Physiology & Behavior, Vol. 49, pp. 869-873. ~ Pergamon Press plc, 1991. Printed in the U.S.A.
0031-9384/91 $3.00 + .00
Monosodium Glutamate as a Palatability Enhancer in the European Diet F. B E L L I S L E , M. O. M O N N E U S E , M. C H A B E R T , C. L A R U E - A C H A G I O T I S , M. T. L A N T E A U M E A N D J. L O U I S - S Y L V E S T R E
Laboratoire de Neurobiologie de la Nutrition, Universit Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris, France
BELLISLE, F., M. O. MONNEUSE, M. CHABERT, C. LARUE-ACHAGIOTIS, M. T. LANTEAUME AND J. LOUISSYLVESTRE. Monosodium glutamate as a palatability enhancer in the European diet. PHYSIOL BEHAV 49(5) 869-873, 1991. -Can monosodium glutamate (MSG) augment palatability in foods of the occidental diet? Its effects on the palatability of two experimental foods were investigated in 36 healthy young men and women. MSG improved palatability ratings, with an optimum at 0.6%. Weekly tests of free intake showed that subjects fed the experimental foods with 0.6% MSG added ate progressively more and faster, indicating increasing palatability with repeated exposure. The effects of MSG on familiar foods were investigated in a group of 65 institutionalized elderly persons. Spontaneous intake was measured at lunch time on 12 test days. Target foods (soup and vegetable) were served either without or with 0.6% MSG added. MSG facilitated intake of some but not all target foods, and was associated with positive (increased calcium and magnesium intake) or adverse (increased fat intake) nutritional effects. It is concluded that MSG can act as a palatability enhancer in the context of the French diet. It can facilitate long-term intake in both young and elderly persons but it should be utilized cautiously so as to improve nutrition. Food intake
Palatability
Human subjects
Monosodium glutamate
MONOSODIUM glutamate (MSG) is used as a flavor enhancer in traditional oriental cuisines. As such, it appears one of the "flavor principles" of oriental foods, according to Rozin's deftnition (18). Is this flavor-enhancing property specific to oriental foods, or oriental taste, or else can MSG also augment palatability in foods of the Western cuisine? Although MSG is present naturally and as an additive in many foods that Europeans consume, untrained European tasters do not spontaneously discriminate its taste. They could nevertheless respond to its flavorenhancing properties. An enhancement of palatability can be measured by various means (1). In human subjects, palatability can be assessed by sensory analysis and rating of subjective sensations. However, ratings of the good taste of a food are not necessarily predictive of the intake response to the same food (2, 12, 13). Gustatory sensations that are pleasant when experienced in a short-exposure taste test are sometimes too intense when experienced over the course of a meal. In humans as well as animals, a decisive sign of an increase in palatability is an augmented free food intake under constant hunger conditions. From the beginning to the end of meals (3,11) and also from one meal to another (16), palatability of a food changes over time, as a person gets repeated exposure to it. In the long run, the response to familiar foods will become adapted to their nutritional value (6). Intake of a variety of foods, whose palatability is constantly modulated by the physiological state of the organism, will thus contribute to long-term nutritional homeostasis.
of MSG on the palatability of new foods in 36 young French men and women. Two experimental foods (Spinach Mousse and Beef and Vegetable Jelly), with familiar flavor but unfamiliar aspect, were prepared either without MSG or with 0.3 to 1.2% MSG added. In sensory evaluation tests, MSG enhanced palatability ratings, with an optimum at 0.6%. Some confusion was noted between the taste of MSG and that of NaC1. Weekly tests of free intake were then carried out under laboratory conditions for four consecutive weeks. The group of 36 people was divided in three subgroups so that test foods could be repeatedly presented at 0% added MSG (n = 12 persons), 0.6% MSG (n = 12) and 1.2% MSG (n = 12). On the first presentation, foods with 1.2% MSG added induced large meals and fast eating rates, two indices of immediate palatability (3). Over repeated weekly exposure, another effect of MSG appeared. The group of subjects fed the test foods with 0.6% added MSG progressively ate more and faster, revealing an increasing stimulation to eat with repeated exposure. In the group exposed to the experimental foods without MSG added, free intake either remained stable or declined over the four weekly tests. This study confirmed that MSG exerts an immediate positive effect on palatability. A moderate concentration (0.6%) of MSG in the test foods was associated with a progressive increase in intake of these foods. This observation suggests that MSG can facilitate the acquisition of a taste for new foods. The generalisation of such an effect should be tested in other contexts (different foods, different types of subjects, etc). It is well known that palatability is modulated on the long-term by the nutritional consequences of ingestion (6). The observation made here with different concentrations of MSG suggests that sensory factors interact with exposure effects in determining palatability.
MSG, NEW FOODS, YOUNGPEOPLE In a recent article (4), we reported the first demonstration of an effect of MSG on long-term food intake. We tested the effects 869
870
BELLISLE ET AI..
METHOD
TABLE 1 EXPERIMENTAL MENUS
Subject Selection
Menu A
Menu B
Vegetable Soup A (asparagus) Cooked rice Veal stew Soft white cheese or Yogurt Sugar Canned fruit salad
The physicians in charge of the various wards selected a sampie of subjects who could benefit from our intervention. Subjects on sodium-restricted diets were excluded. A total of 100 individuals were originally included in the study. Their average age was 84 years. The spontaneous food intake of these persons had never been quantified before our experiment. Prior to the experiment, the subjects were told that a 6-month study would be conducted in the institution, with the aim of improving the quality of meals~
Vegetable Soup B (mushrooms) Mashed potatoes Beef Bourguignon Soft white cheese or Yogurt Sugar Canned apricots
MSG Concentration The study conducted on young adults indicated that the maximal stimulation of intake occurred with 0.6% MSG concentration. This dose was thus selected for the study on elderly subjects.
MSG, TRADITIONAL FOODS, ELDERLY PEOPLE The former experiment shows that, at least in young people with a healthy appetite, MSG enhances the acceptability of dishes not only on first exposure but also over the long-term. Such an effect is important and could be used purposely to improve the motivation to eat and increase intake in certain categories of humans who eat too little. This could be tested, for example, in children with kidney disease whose growth is severely retarded, or in convalescents who could be stimulated to eat a more hearty diet by the utilization of some MSG in target foods. We have examined the long-term effect of M S G on the food intake of elderly persons living in a specialized house. Feeding the elderly is reportedly a difficult problem (5, 8, 10, 14). Many institutionalized elderly people do not show a strong interest in food; many suffer from olfacto-gustatory deficits (e.g., increase in taste thresholds) which might render food less attractive (7, 15, 20). It has also been suggested that the elderly experience weak signals of biological needs and/or overactive satiation (5). Moreover, institutional diets often present mediocre quality and little variety. Consequently, spontaneous food intake in elderly people is sometimes lower than optimal. Protein undernutrition has been presented as a critical issue (9), as well as calcium deficiency (10). Would it be possible to stimulate the intake of target foods in eldedy persons by the use of MSG, in the same way as it was possible in young adults? The present experiment was carried out in an institution for the elderly in the Paris area. Over 400 persons live and eat in this institution. A professional dietician elaborates adequate menus to cover nutritional needs. Our aim was to investigate whether the addition of some MSG to target foods is likely to increase appetite and improve nutrition in this population.
Selection of Experimental Foods After consultation with the dietician and the kitchen personnel, two lunch menus were selected. The menus were of medium palatability and included a soup and a vegetable dish whose homogeneous texture allowed MSG to be incorporated. The menus corresponded to traditional meal habits in France. They are listed in Table l. All foods included in the menus were familiar to the subjects. For the duration of the experiment, they were not served except on test days.
Meal Presentation The menus were presented on six occasions each. The experiment consisted in six blocks of two tests, one of Menu A, the other of Menu B. For the first three blocks, Menu A was presented without added MSG while Menu B was served with 0.6% MSG added to target foods (soup and vegetable). For the last three blocks, Menu B was offered without MSG and Menu A was served with 0.6% MSG added to target foods. Test meals were scheduled on the same day of the week (Tuesday), with a two-week interval between successive tests. Within blocks, the order of presentation of the menus was random. On test days, the experimenters added M S G to target foods whenever appropriate. This was done covertly and the subjects were unaware of the manipulation. Foods were weighed before being presented to the subjects. The subjects ate freely, under habitual conditions. After the end of the meal, food left-over by each individual subject was weighed. The intake of each food by each subject was then computed. The nutritional value of all in-
TABLE 2A INTAKE IN GRAMS (MEAN --_ SEM) MENU A (N = 60-65)
Test Weeks Bread Soup I Veal Rice Soft white cheese + sugar Canned fruits
No MSG 2
1 17.2 131.3 73.1 58.6
-+ --4±
2.0 16.4 6.7 7.8
85.4 -+ 5.8 56.9 --4-- 6.4
16.8 122.2 65.8 50.
+_ 2.3 +_ 16.3 +_ 8,2 + 8.2
83.7 "4- 5.8 60.4 ___ 6.2
3 15.8 121.8 59.9 44.2
+_ --_+ ~
1 2.0 14.7 6.6 7.1
79.9 +-- 5.0 70.6 +-- 7.1
23. 144.4 67.7 37.6
- 2.6 ___ 17.1 _+ 6.8 + 6.4
89.8 +- 3.9 56. + 6.4
+ MSG 2 13. 107.6 66.5 47.5
-+- 1.9 ___ 12.6 ___ 5.4 +- 7.3
88.9 -+ 4.4 67.8 - 6.7
3 16.2 98.7 57.8 38.3
~ _ ---
1.9 11.5 6.0 6.1
97.7 --- 3.8 59.9 --- 6.0
U M A M I IN THE EUROPEAN CONTEXT
871
TABLE 2B INTAKE IN GRAMS (MEAN ___SEM) MENU B (N=60-65)
Test Weeks
No MSG 2
1
Bread Soup II Beef Mashed potatoes Soft white cheese + sugar Canned fruits
17.7 138.0 69.9 124.6
--± ± ±
2.2 15.0 7.4 10.3
17.6 91.6 88.0 132.7
88.4 ___ 4.4 55.0 --- 6.6
± ± ± _+
86.6 ± 54.4 ±
2.2 13.0 7.1 10.3 5.2 8.0
3 15.7 100.3 66.4 128.7
1
± 2.0 ± 12.0 ± 6.9 ± 9.4
93.1 ± 68.4 ±
gested foods was analyzed using a computerized food composition table.
4.0 7.2
17.8 119.5 81.0 171.6
± 2.2 ± 14.4 ± 6.7 ± 16.7
73.5 ___ 5.7 42.7 ± 7.8
+ MSG 2 18. 121.8 66.1 152.7
± 2.3 ± 15.8 ± 7.5 ± 10.4
87.1 --+ 4.4 55.5 ± 5.9
3 15.4 114.0 77.1 126.7
± 2.0 ± 16.0 ± 7.2 ± 13.2
85.9 --- 4.6 62.8 ± 7.8
were noted. Significant interactions of M S G level x weeks were observed for calories, F ( 2 , 9 0 ) = 3 . 2 , p < 0 . 0 5 , and magnesium, F(2,90) = 3.7, p < 0 . 0 5 , intake, indicating different changes in intake over weeks, depending on the M S G conditions. Examination of the data reveals that caloric and magnesium intakes decreased over weeks when no MSG was added while they did not when MSG was present. Significant main effects of Weeks were observed for intakes of proteins, F ( 2 , 9 0 ) = 3 . 6 , p < 0 . 0 5 , fats, F ( 2 , 9 0 ) = 4 . 8 , p < 0 . 0 2 , cholesterol, F ( 2 , 9 0 ) = 4 , 8 , p < 0 . 0 2 , and Na, F ( 2 , 9 0 ) = 5.5, p < 0 . 0 1 , showing a large degree of variability independent of MSG treatment. The intake of Menu B was affected by the presence of MSG: more soup, F ( 1 , 5 3 ) = 4 . 5 , p < 0 . 0 5 , and more mashed potatoes, F ( 1 , 5 3 ) = 5 . 5 , p < 0 . 0 5 , were eaten when MSG was added to them. Less soft white cheese was consumed on MSG weeks, F ( 1 , 5 3 ) = 5 . 8 , p < 0 . 0 5 . A M S G x Week interaction was noted for soup intake, F(2,106)= 3.5, p < 0 . 0 5 : the sharp fall in intake observed after Week I in the No MSG condition was not replicated in the 0.6% M S G condition. More calories, F ( 1 , 5 3 ) = 5 . 3 , p < 0 . 0 5 ) , more fats, F ( 1 , 5 3 ) = 5 . 2 , p < 0 . 0 5 , and more Na, F(1,53) = 8.1, p < 0 . 0 1 , were ingested under the 0.6% MSG condition. Under Menu B, significant main effects of Weeks were seen for soup, F ( 2 , 1 0 6 ) = 3.9, p < 0 . 0 5 ) , soft white cheese, F ( 2 , 1 0 6 ) = 3 . 8 , p < 0 . 0 5 , and canned fruits, F ( 2 , 1 0 6 ) = 5 . 5 , p < 0 . 0 1 , intakes as well as for Na content of the meals, F(2,106) = 4.2, p < 0 . 0 2 ) .
RESULTS Attrition was high due to the age of the subjects. Out of the 100 subjects originally included in the study, 35 have died or had to be excluded for various reasons (loss of autonomy, change of residence, illnesses, etc.). Out of the remaining 65 persons, many occasionally missed a test-meal. In the end, complete sets of data (for all six meals per menu) were available in 46 subjects for Menu A and 54 persons for Menu B. Forty-one subjects participated in all twelve experimental meals. Tables 2A and 2B present the intake in grams of each food on Menus A and B for the six weeks of testing and two MSG conditions (0% or 0.6%), for the whole sample of 60-65 elderly subjects. The target foods to which M S G could be added are underlined. Tables 3A and 3B display the nutritional value of the meals consumed on test days for the same population. Some important variations in intake appeared between test weeks. Analyses of variance were performed on data for subpopulations with complete series of meals. This statistical treatment revealed the following effects. For Menu A, n = 46, the intake of individual foods was not significantly different depending on the presence or absence of MSG. However, significant main effects of weeks appeared for bread, soup, and veal intake [F(2,90)= 3.9, 5.8, and 6, respectively]: intake generally decreased over repeated presentations. When M S G was present, increased intakes of calcium, F(1,45) = 4.5, p < 0 . 0 5 , and magnesium, F ( 1 , 4 5 ) = 5 . 2 , p
0031-9384/91 $3.00 + .00
Monosodium Glutamate as a Palatability Enhancer in the European Diet F. B E L L I S L E , M. O. M O N N E U S E , M. C H A B E R T , C. L A R U E - A C H A G I O T I S , M. T. L A N T E A U M E A N D J. L O U I S - S Y L V E S T R E
Laboratoire de Neurobiologie de la Nutrition, Universit Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris, France
BELLISLE, F., M. O. MONNEUSE, M. CHABERT, C. LARUE-ACHAGIOTIS, M. T. LANTEAUME AND J. LOUISSYLVESTRE. Monosodium glutamate as a palatability enhancer in the European diet. PHYSIOL BEHAV 49(5) 869-873, 1991. -Can monosodium glutamate (MSG) augment palatability in foods of the occidental diet? Its effects on the palatability of two experimental foods were investigated in 36 healthy young men and women. MSG improved palatability ratings, with an optimum at 0.6%. Weekly tests of free intake showed that subjects fed the experimental foods with 0.6% MSG added ate progressively more and faster, indicating increasing palatability with repeated exposure. The effects of MSG on familiar foods were investigated in a group of 65 institutionalized elderly persons. Spontaneous intake was measured at lunch time on 12 test days. Target foods (soup and vegetable) were served either without or with 0.6% MSG added. MSG facilitated intake of some but not all target foods, and was associated with positive (increased calcium and magnesium intake) or adverse (increased fat intake) nutritional effects. It is concluded that MSG can act as a palatability enhancer in the context of the French diet. It can facilitate long-term intake in both young and elderly persons but it should be utilized cautiously so as to improve nutrition. Food intake
Palatability
Human subjects
Monosodium glutamate
MONOSODIUM glutamate (MSG) is used as a flavor enhancer in traditional oriental cuisines. As such, it appears one of the "flavor principles" of oriental foods, according to Rozin's deftnition (18). Is this flavor-enhancing property specific to oriental foods, or oriental taste, or else can MSG also augment palatability in foods of the Western cuisine? Although MSG is present naturally and as an additive in many foods that Europeans consume, untrained European tasters do not spontaneously discriminate its taste. They could nevertheless respond to its flavorenhancing properties. An enhancement of palatability can be measured by various means (1). In human subjects, palatability can be assessed by sensory analysis and rating of subjective sensations. However, ratings of the good taste of a food are not necessarily predictive of the intake response to the same food (2, 12, 13). Gustatory sensations that are pleasant when experienced in a short-exposure taste test are sometimes too intense when experienced over the course of a meal. In humans as well as animals, a decisive sign of an increase in palatability is an augmented free food intake under constant hunger conditions. From the beginning to the end of meals (3,11) and also from one meal to another (16), palatability of a food changes over time, as a person gets repeated exposure to it. In the long run, the response to familiar foods will become adapted to their nutritional value (6). Intake of a variety of foods, whose palatability is constantly modulated by the physiological state of the organism, will thus contribute to long-term nutritional homeostasis.
of MSG on the palatability of new foods in 36 young French men and women. Two experimental foods (Spinach Mousse and Beef and Vegetable Jelly), with familiar flavor but unfamiliar aspect, were prepared either without MSG or with 0.3 to 1.2% MSG added. In sensory evaluation tests, MSG enhanced palatability ratings, with an optimum at 0.6%. Some confusion was noted between the taste of MSG and that of NaC1. Weekly tests of free intake were then carried out under laboratory conditions for four consecutive weeks. The group of 36 people was divided in three subgroups so that test foods could be repeatedly presented at 0% added MSG (n = 12 persons), 0.6% MSG (n = 12) and 1.2% MSG (n = 12). On the first presentation, foods with 1.2% MSG added induced large meals and fast eating rates, two indices of immediate palatability (3). Over repeated weekly exposure, another effect of MSG appeared. The group of subjects fed the test foods with 0.6% added MSG progressively ate more and faster, revealing an increasing stimulation to eat with repeated exposure. In the group exposed to the experimental foods without MSG added, free intake either remained stable or declined over the four weekly tests. This study confirmed that MSG exerts an immediate positive effect on palatability. A moderate concentration (0.6%) of MSG in the test foods was associated with a progressive increase in intake of these foods. This observation suggests that MSG can facilitate the acquisition of a taste for new foods. The generalisation of such an effect should be tested in other contexts (different foods, different types of subjects, etc). It is well known that palatability is modulated on the long-term by the nutritional consequences of ingestion (6). The observation made here with different concentrations of MSG suggests that sensory factors interact with exposure effects in determining palatability.
MSG, NEW FOODS, YOUNGPEOPLE In a recent article (4), we reported the first demonstration of an effect of MSG on long-term food intake. We tested the effects 869
870
BELLISLE ET AI..
METHOD
TABLE 1 EXPERIMENTAL MENUS
Subject Selection
Menu A
Menu B
Vegetable Soup A (asparagus) Cooked rice Veal stew Soft white cheese or Yogurt Sugar Canned fruit salad
The physicians in charge of the various wards selected a sampie of subjects who could benefit from our intervention. Subjects on sodium-restricted diets were excluded. A total of 100 individuals were originally included in the study. Their average age was 84 years. The spontaneous food intake of these persons had never been quantified before our experiment. Prior to the experiment, the subjects were told that a 6-month study would be conducted in the institution, with the aim of improving the quality of meals~
Vegetable Soup B (mushrooms) Mashed potatoes Beef Bourguignon Soft white cheese or Yogurt Sugar Canned apricots
MSG Concentration The study conducted on young adults indicated that the maximal stimulation of intake occurred with 0.6% MSG concentration. This dose was thus selected for the study on elderly subjects.
MSG, TRADITIONAL FOODS, ELDERLY PEOPLE The former experiment shows that, at least in young people with a healthy appetite, MSG enhances the acceptability of dishes not only on first exposure but also over the long-term. Such an effect is important and could be used purposely to improve the motivation to eat and increase intake in certain categories of humans who eat too little. This could be tested, for example, in children with kidney disease whose growth is severely retarded, or in convalescents who could be stimulated to eat a more hearty diet by the utilization of some MSG in target foods. We have examined the long-term effect of M S G on the food intake of elderly persons living in a specialized house. Feeding the elderly is reportedly a difficult problem (5, 8, 10, 14). Many institutionalized elderly people do not show a strong interest in food; many suffer from olfacto-gustatory deficits (e.g., increase in taste thresholds) which might render food less attractive (7, 15, 20). It has also been suggested that the elderly experience weak signals of biological needs and/or overactive satiation (5). Moreover, institutional diets often present mediocre quality and little variety. Consequently, spontaneous food intake in elderly people is sometimes lower than optimal. Protein undernutrition has been presented as a critical issue (9), as well as calcium deficiency (10). Would it be possible to stimulate the intake of target foods in eldedy persons by the use of MSG, in the same way as it was possible in young adults? The present experiment was carried out in an institution for the elderly in the Paris area. Over 400 persons live and eat in this institution. A professional dietician elaborates adequate menus to cover nutritional needs. Our aim was to investigate whether the addition of some MSG to target foods is likely to increase appetite and improve nutrition in this population.
Selection of Experimental Foods After consultation with the dietician and the kitchen personnel, two lunch menus were selected. The menus were of medium palatability and included a soup and a vegetable dish whose homogeneous texture allowed MSG to be incorporated. The menus corresponded to traditional meal habits in France. They are listed in Table l. All foods included in the menus were familiar to the subjects. For the duration of the experiment, they were not served except on test days.
Meal Presentation The menus were presented on six occasions each. The experiment consisted in six blocks of two tests, one of Menu A, the other of Menu B. For the first three blocks, Menu A was presented without added MSG while Menu B was served with 0.6% MSG added to target foods (soup and vegetable). For the last three blocks, Menu B was offered without MSG and Menu A was served with 0.6% MSG added to target foods. Test meals were scheduled on the same day of the week (Tuesday), with a two-week interval between successive tests. Within blocks, the order of presentation of the menus was random. On test days, the experimenters added M S G to target foods whenever appropriate. This was done covertly and the subjects were unaware of the manipulation. Foods were weighed before being presented to the subjects. The subjects ate freely, under habitual conditions. After the end of the meal, food left-over by each individual subject was weighed. The intake of each food by each subject was then computed. The nutritional value of all in-
TABLE 2A INTAKE IN GRAMS (MEAN --_ SEM) MENU A (N = 60-65)
Test Weeks Bread Soup I Veal Rice Soft white cheese + sugar Canned fruits
No MSG 2
1 17.2 131.3 73.1 58.6
-+ --4±
2.0 16.4 6.7 7.8
85.4 -+ 5.8 56.9 --4-- 6.4
16.8 122.2 65.8 50.
+_ 2.3 +_ 16.3 +_ 8,2 + 8.2
83.7 "4- 5.8 60.4 ___ 6.2
3 15.8 121.8 59.9 44.2
+_ --_+ ~
1 2.0 14.7 6.6 7.1
79.9 +-- 5.0 70.6 +-- 7.1
23. 144.4 67.7 37.6
- 2.6 ___ 17.1 _+ 6.8 + 6.4
89.8 +- 3.9 56. + 6.4
+ MSG 2 13. 107.6 66.5 47.5
-+- 1.9 ___ 12.6 ___ 5.4 +- 7.3
88.9 -+ 4.4 67.8 - 6.7
3 16.2 98.7 57.8 38.3
~ _ ---
1.9 11.5 6.0 6.1
97.7 --- 3.8 59.9 --- 6.0
U M A M I IN THE EUROPEAN CONTEXT
871
TABLE 2B INTAKE IN GRAMS (MEAN ___SEM) MENU B (N=60-65)
Test Weeks
No MSG 2
1
Bread Soup II Beef Mashed potatoes Soft white cheese + sugar Canned fruits
17.7 138.0 69.9 124.6
--± ± ±
2.2 15.0 7.4 10.3
17.6 91.6 88.0 132.7
88.4 ___ 4.4 55.0 --- 6.6
± ± ± _+
86.6 ± 54.4 ±
2.2 13.0 7.1 10.3 5.2 8.0
3 15.7 100.3 66.4 128.7
1
± 2.0 ± 12.0 ± 6.9 ± 9.4
93.1 ± 68.4 ±
gested foods was analyzed using a computerized food composition table.
4.0 7.2
17.8 119.5 81.0 171.6
± 2.2 ± 14.4 ± 6.7 ± 16.7
73.5 ___ 5.7 42.7 ± 7.8
+ MSG 2 18. 121.8 66.1 152.7
± 2.3 ± 15.8 ± 7.5 ± 10.4
87.1 --+ 4.4 55.5 ± 5.9
3 15.4 114.0 77.1 126.7
± 2.0 ± 16.0 ± 7.2 ± 13.2
85.9 --- 4.6 62.8 ± 7.8
were noted. Significant interactions of M S G level x weeks were observed for calories, F ( 2 , 9 0 ) = 3 . 2 , p < 0 . 0 5 , and magnesium, F(2,90) = 3.7, p < 0 . 0 5 , intake, indicating different changes in intake over weeks, depending on the M S G conditions. Examination of the data reveals that caloric and magnesium intakes decreased over weeks when no MSG was added while they did not when MSG was present. Significant main effects of Weeks were observed for intakes of proteins, F ( 2 , 9 0 ) = 3 . 6 , p < 0 . 0 5 , fats, F ( 2 , 9 0 ) = 4 . 8 , p < 0 . 0 2 , cholesterol, F ( 2 , 9 0 ) = 4 , 8 , p < 0 . 0 2 , and Na, F ( 2 , 9 0 ) = 5.5, p < 0 . 0 1 , showing a large degree of variability independent of MSG treatment. The intake of Menu B was affected by the presence of MSG: more soup, F ( 1 , 5 3 ) = 4 . 5 , p < 0 . 0 5 , and more mashed potatoes, F ( 1 , 5 3 ) = 5 . 5 , p < 0 . 0 5 , were eaten when MSG was added to them. Less soft white cheese was consumed on MSG weeks, F ( 1 , 5 3 ) = 5 . 8 , p < 0 . 0 5 . A M S G x Week interaction was noted for soup intake, F(2,106)= 3.5, p < 0 . 0 5 : the sharp fall in intake observed after Week I in the No MSG condition was not replicated in the 0.6% M S G condition. More calories, F ( 1 , 5 3 ) = 5 . 3 , p < 0 . 0 5 ) , more fats, F ( 1 , 5 3 ) = 5 . 2 , p < 0 . 0 5 , and more Na, F(1,53) = 8.1, p < 0 . 0 1 , were ingested under the 0.6% MSG condition. Under Menu B, significant main effects of Weeks were seen for soup, F ( 2 , 1 0 6 ) = 3.9, p < 0 . 0 5 ) , soft white cheese, F ( 2 , 1 0 6 ) = 3 . 8 , p < 0 . 0 5 , and canned fruits, F ( 2 , 1 0 6 ) = 5 . 5 , p < 0 . 0 1 , intakes as well as for Na content of the meals, F(2,106) = 4.2, p < 0 . 0 2 ) .
RESULTS Attrition was high due to the age of the subjects. Out of the 100 subjects originally included in the study, 35 have died or had to be excluded for various reasons (loss of autonomy, change of residence, illnesses, etc.). Out of the remaining 65 persons, many occasionally missed a test-meal. In the end, complete sets of data (for all six meals per menu) were available in 46 subjects for Menu A and 54 persons for Menu B. Forty-one subjects participated in all twelve experimental meals. Tables 2A and 2B present the intake in grams of each food on Menus A and B for the six weeks of testing and two MSG conditions (0% or 0.6%), for the whole sample of 60-65 elderly subjects. The target foods to which M S G could be added are underlined. Tables 3A and 3B display the nutritional value of the meals consumed on test days for the same population. Some important variations in intake appeared between test weeks. Analyses of variance were performed on data for subpopulations with complete series of meals. This statistical treatment revealed the following effects. For Menu A, n = 46, the intake of individual foods was not significantly different depending on the presence or absence of MSG. However, significant main effects of weeks appeared for bread, soup, and veal intake [F(2,90)= 3.9, 5.8, and 6, respectively]: intake generally decreased over repeated presentations. When M S G was present, increased intakes of calcium, F(1,45) = 4.5, p < 0 . 0 5 , and magnesium, F ( 1 , 4 5 ) = 5 . 2 , p
