FatBlaster Keto-Fit Fire 60s

MCT oil suits a lot of people and it's simple to use, but there's one condition where it's off the table. These are the questions our naturopaths ask first.

A good fit if

• You're eating keto or low-carb and want your blood ketones up
• You want a fat that disappears into your coffee or smoothie
• You're happy to swap it in for some of the fat you already eat, rather than just adding more

Check with us first if

• You're pregnant or breastfeeding. None of the trials we've looked at included pregnant or breastfeeding women, so safety at supplement doses hasn't been established.
• You take any prescription medicine. Interactions with MCT haven't been studied in the research we've reviewed, so we can't say there are none.
• Your triglycerides or cholesterol are being watched. MCT raised triglycerides slightly across seven trials.
• You'd be replacing olive oil or other mostly unsaturated oils. MCT raised total and LDL cholesterol when it replaced those fats.
• You're following a strict ketogenic diet more broadly. There's high-quality evidence that this diet raises LDL cholesterol, and it reduced muscle mass in healthy people.
• You're due for a urine organic-acid or acylcarnitine test. MCT raises octanoic and decanoic acid in your urine, which can confuse the result.
• It's for a child. There isn't enough evidence to base advice on.

• MCT oil, standard C8/C10 mix (item 3238). Best known for: The everyday form, and close to what most body-composition trials used. Absorption: In a crossover meal study, 30 g raised ketones significantly more than a long-chain oil. Typical use: Coffee, smoothies and food if you're on a keto or low-carb diet.
• C8 MCT oil (caprylic acid, tricaprylin). Best known for: The biggest ketone response, though it's harder to source because coconut oil is only about 6 to 8% C8. Absorption: 20 g gave a ketone response of 0.45 mmol/L, against 0.22 for 30 g of coconut oil. Typical use: If raising ketones is your main goal. No trial has compared it head to head with the C8/C10 blend.
• C8/C10 MCT oil blend. Best known for: The standard blend; C10 turns into ketones more slowly. Absorption: No trial has looked at what C10 does on its own. Typical use: General keto and low-carb use.
• MCT oil powder. Best known for: Travel and mixing; the carrier usually makes it gentler on your stomach. Absorption: No trial has tested powdered MCT; everything we know comes from the liquid oil. Typical use: Shakes and drinks on the go.
• Coconut oil (a different product, not an MCT form). Best known for: Cooking. Its main fatty acid is lauric acid, not C8 or C10. Absorption: Its ketone response wasn't significantly different from sunflower oil's. Typical use: Cooking. It isn't a substitute for MCT oil.

Reference values. There's no Australian recommended intake (NRV or RDI) for MCT. It isn't an essential nutrient, so you can't be deficient in it.

Typical supplemental range. Australian labels usually suggest 1 tablespoon of oil (about 15 mL, or roughly 14 g) or one scoop of powder, once or twice a day. Trials mostly used 15 to 20 g a day, so one or two serves sits right in that range. The body-composition trials swapped at least 5 g a day of other fats for MCT for four weeks or more, rather than adding it on top.

Upper level. There's no official upper limit. The practical ceiling comes from a systematic review: "Thirty grams of MCTs seems to be the safe maximal dosage to minimize adverse reactions during or after exercise." An upset stomach is the usual sign you've had too much at once.

Worth knowing. If ketones are the goal, take it away from carbohydrate. In one trial, having 50 g of glucose with C8 cut the ketone response from 0.45 to 0.28 mmol/L. Start with a teaspoon and work up. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• Coconut oil: about two thirds medium-chain fats, but only about 6 to 8% C8
• Milk fat: A natural source; no per-serve figure held
• Palm kernel oil: A natural source; no per-serve figure held

If any of these sound like you, talk to one of our naturopaths or your doctor before you start.

• MCAD deficiency. Don't take it at all. GeneReviews lists "infant formulas, coconut oil, and other manufactured foods containing medium-chain triglycerides as the primary source of fat" among things to avoid.
• Urine organic-acid or acylcarnitine tests. MCT raises octanoic and decanoic acid in urine, which shouldn't be mistaken for MCAD deficiency.
• Large single doses. About 30 g is the practical limit before gut side effects, especially around exercise.
• Triglycerides. MCT raised them by 0.14 mmol/L across seven randomised trials.
• Replacing unsaturated oils. Total and LDL cholesterol rose when MCT replaced mostly unsaturated fats.
• Ketogenic diets in general. There's high-quality evidence they raise LDL cholesterol and reduce muscle mass in healthy people.
• Children. The evidence is too thin to base advice on.
• Pregnancy and breastfeeding. Safety isn't established; no trial included these groups.
• Medicine interactions. Our sources didn't assess these, so none are stated and none are ruled out.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before you start.