Vitamin K

Vitamin K is a coenzyme for a microsomal enzyme involved in the process and regulation of blood clotting, tissue mineralization, and cell proliferation.

Deficiencies: Infants are at risk for cerebral hemorrhage during the first three to four months after birth if they do not get enough vitamin K. The reason for vitamin K deficiency in these children is usually impaired fat absorption in conjunction with a low vitamin intake from breastfeeding. Bleeding due to the lack of vitamin K is very rare in older children and adults, presumably because vitamin K is produced by intestinal bacteria and a small fraction is absorbed from ileum and colon. Oral antibiotic treatment, in conjunction with low vitamin K intake, can induce bleeding. Less than a few days' intake of vitamin K is stored, most of it in liver and bone; in the absence of dietary or intestinal vitamin K sources, symptoms appear rapidly.

Suboptimal vitamin K status, which is far more common than outright deficiency, may contribute to the progression of osteoporosis and atherosclerosis.

Food Sources: Cooked dark green vegetables such as spinach, kale, and broccoli can provide more than one RDA in a single serving. The bioavailability of vitamin K from different food sources and the effect of food processing is insufficiently known. A small amount of fat is needed for absorption. Natto and similar fermented Asian soy foods also are excellent vitamin K sources. Kiwi, cabbage, liver, soybean, canola and olive oils, including margarine and mayonnaise made from these oils, contain 20-50% of current RDAs per serving.

2000-Calorie Diet Recommendations

Shown below are the reference numbers used to compute the Daily Value percentages that appear on the Nutrition Facts labels on foods sold in the U.S. These numbers are meant to approximate the nutrients needed for the average person consuming 2000 calories per day.

Click any of the vitamin or nutrient names below to learn more about the importance of each element, and to see detailed dietary allowances for specific population groups.

***Daily Value recommendations are based on a 2000-calorie diet. Recommendations for individuals will vary depending on gender, age, weight, and other factors.