Nutrition Diet: Who Should Avoid MCT Oil?

October 8, 2025 •

4 min read

While MCT oil is popular in ketogenic and low-carb diets, studies indicate that excessive consumption can lead to fat accumulation in the liver, particularly in those with pre-existing conditions. For this reason and others, it is crucial to understand who should avoid MCT oil and the specific circumstances where its use is contraindicated.

Quick Summary

This article explains which individuals should exercise caution or completely avoid MCT oil, including those with liver disease, uncontrolled diabetes, digestive disorders, and certain allergies, based on potential health risks.

Key Points

Liver Disease: Individuals with any form of liver dysfunction, including cirrhosis and NAFLD, should avoid MCT oil as it can strain the liver and worsen existing conditions.
Uncontrolled Diabetes: People with uncontrolled diabetes should not use MCT oil due to the risk of increasing ketone levels and potentially triggering diabetic ketoacidosis.
Gastrointestinal Issues: Those with conditions like IBS, IBD, or pancreatitis are prone to digestive side effects like diarrhea, cramping, and bloating, especially with high doses.
Coconut or Palm Oil Allergies: Since MCT oil is derived from coconut or palm oils, individuals with allergies to these should avoid the supplement to prevent allergic reactions.
Pregnancy and Breastfeeding: Limited safety research means pregnant or nursing women should avoid MCT oil unless advised by a healthcare professional.
Heart Conditions: People with heart disease or high cholesterol should be cautious, as MCT oil's high saturated fat content can impact lipid profiles.
Medical Consultation is Key: Always consult a doctor before starting MCT oil, especially if you have pre-existing health conditions or take other medications.

Medium-chain triglyceride (MCT) oil has gained popularity for its potential benefits, including boosting energy and supporting weight management. However, its rapid metabolism and high saturated fat content mean it is not suitable for everyone. Individuals with certain health conditions must approach MCT oil with caution, or avoid it altogether, to prevent serious complications.

Liver Disease and Dysfunction

One of the most significant contraindications for MCT oil is liver disease. The liver is the primary organ responsible for processing MCTs, and for those with existing liver conditions, such as cirrhosis, hepatitis, or non-alcoholic fatty liver disease (NAFLD), the added metabolic load can cause problems. In fact, excessive intake may potentially exacerbate hepatic steatosis and inflammation.

Why it affects the liver

MCTs are absorbed directly into the bloodstream and sent straight to the liver, bypassing the lymphatic system. While this is beneficial for quick energy conversion in healthy individuals, it can overtax a compromised liver. Patients with intestinal failure-associated liver disease (IFALD) or parenteral nutrition-associated liver disease (PNALD) should be particularly cautious. The cumulative effect of high doses over time can contribute to fat accumulation within the liver, further worsening the condition. Therefore, individuals with any form of liver dysfunction should consult a healthcare provider before considering MCT oil.

Uncontrolled Diabetes

Individuals with uncontrolled diabetes, particularly type 1, should avoid MCT oil. The reason is rooted in the metabolic process. MCT oil promotes the production of ketones in the liver. While nutritional ketosis in a managed ketogenic diet is generally safe, high ketone levels combined with insulin deficiency can trigger diabetic ketoacidosis (DKA), a life-threatening complication. People with diabetes must monitor their glucose levels closely if they use MCT oil and only do so under strict medical supervision.

Gastrointestinal Disorders

Even healthy individuals can experience gastrointestinal side effects from MCT oil, especially at higher doses. Those with pre-existing digestive issues, such as irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), or pancreatitis, are at a higher risk for adverse reactions.

Common digestive side effects

Diarrhea: Rapid absorption and the hyperosmotic nature of MCTs can draw water into the intestines, causing loose stools. This is one of the most common complaints, particularly when starting with too high a dose.
Nausea, cramps, and bloating: The quick passage of MCTs can irritate the digestive tract, leading to significant discomfort.

For patients with pancreatitis, while MCTs are theoretically easier to absorb than long-chain fats, studies have not shown clear benefits over standard treatments with enzyme supplementation, and digestive side effects can be a problem.

Allergies to Coconut or Palm Oil

MCT oil is almost exclusively derived from coconut or palm kernel oil. Therefore, anyone with a known allergy or sensitivity to either of these ingredients should avoid MCT oil to prevent allergic reactions. Reactions can range from mild skin irritations to severe anaphylaxis.

Pregnancy and Breastfeeding

There is limited scientific research available regarding the safety of MCT oil for pregnant or breastfeeding women. Until more reliable information is available, it is recommended to err on the side of caution and avoid its use during these sensitive periods.

Comparison of MCT Oil and LCT Oil

To further understand the differences and contraindications, consider the properties of MCT oil compared to the more common long-chain triglyceride (LCT) oils, like olive oil.


Feature	Medium-Chain Triglycerides (MCTs)	Long-Chain Triglycerides (LCTs)
Chain Length	6-12 carbon atoms	13-21+ carbon atoms
Digestion	Absorbed directly into the bloodstream; no bile or pancreatic enzymes needed.	Requires bile and pancreatic enzymes for breakdown.
Absorption	Absorbed rapidly and directly to the liver.	Absorbed via the lymphatic system before entering the bloodstream.
Energy Source	Converted quickly into ketones for immediate energy.	Metabolized more slowly and primarily used as fuel or stored as body fat.
Dietary Sources	Coconut oil, palm kernel oil, dairy products.	Oily fish, red meat, nuts, seeds, and vegetable oils.

Conclusion: Consult a Healthcare Professional

While MCT oil has specific therapeutic applications, particularly for those with malabsorption disorders, it is not a suitable supplement for everyone. Individuals with liver disease, uncontrolled diabetes, or certain gastrointestinal conditions face potential health risks and should proceed with extreme caution or avoid it entirely. As with any dietary change or supplement, the most responsible approach is to consult a qualified healthcare provider or registered dietitian. They can assess your individual health status and determine if MCT oil is appropriate for you, ensuring that you can pursue your health goals safely and effectively. For further reading on the use of MCTs in gastrointestinal disorders, consult authoritative medical resources such as this document from the University of Virginia School of Medicine.

Special Considerations for Those at Risk

For individuals with heart conditions or high cholesterol, the high saturated fat content of MCT oil warrants caution. Though research is mixed, some studies indicate it may increase 'bad' LDL cholesterol in certain people. Those on medications for diabetes, cholesterol, or blood thinners should also seek medical advice, as potential interactions exist. The long-term effects of high-dose MCT oil consumption are not fully understood, reinforcing the importance of medical guidance.

Frequently Asked Questions

While moderate use is generally considered safe, excessive and long-term consumption of MCT oil can contribute to fat accumulation in the liver, particularly in individuals with pre-existing liver conditions.

MCT oil can affect blood sugar and ketone levels. While some studies show potential benefits, individuals with diabetes should use it with caution and only under the supervision of a healthcare provider who can monitor their glucose levels.

MCTs are absorbed very quickly, which can irritate the intestinal lining, especially at high doses or on an empty stomach. The glycerol in MCTs also has a laxative effect, drawing water into the intestines.

To minimize side effects, start with a small dose (e.g., one teaspoon) and gradually increase it. Taking MCT oil with food instead of on an empty stomach can also help improve tolerance.

Due to a lack of sufficient research on safety, pregnant and breastfeeding women should avoid MCT oil unless specifically advised by their doctor.

Yes, potential interactions may exist, especially with blood thinners and certain cholesterol or diabetes medications. Always inform your doctor about all supplements you are taking.

For a fat-based energy source, options include fatty fish, avocado, or nuts. For quick energy from carbohydrates, consider balanced snacks like fruit or whole-grain options.