How much vitamin D do we need?
This can depend on the individual. Factors such as chronic illness, skin colour and exposure to the sun can change a person’s risk of deficiency. The NHS recommends that adults in the UK consider taking a daily supplement with 10mcg (400IU) of vitamin D.
However, this may not be a sufficient dose for those who are already deficient in vitamin D. Research suggests that 25mcg, or 1000IU, would bring 50% of the population’s vitamin D levels into a beneficial range for wellbeing. 50mcg, or 2000IU, would help nearly everyone reach optimal vitamin D levels.
Why we suggest taking vitamin D with vitamin K2
You might have heard that it’s best to take vitamin D with vitamin K2. This comes back to how too much vitamin D taken without vitamin K could increase the risk of heart disease and other chronic conditions.
One of the roles of vitamin D is to maintain calcium levels in the blood. It enhances the absorption of calcium from food. If there isn’t enough calcium in the foods you eat, vitamin D will draw on the calcium from your bones.
Although vitamin D maintains the blood levels of calcium, it doesn’t control where extra calcium ends up in the body. That is the role of vitamin K. Vitamin K promotes the accumulation of calcium in your bones and teeth. It also prevents calcium from accumulating in tissues such as blood vessels and the kidneys.
Excess calcium in blood vessels is believed to play a role in chronic diseases such as heart and kidney disease.
What does this have to do with vitamin D? Excess vitamin D can cause hypercalcaemia – extremely high levels of calcium in the blood. This is known to lead to calcium in the blood vessels, or BVC. BVC is one of the main underlying causes of heart disease.
Low vitamin K is associated with BVC. Research has shown that vitamin K can prevent blood vessels from calcifying in animal studies. Although there are limited studies in humans, people who eat a high amount of K2 in the diet have a reduced risk of BVC and heart disease.
So to summarise – excess vitamin D may cause blood vessels to calcify, but vitamin K may help to prevent this from occurring.
If that wasn’t reason enough, combining vitamin D and K2 may be beneficial in itself. The two vitamins have synergistic effects, meaning that they work as a team to support healthy bones.