Vitamin K deficiency from dietary vitamin K restriction in humans.

Vitamin K is required for the maintenance of normal hemostatic function. Ten college-aged male subjects chose diets restricted in vitamin K content for 40 d. Median phylloquinone intakes based on analysis of food composites dropped from 82 micrograms/d during the prestudy period to 40 and 32 micrograms/d at d 9 and 27 of dietary restriction, respectively. Serum phylloquinone concentrations fell from a mean of 0.87 to 0.46 ng/mL during a 21-d period of vitamin K restriction. Supplementation with 50 micrograms phylloquinone/d for 12 d increased serum phylloquinone to 0.56 ng/mL, and supplementation with 500 micrograms phylloquinone/d increased serum phylloquinone to 1.66 ng/mL. Vitamin K restriction resulted in alterations in a functional clotting assay that detects undercarboxylated prothrombin species in plasma and in a decrease in urinary gamma-carboxyglutamic acid. Supplementation with either 50 or 500 micrograms of phylloquinone restored both these indices to near normal values. These data are consistent with a human dietary vitamin K requirement of approximately 1 microgram/kg body wt/d.

Vitamin K1 (phylloquinone) and vitamin K2 (menaquinone) status in newborns during the first week of life.

Since 1961 the Committee on Nutrition of the American Academy of Pediatrics has recommended that prophylactic vitamin K be administered parenterally to all newborn infants, although the exact requirement for vitamin K in the newborn infant is unknown. There is little information about the vitamin K1 (phylloquinone, present in green vegetables) and vitamin K2 (menaquinones, synthesized by intestinal flora) status of newborn infants. In this study during the first week of life vitamin K status was assessed by measuring serum concentrations of phylloquinone in 23 mother-infant pairs at the time of birth. Maternal phylloquinone concentration (1.7 +/- 1.0 ng/mL, mean +/- SD) was significantly higher (P less than .02) than cord serum concentration (1.1 +/- 0.6 ng/mL). All infants were then given a standard 1-mg injection of vitamin K1. Ten infants were fed formula (containing 58 ng/mL of vitamin K1) and 13 were exclusively breast-fed. On day 5 of life, serum concentrations of vitamin K1 did not differ between breast-fed (21.0 +/- 12.4 ng/mL) and formula-fed (27.5 +/- 9.7 ng/mL) infants, reflecting the large amounts of parenteral vitamin K1 at birth. During the first week of life, formula-fed infants had much higher fecal concentrations of vitamin K1 (due to large oral intake) and more significant quantities (greater than or equal to 200 pmol/g of dry weight) of fecal menaquinones (reflecting differences in bacterial flora) than did breast-fed infants.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of a vitamin K-deficient diet and antibiotics in normal human volunteers.

Decreased concentrations of vitamin K-dependent plasma clotting factors are a well-documented response of vitamin K-deprived patients administered broad-spectrum antibiotics. It has recently been claimed that antibiotics containing a N-methylthiotetrazole (NMTT) side chain cause this response through a direct effect of NMTT on the vitamin K-dependent posttranslational carboxylation of these clotting factors. To further study these relationships, 11 groups of three volunteers were fed a synthetic vitamin K-free diet for 2 weeks. During the last 10 days of vitamin K restriction, seven of the volunteer groups received a therapeutic dose of antibiotics not containing NMTT: ampicillin, sulfamethoxazole-trimethoprim (Bactrim), cefoxitin, cefotaxime, ceftazidime, clindamycin, and piperacillin, and three groups received NMTT-containing antibiotics: moxalactam, cefamandole, and cefoperazone. Serum phylloquinone (vitamin K1) concentrations reflected dietary intake and fell from 1.4 +/- 0.9 ng/ml after 3 days of hospital diet to 0.4 +/- 0.3 ng/ml after 13 days of vitamin K-free diet. Median stool excretion of phylloquinone was 19 micrograms/day while subjects consumed the hospital diet, and fell to 3 micrograms/day by day 6 on vitamin K-free diet. Prothrombin times remained within the normal range throughout the study. Suppression of vitamin K-dependent clotting factor biosynthesis was evident by decreased factor VII levels in seven of the volunteers and by an increased concentration of des-gamma-carboxy (abnormal) prothrombin in 21 of the volunteers. The changes occurred in the control subjects and in subjects receiving all nine of the 10 antibiotics with no consistent pattern.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum phylloquinone concentrations in a normal adult population.

The concentration of serum phylloquinone was assessed in a population of normal healthy Red Cross volunteer blood donors. The median value for 95 subjects was 1.1 ng/ml with a mean of 1.3 +/- 0.64 (SD) ng/ml. Sex, age, smoking habits, alcohol intake, and consumption of foods high in vitamin K were not found to influence serum phylloquinone concentrations.