| 
      
        | metabolites | retention time | P valuea | A(healthy    controls) | B(cancer) | Rb |  
        | lactic acid | 7.069 | 0.000 | 0.0022 ± 0.0002 | 0.0031 ± 0.0008 | 0.41 |  
        | glycerol | 12.373 | 0.038 | 0.0145 ± 0.0069 | 0.0086 ± 0.0054 | -0.41 |  
        | butanedioic acid | 13.801 | 0.014 | 0.0005 ± 0.0001 | 0.0004 ± 0.0001 | -0.20 |  
        | L-serine | 15.134 | 0.000 | 0.0014 ± 0.0004 | 0.0006 ± 0.0003 | -0.57 |  
        | L-threonine | 15.938 | 0.002 | 0.0011 ± 0.0002 | 0.0006 ± 0.0004 | -0.45 |  
        | citric acid | 28.678 | 0.026 | 0.0045 ± 0.0013 | 0.0034 ± 0.0012 | -0.24 |  
        | hexadecanoic    acid | 34.543 | 0.000 | 0.0665 ± 0.0075 | 0.1213 ± 0.0282 | 0.82 |  | 
  
    | aP values were calculated based on Mann-Whitney test (significance at P<0.05). bR value was calculated from the arithmetic mean values of each group. R=(B-A)/A. R
with a positive value indicates a relatively higher concentration present in cancer group while a negative value means a relatively lower concentration as compared to the
healthy controls. | 
  
    | Table 3a: List of different metabolites identified in healthy controls and gastric cancer patients. |