Objective: To estimate dietary intakes of phylloquinone and dihydrophylloquinone in a representative sample of the American population using 14-day food diaries.
Design: Vitamin K food composition data were applied to 14-day food diaries completed by a nationally representative sample of approximately 2,000 households that participated in a Market Research Corporation of America menu census survey between July 1991 and June 1992. Dietary intakes were estimated for phylloquinone and dihydrophylloquinone.
Subjects: Subjects were 4,741 men, women and children with demographic characteristics similar to those of the US census population.
Statistical analysis performed: Descriptive statistics and 2-sample t tests.
Results: Mean reported intakes of phylloquinone among adults increased with age. Men and women in the 18- to 44-year-old groups reported mean phylloquinone intakes below the current Recommended Dietary Allowance for vitamin K. Of all study participants, 99.3% reported consumption of dihydrophylloquinone during the 14 days of diet recording; reported intakes peaked before the age of 6 years; after the age of 6 years intakes were constant.
Applications: The Market Research Corporation of America data provide a reference range for dietary intakes of 2 forms of vitamin K in the US diet: phylloquinone and dihydrophylloquinone. Given the putative role of vitamin K in bone mineralization, low intakes of phylloquinone reported among young adults highlight the need to educate the US population about the requirement for and sources of vitamin K. The abundance of dihydrophylloquinone in the US diet suggests the need for study of its biological activity relative to phylloquinone.