A single measurement of serum phylloquinone is an adequate indicator of long-term phylloquinone exposure in healthy older adults.
Assessment of long-term phylloquinone exposure is challenging in studies investigating vitamin K in health. Data are equivocal as to whether a single measurement of circulating phylloquinone would be adequate. The primary purpose of the present study was to validate the use of a single measurement of serum phylloquinone as a surrogate for long-term phylloquinone exposure in healthy older adults. Using data from the Québec Longitudinal Study on Nutrition and Successful Aging, the objectives were to: 1) determine the reproducibility of circulating phylloquinone over 2 y (n = 234); 2) calculate how a single measurement would rank or classify individuals and attenuate the regression coefficient between circulating phylloquinone and a health outcome; and 3) investigate the association of a single measurement of serum phylloquinone with long-term phylloquinone intakes assessed over the year prior to the blood draw (n = 228). The variance analysis based on 2 blood samples showed a fair to good reproducibility for serum phylloquinone (intra-class correlation = 0.49). The correlation coefficient between the ranking of individuals based on a single measurement of circulating phylloquinone and the "true" ranking would be 0.70. The multiple regression analysis showed that long-term phylloquinone intake was the strongest predictor of serum phylloquinone (t = 4.94; P < 0.001). The partial correlation coefficient (r = 0.32) was comparable with those reported in studies where blood sampling and diet recording were juxtaposed and/or multiple blood samples were used. The present study provides evidence that the use of a single measurement of circulating phylloquinone is adequate for assessing long-term phylloquinone exposure in healthy older adults.
Centre de recherche, Institut Universitaire de Gériatrie de Montréal, Montréal, QC, Canada.
Nancy
N
Presse
Pierrette
P
Gaudreau
Carol E
CE
Greenwood
Marie-Jeanne
MJ
Kergoat
Jose A
JA
Morais
Hélène
H
Payette
Bryna
B
Shatenstein
Guylaine
G
Ferland
D000368:Aged; D000369:Aged, 80 and over; D004032:Diet; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D015596:Nutrition Assessment; D011446:Prospective Studies; D011792:Quebec; D012044:Regression Analysis; D015203:Reproducibility of Results; D013997:Time Factors; D014812:Vitamin K / Q000097:blood; D010837:Vitamin K 1 / Q000097:blood*
D014812:Vitamin K; D010837:Vitamin K 1