Table 3.

Differences in average glycine levels by age.

Glycine levels
Age	N	Mean	SD	Minimum	Maximum	p-value
Youth age	4	0.59	0.18	0.47	0.87	0.025
Young age	31	0.59	0.15	0.18	0.86
Middle age	32	0.50	0.14	0.26	0.85
Elderly age	5	0.40	0.04	0.36	0.46