Should You Take Vitamin K and Fish Oil?

A lesser-known micronutrient, vitamin K hasn’t received the same mainstream attention as other vitamins in the nutrition and supplements world. However, it serves several crucial roles in the body.

On the flip side, fish oil is extremely sought after and more commonly understood. More people are beginning to consider whether these two nutrients can complement one another when taken together.

Brief History and Primary Roles of Vitamin K

Since the importance and roles of vitamin K are not common knowledge, let’s learn a little about its history and uses.

The term “K” from vitamin K came about due to its part of the coagulation pathway, as it is a key vitamin for blood clotting.* Western A. Price discovered vitamin K in the late 1920s, a well-known dentist who traveled the world studying indigenous cultures and their dental health related to their diets.

The two primary forms of vitamin K are phylloquinone (K1), which is mainly found in plant foods like spinach, kale, Brussels sprouts, and other leafy greens. The second storage form is K2, which comes from animal sources and fermented foods, especially whole-fat dairy, liver, raw sauerkraut, miso, and eggs. Vitamin K deficiency is uncommon for people who eat these foods regularly.

Along with vitamins A, E, and D, vitamin K is a fat-soluble vitamin. Those who tend to be more at risk of deficiency include those with malabsorption challenges from cystic fibrosis, celiac disease, or ulcerative colitis. Vitamin K is best known for its significant role in the blood’s ability to clot effectively, working hand in hand with calcium for this purpose.* Studies show that one of vitamin K’s primary roles is to allow for the binding of calcium by modifying proteins –calcium cannot function properly without vitamin K.*[1]

Discussions also exist around vitamin K’s potential support for heart issues, a healthy inflammatory response, and immune strength, although more research is needed.*

Primary Roles of Fish Oil

Omega-3 fatty acids are likely the second biggest nutritional challenge behind vitamin D in the United States. They are known as “essential fatty acids,” as the body cannot produce these polyunsaturated fats and are and are commonly taken in supplement form as fish oil. The word “polyunsaturated” refers to its specific chemical structure, as “poly” means many, and “unsaturated” refers to places where hydrogen atoms are not attached to the compound, allowing for double-bonds between carbon atoms.

The most common forms of omega-3 fatty acids include docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and alpha-linolenic acid (ALA). All omega-3s form critical components of the body’s cell membranes and contribute to the maintenance of healthy cholesterol levels, balanced triglycerides, mood and weight support, normal inflammation response, support heart health, and overall cognitive wellness.*[2][3][4]

Food sources include sardines, anchovies, mackerel, chia and flax seeds, and walnuts. Getting enough omega-3 fats from plant sources alone can be difficult, as most people have an inefficient conversion of tALA to DHA and EPA fatty acid. Some women are extraordinarily inefficient due to genetic factors that make the body unable to handle these conversions.

RELATED CONTENT: What Are the Benefits of Adding Vitamins A, D, and K Together? 

Supplementation of Vitamin K and Fish Oil

Taking vitamin K as a regular vitamin in relatively low doses – for example, as part of a multivitamin– is suitable for most people and is well-tolerated. However, mega-dosing with vitamin K should only be done under the supervision of your doctor or qualified healthcare provider, as this fat-soluble nutrient is stored in the body and can have adverse effects on those predisposed to clotting events and hypercoagulation.

Omega-3 fatty acids from fish oil and other supplements are popular and are sometimes used to help with the issues described above. They offer support to those already taking vitamin K. One reason for this is that taking vitamin K with fats (like fish oil or cod liver oil) increases its bioavailability and absorption, and taking these two together could promote healthy coagulation.* Omega-3 fatty acids promote platelet inhibition, meaning they have mechanisms that work to thin the blood.*

Therefore, if you take vitamin K, fish oil could increase the vitamin’s absorbability and balance out fish oil’s platelet inhibition.* Conversely, for those who have thinner blood or bruise easily, omega-3 supplements may exacerbate their situation but vitamin K can be used to create a better balance.*

Vitamin K deficiency is not typical. However, those with absorption challenges and problems digesting fats and fat-soluble vitamins may benefit from working with their integrative doctor on an appropriate vitamin K supplementation dosage. On the other hand, omega three fatty acid insufficiency is quite common, and supplementation is often very beneficial for a better mood, heart and inflammation support, and more.*

If you’re already supplementing vitamin K, adding in fish oil could help with absorption and healthy blood coagulation.* If you have no real reason to supplement with vitamin K on its own (as opposed to taking it as part of a multivitamin), it’s likely best to take a high-quality omega-3 product.

See why vitamins A, D, and K work so well when taken together, download our whitepaper now!

[1] Spronk HM, Soute BA, Schurgers LJ, Thijssen HH, De Mey JG, Vermeer C. Tissue-specific utilization of menaquinone-4 results in the prevention of arterial calcification in warfarin-treated rats. J Vasc Res. 2003;40(6):531-537. doi:10.1159/000075344

[2] Leaf A. Historical overview of n-3 fatty acids and coronary heart disease. Am J Clin Nutr. 2008;87(6):1978S-80S. doi:10.1093/ajcn/87.6.1978S

[3] Grosso, G., Galvano, F., Marventano, S., Malaguarnera, M., Bucolo, C., Drago, F., & Caraci, F. (2014). Omega-3 fatty acids and depression: scientific evidence and biological mechanisms. Oxidative medicine and cellular longevity, 2014, 313570. https://doi.org/10.1155/2014/313570

[4] Calder PC. n-3 polyunsaturated fatty acids, inflammation, and inflammatory diseases. Am J Clin Nutr. 2006;83(6 Suppl):1505S-1519S. doi:10.1093/ajcn/83.6.1505S