Who should not take MCT oil
MCT oil is considered a safe food product, but its metabolism has features that make its use undesirable for certain people. Our editorial team examined for whom MCT oil is contraindicated, who may take it only with a doctor's permission, and for whom increased caution is enough.
Why MCT oil has contraindications
MCT oil is perceived as a neutral food product, and for most healthy adults it really is safe. However, the features of its metabolism create situations in which its use may be undesirable or even dangerous.
Medium-chain fatty acids are absorbed directly into the portal vein and are almost entirely processed by the liver. There they are quickly oxidized in the mitochondria, largely independently of carnitine transport, and the excess is converted into ketone bodies. Any disruption along this pathway — in the liver, in the oxidation enzymes, or in the regulation of ketogenesis — makes MCT a potential problem.
Toxicological data (Traul et al., 2000) indicate low systemic toxicity of MCT, but they were obtained mainly for healthy organisms. In people with chronic diseases, the limitations are determined not by toxicity but by the functional capabilities of the organs.
Our editorial team has divided the risk groups into three categories: absolute contraindications, situations where intake is possible only under a doctor's supervision, and conditions that require caution.
Absolute contraindications
Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency.This is a congenital disorder in which the body is unable to properly oxidize medium-chain fatty acids specifically. For such people MCT oil is contraindicated, since it can provoke a metabolic crisis with hypoglycemia. Interestingly, in some other oxidation disorders — long-chain ones — MCT is, on the contrary, used as a therapeutic agent, but exclusively as prescribed by a metabolic specialist.
Severe liver diseases.In decompensated cirrhosis and liver failure, the additional load of medium-chain fatty acids, which the liver must quickly process, is undesirable. Even in the classic reviews (Bach, Babayan, 1982), severe liver pathology was mentioned as a limitation for MCT. Any dietary intervention in such cases is determined by a hepatologist.
Contraindications for ketogenic approaches in general also include rare congenital conditions — pyruvate carboxylase deficiency, porphyria, and primary carnitine deficiency (Kossoff et al., 2018). Although MCT oil itself is not a keto diet, self-administered use of ketogenic supplements is unacceptable with these diagnoses.
For people with a confirmed allergy to the components of a specific product — for example, sodium caseinate in a powdered form — such a product is obviously contraindicated.
When intake is possible only with a doctor
Type 1 diabetes and insulin-dependent type 2 diabetes.MCT enhances the formation of ketone bodies. With good glycemic control this usually does not create problems, but with insulin deficiency additional ketone production theoretically increases the risk of ketoacidosis. In addition, a change in diet may require adjustment of the dose of glucose-lowering medications.
Pregnancy and breastfeeding.MCT is part of some formulas for premature infants, but there are insufficient data on the safety of concentrated MCT supplements for pregnant women. Therefore our editorial team advises not starting intake without a doctor's agreement.
Children.In pediatrics, MCT is used in the ketogenic therapy of epilepsy (Neal et al., 2008) and for fat malabsorption disorders. However, this is always medical nutrition with a calculated diet and monitoring of tests, not self-administered use of a supplement.
Diseases of the pancreas and biliary tract.In exocrine pancreatic insufficiency, MCT is sometimes prescribed as a more easily absorbed fat. However, in acute pancreatitis or an exacerbation of the chronic form, all fats are restricted, and the decision is made by a gastroenterologist.
Taking medications.People receiving antiepileptic, glucose-lowering, or lipid-lowering medications should discuss any significant dietary changes with a doctor, including regular use of MCT.
Who needs increased caution
The following groups can usually consume MCT oil, but it is worth monitoring your well-being and starting with minimal doses.
| Group | Reason for caution | Editorial recommendation |
|---|---|---|
| Irritable bowel syndrome, sensitive GI tract | MCT accelerates peristalsis and can provoke diarrhea | Start with 2–5 g, only with food, consider powder |
| Inflammatory bowel disease in remission | The individual reaction is unpredictable | Discuss with a gastroenterologist |
| Elevated cholesterol | Data on the effect on lipids are ambiguous | Monitor the lipid panel after 2–3 months |
| Goal — weight loss | High calorie content | Replace other fats rather than adding |
| Coconut allergy | Raw material — coconut oil | Check the origin and degree of purification |
For people with cardiovascular risks, it is important to understand that MCT is a saturated fat. The review by Eyres and colleagues (2016) on coconut oil showed that it raises LDL cholesterol levels compared with unsaturated oils. MCT oil differs from coconut oil in composition, but caution in this group is appropriate.
Athletes planning to use MCT during competitions should take into account that large doses during exercise can cause gastric upset (Jeukendrup et al., 1998). Any new products are tested during training.
Older people taking several medications should show the product to a doctor to assess its appropriateness and dose.
Warning symptoms: when to stop taking it
Even if you have none of the conditions described, some symptoms are a signal to stop taking it immediately and see a doctor:
- severe abdominal pain, especially in the upper part or radiating to the back;
- prolonged vomiting or diarrhea with signs of dehydration;
- marked weakness, confusion, an acetone smell on the breath in people with diabetes;
- jaundice, darkening of the urine, pain in the right upper abdomen;
- skin rashes, swelling of the lips or face.
Such symptoms are not typical of MCT in healthy people, but they may point to a hidden disease that had not manifested before.
Mild gastric discomfort at the start is not a contraindication but a signal to reduce the dose. However, if it persists even at the minimum amount, the product most likely does not suit you.
Our editorial team advises documenting the dose and reaction during the first weeks of use: this will help you and your doctor draw the right conclusions.
Editorial conclusions
MCT oil is safe for most healthy adults, but not for everyone. Absolute contraindications are MCAD deficiency and severe liver diseases, as well as rare congenital metabolic disorders.
For people with diabetes, pregnant and breastfeeding women, children, and patients with pancreatic diseases, intake is possible only after consulting a doctor.
Groups with sensitive digestion, elevated cholesterol, and those controlling their weight can consume MCT, but with caution and monitoring.
For more on tolerance, read our articles “Side effects of MCT oil,” “How to take MCT oil,” and “What to combine MCT oil with.”
References
- Bach AC, Babayan VK. Medium-chain triglycerides: an update. Am J Clin Nutr. 1982;36(5):950–962.
- Traul KA, Driedger A, Ingle DL, Nakhasi D. Review of the toxicologic properties of medium-chain triglycerides. Food Chem Toxicol. 2000;38(1):79–98.
- Kossoff EH, Zupec-Kania BA, Auvin S, et al. Optimal clinical management of children receiving dietary therapies for epilepsy: updated recommendations of the International Ketogenic Diet Study Group. Epilepsia Open. 2018;3(2):175–192.
- Neal EG, Chaffe H, Schwartz RH, et al. The ketogenic diet for the treatment of childhood epilepsy: a randomised controlled trial. Lancet Neurol. 2008;7(6):500–506.
- Liu YM. Medium-chain triglyceride (MCT) ketogenic therapy. Epilepsia. 2008;49(Suppl 8):33–36.
- Eyres L, Eyres MF, Chisholm A, Brown RC. Coconut oil consumption and cardiovascular risk factors in humans. Nutr Rev. 2016;74(4):267–280.
- Jeukendrup AE, Thielen JJ, Wagenmakers AJ, Brouns F, Saris WH. Effect of medium-chain triacylglycerol and carbohydrate ingestion during exercise on substrate utilization and subsequent cycling performance. Am J Clin Nutr. 1998;67(3):397–404.
Andriy Melnyk
A strength-sports coach and author of programs for beginner and intermediate levels. Writes about training planning.
