Is vitamin D only effective in combination with vitamin K?
11.12.2024
Translation: Jessica Johnson-Ferguson
Vitamin D deficiency is common in northern countries. Upping your intake with supplements can often be a good idea. But is it true that you need to take vitamin K for vitamin D to be effective? This is what experts say about the combination.
In countries that aren’t blessed with heaps of sunshine, such as Germany or Switzerland, many people are vitamin D deficient (link in German). This is because our body produces most of its vitamin D with the help of sunlight. Our bodies’ ability to produce vitamin D depends on several factors, including your geographic location, time of the year, time of day, cloud cover, smog, skin pigmentation and use of sunscreen. In certain cases, taking supplements after consulting with your doctor may be helpful (linked article in German).
What experts say about the combination of vitamin D and K?
It’s repeatedly been reported that vitamin D can only be absorbed via the intestine if vitamin K’s supplied at the same time. This claim has become more prevalent in recent years. But is this true, or just a widespread misconception?
Currently, there aren’t enough studies on the combined intake of vitamin D and K to make a clear statement. Neither the World Health Organisation (WHO) nor German or Swiss health authorities officially recommend combined supplementation of vitamin D and K.
Vitamin D can also be absorbed and utilised by the body without the addition of vitamin K. However, there’s evidence that both vitamins interact in certain metabolic processes, particularly in calcium metabolism and bone health.
Researchers are currently intensively investigating the role vitamin K plays in relation to vitamin D. Some studies suggest that vitamin K may support the effects of vitamin D, but further research is needed to confirm this hypothesis.
What vitamin K does for bone health
While vitamin D plays a central role in the absorption of calcium in the intestine and therefore contributes to bone health, the importance of vitamin K’s increasingly being researched. Vitamin K’s known for its role in activating proteins that are responsible for calcium binding in the bones. One such protein is osteocalcin, which requires vitamin K to function properly. This means a sufficient supply of vitamin K could help optimise calcium deposits in the bones and, at the same time, prevent calcium deposits in the arteries, which could reduce the risk of cardiovascular disease.
Some studies suggest that a combined intake of vitamin D and K may work together to improve bone health by increasing bone density and reducing the risk of fractures. However, these potentially positive interactions are still the subject of intensive research. Until clear scientific evidence is available, it’s still important to include vitamin K as part of a balanced diet, particularly by consuming leafy greens, which are rich in this vitamin.
Individual consultation crucial
If you suspect you have a vitamin D deficiency, you should have a blood test carried out by a doctor. In general, it’s important to consult with a healthcare professional before you start taking supplements, as individual needs can vary greatly.
Until clear scientific evidence is available, the combined intake of vitamin D and K remains a personal decision that’s best discussed with a doctor. A balanced diet with foods rich in vitamin D and K can help improve your vitamin supply overall.
Learn more about vitamins, minerals and the role they play in maintaining a healthy body here:
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Science editor and biologist. I love animals and am fascinated by plants, their abilities and everything you can do with them. That's why my favourite place is always outside - somewhere in nature, preferably in my wild garden.