Vitamin D3, K2 and Omega-3: Can You Take Them Together?

Yes, most people can take vitamin D3, vitamin K2 and omega-3 together, and the easiest way is with the same meal. Vitamins D and K are fat-soluble and omega-3s are fats themselves, so all three are absorbed alongside dietary fat. They do different jobs: vitamin D helps you absorb calcium, vitamin K2 activates proteins for normal blood clotting and bone, and omega-3s are part of every cell membrane.

Key Takeaways

• Vitamins D and K are fat-soluble, and vitamin D absorption depends on the gut's ability to absorb dietary fat (NIH ODS).
• In 50 healthy older adults, vitamin D3 taken with a meal containing fat reached a peak blood level 32 percent higher than with a fat-free meal (Dawson-Hughes et al., 2015).
• The VITAL trial gave 25,871 adults vitamin D3 (2,000 IU a day), omega-3 (1 g a day), both or placebo for a median of 5.3 years (Manson et al., 2019).
• Vitamin D3 with K2 and fish oil are not substitutes for each other: they supply different nutrients with different roles.
• If you take warfarin or another blood thinner, check with your clinician first: vitamin K intake should stay steady, and high doses of omega-3s may affect bleeding (NIH ODS).

What Vitamin D3, K2 and Omega-3 Each Do

	Vitamin D3	Vitamin K2	Omega-3
Type	Fat-soluble vitamin	Fat-soluble vitamin	Fatty acids (ALA, EPA, DHA)
Main role	Calcium absorption, bone, muscle, nerve and immune function	Activates proteins for normal blood clotting and bone	Part of every cell membrane; DHA is concentrated in the eyes and brain
Adult daily target	600 IU (15 mcg), 800 IU (20 mcg) over 70	120 mcg men, 90 mcg women (all vitamin K)	ALA: 1.6 g men, 1.1 g women; no set amount for EPA and DHA
Food sources	Made in skin from sunlight; salmon, tuna, mackerel, fortified foods	Natto, cheese; modest amounts in meat, dairy and eggs	Salmon, mackerel, herring, sardines; flaxseed, chia, walnuts

The figures come from the NIH fact sheets on vitamin D, vitamin K and omega-3s. The upper limit for vitamin D from all sources is 4,000 IU (100 mcg) a day for adults, while vitamin K has no upper limit because of its low potential for toxicity. For how D3 and K2 work as a pair, see our guide to vitamin D3 and K2.

Can You Take Vitamin D3, K2 and Omega-3 Together?

Yes. All three are nutrients your body uses every day, and taking them at the same time suits how they are absorbed. The best known study of this pairing is VITAL, a nationwide trial in the United States. It enrolled 25,871 men aged 50 and older and women aged 55 and older and used a two-by-two design: people took vitamin D3 at 2,000 IU a day, omega-3s at 1 g a day (460 mg of EPA and 380 mg of DHA), both together, or placebo, for a median of 5.3 years (Manson et al., 2019; NIH ODS).

VITAL was built to study long-term health outcomes rather than daily wellbeing, and it is a useful reference for safety: the researchers reported no excess risk of high blood calcium or other adverse events with vitamin D3 at that dose (Manson et al., 2019). VITAL did not include vitamin K2. K2 is usually paired with D3 because vitamin D raises calcium absorption and vitamin K activates bone proteins such as osteocalcin, which our D3 and K2 guide explains.

Why Fat Matters: Take Them With a Meal

Because these nutrients travel with dietary fat, a meal that contains some fat is the simplest way to take all three.

• Vitamin D3: 50 healthy older adults took a single 50,000 IU dose of vitamin D3 with breakfast. With a meal containing fat, the peak blood level 12 hours later was 32 percent higher than with a fat-free meal, and the type of fat did not matter (Dawson-Hughes et al., 2015).
• Vitamin K: eating some fat at the same time improves absorption of vitamin K from vegetables (NIH ODS).
• Omega-3: in a small study of male volunteers, taking fish oil with a meal containing 44 g of fat rather than 8 g raised EPA absorption from the triglyceride form from 69 to 90 percent, and tripled absorption of EPA and DHA from the ethyl ester form to about 60 percent (Lawson and Hughes, 1988).

Best time to take vitamin D3, K2 and omega-3

The meal matters more than the clock. Pick a meal you eat every day that includes some fat, such as eggs, yogurt, avocado, nuts or olive oil, and take all three with it. Breakfast or lunch works well for most people because it is easy to remember. Our guide to the best time to take vitamin D covers morning versus night.

Vitamin D3 and K2 vs Fish Oil

People sometimes ask whether they need vitamin D3 and K2 or fish oil. The honest answer is that one does not replace the other.

	Vitamin D3 + K2	Fish oil
What it supplies	Two vitamins	EPA and DHA fatty acids
Main focus	Calcium use, bone, muscle and immune function	Cell membranes, eyes and brain
Typical amount	Micrograms	Grams (VITAL used 1 g a day)
Vegan option	D3 from lichen	Algal oil
Take with	A meal that contains some fat

Omega-3 supplements come as fish oil, krill oil, cod liver oil and algal oil (NIH ODS). If you eat fatty fish such as salmon or sardines regularly, you may already get the EPA and DHA you want from food.

Who Might Choose Which

• Vitamin D3 and K2: for people who get little sun, spend winters indoors or want steady bone and calcium support. See foods high in vitamin D for food sources.
• Omega-3: for people who rarely eat fatty fish.
• All three: for people who want both and like a single routine with one meal.
• Adding cofactors: magnesium also works alongside vitamin D; see vitamin D and magnesium.

Safety: Who Should Check First

Most people take these nutrients without trouble at everyday amounts. Side effects of omega-3 supplements are usually mild, such as an unpleasant taste, bad breath, heartburn, nausea or loose stools (NIH ODS). For vitamin D, the adult upper limit of 4,000 IU a day is the most that is unlikely to cause problems, so check your total from all supplements.

The one group that should talk with a clinician first is people on warfarin or another blood thinner. People on warfarin need to keep their vitamin K intake consistent, and high doses of omega-3s may affect bleeding when taken with anticoagulants (NIH ODS: Vitamin K; NIH ODS: Omega-3). If you take any prescription medicine, check with your clinician before starting. Our guide to vitamin K2 side effects has more detail.

Where Our Vitamin D3 + K2 Drops Fit

We do not sell an omega-3 or fish oil supplement, so if you want one, choose it separately. For the vitamin side, our Vitamin D3 + K2 Drops combine vegan vitamin D3 (cholecalciferol from lichen) with vitamin K2 as both MK-4 and MK-7, in MCT oil with sunflower vitamin E, made with third-party tested ingredients. Take 1 drop a day with a meal that contains some fat, which makes it easy to pair with an omega-3 at the same meal.

Benefits build with consistent daily use. Months 1 to 2 can bring early changes, and 3 months and beyond is where the full benefit builds. Our Vitamin D Cofactor Capsules, with magnesium, zinc and boron, are coming soon to pair with the drops; join the waitlist to hear when they launch. See also our vitamin D3 ingredient page, our vitamin K2 ingredient page, our guide to vitamin D cofactors and our immune system guide.

Frequently Asked Questions

Can I take vitamin D3, K2 and omega-3 together?

Yes. Most people can take all three at the same meal, and a meal with some fat helps absorption. If you take a blood thinner, check with your clinician first.

Can I take vitamin D3 and K2 with fish oil?

Yes. Fish oil supplies omega-3 fats and D3 with K2 supplies two vitamins, so they complement each other rather than overlap.

Is vitamin D3 and K2 better than fish oil?

Neither is better; they do different jobs. D3 and K2 support calcium use, bone and immune function, while omega-3s are part of cell membranes, especially in the eyes and brain.

What is the best time to take vitamin D3, K2 and omega-3?

With a meal that contains some fat, at the same time each day. Breakfast or lunch is easy to remember for most people.

Should I take omega-3 with food?

Yes. In one study, absorption of EPA and DHA from fish oil was higher when it was taken with a higher-fat meal.

Does vitamin D need fat to absorb?

It absorbs best with fat. In a study of 50 older adults, a meal containing fat raised the peak blood level of vitamin D3 by 32 percent compared with a fat-free meal.

Was vitamin D taken with omega-3 in any large trial?

Yes. VITAL gave 25,871 adults vitamin D3, omega-3, both or placebo for a median of 5.3 years.

Do you sell an omega-3 supplement?

No. We make Vitamin D3 + K2 Drops, which you can take at the same meal as the omega-3 of your choice.

Sources

• National Institutes of Health, Office of Dietary Supplements. Vitamin D: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
• National Institutes of Health, Office of Dietary Supplements. Vitamin K: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/
• National Institutes of Health, Office of Dietary Supplements. Omega-3 Fatty Acids: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/
• National Institutes of Health, Office of Dietary Supplements. Omega-3 Fatty Acids: Fact Sheet for Consumers. https://ods.od.nih.gov/factsheets/Omega3FattyAcids-Consumer/
• Dawson-Hughes B, Harris SS, Lichtenstein AH, et al. Dietary fat increases vitamin D-3 absorption. Journal of the Academy of Nutrition and Dietetics, 2015. https://pubmed.ncbi.nlm.nih.gov/25441954/
• Lawson LD, Hughes BG. Absorption of eicosapentaenoic acid and docosahexaenoic acid from fish oil triacylglycerols or fish oil ethyl esters co-ingested with a high-fat meal. Biochemical and Biophysical Research Communications, 1988. https://pubmed.ncbi.nlm.nih.gov/2847723/
• Manson JE, Cook NR, Lee IM, et al. Vitamin D supplements and prevention of cancer and cardiovascular disease. New England Journal of Medicine, 2019. https://pubmed.ncbi.nlm.nih.gov/30415629/

These statements have not been evaluated by the Food and Drug Administration. This content is for education and is not medical advice. Our products are not intended to diagnose, treat, cure or prevent any disease. Talk with a healthcare provider before starting a new supplement if you are pregnant, breastfeeding or taking medication.