Did You Get Enough K Today?
January 10, 2000
If youre between the ages of
18 and 44, chances are you didnt get enough vitamin K today--or any other
day, according to a survey by the Agricultural Research Service and a private
Vitamin K, long known for its role in blood clotting, is gaining recognition
for its importance to the integrity of bones: It activates at least three
proteins involved in bone health.
Sarah Booth at the Jean Mayer USDA Human Nutrition Research Center on Aging at
Tufts University in Boston collaborated with Proctor & Gamble Company
researchers to estimate vitamin K intake from a nationwide sample of 4,741 men,
women and children.
People over age 65 consumed more phylloquinone--the most common form of
vitamin K--than 20- to 40-year-olds. Only half the females age 13 and
older--and less than half the males--got the Recommended Dietary Allowance,
based on food intake diaries the survey volunteers kept for 14 days. The RDA is
65 micrograms per day for adult females and 80 mcg/day for adult males.
Phylloquinone is found in some oils, especially soybean oil, and in
dark-green vegetables such as spinach and broccoli. One serving of spinach or
two servings of broccoli provide four to five times the RDA.
In another study, with Yale
University School of Medicine, Booth found that people absorb vitamin K
just as well from broccoli as they do from oil. Thats contrary to the
accepted notion that this fat-soluble vitamin is better absorbed from oil or
oil-based supplements than from vegetables, with their high water content.
The study also showed that elders can benefit just as much as younger people
from increasing vitamin K intake. The 60- to 80-year-old volunteers increased
their blood levels from a high-K diet as readily as the 20- to 40-year-olds.
Read more about vitamin K research in the January issue of Agricultural Research magazine.
Click here to
view it on the web.
ARS is USDAs chief scientific arm.
Scientific contact: Sarah L. Booth,
Jean Mayer USDA Human Nutrition Research Center on Aging at
Tufts University, Boston, Mass.,
phone (617) 556-3231, fax (617) 556-3149;