Vitamin K is fat-soluble and regulates blood clotting and calcium metabolism (incorporating calcium into bone). Intestinal bacteria produce it as K2 in amounts that are almost 100% sufficient for the body’s needs [1].
What it contains: The intestinal microbiome, liver, egg yolks, uncleaned beef rumen and sea algae. In a varied diet it usually does not require additional supplementation.
Deficiency: Spontaneous bleeding from the nose and gums and subcutaneous hematomas. It can be caused by rodenticides, severe liver disease or sterilisation of the intestines with antibiotics [2].
Excess: Natural forms of vitamin K (K1 from plants and K2 from animal tissues and the microbiome) are safe. Although vitamin K is fat-soluble, overdosing from natural food does not occur in practice. The danger arises only with an extreme overdose of the synthetic form (vitamin K3), which can damage the liver and cause haemolytic anaemia [2].
Sources
- National Research Council (NRC) (2006). Nutrient Requirements of Dogs and Cats, chapter 5 - fat-soluble vitamins. https://nap.nationalacademies.org/catalog/10668/nutrient-requirements-of-dogs-and-cats
- Delaney SJ, Dzanis DA (2018). Safety of vitamin K, and its use in pet foods. JAVMA 252(5):537–542. https://doi.org/10.2460/javma.252.5.537