Vitamin K is an essential nutrient that plays a role in your blood’s clotting ability, helps strengthen your bones, and improves your cardiovascular health by preventing arteries from stiffening and calcifying.
While it’s found in green leafy vegetables, it can be hard for many people to get enough of them in their diet to keep their vitamin K levels high.
This is where a vitamin K supplement can be useful. If you want to take advantage of the bone strengthening and heart-health benefits, our research team has come up with the ten most effective vitamin K supplements on the market.
1. Zhou Nutrition K2 + D3
Zhou Nutrition exploits the synergy between vitamin D3 and vitamin K2 for optimal bone and heart health.
This supplement delivers 5000 IUs of vitamin D3, which should be enough even for people with darker skin who live in northern climates, as well as 90 mcg of vitamin K2.
For ensuring adequate vitamin K intake, it’s an excellent choice, thanks to its ultra-pure formulation: other than rice flour and cellulose to make up the capsule, there are zero additional ingredients.
2. Life Extension Super K with Advanced K2 Complex
Life Extension includes three different forms of vitamin K in varying amounts, but the overall dosage is 2600 mcg—a very high dosage, which is even more effective thanks to the multiple forms of vitamin K present.
The vitamin K is also dissolved in olive oil, which will also aid bioavailability: vitamin K, unlike many other vitamins, is only soluble in fat, not water. If you are looking for a high-dose vitamin K supplement, this should be your top choice.
3. Peak Performance Advanced D+K
Peak Performance Advanced D+K uses a combination of 2000 IUs of vitamin D, plus three different forms of vitamin K, both K1 and two forms of K2. This comes alongside the black pepper extract BioPerine, which helps boost absorption, and it’s delivered in a clean and simple cellulose capsule. At 225 mcg per capsule, the dosage is just right for a lot of people.
4. Garden of Life Vitamin Code Raw K-Complex
Garden of Life specializes in making supplements that include vitamins and minerals alongside the other phytonutrients present in the plants they come from.
Given that the foods richest in vitamin K are green leafy vegetables, Garden of Life delivers when it comes to supplying vitamin K along with the other nutrients you’d find in a natural source.
In addition to 120 mcg of vitamin K dissolved in cold-pressed flax oil, you’ll also get extracts from spinach, brussel sprouts, kale, and a whole host of other fruits and vegetables. If you want a vitamin K supplement that takes a more holistic approach, this should be your choice.
5. Solaray Vitamin K
Solaray makes a pretty basic vitamin K supplement. It delivers 100 mcg per capsule, and these capsules are vegetarian friendly.
The presence of a few binders and fillers isn’t to the liking of supplement purists, but that aside, it’s a decent choice.
6. Bronson Vitamin K Triple Play
Bronson Vitamin K Triple Play is another take on the triple-sourced vitamin K combination. This isn’t the highest dose version on the market, but you’ll still get 550 mcg of vitamin K all together.
The capsules are gelatin-based, which won’t please strict vegetarians and vegans, but the bigger issue is the presence of fillers and additives that you won’t find in some other competitors. It’s not a dealbreaker; the vitamin K content is still good enough to make up for it.
7. NOW MK-7 Vitamin K-2
NOW MK-7 Vitamin K-2 is fairly middle of the road as far as ingredients and dosage. At 100 mcg of vitamin K2 per capsule, it’s adequate but not stellar.
The ingredients are reasonably simple, though the cellulose-based capsules could probably do without silica. While NOW MK-7 Vitamin K-2 doesn’t stand out in any particular way, it’s still a reasonable choice for a lower-dose vitamin K2 supplement.
8. Jarrow Formulas MK-7
Jarrow Formulas takes a bit of a different tack with their MK-7 supplement. It uses vitamin K2 derived from natto, a fermented form of soybeans, which is a more bioactive source of vitamin K.
The dosage itself is not particularly high, at 90 mcg per capsule. While it’s good to see the supplement dissolved in oil, the low dose makes it hard to rank higher. Still, Jarrow Formulas MK-7 isn’t a bad choice, but isn’t the best either.
9. Doctor’s Best Natural Vitamin K2
Doctor’s Best Natural Vitamin K2 uses a proprietary form of vitamin K2 called MenaQ7, but the overall dosage is still on the low end at 100 mcg per capsule.
These capsules also don’t dissolve the vitamin K2 in any high-quality oil, so the bioavailability of the vitamin K2 might suffer. With a few more additives than a purist would like, Doctor’s Best Natural Vitamin K2 finds itself further down in the rankings.
10. 365 Everyday Value Vitamin K
365 Everyday Value Vitamin K is a pretty basic vitamin K supplement. The dosage, 125 mcg, is not very high, and moreover, the capsule contains the vitamin in powder form, not dissolved in a fat.
The rest of the ingredients are somewhat bloated with additives, so most people will be better served with a different vitamin K supplement.
Vitamin K benefits and side effects
Vitamin K is a compound found naturally in green leafy vegetables that can be taken as a supplement to improve heart health and bone strength, particularly when combined with vitamin D3.
It’s a vitamin whose uses are fairly narrow, but have been studied in-depth, and the mechanism of its effects are fairly well-understood.
We’ll take a look at the science behind how vitamin V leads to better bone strength and improved cardiovascular health.
The MK-7 form of vitamin K2 is more effective than the K1 form. In the early days of vitamin K supplements, most products used the synthetic “K1” form of the vitamin.
As nutritionists started to understand the natural biochemistry of vitamin K better, they were able to derive the MK-7 form, usually directly from plant sources like soybeans.
A 2005 scientific article in Blood, a scientific journal run by the American Society of Hematology, investigated the efficacy of both the K1 and MK-7 forms of vitamin K (1).
In the study, healthy volunteers took similar doses of either a K1 or an MK-7 vitamin K supplement. The researchers then observed how much vitamin K was absorbed, and how long blood levels of vitamin K stayed elevated.
Both supplements were absorbed equally well, but the MK-7 form of vitamin K led to blood levels that stayed elevated for much longer.
This suggests that if you are aiming to keep your body’s reserves of vitamin K high, a supplement that incorporates the MK-7 form will be better than one that is purely K1-based.
Still, some manufacturers believe there are advantages to the K1 form, which is why you’ll see many combination K1/MK-7 supplements on the market. The efficacy of K1, though, remains unproven compared to the MK-7 form.
Vitamin K can improve the health of your arteries. One of the major causes of cardiovascular disease is the stiffening and calcification (literally, the formation of calcium deposits) of the major arteries of your body.
As these arteries become harder and less elastic, your blood pressure increases, and arterial stiffness often goes hand in hand with thickening of the artery walls. All of these can lead to heart disease.
Vitamin K, however, appears to be a very effective way to reduce arterial thickness, according to a clinical trial published by researchers in the Netherlands in the journal Thrombosis and Haemostasis (2).
In the study, the authors randomly assigned 244 older women to either a placebo supplement or an MK-7 vitamin K supplement (180 mcg per day). Unlike many supplement trials, the follow-up period in this study was quite long, at three full years.
The researchers used advanced imaging techniques to objectively measure the stiffness of the aorta, the biggest artery coming out of the heart.
After the study’s data had been analyzed, the researchers found that the arteries of the women on the vitamin K supplement had significantly improved compared to the women in the placebo group, along with biomarkers indicative of better arterial health.
Vitamin K could improve your bone strength. Vitamin K plays a number of roles in biochemical processes linked to bone synthesis, so researchers naturally wondered whether vitamin K intake was linked to bone strength.
A 2008 study in the Journal of Clinical Endocrinology & Metabolism set out to determine whether vitamin K played a role in bone strength (3). In the study, researchers at Tufts University reviewed the dietary intake of vitamin K among people enrolled in a large cohort study.
They attempted to find any evidence for a connection between vitamin K intake and either bone density or hip fracture, which is associated with poor bone strength.
The researchers found that the vitamin K supplement did not result in a significant increase in bone density, but it did result in fewer hip fractures. This is in line with other findings that indicate that vitamin K does not necessarily increase bone density by itself (4).
However, bone density is not the whole story when it comes to bone strength: bones of the same density can have micro-architecture that is organized in a better or worse fashion for strength, so vitamin K may have more to do with how bone tissue is organized versus its bulk density.
Vitamin K works in conjunction with vitamin D to improve bone health. While the synergistic effects of vitamin D and calcium for improving bone strength are well-known, the influence of vitamin K in this process has been less-publicized.
A study published by researchers at CHA University in Korea in 2011 examined the specific effects of vitamin D and vitamin K in combination in a calcium supplement to improve bone density in older women (5).
Over the course of three months, the researchers demonstrated that the calcium plus vitamin D3 plus vitamin K supplement outperformed the calcium-only supplement in terms of increasing bone mass density in the lower back of the women in the study.
If you are specifically using vitamin K for bone health, you should definitely be taking it in conjunction with both calcium and a high dose of vitamin D.
Vitamin K is a fat soluble vitamin, which typically means that there is a higher risk of toxicity from extremely high doses, since your body can’t eliminate it as easily as a water soluble vitamin like vitamin C.
However, in the case of vitamin K, no risks have been established in healthy people even at very high vitamin K intake levels, according to the National Institutes for Health’s Office of Dietary Supplements (6).
However, vitamin K does interact with a few medications, most notably warfarin and other blood thinners. Because vitamin K plays an important role in the blood clotting process, it can interfere with the activity of drugs that are supposed to thin your blood.
As such, anyone on blood thinners should talk to their doctor before taking a vitamin K supplement.
The minimum recommended intake of vitamin K for optimum health is 120 mcg per day for men and 90 mcg per day for women (7).
This is in line with what you’ll find in lower dose vitamin K supplements, but many clinical trials use doses closer to 200 mcg per day. A few have gone higher, to 500 mcg per day, with some success.
For ensuring continued heart health and bone strength, 90 to 125 mcg should be adequate, but if you are looking to correct a deficiency or actively increase bone strength or improve your heart health from where it already is, a higher dose might be necessary. The heart health study performed in the Netherlands, for example, used 180 mcg per day.
Vitamin K plays an important role in maintaining strong and healthy bones, especially when combined with vitamin D. It’s also effective for decreasing stiffness in your arteries and improving your cardiovascular health.
The most effective form of vitamin K appears to be the MK-7 form, because this naturally-derived variant keeps your blood levels of vitamin K elevated for longer.
The optimal dosage of vitamin K to get these benefits is between 90 and 200 mcg per day for most people, though no known risks have been associated with higher doses.
The only side effects to be aware of are the potential interactions with medications for blood thinning, like warfarin.
Though its applications are fairly narrow, vitamin K is a safe, effective, and easy way to improve both bone and heart health.