Glutamic acid, the main dietary amino acid, and blood pressure: the INTERMAP Study (International Collaborative Study of Macronutrients, Micronutrients and Blood Pressure).
BACKGROUND
Data are available that indicate an independent inverse relationship of dietary vegetable protein to the blood pressure (BP) of individuals. Here, we assess whether BP is associated with glutamic acid intake (the predominant dietary amino acid, especially in vegetable protein) and with each of 4 other amino acids that are relatively higher in vegetable than animal protein (proline, phenylalanine, serine, and cystine).


RESULTS
This was a cross-sectional epidemiological study with 4680 persons 40 to 59 years of age from 17 random population samples in China, Japan, the United Kingdom, and the United States. BP was measured 8 times at 4 visits; dietary data (83 nutrients, 18 amino acids) were obtained from 4 standardized, multipass, 24-hour dietary recalls and 2 timed 24-hour urine collections. Dietary glutamic acid (percentage of total protein intake) was inversely related to BP. Across multivariate regression models (model 1, which controlled for age, gender, and sample, through model 5, which controlled for 16 possible nonnutrient and nutrient confounders), estimated average BP differences associated with a glutamic acid intake that was higher by 4.72% of total dietary protein (2 SD) were -1.5 to -3.0 mm Hg systolic and -1.0 to -1.6 mm Hg diastolic (z scores -2.15 to -5.11). Results were similar for the glutamic acid-BP relationship with each of the other amino acids also in the model; eg, with control for 15 variables plus proline, systolic/diastolic pressure differences were -2.7/-2.0 mm Hg (z scores -2.51, -2.82). In these 2-amino acid models, higher intake (by 2 SD) of each of the other amino acids was associated with small BP differences and z scores.


CONCLUSIONS
Dietary glutamic acid may have independent BP-lowering effects, which may contribute to the inverse relation of vegetable protein to BP.
Stamler
Jeremiah
J
Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA. j-stamler@northwestern.edu
Brown
Ian J
IJ
Daviglus
Martha L
ML
Chan
Queenie
Q
Kesteloot
Hugo
H
Ueshima
Hirotsugu
H
Zhao
Liancheng
L
Elliott
Paul
P
D000328:Adult; D000596:Amino Acids / Q000008:administration & dosage; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology*; D003299:Cooperative Behavior; D003430:Cross-Sectional Studies; D004044:Dietary Proteins / Q000008:administration & dosage; D005260:Female; D018698:Glutamic Acid / Q000008:administration & dosage*; D006801:Humans; D006973:Hypertension / Q000178:diet therapy / Q000453:epidemiology; D038622:Internationality; D008297:Male; D018977:Micronutrients / Q000008:administration & dosage*; D008875:Middle Aged
D000596:Amino Acids; D004044:Dietary Proteins; D018977:Micronutrients; D018698:Glutamic Acid