I had read this study a while back when i first got involved in my mom's treatment. It made a lot of sense to me, so she started taking various l-dopa precursors like tyrosine, phenylalanine, etc. ... She did not gain any benefits from this approach, in fact she stopped because there was some question as to whether the supplements were making her feel ill.

A few months after this trial and error effort, my mom ran an organic acids profile test that measures functional levels of vitamins, minerals, and amino acids using metabolites excreted in the urine as markers for these nutrients. It turns out that she had adequate levels of tyrosine and phenylalanine, which would explain why she did not benefit from them. After a number of failed trial and error approaches to supplementing, i've learned that this kind of nutritional functional testing is invaluable ... it reduces the pill and pray ... It also has provided important insight to what is going right and wrong in terms of my mom's metabolic function specifically in the areas of mitichondrial function, methylation, oxidative damage levels, and gut function.