An efficacy study on the main constituent of Dopavite, L-tyrosine, has shown it is effective. This study was published in Comptes rendus academie des sciences (III) [1989] 309 (2) : 43. An 80% benefit was found without side effects. Efficacy studies on other constituents, for example ferrous iron, demonstrated efficacy in all patients tested (Journal of neural transmission [1989] 323 (W.Birkmayer, G.J.D.Birkmayer).

The diagram shows how L-Tyrosine and the other constituents are essential for the biosynthesis of dopamine in body.

Without the presence of tetrahydrofolic acid and ferrous iron, the formation of optimal levels of L-dopa is impossible, leading inevitably to low levels of dopamine. Tetrahydrofolic acid cannot really be administered, as it is not easily absorbed intact. However, folic acid can be administered in its place as it readily forms tetrahydrofolic acid. Ferrous sulphate in adequate quantities can supply sufficient ferrous iron in order to enable the optimal formation of L-dopa.

For L-dopa to become dopamine, pyridoxal phosphate is required:

L-dopa + pyridoxal phosphate dopamine + pyridoxal phosphate + CO

Pyridoxal phosphate cannot be administered in order to aid the biosynthesis of dopamine as it is not easily absorbed intact. However, pyridoxine (Vit.B6) can be administered in its place as it readily forms pyridoxal phosphate in the body. This reaction requires zinc as a cofactor.

The biosynthesis of tetrahydrofolic acid and pyridoxal phosphate requires the biosynthesis of the nicotinamide coenzymes NADP, NADPH and NADH. This requires the administration of nicotinamide (Vit.B3) from which they are all formed. By supporting dietary levels of all these constituents, the brain may be able to maintain dopamine levels more effectively.

The enzymes involved in the pathway.

The formation of dopamine takes place by two enzymes commonly known as Tyrosine hydroxylase and Dopa decarboxylase. The following are the known studies on the properties of these enzymes :

Tyrosine hydroxylase : Journal of biological chemistry [1964] 239 : 2910, Archives of biochemistry and biophysics [1967] 120 : 420, Nature [1983] 302 : 830, Comptes rendus academie des sciences [1986] 302 : 435.

Dopa decarboxylase : Journal of biological chemistry [1948] 174 : 813, Journal of biological chemistry [1957] 227 : 617, Journal of biological chemistry [1962] 237 : 89, Hoppe-Seyler's zeitschrift fuer physiologische chemie [1963] 332 : 70, Proceedings, national academy of sciences USA [1972] 69 : 343.

All studies available on each of the constituents used in Dopavite have confirmed that they are entirely without toxicity, side effects, or after effects at the levels recommended. Each of the constituents forms part of normal human biochemistry.

L-TYROSINE : Naunyn Schmiederbergs archiv fuer pharmakologie [1976] 293 (1) : 15 (J.C.David); Archives of pathology [1967] 84 : 238 (J.V.Klavins)

FERROUS SULPHATE : The Lancet [1958] 2 : 489 (D.N.S.Kerr, S.Davidson)

ZINC SULPHATE : American journal of clinical nutrition [1990] 51 (2) : 225 (G.J.Fosmire)

NICOTINAMIDE : Schizophrenia [1968] 2 : 3 (Hawkins)

PYRIDOXINE HYDROCHLORIDE : Toxicology letters [1986] 34 : 129 (M.Cohen, A.Bendich)

FOLIC ACID : American journal of clinical nutrition [1989] 50 : 353 (C.E.Butterworth Jnr, T.Tamura)