Table 2. Effect of smoking on concentrations of plasma/serum homocysteine, folate, vitamin B12 and PLP and blood Pb in normal healthy adult males.

Mean±SD
Variables	Concentration		p-value*
	Nonsmokers	Smokers
	(n = 276)	(n = 79)
Homocysteine (µmol/L)	19.80±12.46	19.36±10.0	0.77
Folate (ng/mL)	5.67±3.52	5.35±4.0	0.49
Vitamin B12 (pg/mL)	431±194	413±186	0.46
PLP (nmol/L)	37.6±27.6	34.2±32.9	0.35
Blood Pb (µg/dL)	11.5±5.3	12.5±5.8	0.13

^*Independent sample t-test was used to compare mean values between nonsmokers and smokers.