TABLE 1.

Interaction between vitamin B-12 status and serum folate in relation to anemia and cognitive impairment among nonexcluded senior participants in the National Health and Nutrition Examination Survey (1999–2002) (31)

	Vitamin status
Outcome	B-121	Folate2	No. of Subjects	Percentage with outcome	OR (95% CI)	OR (95% CI)	OR (95% CI)
Anemia	Normal	Normal	913	3.5	1.0	1.0	1.0
	Normal	High	198	2.5	0.5 (0.2, 1.8)	0.6 (0.2, 2.5)	0.7 (0.2, 2.5)
	Low	Normal	297	6.9	1.6 (1.02, 2.6)	2.1 (1.1, 3.8)	1.9 (0.99, 3.7)
	Low	High	49	15	5.1 (2.1, 8.0)	5.2 (2.5, 11.0)	5.0 (2.4, 10.6)
Cognitive impairment	Normal	Normal	826	18	1.0	1.0	1.0
	Normal	High	180	11	0.4 (0.2, 0.7)	0.4 (0.2, 0.9)	0.5 (0.2, 0.96)
	Low	Normal	253	25	1.6 (0.99, 2.4)	1.7 (1.01, 2.9)	1.5 (0.9, 2.5)
	Low	High	42	45	4.3 (2.3, 8.0)	5.1 (2.7, 9.5)	4.7 (2.5, 8.7)

¹Low serum vitamin B-12 < 148 pmol/L or serum methylmalonic acid above reference range (ie, 60–210 nmol/L) for vitamin B-12–replete participants with normal serum creatinine.

²High serum folate > 59 nmol/L (80th percentile).