) universal problem of raising homocysteine levels by taking the amino acid levodopa:
Homocysteine and levodopa: should Parkinson disease patients receive preventative therapy?
"Although B vitamin status and genetic factors are important modifying influences determining the degree of this elevation, the main cause appears to be therapy with L-dopa."
B vitamin status generally speaks of folate and, cobalamin (B12):
Cobalamin, folic acid, and homocysteine
"Cobalamin deficiency can lead to several adverse health consequences: folate trapping in the methylation cycle and subsequent impaired DNA biosynthesis; pernicious anemia hematologically, similar to that caused by folate deficiency; elevated blood homocysteine...."
Dr. Ben Lynch, an expert on the MTHFR gene:
Dr. Ben developed a really good B vitamin that has most of the good B vitamins that PWP need, it is called HomocysteX Plus:
The ingredients include:
Riboflavin (as riboflavin-5-phosphate sodium)25 mg1471%
Vitamin B6 (as pyridoxal-5-phosphate)15 mg750%
Folate (as Quatrefolic (6S)-5-methyltetrahydrofolic acid, glucosamine salt)800 mcg200%
Vitamin B12 (as methylcobalamin and adenosylcobalamin)1000 mcg16667%
TMG (trimethylglycine - also called betaine)700 mg**
I take the above B vitamins separately and have found a source that happily combines them and after I run out of them I will try this supplement. It looks good but I additionally take thiamine because of possible depeletion caused by alpha lipoic acid (and acetyl l carnitine). Also, I found I need between 2,500 - 5,000 mcg (2.3 - 5 grams/day). And I will continue to use methyltetrahydrofolic acid (the bioavailable form of B6) at bedtime because it is a precursor of GABA which helps to make me sleep:
The final B vitamin I take is niacinamide/nicotinamide because it has many functions in the human body and is good for PD:
Pantothenic acid, B5, and Biotin are also good energy vitamins but do not have a clinical relationship with PD - though all the B vitamins work well together:
B Vitamins and the Brain: Mechanisms, Dose and Efficacy—A Review
"This review describes the closely inter-related functions of the eight B-vitamins and marshals evidence suggesting that adequate levels of all members of this group of micronutrients are essential for optimal physiological and neurological functioning."