Dietary Influences on the Synthesis

of Neurotransmitters in the Brain

Linus Pauling, Ph. D.

Dr. Pauling is Director of the Linus Pauling Institute
of Science and Medicine, Menlo Park, California 94025


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An interesting paper with the above title, by John H. Growdon

and R.ichard J. Wurtman, was recently published in this journal. 1

The authors point out that traditional concerns with the effects of nutrition

on the brain have centered on the consequences of protein or protein-calorie

restriction for the immature nervous system.  They then say that they and

their associates have been interested in another aspect of nutritional effects

on the brain, that is, the changes in its biochemical composition that occur

normally, after consumption of a single meal.  They say that eight years ago
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(1972) they observed  that the composition of each meal can influence the

synthesis of the neurotransmitter serotonin, and that subsequent studies

have shown that this kind of control is fairly general.  They noted that the

availability of tryptophan and tyrosine to the brain causes major changes

in the rates at which neurons synthesize serotonin and the catecholamines,

respectively.  They also say that the rate-limiting step in the formation of

s erotonin is the hydroxylation of tryptophan to 5 -hydroxytryptophan,

catalyzed by the enzyme tryptophan hydroxylase, and, since tryptophan

hydroxylase is not fully saturated with its amino-acid substrate at normal

values of the brain tryptophan concentration, variations in this concentration

can control the rate of serotonin synthesis.  A similar effect of increasing

the intake of choline (usually as lecithin, phosphatidylcholine) to increase

the saturation of the enzyme choline acetyltransferase and thus cause
increased synthesis of acetylcholine was reported by them3 in 1975.

It has been found, moreover, that a high intake of lecithin has clinical value

in the treatment of tardive dyskinesia, 4 and the authors suggest that an


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increased intake of choline or lecithin might have value also in treating

Huntington's disease, Friedreich's ataxia, Alzheimer's dementia, mania,

loss of memory, and aberrant social behavior.

    Growdon and Wurtman say that "Taken together, these findings

illustrate a novel and previously unsuspected aspect of nutrition's effects

on the brain and provide the basis for new modes of therapy for patients.

with some neurologic and psychiatric brain diseases. . . . Certainly it is

startling to discover that dietary constituents normally influence such an

important process as neurotransmitter synthesis.. . . This general principle

provides a new strategy for designing treatments for non-nutritional

neurologic and psychiatric diseases in which physicians may wish

specifically to increase cholinergic, serotoninergic, or catecholaminergic

tone. "

     Some of these statements are seriously misleading.  Their

findings do not "illustrate a novel and previously unsuspected aspect of

nutrition's effects on the brain;" they do not "provide the basis for new

modes of therapy;" it was not "startling to discover that dietary constituents,

normally influence such an important process as neurotransmitter synthesis;"

and their "new strategy" is not new.

Growdon and Wurtman give no references to the literature

before 1972, except for one 1961 paper on the origin of blood choline.  There

is, however, an extensive body of early publications in this field.  In 1968

I summarized the earlier literature and formulated the'general principles
in my paperi " : ,.Orthomolecular Psychiatry, " which had the subtitle


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"Varying the concentrations of substances normally present in the

human body may control mental disease. " After mentioning the methods

then principally used for treating patients with mental disease, I wrote

that "I have reached the conclusion, through arguments summarized in

the following paragraphs, that another general method of treatment,

which may be called orthomolecular therapy, may be found to be of great

value, and may turn out to be the best method of treatment for many

patients. Orthomolecular psychiatric therapy is the treatment of

mental dis-ease by the provision of the optimum molecular environment

for the mind, especially the optimum concentrations of substances

normally present in the human body. " In this paper there is emphasis

on the vitamins and amino acids.  Tryptophan is mentioned, but not

choline.  Choline is, of course, an orthomolecular substance, normally

present in the human body (both by synthesis by methylation of ethanolamine

and from ingested foods), and the "novel and previously unsuspected

aspects of nutrition" and "new methods of therapy" mentioned by

Growdon and Wurtman are just those of orthomolecular psychiatry,

formulated and clearly expressed in 1968 and then discussed at length in

the 1973 book "Orthomolecular Psychiatry: Treatment of Schizophrenia. ,&3


    The close similarity of the discussion by Growdon and Wurtman

and my earlier discussion can be seen by comparing their paper with

mine. In my 1968 paper there are the following sentences: "The functioning

of the brain and nervous tissues is more sensitively dependent on the rate

of chemical reactions than the functioning of other organs and tissues.


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I believe that mental disease is for the most part caused by abnormal

reaction rates, as determined by genetic constitution and diet, and by

abnormal molecular concentrations of essential substances. . . . The rate

of an enzyme-catalyzed reaction is approximately proportional to the

concentration of the reactant, until concentrations that largely saturate

the enzyme are reached.  The saturating concentration is larger for a

defective enzyme with decreased combining power for the substrate

than for the normal enzyme.  For such a defective enzyme the

catalyzed reaction could be made to take place at or near its normal rate

by an increase in its substrate concentration. . . . This mechanism of

action of gene mutation is only one of several that lead to disadvantageous

manifestations that could be overcome by an increase, perhaps a great

increase, in the concentration of a vital substance in the body.  These

considerations obviously suggest a rationale for megavitamin therapy. "

     The discoveries about the effect of an increased intake of

choline or lecithin in increasing the rate of synthesis of acetylcholine

and in controlling some neurological diseases, discussed by Growdon and

Wurtman, are important contributions to the field of orthomolecular

medicine, illustrating the general principles that had been formulated

more than a decade ago, but neither changing them or expanding them. El


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J. H. Growdon and R.. J. Wurtman, Nutr. R.ev. 37: 129-136, 1979

J. D. Fernstrom and R.. J. Wurtman, Science 178: 414-416, 1972

E. L. Cohen and R. J. Wurtman, Life Sci. 16: 1095-1102, 1975

K. L. Davis, P. A. Berger, and L. E. Hollister, New Engl. J. Med. 293: 152,1975.

L. Pauling, Science 160: 265-271, 1968

D. Hawkins and L. Pauling, Editors, Orthomolecular Psychiatry:
Treatment of Schizophrenia, 697 pages, W. H. Freeman and Co.,
San Francisco, 1973