Riboflavin, flavin mononucleotide, and flavin adenine dinucleotide in human plasma and erythrocytes at baseline and after low-dose riboflavin supplementation.
BACKGROUND
Vitamin B(2) exists in blood as riboflavin and its cofactors, flavin mononucleotide (FMN) and FAD. The erythrocyte glutathione reductase activation coefficient (EGRAC) has traditionally been used to assess vitamin B(2) status in humans. We investigated the relationships of EGRAC and plasma and erythrocyte concentrations of riboflavin, FMN, and FAD in elderly volunteers and their responses to riboflavin administration.


METHODS
EGRAC and plasma and erythrocyte concentrations of riboflavin, FMN, and FAD were determined in 124 healthy individuals with a mean age of 69 years. The same measurements were made in a subgroup of 46 individuals with EGRAC > or =1.20 who participated in a randomized double-blind 12-week intervention study and received riboflavin (1.6 mg/day; n = 23) or placebo (n = 23).


RESULTS
Median plasma concentrations were 10.5 nmol/L for riboflavin, 6.6 nmol/L for FMN, and 74 nmol/L for FAD. In erythrocytes, there were only trace amounts of riboflavin, whereas median FMN and FAD concentrations were 44 and 469 nmol/L, respectively. Erythrocyte FMN and FAD correlated with each other and with EGRAC and plasma riboflavin (P <0.05). All variables except plasma FAD responded significantly to riboflavin supplementation compared with placebo (P < or =0.04). The strongest increases were for riboflavin in plasma (83%) and for FMN in erythrocytes (87%).


CONCLUSIONS
Concentrations of all B(2) vitamers except plasma FAD are potential indicators of vitamin B(2) status, and plasma riboflavin and erythrocyte FMN may be useful for the assessment of vitamin B(2) status in population studies.
Hustad
Steinar
S
LOCUS for Homocysteine and Related Vitamins, University of Bergen, Armauer Hansens Hus, N-5021 Bergen, Norway. steinar.hustad@farm.uib.no
McKinley
Michelle C
MC
McNulty
Helene
H
Schneede
Jørn
J
Strain
J J
JJ
Scott
John M
JM
Ueland
Per Magne
PM
D000368:Aged; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004912:Erythrocytes / Q000737:chemistry*; D005260:Female; D005486:Flavin Mononucleotide / Q000097:blood*; D005182:Flavin-Adenine Dinucleotide / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012256:Riboflavin / Q000008:administration & dosage* / Q000097:blood*
D005182:Flavin-Adenine Dinucleotide; D005486:Flavin Mononucleotide; D012256:Riboflavin