Table 2.

Sample sizes and percentages for serum vitamin B-12 and methylmalonic acid by variable categories in US persons ≥20 y of age, NHANES 2011–2014¹

	Serum vitamin B-12				Serum MMA
Variable categories	2011–2012		2013–20142		2011–2012		2013–20142
	n	%	n	%	n	%	n	%
All	4,804	-	5,216	-	4,807	-	5,213	-
Age, y
20–39	1,670	35.2	1,705	35.2	1,670	35.1	1,703	35.2
40–59	1,608	38.8	1,823	37.4	1,608	38.8	1,821	37.4
60–69	800	14.0	866	14.8	800	14.0	867	14.8
≥70	726	12.0	822	12.6	729	12.1	822	12.6
Sex
Male	2,424	49.1	2,535	49.3	2,424	49.1	2,534	49.3
Female	2,380	50.9	2,681	50.7	2,383	50.9	2,679	50.7
Race-ethnicity
Hispanic	974	14.3	1,172	14.7	974	14.3	1,174	14.8
Mexican American	481	7.8	709	9.2	481	7.8	711	9.2
Non-Hispanic Black	1,220	10.8	1,026	10.8	1,220	10.8	1,024	10.8
Non-Hispanic White	1,805	67.4	2,279	66.6	1,807	67.4	2,275	66.6
Non-Hispanic Asian	670	5.0	588	5.2	671	5.0	589	5.3
B-12 supplement use
No	3,303	66.1	3,514	64.1	3,304	66.0	3,515	64.1
Yes	1,467	33.9	1,672	35.9	1,469	34.0	1,668	35.9
Fasting
<3 h	1,347	29.4	1,689	35.5	1,347	29.4	1,688	35.5
3–<8 h	982	18.7	983	16.8	983	18.7	980	16.8
≥8 h	2,475	51.9	2,544	47.7	2,477	51.9	2,545	47.7
Renal function
Normal	3,730	82.2	3,989	80.1	3,731	82.2	3,987	80.1
CKD stage 1–2	613	10.6	693	11.8	614	10.6	693	11.8
CKD stage 3–5	424	7.3	482	8.1	425	7.3	481	8.1

¹Values are weighted percentages. Pregnant and lactating women were excluded; available-case analysis was used to handle missing or incomplete data (e.g., B-12 supplement use, renal function). CKD, chronic kidney disease; MMA, methylmalonic acid.

²While NHANES 2013–2014 collected samples from participants ≥19 y of age, we only included data for participants ≥20 y of age.