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News Article

Vitamin K - not just in your greens

Researchers find significant vitamin K levels in dairy products

A study this week led by researchers at Tufts University shows that milk products could be a good source of vitamin K. The study measures menaquinones, one form of the vitamin, in milk, cheeses and yogurts and found that the highest amounts of the vitamin in full fat dairy products and in fermented ones. The study will help develop better dietary guidelines for vitamin K and guide producers enriching foods with vitamin K.

Vitamin K aids blood clotting and bone formation and its deficiency in babies can be fatal. Vitamin K exists in several forms in our food. Phylloquinone is the most widespread form and the US dietary guidelines for vitamin K of 90 and 120 μg/day for women and men, are based only on intakes of phylloquinone, according to the authors of this paper. Animal products contain vitamin K in a variety of forms, collectively called menaquinones, as well as phylloquinone. Bacteria synthesise menaquinones during fermentation and milk production. There is some research interest around harnessing these natural fermentations to make functional foods high in vitamin K

The researchers led by Xueyan Fu of the Vitamin K laboratory decided to study vitamin K in US dairy foods after seeing work from dairy producing countries in Europe that suggested these foods could be a good source. One study suggested menaquinones in dairy foods could provide 10-25% of vitamin K requirements. They also decided to examine the effect of fat content on vitamin K content. Previous work by the team includes characterising vitamin K composition of meat products, and oils.

They found most vitamin K in products containing most fat. For example in milk they found nearly 8 times as much in full fat as in fat free milk (38.1±2.7 vs. 7.7 ±2.9 μg/100 g). Cheese was a much better source of vitamin K than milk with soft cheese having the highest concentration, followed by blue cheese, semi-soft cheese and hard cheese (506±63, 440±41, 289±38 and 282±5.0 μg/100 g, respectively). Non-fermented cheeses had much lower levels around 100 μg/100 g.

The study authors say the next step in research is to see if the vitamin K in dairy products is in a form that can be used by the body, i.e. how bioavailable it is.

Fu, X., Harshman, S. G., Shen, X., Haytowitz, D. B., Karl, J. P., Wolfe, B. E., & Booth S. L. (June 2017). Multiple vitamin K forms exist in dairy foods. Current Developments in Nutrition. (Open access paper).

Article details

  • Author(s)
  • I.Hoskins
  • Date
  • 05 June 2017
  • Source
  • Current Developments in Nutrition
  • Subject(s)
  • Food science