Numerous vitamins and minerals can help with symptoms. Perhaps most important are a number of the B vitamins. High levels of thiamine are thought to prevent Parkinson's; in one laboratory study, thiamine was one of the best inhibitors of dopamine oxidation (Lancet, 1988; i: 363). A deficiency of folic acid is also associated with developing Parkinson's (J Neurol Neurosurg Psychiatry, 1986; 49: 920-7).
The other vitamin intimately associated with L-dopa absorption is vitamin B6. An enzyme which converts L-dopa to dopamine is dependent upon vitamin B6; treatment with L-dopa on its own can raise blood concentrations of pyridoxal-5-phosphate, the precursor of vitamin B6, while treatment with L-dopa plus a decarboxylase inhibitor may cause a vitamin B6 deficiency (Clin Sci, 1979; 56: 89-93).
Parkinson's patients can benefit from taking vitamin B6 supplements, although results are mixed, with some studies showing improvement in numerous symptoms (Soy Med, 1979; 7: 14-9; JAMA, 1941; 116: 2484-7) and some showing no improvement (Bull Johns Hopkins Hosp, 1941; 69: 266-75; JAMA, 1941; 116: 2148). Those patients who most benefit receive large doses (100-400 mg per dose). Note: patients with heart conditions, specifically angina or coronary insufficiency, should not receive vitamin B6.
Good results have been achieved by intraspinal injection of 5-10 mg of thiamine and vitamin B6 (5-25 mg) in helping with rigidity (Dis New Sys, 1950; 11: 131-8).
Patients who are on constant doses of L-dopa may be deficient in niacin, says Werbach, since decarboxylase inhibitors also appear to reduce the sythesis of this vitamin. Niacin is also helpful in extending the levels of brain dopamine in patients taking L-dopa (Biochem Med Metabol Biol, 1986; 36: 244-51). In patients who have already developed Parkinson's, nicotinamide adenine dinucleotide (NADH), a coenzyme made from niacin, helps to convert tyrosine to L-dopa; in one small study, 62 per cent of patients receiving NADH intravenously improved in symptoms by at least 30 per cent. The optimum dosage was 25-30 mg per day (Ann Clin Lab Sci, 1989; 19: 38-43).
Other vital nutrients include vitamin C, which can counteract the adverse side effects of L-dopa (Adv Neurol, 1983; 37: 51-60); 400-3200 IU of vitamin E (SA Factor, presented at Vitamin E: Biochemistry and Health Implications, NY Academy of Sciences Meeting, NY, November 1988); magnesium (Can J Neurol Sci, 1989; 16: 310-4); and omega-6 fatty acids in evening primrose oil, which can reduce tremors (EMR Critchley in DF Horrobin, ed. Clinical Uses of Essential Fatty Acids, Montreal: Eden Press, 1982: 205-8).