The suggested maximum limits for vitamin K in food supplements are below guidance level for upper intake level for adults and adolescents above 15 years.
The Norwegian Scientific Committee for Food and Environment has assessed dietary intake of vitamin K, tolerable upper intake levels and consequences of establishing maximum limits for vitamin K at 100, 200, 300, 600 or 800 µg per day.
No tolerable upper intake levels (ULs) have been established for any form of vitamin K (phylloquinone or menaquinones) due to insufficient evidence. Previous reports have, however, stated that no adverse effects associated with vitamin K consumption from food or supplements had been reported in humans or animals.
In 2003, the UK Expert Group on Vitamins and Minerals (EVM) proposed a guidance level (GL) for safe upper intake of supplemental phylloquinone of 1 mg/day in adults.
This GL was later supported by a double-blind randomised study cited in the Nordic Nutrition Recommendations in 2012.
Corresponding GLs for children and adolescents have been derived by adjusting for reference body weights.
For vitamin K1, VKM concludes that:
- In adults and adolescents 15-17 years old, maximum limits of 100, 200, 300, 600 and 800 µg/day are below GL.
- In adolescents 11-14 years old, maximum limits of 100, 200, 300 and 600 µg/day are below GL while the maximum limit of 800 µg exceeds GL.
- In children 4-10 years old, maximum limits of 100, 200 and 300 µg/day are below GL while maximum limits of 600 µg/day and 800 µg/day exceeds GL.
- In children 1-3 years old, maximum limits of 100 µg/day and 200 µg/day are below GL while maximum limits of 300, 600 and 800 µg/day exceeds GL.
There is insufficient evidence to make any conclusions for vitamin K2.
The current assessment is merely based on published reports concerning upper levels. VKM has not conducted any systematic review of the literature, as this was outside the scope of the terms of reference.