- Although allergic reactions are possible, no toxicity has been associated with high doses (from diet or supplements) of the phylloquinone (vitamin K1) or menaquinone (vitamin K2) forms of vitamin K.
- The same cannot be said for vitamin K3 or synthetic menadione, which can interfere with the function of glutathione, one of the body’s main natural antioxidants, causing oxidative damage to cell membranes.
- Menadione administered by injection has caused liver toxicity, jaundice, and haemolytic anaemia (due to the breakdown of red blood cells) in infants; therefore, menadione is no longer used to treat vitamin K deficiency.
- As a result, no tolerable upper intake level (UL) has been established for vitamin K.
Vitamin K is an essential fat-soluble vitamin that plays a vital role in the production of blood clotting proteins. It also has an important role in bone health.
How Can I Tell if I Have a High Level of Vitamin K?
It has been shown that even consuming large amounts of vitamin K in the form of K1 (phylloquinone), which is obtained through diet, does not lead to toxicity.
Vitamin K2 also shows no adverse effects when taken orally. Studies have shown that blood coagulation tests in humans did not show an increased risk of blood clots when 45 mg per day of vitamin K2 (as MK-4) was consumed. Researchers observed this in a patient who took more than 135 mg per day (45 mg three times a day).
As mentioned, it is very unusual to experience vitamin K toxicity. However, normal blood levels are determined by:
| Age | Values (μg/day) |
| Infants (7-11 months) | 10 |
| 1-3 years | 12 |
| 4-6 years | 20 |
| 7-10 years | 30 |
| 11-14 years | 45 |
| 15-17 years | 65 |
| Adults (including pregnant and lactating women) | 70 |
Diseases Related to Excess Vitamin K
The only reported toxicity comes from menadione, which has no utility in humans. Its toxicity is believed to be associated with its water-soluble properties. When toxicity occurs, it presents with signs of jaundice, hyperbilirubinemia, haemolytic anaemia, and kernicterus in infants.
How to Regulate Your Vitamin K Levels
To regulate vitamin K levels, given that there is no upper toxic level, it is important to address any nutritional deficiency determined by a blood test. A medical professional can then recommend the appropriate treatment for such cases.
References
- https://www.ncbi.nlm.nih.gov/books/NBK551578/
- https://lpi.oregonstate.edu/mic/vitamins/vitamin-K
Symptoms of Excess in Other Vitamins:
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