Table 1

Micronutrient assay methods.

Analyte	Method	Ref.
RBC folate (nmol/L)	Quantaphase Folate Radioassay Kit, Bio-Rad Laboratories	7
Retinol (μg/dL)	Isocratic reversed-phase HPLC with UV/Vis detection	8
Ascorbic acid (mg/dL)	Isocratic reversed-phase HPLC with Electrochemical detection*	7
Alpha tocopherol (mg/dL)	Isocratic reversed-phase HPLC with UV/Vis detection	8
Alpha carotene (μg/dL)	Isocratic reversed-phase HPLC with UV/Vis detection	8
Beta carotene (μg/dL)	Isocratic reversed-phase HPLC with UV/Vis detection	8
Ferritin (μg/L)	Quantlmune Ferritin IRMA kit, Bio-Rad Laboratories	7
25-hydroxyvitamin D (nmol/L)	Quantlmune Ferritin IRMA kit, Bio-Rad Laboratories	7
Homocysteine (μmol/L)	Isocratic reversed-phase HPLC with Fluorescence detection	9
C-reactive protein (mg/L)	Latex-enhanced nephelometry, Behring Nephelometer Analyzer for NHANES assays and Hitachi 917 Analyzer for Multiple Supp user assays	7
Total cholesterol (mg/dL)	Timed endpoint, coupled enzymatic methodology	10
LDL-cholesterol (mg/dL)	Calculated**	7
HDL-cholesterol (mg/dL)	Polyanion/divalent cation precipitation of other lipoproteins followed by timed endpoint, coupled enzymatic methodology	10
Triglycerides (mg/dL)	Timed endpoint, coupled enzymatic methodology	11

*Use of 1 part serum plus 1 part 10% meta-phosphoric acid for Multiple Supp users versus NHANES use of 1 part serum plus 4 part meta-phosphoric acid.

** Calculated: LDL-cholesterol = [total cholesterol - HDL-cholesterol - (triglycerides/5)] Ref = reference, LDL = low-density lipoprotein, HDL = high-density lipoprotein.