was ist vitamin k3 — what does this mean exactly?

Vitamin K3 (menadione) is a synthetic form of vitamin K not found naturally in foods. It was once used in supplements and animal feed but is banned for human oral use in many countries (e.g., EU, USA) because it can cause oxidative stress, hemolytic anemia, and liver damage. While menadione is partially converted to vitamin K2 in the body, its toxicity outweighs any potential benefit. MyBody-X does not test for vitamin K3, as it is not a relevant nutrient for human health. Evidence is based on mechanistic studies and case reports; there are no proven benefits for supplementation. If you want to assess your vitamin K status, focus on natural forms K1 (phylloquinone) and K2 (menaquinone), which can be measured in blood or stool tests. Be cautious of products containing menadione – they are potentially harmful.