TABLE 1.

tHcy and MMA concentrations by serum vitamin B-12 and folate categories in NHANES III (1991–1994) and NHANES (1999–2002)¹

	tHcy			MMA
	Serum vitamin B-12			Serum vitamin B-12
Folate	<148 pmol/L	≥148 pmol/L	P	<148 pmol/L	≥148 pmol/L	P
1991–1994
7 nmol/L	15.5	10.9	<0.001	347	202	0.194
	(13.2, 18.1)	(10.5, 11.3)		(178, 676)	(180, 228)
11 nmol/L	12.2	9.2	<0.001	290	191	0.140
	(10.4, 14.2)	(8.8, 9.2)		(155, 543)	(176, 206)
23 nmol/L	11.9	7.6	0.009	523	191	0.002
	(8.7, 16.3)	(7.5, 7.8)		(333, 821)	(180, 202)
1999–2002
16 nmol/L	9.9	9.2	0.222	175	138	0.005
	(8.8, 11.1)	(9.0, 9.4)		(149, 204)	(133, 145)
23 nmol/L	10.8	8.0	<0.001	265	137	<0.001
	(9.4, 12.4)	(7.8, 8.2)		(218, 322)	(132, 142)
30 nmol/L	10.5	7.5	0.001	265	132	<0.001
	(9.1, 12.0)	(7.4, 7.7)		(194, 363)	(127, 137)
44 nmol/L	11.8	7.1	<0.001	314	128	<0.001
	(10.1, 13.8)	(7.0, 7.2)		(234, 421)	(125, 130)

¹Serum folate values are category medians. Values for tHcy (μmol/L) and MMA (nmol/L) are least-square geometric means (95% CI). MMA, methylmalonic acid; tHcy, total homocysteine. Adapted from reference 40. Copyright (2007) National Academy of Sciences.