Why We Use MCT Oil in Our Vitamin D and K Products
If you’ve ever stood in the supplement aisle staring at five different versions of the same vitamin - chewable tablets, capsules, soft gels, liquids - you know the feeling. Same nutrient, completely different formats, and nobody seems to explain why it matters.
The truth is, for most vitamins, it doesn't matter that much. But for fat-soluble vitamins like D and K, how they're delivered, actually does make a difference.
Here's why we use MCT (medium-chain triglyceride) oil for our vitamin D & K products - and why we think it's the right call.
Fat-Soluble vs. Water-Soluble Vitamins
Vitamins are grouped into two categories: water-soluble (B and C), and fat-soluble (A, D, E, and K). Just like how oil doesn’t dissolve in water, fat-soluble vitamins don’t absorb well without fat present in your digestive tract1. This is why you'll often see these vitamins offered in an oil-based liquid form - the fat is there to support absorption.
The question is: which fat, and why?
What Is MCT Oil?
MCT oil is used as the liquid in which the vitamins are added 2. MCT stands for medium-chain triglyceride. It's a type of fat where all three fatty acid chains attached to the glycerol backbone are medium-length — meaning six to twelve carbons long.³ These medium-chain fatty acids (caprylic acid, capric acid, and lauric acid) occur naturally in coconut oil, palm kernel oil, and dairy fat.³,⁵.MCT oil is derived and concentrated from these sources, making it a clean, efficient carrier for nutrients like vitamin D and K2.²
Why MCT Oil Absorbs Faster Than Other Fats
Not all fats are processed by your body the same way. Long-chain fats - the kind found in most cooking oils and foods — require bile salts and pancreatic enzymes to break down, get packaged into transport molecules called chylomicrons, and then slowly make their way into circulation.⁴˒⁵
MCTs skip most of that process. They're hydrolyzed quickly and transported directly to the liver via the hepatic portal vein, where they're converted into ketones and used as immediate energy.³˒⁵ That rapid absorption is exactly what makes MCT oil an effective carrier for fat-soluble vitamins - it gets into your system faster, which improves bioavailability.²
Health Benefits of MCT Oil
One of the reasons we specifically chose MCT oil, rather than another carrier fat, is that it brings its own health benefits along for the ride..
Because MCTs go straight to the liver for immediate use, rather than being stored in fat issue, they function as a quick, clean energy source3. Research shows MCT oil can enhance metabolism, support fat loss, help preserve muscle mass, and even support cognitive function, since ketones serve as fuel for the brain.²˒⁵. When taking MCT oil for these benefits, the dose required is 1 teaspoon to 2 tablespoons per day - and while the amount in your vitamin drops is on the lower end of that, you're still getting meaningful exposure without any risk of overconsumption5.
How Does It Compare to Tablets, Capsules, and Soft Gels?
All of those formats can deliver fat-soluble vitamins, but they come with trade-offs.
Soft gels typically contain gelatin and soy in addition to the active ingredients, which isn't ideal if you have allergies or dietary restrictions. Tablets and capsules often include fillers and binders that add no nutritional value. And none of them offer the added metabolic benefits that come with MCT oil.
For most people, oil drops are more readily absorbed. The exception is individuals , with fat malabsorption issues (ex. patients with cystic fibrosis), who may actually absorb tables more effectively than oil-based formulas⁶˒⁸.
As for clinical evidence: the few studies comparing vitamin D3 tablets versus oil drops found significant difference inraising serum vitamin D levels6. More commonly found is research investigating methods for those with fat malabsorption and not comparisons for immunocompetent individuals8. One study in 2020 in immunodeficient patients did find that oil drops were associated with less frequent and shorter antibiotic use compared to tablets - though the researchers noted this wasn't a primary outcome measure6.
Research directly comparing supplement formats for vitamin K2 is even more limited, with most research focused on comparing K1 versus K2 rather than delivery methods.
Given the limited research comparing the effectiveness of different supplements (oil versus capsule versus tablet) and the known benefits of MCT oil and its rapid absorption, our team at ImmunoCeutica chose to use MCT oil and develop liquid products to provide a quality supplement.
Future of liquid products
The science of nutrient delivery is evolving quickly for fat-soluble vitamins - to improve absorption and bioavailability9. Researchers are actively exploring nanoemulsions - ultra-fine droplet systems that can further improve bioavailability of fat-soluble vitamins, particulary for nutrients that are prone to degradation from heat, , light, and oxygen exposure, and alkaline conditions10. MCT oil remains the gold standard for carrier oils right now, but this is a space worth watching as the research grows10.
The Bottom Line
MCT oil isn't just a convenient way to deliver vitamin D and K2 — it's the format that supports the best absorption, avoids unnecessary additives, and brings its own health benefits to the table. That's why it's what we use in ImmunoDrops Vitamin D3 + K2.
Want to know where your vitamin D levels actually stand? Don't guess — test. ImmunoCeutica's at-home dried blood spot test gives you your exact blood concentration along with a personalized report, so you can supplement with confidence.
👉 Shop ImmunoDrops Vitamin D3 + K2
Frequently Asked Questions
- Why do ImmunoCeutica's vitamin D and K products use MCT oil?
MCT oil is absorbed faster than most other fats, which makes it an effective carrier for fat-soluble vitamins like D and K. It gets into your system quickly and improves the bioavailability of the nutrients it delivers.
- Does MCT oil offer any health benefits on its own?
Yes — and that's part of why we chose it. MCT oil supports metabolism, quick energy production, fat loss, muscle preservation, and brain function. Unlike other carrier oils, it's doing more than just delivering the vitamins.
- Is an oil-based supplement more effective than a tablet or capsule?
For most people, there's no significant difference in how much vitamin D ends up in your bloodstream between formats. The limited research available found comparable results across methods when looking at serum vitamin D levels.
- Should everyone use oil drops over tablets?
Not necessarily. For individuals with fat malabsorption conditions — such as cystic fibrosis — tablets may actually be better absorbed than oil-based formats. If you have a digestive condition, it's worth discussing with your healthcare provider which delivery method is right for you.
- Why is MCT oil a better choice for people with dietary restrictions or allergies?
MCT oil is a clean carrier with no unnecessary additives. Soft gels typically contain gelatin and soy, and tablets often include fillers and binders — none of which are present in our liquid drops.
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References
1. National Institutes of Health. (2025). Vitamin D. National Institutes of Health. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
2. Cleveland Clinic. (2022). Potential health benefits of MCT oil. https://health.clevelandclinic.org/mct-oil-benefits
3. Jadhav, H. B., & Annapure, U. S. (2022). Triglycerides of medium-chain Fatty acids: a Concise Review. Journal of Food Science and Technology, 60(8). https://doi.org/10.1007/s13197-022-05499-w
4. McKenzie, K. M., Lee, C. M., Mijatovic, J., Haghighi, M. M., & Skilton, M. R. (2021). Medium-Chain Triglyceride Oil and Blood Lipids: A Systematic Review and Meta-Analysis of Randomized Trials. The Journal of Nutrition, 151(10), 2949–2956. https://doi.org/10.1093/jn/nxab220
5. What Is MCT Oil? Benefits, Dosage And Side Effects. (2024, January 24). Forbes Health. Retrieved April 2, 2026 from https://www.forbes.com/health/supplements/what-is-mct-oil/
6. Frankling, M.H., Norlin, A-C., Hansen, S., Borgström, E.W., Bergman, P., & Björkhem-Bergman, L. (2020). Are Vitamin D3 Tablets and Oil Drops Equally Effective in Raising S-25-Hydroxyvitamin D Concentrations? A Post-Hoc Analysis of an Observational Study on Immunodeficient Patients. Nutrients, 12(5), 1230. https://doi.org/10.3390/nu12051230
7. WebMD. (2024). MCT oil: Health benefits, common uses and side effects. https://www.webmd.com/diet/mct-oil-health-benefits-common-uses
8. Nowak, J. K., Sobkowiak, P., Drzymała-Czyż, S., Krzyżanowska-Jankowska, P., Sapiejka, E., Skorupa, W., Pogorzelski, A., Nowicka, A., Wojsyk-Banaszak, I., Kurek, S., Zielińska-Psuja, B., Lisowska, A., & Walkowiak, J. (2021). Fat-Soluble Vitamin Supplementation Using Liposomes, Cyclodextrins, or Medium-Chain Triglycerides in Cystic Fibrosis: A Randomized Controlled Trial. Nutrients, 13(12), 4554. https://doi.org/10.3390/nu13124554
9. Mulrooney, S. L., O’Neill, G. J., Brougham, D. F., & O’Riordan, D. (2022). Enhancing the bioaccessibility of vitamin D using mixed micelles – An in vitro study. Food Chemistry, 395, 133634. https://doi.org/10.1016/j.foodchem.2022.133634
10. Zeng, T., Song, F., Yang, Z., Yan, X., Jiang, L., Li, D., & Huang, Z. (2026). Nanoemulsion Encapsulation of Fat-Soluble Vitamins: Advances in Technology, Bioaccessibility and Applications. Foods, 15(1), 156. https://doi.org/10.3390/foods15010156
Disclaimer: This article is for informational purposes only and is not medical advice. Always consult your healthcare professional before starting any supplement, especially if you have an existing medical condition or take medications.
Reviewed by Erica Johncox, M.Sc., University of Guelph