Ingredients and labels

D3 K2 Omega-3 MCT Oil: How to Read a Combination Supplement Label

D3 K2 omega 3 MCT oil labels explained: what each ingredient line means, where MCT oil sits, and four real labels compared.

By Cardio Guardian Editorial TeamPublished October 14, 202611 min read

A D3 K2 omega-3 MCT oil label puts up to four separate ingredients in one product: vitamin D3 (cholecalciferol), vitamin K2 (menaquinones such as MK-7), the omega-3 fatty acids EPA and DHA from fish, krill or algal oil, and medium-chain triglyceride (MCT) oil, a fat that usually appears among the other ingredients without an amount. Each one has its own line, unit and cautions, so read each line on its own. Combining them is a formulation choice; the label does not show that the ingredients change one another’s effects, and this page makes no such claim. Among four real labels compared below, only one names the K2 form as MK-7, two list vitamin D in IU only, and three list MCT oil with no amount and no source. The NIH Office of Dietary Supplements (ODS) describes D2 and D3 as the two main forms of vitamin D in foods and supplements, and K1 (phylloquinone) and K2 (menaquinones) as the forms of vitamin K. [1] [2] It also says omega-3 formulations vary widely, so the label is where you find the types and amounts. [3]

This page is general education about reading supplement labels. It does not recommend any product or amount, it does not describe health effects of these ingredients, and the label records below are examples, not endorsements.

Safety first: if you take warfarin or another blood thinner, take orlistat, a statin, a steroid, a thiazide diuretic or a bile acid sequestrant, are allergic to fish, are pregnant or breastfeeding, or are choosing for a child, ask your doctor or pharmacist before using any product with these ingredients, and count the vitamin D in every supplement you take. ODS calls the interaction between vitamin K and warfarin “serious and potentially dangerous,” says fish oil might prolong clotting times when taken with warfarin, and lists orlistat, statins, steroids and thiazide diuretics among medicines that interact with vitamin D. [2] [3] [1] ODS also says many supplements have not been well tested for safety in children or in women who are pregnant or nursing. [4]

Use the ingredient-label checklist

What each line on the label means

Vitamin D3. ODS describes vitamin D as a fat-soluble vitamin with two main forms in supplements, D2 (ergocalciferol) and D3 (cholecalciferol), which differ only in their side chains. [1] D3 is typically made from lanolin, a substance from sheep’s wool, and an animal-free D3 made from lichen also exists; ODS suggests that people who avoid animal products ask the manufacturer about sourcing. [1] A label that says only “vitamin D3” or “cholecalciferol” does not say which source was used. For how labels show the source of vitamins for plant-based eating, see the guide to a plant based vitamin b complex.

Vitamin K2. Vitamin K is a family of compounds: phylloquinone is vitamin K1, and menaquinones are vitamin K2, named MK-4 through MK-13 by the length of their side chain. [2] Menaquinones are mostly made by bacteria, and natto, a fermented soybean food, is a rich food source. [2] ODS lists the forms used in supplements as K1 (phylloquinone, or phytonadione, a synthetic K1) and K2 as MK-4 or MK-7, and says few data compare how well the forms are absorbed. [2] So “vitamin K” on a panel may mean K1, K2 or both; look for the form named after it.

Omega-3s (EPA and DHA). EPA and DHA come from fish, fish oil and krill oil, and are first made by microalgae; supplements may use fish oil, krill oil, cod liver oil or algal oil. [3] The weight of the oil is not the omega-3 amount: ODS gives a typical example of 1,000 mg of fish oil providing 180 mg of EPA and 120 mg of DHA, and notes that amounts vary widely. [3] The omega-3s can also be in different chemical forms, including natural triglycerides, ethyl esters, re-esterified triglycerides and phospholipids. [3]

MCT oil. Medium-chain triglycerides are fats built from fatty acids with 6 to 12 carbon atoms, and their makeup depends on the source and how they are extracted. [5] MCT production in the United States began as a use for fatty acids left over from processing coconut oil, and MCT compositions now vary among manufacturers with no clear definition. [6] Industrial MCT is made by joining caprylic (C8) and capric (C10) acids to glycerol, and MCTs are sold in the United States as food ingredients and supplements. [7] The authors of two of these reviews work for a company that makes MCT products. In a vitamin or fish oil product, MCT oil is usually a carrier listed among the other ingredients; the label does not show that it changes how much vitamin D or K your body takes up.

Where the ingredients overlap

Vitamin D can come from more than one line. Cod liver oil supplies vitamin A and vitamin D along with omega-3s. [3] Vitamin D is also common in other supplements; ODS notes that vitamin K products are frequently combined with calcium, magnesium and/or vitamin D. [2] If you take more than one supplement, add up the vitamin D in all of them.

The vitamin D ceiling counts every source. For adults, ODS lists a tolerable upper intake level (UL) for vitamin D of 100 mcg (4,000 IU) a day. ODS defines a UL as the “maximum daily intake unlikely to cause adverse health effects”; it is a ceiling, not a recommended amount, and the Food and Nutrition Board noted that even intakes below the UL might have adverse effects over time. [1] ODS says vitamin D toxicity almost always comes from supplements. [1] No UL was set for vitamin K or for omega-3s, but that does not remove the warfarin cautions, and ODS notes that high intakes of EPA and DHA might increase bleeding time. [2] [3]

Units and Daily Values differ by line. Federal rules require vitamin D in micrograms (mcg); IU may be added in parentheses after it. [8] One mcg of vitamin D equals 40 IU, and the Daily Value is 20 mcg (800 IU). [1] The Daily Value for vitamin K is 120 mcg. [2] FDA has a Daily Value for total fat but none for omega-3s, so EPA, DHA and MCT lines are marked “Daily Value not established.” [3] [8] For practice reading panels like these, use the food label reading worksheet.

Source ingredients are shown with “as” or “from.” A panel can name the compound that supplies a vitamin in parentheses, as in vitamin D (as cholecalciferol) or vitamin K2 (as menaquinone-7). [8] When that detail is missing, the label does not tell you which form you are getting.

Carriers, capsules and allergens

Where MCT oil appears tells you its role on the label. If MCT oil, caprylic acid or capric acid is listed in the Supplement Facts panel, it has an amount per serving. If it is listed under other ingredients, it usually has no amount and is acting as a carrier or base. Ingredients without a Daily Value are listed in the panel by their common name. [8]

Fish must be named by species. FDA guidance says the allergen declaration must give the specific species of fish, such as bass, flounder, tilapia, salmon or cod, and cannot just say “fish.” [9] For supplements, FDA considers a major food allergen declared when it appears within the Supplement Facts panel. [9] Algal oil comes from microalgae, not fish, but read the label for the source rather than assuming. [3]

Coconut and other oils. FDA’s current allergen guidance lists the tree nuts it considers major food allergens in a table, and coconut is not on it; FDA says tree nuts outside that table should not go in a “Contains” statement. [9] Highly refined oils from major food allergens are exempt from allergen labeling, but the source of an oil still has to be part of its name in the ingredient list, as in “soybean oil.” [9] A label that says only “medium chain triglycerides” does not name the source; if you avoid coconut, ask the manufacturer.

Capsule shells and preservatives count too. Capsules and softgels may be made with gelatin, with or without its animal source named, or without gelatin, and liquids may contain flavors and antioxidants such as tocopherols. The four labels below show each of these. [10] [11] [12] [13]

Four real labels compared

Method. The table compares four supplements that list vitamin D, vitamin K, fish oil omega-3s and MCT, as recorded in the NIH Dietary Supplement Label Database (DSLD), which captures the information printed on supplement labels sold in the United States, including products no longer sold. [14] All four records are marked as on the market; they were entered between 2012 and 2024. They are every on-market record found that combines these four and lists no more than two other dietary ingredients; multivitamins, nutrition packs and powders with many more ingredients were left out. The search was not a census of every label. They are not a ranking, and each is identified by its DSLD record number only. DSLD records are label text, not test results. Amounts are per serving as listed, and marketing statements are noted but not repeated.

How four supplement labels list vitamin D, vitamin K, omega-3s and MCT, from the NIH Dietary Supplement Label Database
Label	Form and record	Vitamin D as listed	Vitamin K as listed	Omega-3 source and amounts	Where MCT appears	Fish or allergen statement
A	Liquid (DSLD 265399, entered 2022)	50 mcg (2,000 IU), as cholecalciferol [10]	“Vitamin K2,” 90 mcg, as “Menaquinone-7”	“Norwegian Fish Oil” 4.6 g; total omega-3s 1,430 mg; EPA 360 mg; DHA 890 mg; form listed as “Triglycerides”	Other ingredients: “Medium Chain Triglyceride Oil,” no amount, no source	Fish named: cod, pollock, haddock, whiting
B	Softgel Capsule (DSLD 312237, entered 2024)	20 mcg (800 IU), as cholecalciferol [11]	“Vitamin K,” 1.15 mg, K1 and K2 under one amount	“Fish Oil Omega-3 Complex” among the other ingredients; EPA 725 mg; DHA 275 mg; no total listed	Other ingredients: “Medium Chain Triglyceride,” no amount, no source	No fish species statement in the record
C	Capsule (DSLD 10457, entered 2012)	800 IU, no mcg amount, as cholecalciferol [12]	“Vitamin K1,” 100 mcg, as “Phytonadione”; no K2	“Ultra-Pure Fish Oil Concentrate” 1,460 mg; total omega-3s 1,000 mg; EPA 535 mg; DHA 260 mg	Other ingredients: “Medium Chain Triglycerides,” no amount, no source	Fish named: anchovies and sardines
D	Softgel Capsule (DSLD 80926, entered 2017)	800 IU, no mcg amount, as cholecalciferol [13]	“Vitamin K,” 1,600 mcg, as “Menaquinone,” MK form not stated	“Fish Oil” 800 mg; total omega-3s 240 mg; EPA and DHA not listed separately	Supplement Facts: “Caprylic Acid,” 2,400 mg; a label statement names coconut oil	Fish named: anchovy, sardine, mackerel; also soy and “tree nut (coconut)”

K2 is not guaranteed. Only label A names a K2 form, menaquinone-7. Label B lists K1 and K2 together under one amount, label C lists only K1 as phytonadione, and label D lists menaquinone without saying which one. [10] [11] [12] [13] Vitamin K amounts range from 90 mcg to 1,600 mcg per serving, and label B gives its amount in milligrams (1.15 mg, which is 1,150 mcg). ODS says few data compare the forms. [2]

Vitamin D units vary with the label’s age. Labels A and B list vitamin D in mcg with IU in parentheses. Labels C and D, entered in 2012 and 2017, list 800 IU with no mcg amount; current rules require mcg, so the label now on store shelves may differ. [12] [13] [8] At 40 IU per mcg, 800 IU is 20 mcg, so the four labels list 20 mcg to 50 mcg per serving. [1]

Omega-3 amounts are listed in different ways. Labels A and C give the oil weight, the total omega-3s, and EPA and DHA separately. Label B gives EPA and DHA but no total, and label D gives a total of 240 mg from 800 mg of fish oil without separating EPA and DHA. [10] [11] [12] [13] Only label A names the chemical form. Comparing products means comparing EPA plus DHA per serving, not the oil weight. [3]

MCT is mostly a carrier. Labels A, B and C list MCT among the other ingredients with no amount and no source. Label D lists caprylic acid, one of the fatty acids in MCT, in the Supplement Facts panel at 2,400 mg, and a statement on that label names coconut oil as its source. [13] [7]

Allergen statements are uneven. Labels A, C and D name the fish species; label B’s record shows no fish species statement, so check the package itself. [11] [9] Label D also declares soy and “tree nut (coconut)”; that record dates from 2017, and coconut is not on the tree nut table in FDA’s current guidance. [13] [9] Label D lists bovine gelatin, label B lists gelatin without a source, label C says its capsule shell has no gelatin, and label A is a liquid with tocopherols and rosemary extract. [13] [11] [12] [10]

Other ingredients ride along. Label A lists no other dietary ingredient. Label B adds vitamin E, label C adds genistein, and label D adds vitamin C and caffeine and carries a caffeine warning. [11] [12] [13] A product named for four ingredients can contain more.

Warnings and statements. Labels A and C carry a warfarin warning about their vitamin K; labels B and D carry a general warning to ask a health care provider first. [10] [12] [11] [13] Three labels also carry structure/function statements. Those are the manufacturer’s statements; FDA does not approve them before sale, though the manufacturer must have substantiation. [15]

Ingredient-label checklist for D3 K2 omega-3 MCT oil

Use these steps with each package in front of you, and write down the date you checked.

Find the vitamin D line. Look for the amount in mcg, any IU in parentheses, and the form, D3 (cholecalciferol) or D2. [8] [1]
Add up vitamin D from every supplement you take. The adult UL of 100 mcg (4,000 IU) is a ceiling for all sources combined, not a target. [1]
Find the vitamin K form. Check whether the label names K2 as MK-7 or MK-4, lists K1 (phylloquinone or phytonadione), or gives both under one amount, and note whether the unit is mcg or mg. [2] [11]
Find EPA and DHA, not just the oil weight. Add EPA and DHA per serving; the fish oil weight is a different number. [3]
Find the omega-3 source. Fish oil, krill oil, cod liver oil and algal oil are all used; cod liver oil also supplies vitamins A and D. [3]
Find where MCT oil is listed. In the Supplement Facts panel it has an amount; among the other ingredients it is usually a carrier with no amount. [8]
Check the oil source if you avoid coconut. “Medium chain triglycerides” alone does not name a source, and coconut may not appear in a “Contains” statement. [9] [6]
Check fish species if you are allergic. The label should name the species, not just “fish.” [9]
Check the capsule. Look for gelatin and its source, or a non-gelatin shell, and for soy. [13] [12]
Count the other dietary ingredients. Products named for these four can include vitamin E, vitamin C, caffeine or others. [11] [13]
Read structure/function statements as the manufacturer’s. They are not approved by FDA before sale. [15]
Bring medicine questions to your pharmacist. Mention warfarin or other blood thinners, orlistat, statins, steroids, thiazide diuretics and bile acid sequestrants, and every supplement you take. [2] [1] [4]
Match the record to your package. DSLD includes labels for products no longer sold, and labels change. [14]

Safety notes

ODS says vitamin K can interact seriously with warfarin and similar anticoagulants, and that people taking them need a consistent vitamin K intake from food and supplements. [2]
ODS says fish oil might prolong clotting times with warfarin, and that high intakes of EPA and DHA might increase bleeding time. [3]
ODS lists orlistat, statins, steroids and thiazide diuretics among medicines that interact with vitamin D, and says orlistat and bile acid sequestrants can reduce the uptake of vitamin K. [1] [2]
ODS lists usually mild side effects of omega-3 supplements, including unpleasant taste, bad breath, heartburn, nausea, digestive discomfort, diarrhea and headache. [3]
Reviews of MCT note limited information on long-term use and on effects in specific groups of people. [5]
ODS asks readers to tell their health care providers, including pharmacists, about any supplements they take. [4]

Where to go next

More label guides are listed under Ingredients and labels.

Common questions

What is in a D3 K2 omega-3 MCT oil supplement?

Usually vitamin D3, vitamin K2, the omega-3s EPA and DHA from an oil such as fish oil, and MCT oil as a carrier. Each has its own line on the label, and the four labels above show that the K form, the vitamin D units and the omega-3 detail all vary. [1] [2] [3] [12]

Is MCT oil an active ingredient or a carrier?

It depends on where it is listed. In three of the four labels above it is among the other ingredients with no amount; in one, caprylic acid is in the Supplement Facts panel with an amount. [10] [13]

Does MCT oil come from coconut?

Often, but not always. MCT production began with fatty acids left over from coconut oil processing, and compositions vary among manufacturers. [6] A label that says only “medium chain triglycerides” does not name the source. [9]

Is the vitamin K on the label always K2?

No. Supplements use K1 (phylloquinone or phytonadione) and K2 (MK-4 or MK-7). Among the four labels above, one names MK-7, one lists K1 and K2 together, one lists only K1 and one lists menaquinone without a number. [2] [12]

Why does the label show both mcg and IU for vitamin D?

Federal rules require the amount in mcg and allow IU in parentheses after it; 1 mcg equals 40 IU. Older labels may list IU only. [8] [1]

How do I find the EPA and DHA amount?

Look for the EPA and DHA lines in the Supplement Facts panel and add them. The oil weight is not the omega-3 amount, and some labels give a total without separating EPA and DHA. [3] [13]

Does combining these ingredients change what each one does?

The label does not show any combined effect, and none of the sources cited here studied these four ingredients as one product. Each is listed and measured separately on the panel, so read each line as its own ingredient. [8] [15]

Can I take a D3 K2 omega-3 supplement with warfarin?

Ask your doctor or pharmacist first. ODS describes the interaction between vitamin K and warfarin as serious and potentially dangerous, and says fish oil might prolong clotting times with warfarin. [2] [3]

If you take warfarin or another blood thinner, take orlistat, a statin, a steroid, a thiazide diuretic or a bile acid sequestrant, are allergic to fish, are pregnant or breastfeeding, or are choosing for a child, ask your doctor or pharmacist before using any product with these ingredients, and count the vitamin D in every supplement you take. [2] [1] [4]