Table 2 Plasma concentrations of amino acids by habitual diet groupa

From: Plasma concentrations and intakes of amino acids in male meat-eaters, fish-eaters, vegetarians and vegans: a cross-sectional analysis in the EPIC-Oxford cohort

  Geometric mean concentration (95% confidence interval), μmol/l % mean difference compared with meat-eaters Pdifferenceb
  Meat-eaters Fish-eaters Vegetarians Vegans  
  (n=98) (n=98) (n=98) (n=98)  
Branched-chain essential amino acids
 Isoleucine 99 (94, 103) 99 (95, 103) 102 (97, 106) 96 (92, 100) 0.3
  Ref. 0 +3 −3  
 Leucine 205 (197, 214) 208 (200, 216) 210 (202, 218) 191 (184, 199) 0.005
  Ref. +1 +2 −7  
 Valine 230 (221, 239) 233 (225, 242) 233 (225, 242) 217 (209, 225) 0.02
  Ref. +1 +1 −6  
Other essential amino acids
 Histidine 114 (110, 118) 122 (118, 126) 119 (115, 122) 117 (113, 120) 0.04
  Ref. +7 +4 +2  
 Lysinec 241 (230, 253) 242 (232, 253) 234 (224, 245) 210 (201, 219) <0.0001
  Ref. +1 −3 −13  
 Methionine 29 (28, 31) 30 (29, 31) 31 (30, 32) 27 (26, 28) 0.0001
  Ref. +2 +5 −8  
 Phenylalaninec 95 (92, 99) 101 (97, 105) 100 (97, 104) 97 (93, 101) 0.1
  Ref. +6 +5 +2  
 Threonine 164 (158, 170) 168 (163, 174) 167 (162, 173) 165 (159, 171) 0.7
  Ref. +3 +2 +1  
 Tryptophanc,d 69 (67, 72) 71 (68, 73) 72 (70, 74) 65 (63, 68) 0.001
  Ref. +2 +4 −6  
Non-essential amino acids
 Alanine 564 (540, 590) 644 (618, 671) 627 (602, 654) 621 (595, 648) 0.0004
  Ref. +14 +11 +10  
 Arginine 51 (46, 57) 44 (40, 49) 44 (40, 49) 44 (39, 48) 0.1
  Ref. −14 −14 −15  
 Asparagine 92 (89, 95) 97 (94, 101) 96 (92, 99) 98 (95, 102) 0.07
  Ref. +6 +4 +7  
 Aspartated 66 (62, 69) 64 (61, 67) 69 (66, 72) 69 (66, 72) 0.04
  Ref. −3 +5 +5  
 Glutamate 261 (247, 277) 296 (281, 312) 277 (263, 292) 262 (248, 277) 0.004
  Ref. +13 +6 0  
 Glutaminec,d 517 (497, 536) 506 (488, 525) 525 (507, 544) 547 (529, 566) 0.02
  Ref. −2 +2 +6  
 Glycine 390 (375, 407) 422 (406, 439) 411 (395, 427) 452 (434, 470) <0.0001
  Ref. +8 +5 +16  
 Prolinec 245 (233, 258) 255 (243, 268) 265 (253, 278) 244 (233, 256) 0.06
  Ref. +4 +8 −1  
 Serine 191 (183, 198) 201 (194, 208) 197 (190, 204) 197 (190, 205) 0.3
  Ref. +5 +3 +3  
 Tyrosine 77 (74, 81) 83 (80, 86) 83 (80, 86) 73 (70, 76) <0.0001
  Ref. +7 +7 −5  
Non-standard amino acids
 Citrulline 37 (35, 39) 37 (36, 39) 41 (39, 43) 40 (38, 42) 0.02
  Ref. +1 +10 +8  
 Ornithinec 182 (174, 191) 195 (187, 203) 191 (184, 200) 205 (197, 215) 0.005
  Ref. +7 +5 +13  
  1. Abbreviation: Ref., reference.
  2. aAdjusted for age (30–34; 35–39; 40–44; 45–49 years), body mass index (<22.5; 22.5–24.9; 25 kg/m2; unknown), smoking status (never; former; current), alcohol intake (<1; 1–7; 8–15; 16 g/d), time since last food or drink at blood collection (<1.5; 1.5–2.9; 3.0–4.4; 4.5 h; unknown) and time between blood collection and processing (fourths of the distribution; unknown).
  3. bP-values refer to P for the difference across all four diet groups calculated by analysis of variance. Conventional P-values are shown, and those marked in bold were significant after Bonferroni correction (P<0.0024).
  4. cMissing concentration of amino acid for some participants.
  5. dNon-transformed data were used, and arithmetic means are displayed.