Onnit MCT Oil is a pure C8/C10 medium-chain triglyceride oil sourced entirely from coconut, with no palm oil. MCTs bypass normal fat digestion and convert rapidly to ketones in the liver — a fast, clean energy source for brain and body that supports keto and low-carb diets. Unflavoured, odourless, in a 709ml bottle.

Pure C8/C10 MCT oil from coconut. Clean fuel for brain and body.

MCT oil is one of the most well-researched fat supplements available - and one of the few with a legitimate claim to supporting both physical performance and cognitive function through the same mechanism. Onnit's MCT Oil is sourced entirely from coconut, delivers a pure C8/C10 medium-chain triglyceride profile, and comes in a 709ml bottle - roughly a 2-3 month supply at typical daily use.

What MCTs actually are and why they work differently

Most dietary fats follow a long route to become usable energy - they're absorbed via the lymphatic system, packaged into lipoproteins, and eventually reach the liver for processing. Medium-chain triglycerides bypass this entirely. They're absorbed directly into the portal vein and transported straight to the liver, where they're rapidly converted into ketones - an alternative fuel source your brain and muscles can use without the multi-step conversion process carbohydrates require.

The practical result: MCT oil provides fast, clean energy without an insulin spike, without being stored as fat in the way longer-chain fats are, and without the crash that typically follows carbohydrate-based energy sources.

The research behind it

A meta-analysis published in the Journal of the Academy of Nutrition and Dietetics found that MCT oil consumption was associated with greater reductions in body weight and waist circumference compared to long-chain triglycerides, with effects attributed to the thermogenic properties of MCTs and their role in satiety signalling. A separate randomised controlled trial found that replacing long-chain fat with MCT in the diet led to greater reductions in body fat and appetite with no adverse effects on blood lipids.

On the cognitive side, research into ketones and brain energy metabolism has found that ketones can provide an alternative fuel source for the brain when glucose availability is reduced - relevant for low-carb dieters, intermittent fasters, and anyone managing cognitive energy across a demanding day.

C8, C10 and lauric acid - what's in this bottle

Onnit's MCT Oil provides a blend of C8 (caprylic acid) and C10 (capric acid) - the two medium-chain fatty acids most efficiently converted to ketones in the liver, extracted from coconut oil. It also contains lauric acid, a longer medium-chain fatty acid that converts to energy more slowly but has well-documented antimicrobial properties and a strong safety profile from decades of dietary research.

MCT oil and the ketogenic diet

MCT oil has become a genuine staple of the ketogenic diet for a straightforward reason - MCTs are converted directly to ketones in the liver, bypassing the usual fat metabolism pathway, which means they actively support ketosis rather than simply complementing it. For anyone following a keto or low-carbohydrate approach, it's one of the most practical supplements available.

Who it's for

MCT oil has a particularly strong track record with three groups: people following a ketogenic or low-carbohydrate diet (where it helps maintain ketone production), intermittent fasters (where it provides fuel without breaking a fast in the way carbohydrates would), and anyone who adds it to coffee as a sustained morning energy source rather than relying on caffeine alone.

How to use it

Start with 1 teaspoon per day and increase gradually to 1-2 tablespoons - jumping straight to a full dose can cause digestive discomfort in some people. Add to coffee, smoothies, salad dressings, or use as a cooking oil for low-heat preparation. Unflavoured. Mixes cleanly with a spoon - no blender required.

709ml bottle | ~60-90 day supply
100% coconut sourced. No palm oil. Unflavoured and odourless.

Not suitable for those with medium-chain acyl-CoA dehydrogenase deficiency (MCADD). Consult your doctor if pregnant, nursing, or taking medications.

Stocked and shipped from Dublin. Order before 4pm for same-day dispatch.

Frequently Asked Questions

What is MCT oil used for?

MCTs are converted rapidly to ketones in the liver, providing a fast, clean energy source without an insulin spike. People use it for sustained morning energy (often in coffee), on keto or low-carb diets to support ketosis, and during intermittent fasting.

Is Onnit MCT Oil made from coconut or palm?

100% coconut, with no palm oil. It delivers a pure C8/C10 medium-chain triglyceride profile.

How do I take MCT oil without stomach upset?

Start with 1 teaspoon per day and build up gradually to 1-2 tablespoons. Jumping straight to a full dose can cause digestive discomfort. Add it to coffee, smoothies, or salad dressings.

Does MCT oil break a fast?

MCT oil provides fuel without the carbohydrate-driven insulin response that would break a fast in the metabolic sense, which is why intermittent fasters commonly use it. If your fasting goal is zero calories, note that it does contain calories from fat.

Can I cook with MCT oil?

Yes, for low-heat preparation — it's unflavoured and odourless. It's not suitable for high-heat frying. It also works as a salad dressing base or blended into drinks.