Can I take vitamin D and vitamin K2 together?
Yes. The NIH says vitamin K supplements are frequently combined with vitamin D, calcium or magnesium, and several vitamin K studies gave vitamin D at the same time [1]. No source we checked says to separate them. Anyone on warfarin should talk to their doctor first, because vitamin K intake needs to stay consistent [1].
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What the sources say about vitamin D and vitamin K2
The NIH says vitamin K is sold alone or combined with a few other nutrients, frequently calcium, magnesium and/or vitamin D [1]. Vitamin K2 comes as menaquinones such as MK-4 and MK-7, and one study found MK-7 supplements are well absorbed and have a longer half-life [1]. Several vitamin K bone studies also gave vitamin D, and the NIH notes that giving vitamin D alongside vitamin K could partly explain why results differ between studies [1]. Vitamin D promotes calcium absorption in the gut [2]. No source we checked sets a ratio of K2 to D.
How to time them
No official source gives a timing rule for the pair. Both are fat-soluble: like dietary fats, vitamin K is absorbed in the small intestine with the help of bile and pancreatic enzymes [1], and fat in the gut improves vitamin D absorption, although some is absorbed without fat [2]. The adult upper limit for vitamin D is 100 mcg (4,000 IU) a day [2]. No upper limit was set for vitamin K because of its low potential for toxicity [1]. The NIH adequate intake for vitamin K is 120 mcg a day for men and 90 mcg for women [1].
Who should ask a doctor or pharmacist first
Ask your doctor or pharmacist first if you take warfarin (Coumadin) or a similar blood thinner: vitamin K can interact seriously with these, and sudden changes in vitamin K intake can raise or lower their effect [1]. Bile acid sequestrants and orlistat can reduce absorption of vitamin K, and orlistat can also reduce vitamin D absorption [1][2]. Vitamin D may interact with statins, steroids and thiazide diuretics; thiazides plus vitamin D might lead to high blood calcium, especially in older adults and people with reduced kidney function [2].
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Questions people ask next
The NIH says vitamin K supplements frequently also contain vitamin D [1]. It does not say vitamin D must be taken with K2, and no source we checked sets a ratio.
Ask your doctor first. Vitamin K can have a serious interaction with warfarin, and people taking it need a consistent vitamin K intake from food and supplements [1].
The NIH says few data compare the forms of vitamin K in supplements; one study found MK-7 well absorbed with a longer half-life [1].
Sources
- Vitamin K: Fact Sheet for Health Professionals — NIH Office of Dietary Supplements
- Vitamin D: Fact Sheet for Health Professionals — NIH Office of Dietary Supplements
Educational information, not medical advice, and not a recommendation for you. Check with your doctor or pharmacist before starting, combining or changing supplements, especially if you take medication, are pregnant or have a health condition. Supin sells a subscription, not supplements. Last reviewed .