Table 4.

Homocysteine and Serum Folate Concentrations^a Before and After a 6-Week Intervention Period Involving Folic Acid Supplementation Among Adults Aged 60–90 Years and Median Changes After Intervention by Intervention Group for Persons in the Highest Tertile (≥9.19 mmol/L) of Baseline Plasma Homocysteine Concentration, Baltimore, Maryland, 1996

	All Participants (n = 45)		Placebo Group (0 μg/day) (n = 12)		Folic Acid Supplement Dose, μg/day								P-Trend
					100 (n = 6)		400 (n = 9)		1,000 (n = 12)		2,000 (n = 6)
	Median	IQRb	Median	IQR	Median	IQR	Median	IQR	Median	IQR	Median	IQR
Week 0
Folate RIA, ng/mL	4.4	3.3–6.4	4.6	3.8–6.4	4.1	2.1–4.5	3.7	2.5–8.7	4.4	3.5–6.3	5.8	4.9–7.6
Homocysteine, μmol/L	11.0	9.9–12.6	11.7	10.5–12.7	11.5	10.4–13.2	11.2	9.9–12.6	10.8	9.5–11.1	11.5	9.6–18.5
Week 6
Folate RIA, ng/mL			3.8	3.3–5.5	6.8	4.9–10.0	10.8	6.6–15.4	16.5	12.3–32.9	61.5	11.6–105.8
Homocysteine, μmol/L			9.7	8.3–11.7	9.1	8.8–9.8	10.0	9.2–11.1	9.1	8.3–9.7	9.7	8.3–18.2
Within-group change postintervention
Folate RIA, ng/mL			−0.7	−3.3 to 0.6	3.4	0.9 to 6.2	3.3	3.1 to 9.4	13.0	7.8 to 28.7	52.5	5.9 to 102.4	<0.001
Homocysteine, μmol/L			−0.9	−2.1 to −0.1	−2.3	−4.2 to −1.3	−2.8	−3.2 to 0.2	−1.6	−2.1 to −0.4	−1.0	−1.5 to −0.7	0.84
Between-group change postintervention (active dose vs. placebo)					Median	95% CI	Median	95% CI	Median	95% CI	Median	95% CI
Folate RIA, ng/mL					4.5	−1.7, 10.7	4.0	1.1, 6.9	14.7	8.4, 21.0	98.9	87.3, 110.5
Homocysteine, μmol/L					−1.4	−5.3, 2.5	−1.9	−4.3, 0.4	−0.5	−1.8, 0.8	−0.2	−1.7, 1.2

Abbreviations: CI, confidence interval; IQR, interquartile range; RIA, radioimmunoassay.

^aTo convert ng/mL to nmol/L, multiply by 2.27.

^b25th–75th percentiles.