Daily Tryptophane Consumption and Psychologic State

Abstract

Two hundred fifteen presumably healthy dentists and their wives participated in an experiment in which daily tryptophane consumption, as judged by a dietary frequency questionnaire, was correlated with psychologic state as measured by a controlled association test.

The results suggest that the higher the tryptophane intake the better the psychic rating. Additionally, the data indicate the possible need for a higher intake of tryptophane than traditionally held.

The question immediately arises whether the relationship between psychologic status and protein is unique by virtue of the tryptophane consumption. To resolve this question, a report to follow¹ will analyze psychologic state and daily phenylalanine consumption.

Introduction

Four interdependent observations serve as a prelude to and justification for this report. First, the literature is replete with evidence to underscore the relationship of hyponiacinosis and pellagra.^2,3 Second, numerous reports in recent times have indicated the utility of megavitamin B3 therapy in seemingly nonpellagrous psychologic disorders [e.g. schizophrenia].^4,5 Third, there is reasonable proof that tryptophane is a precursor of nicotinic acid.^6,7 Finafly, limited data suggest a positive correlation between psychologic rating scores and protein-nicotinic acid consumption in subjects who, by all traditional criteria, are neither schizophrenic or pellagrous.^8,9

This report is designed to cast additional light upon the possible interdependency of the four items just listed by a study of the relationship between daily tryptophane intake and psychologic state in subjects who are apparently without schizophrenia and pellagra. Specifically, an attempt will be made to answer the following four questions:

1. What is the daily tryptophane consumption of a sample of presumably healthy subjects?
2. How do the findings compare with the Recommended Dietary Allowances?
3. Is there any relationship between the daily tryptophane intake and psychologic state?
4. Of what significance are these findings?

Method of Investigation

Two hundred fifteen presumably healthy dentists and their wives [including five children) shared in this experiment. These individuals are currently participating in a multiple testing health evaluation program in Los Angeles under the sponsorship of the Southern California Academy of Nutritional Research, in Columbus under the Auspices of the Ohio Academy of Clinical Nutrition, and in Tampa under the aegis of the Southern Academy of Clinical Nutrition. The age and sex distribution is summarized [Table I].

Table I–age and sex distribution

Each subject completed a Dietronics Dietary Analysis form. This technique is based upon significant observations in Israel¹⁰ and England¹¹ which suggest that the most practical method for deriving data is by means of a food frequency questionnaire. Dietronics Dietary Analysis consists of a simple questionnaire completed by the subject in a matter of a few minutes. The form is submitted for computer analysis and a printout is returned showing the daily intake of the major foodstuffs and the most common vitamins and minerals. By this method, it is possible to ascertain the daily individual amino acid consumption. For purposes of this report, only tryptophane will be considered. Table II summarizes the findings. 

Table II–daily tryptophane consumption

Finally, each subject completed the Cornell Word Form-2 [abbreviated CWF-2]. This questionnaire is a modification of the ordinary type of individually-administered word association technique in that it is a forced choice method.¹² The subject is presented with a list of stimulus words, each followed by two other [response] words. The subject is asked to choose the one he or she thinks relates better with the stimulus word. The CWF-2 has been devised as an instrument to make quickly a descriptive sketch of the individual’s attitude, feeling states and emotions or bodily reactions for clinical interpretation. It has been devised to do so in a manner not readily discernable to the subject in order to enhance the degree of objectivity. The results are summarized [Table III].

Table III–Cornell Word Form-2 [CWF-2] distribution

Results

Question One: Table II summarizes the daily tryptophane intake for the entire sample and the sexes separately. Several points deserve special mention. First, for the entire group, there is considerable variation ranging from a low of 360 to a high of 3970 mgm. tryptophane intake per day. Hence, there is an eleven-fold range. Second, the mean consumption is considerably higher in the male than in the female. Finally, the range is much broader in the male than in the female group.

Question Two: According to the Food and Nutrition Board of the National Research Council, the Recommended Dietary Allowance [RDA]¹³ for tryptophane is 500 mgm. per day for both the reference man and woman. On this basis, 1.6 and 1.1 per cent of the male and female groups, respectively, are consuming suboptimal amounts of tryptophane. Additionally, on this basis, over one-half of the men and almost one-half of the women are consuming double the Recommended Dietary Allowance.

Question Three: The group was divided into two subcategories based upon age. One group of 105 subjects were under 42 years; the remaining 110 subjects were 42 or more years of age. Furthermore, the entire group was subdivided into those individuals consuming less than 1000 mgm. tryptophane per day versus those with an intake of 1000+ mgm. daily. Table IV summarizes the findings for the four subgroups. It will be noted that, in the younger category [<42 years of age], the mean psychologic scores were not statistically significantly different in terms of daily tryptophane intake [t = 0.301, P > 0.500]. In contrast, in the older group, the findings were different. First, the mean CWF-2 score was considerably higher in the group consuming the lesser amount of tryptophane [2.0 versus 1.1]. Second, the difference is statistically significant [t = 2.568, P<0.025] between the two groups.

Table IV–relationship of daily tryptophane consumption and Cornell Word Form-2 [CWF-2] scores

Discussion

It must be granted that the sample is unusual in that it is composed almost exclusively of members of the health profession and their wives. From a qualitative standpoint, the men consume greater amounts of tryptophane [Table II] and display better psychologic scores [Table III]. The most apparent quantitative observation is the fact that there is a statistically significant relationship between psychologic state [as judged by the CWF-2] and diet [as determined by tryptophane consumption]. These data are significant for several reasons.

Question Four: First, it is interesting that the correlation between psychologic state and tryptophane intake in this experiment parallels the earlier reported relationship between protein-nicotinic acid consumption and psychologic responses.8,9 This, in a circumstantial manner, interrelates psychic health with protein, niacin, and tryptophane. Second, these relationships suggest either that pellagra can exist in a subclinical form or that protein-tryptophane-niacin correlate with nonpellagrous psychic disorders. Third, the observations reported here question the current Recommended Dietary Allowance for tryptophane [500 mgm. per day]. It may be too low13 with regard to psychic balance. This seems tenable since those subjects consuming twice the RDA [1000 mgm. per day] showed poorer psychologic responses than those with an intake of 1000+ mgm. daily. Finally, the limited evidence presented here adds credence to the case for megavitamin therapy.4,5

References Cited:

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13. Food and Nutrition Board. Recommended Dietary Allowances. Publication 1694. Seventh revised edition. 1968. National Academy of Sciences, Washington, D. C.