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. Author manuscript; available in PMC: 2011 Jan 1.
Published in final edited form as: Eur Neuropsychopharmacol. 2010 Jan;20(1):18–24. doi: 10.1016/j.euroneuro.2009.10.003

Table 2.

Plasma Amino Acid Levels During TRP Depletion and Sham Condition

Plasma Levels Active Depletion
Mean ± S.D.		 Paired t-test
p value 2-tailed		 Sham Condition
Mean ± S.D.		 Paired t-test
p value 2-tailed
Total TRP at 6:00 AM (μg/ml) 11.21 ± 1.89 (N=21) P<.01 11.66 ± 2.06 (N=24) P<.01
Total TRP at 11:30 AM (μg/ml) 1.23 ± 0.36 (N=22) 22.21 ± 7.53 (N=24)
ΣLNAA at 6:00 AM (μg/ml) 1403.7 ± 260.4 (N=24) P<.01 1501.8 ± 430.2 (N=24) P<.01
ΣLNAA at 11:30 AM (μ/ml) 4249.4 ± 1326.3 (N=24) 4007.4 ± 1672 (N=24)
TRP/ΣLNAA at 6:00 AM .00828 ± .00227 (N=21) P<.01 .00814 ± .00193 (N=24) P<.01
TRP/ΣLNAA at 11:30 AM .00032 ± .00015 (N=21) .00608 ± .00195 (N=24)

Abbreviations: N= number of subjects, TRP= tryptophan, Total TRP at 6:00AM= total tryptophan level obtained immediately prior to ingestion of the test drink, Total TRP at 11:30 AM= total tryptophan level obtained 5 hours after ingestion of the test drink, μg/ml= micrograms per milliliter, S.D.= standard deviation, ΣLNAA= sum of large neutral amino acids, TRP/ΣLNAA= Ratio of tryptophan to the sum of large neutral amino acids.