Vitamin K
Together with vitamin K2, vitamin D ensures the normal absorption of calcium and phosphorus into the intestines and is responsible for incorporating them into bones. If a vitamin K2 deficiency exists, the calcium may be absorbed but not fully utilised by the body. The consumption of vitamin K together with vitamin D is important, especially when taking high doses of vitamin D.
Vitamin K2 exists in two different molecular forms, called trans- and cis-forms, which differ in terms of their structures. It is important to ensure that vitamin K2 is consumed in its all-trans form, as this is the only form that can be utilised by the body.
Magnesium
Magnesium is essential for the conversion of vitamin D3 into its transport form and its active hormone form. When a magnesium deficiency is present, the body's ability to carry out this conversion is limited. In order for vitamin D to be effective, a consistent magnesium supply is therefore also required.
Calcium
Vitamin D is responsible for the absorption of calcium in the intestines. Calcium can only be absorbed if it is consumed in sufficient quantities.
Vitamin A
Vitamin D and vitamin A regulate each other.
Zinc
Zinc is needed for the formation of vitamin D receptors.