Benefits
Body weight and body fat compared with ordinary cooking oil
In a 12 week maker-run trial in 82 healthy Japanese adults on controlled meals, 14 g a day of MLCT in breakfast bread was followed by an average weight loss of 4.5 kg versus 3.3 kg on the same amount of ordinary oil, with greater losses of body fat and abdominal fat. An 8 week trial of 25 to 30 g a day as cooking oil found similar differences, mainly in men.
Body fat during added calories in young men
In a 12 week randomized trial in 13 young men, a daily drink adding about 20 g of structured MLCT raised body fat percentage less than the same drink made with soybean oil, while body weight rose slightly in both groups with no significant difference. The trial was very small and two of its four authors came from the oil maker.
Blood triglycerides, a lipid marker
In an 8 week trial in 101 Chinese adults with raised triglycerides, cooking with 25 to 30 g a day of MLCT gave lower serum triglycerides than ordinary oil; subgroup reports found the difference in men and in adults under 60 but not in women or older adults. In the 12 week Japanese trial, triglycerides did not differ, and total cholesterol fell more only at 8 weeks.
Calorie burning after a meal, a marker
In a crossover in 20 lean young adults, one liquid meal made with 14 g of MLCT raised energy expenditure over 6 hours by about 14 kcal more than the same meal made with canola oil. A single-dose study in 15 young women found a similar small rise with an MLCT holding 20 percent medium-chain fatty acids. Neither study measured weight.
Burning of dietary fat after meals, a marker
In a 4 week maker-funded crossover in 30 adults with overweight, 14 g a day of MLCT was followed by more of a labeled test fat being burned over 4 hours than after rapeseed oil (2.3 versus 1.8 percent of the dose). The study was not designed to test changes in weight or body fat.
Muscle strength recovery after damaging exercise
In a randomized, placebo-controlled trial in 40 recreationally active women, a structured MLCT supplement taken for at least 6 days around 300 maximal eccentric leg contractions did not change strength recovery, soreness, muscle size or jump performance compared with placebo. The trial was funded by an ingredient supplier, with academic investigators.
Mechanism of action
Medium-chain and long-chain fatty acids on one molecule
MLCT is made by enzymatically reshuffling the fatty acids of MCT and a vegetable oil, so medium-chain and long-chain fatty acids share the same glycerol. That differs from MCT oil, which is almost all medium-chain, and from a physical mixture of the two oils. In one study the smoke point was 210 degrees C for structured MLCT versus 143 for MCT and 160 for a physical mixture, which is why it can be used as an everyday cooking oil.
Medium-chain fatty acids routed to the liver
When MLCT is digested, its medium-chain fatty acids are absorbed directly into the portal vein and carried to the liver for rapid oxidation, while its long-chain fatty acids follow the usual lymphatic route. In a maker-run rat study, MLCT feeding gave lower body fat, higher 24 hour energy expenditure and higher liver activity of a fat-oxidizing enzyme measured with a medium-chain substrate than ordinary oil; in people, only short-term markers such as post-meal energy use and test-fat oxidation have been measured.
Clinical trials
Double-blind randomized controlled trial; bread made with 14 g of MLCT (1.7 g of medium-chain fatty acids) or 14 g of a rapeseed and soybean oil blend at breakfast, with standard packaged lunches and dinners, for 12 weeks; the stated aim was body fat accumulation; 8 of 11 authors from Nisshin Oil Mills, which made the test oils; no funding statement or registry number; analysis excluded 11 of 93 participants who did not eat the specified meals or opted out (Kasai et al. 2003, Asia Pac J Clin Nutr)
82 healthy Japanese adults analyzed (75 men, 7 women), aged 21 to 59, average BMI 24.6; 40 received MLCT and 42 the control oil.
Both groups lost weight on the controlled diet. At 12 weeks body weight had fallen 4.5 kg on MLCT versus 3.3 kg on the control oil (p < 0.05), with greater falls in body fat and in subcutaneous and visceral fat areas on CT. Total cholesterol fell more on MLCT at 8 weeks but not significantly at 12 weeks (p = 0.07). Triglycerides, glucose, insulin, ketone bodies and liver enzymes did not differ between groups.
Double-blind randomized controlled trial; MLCT oil (14 percent MCT interesterified with 86 percent canola oil) or ordinary oil at 25 to 30 g a day as household cooking oil, with fixed energy intake, for 8 weeks; the stated objective was blood triglycerides; the same trial was published in at least four papers split by sex, age and BMI; 5 of 15 authors from The Nisshin OilliO Group, and a companion report states the work was supported by the company; no registry number (Xue et al. 2009, Eur J Clin Nutr)
112 Chinese adults aged 18 to 65 with raised fasting triglycerides (1.7 to 5.6 mmol/L) recruited at the Chinese PLA General Hospital, Beijing; 101 completed (50 control, 51 MLCT).
Body weight, BMI, waist, body fat and subcutaneous and visceral fat fell more on MLCT than on the control oil, and serum triglycerides were lower on MLCT. In subgroup reports of the same trial, between-group differences appeared in men but not women, in those under 60 but not over 60, and in those with BMI 24 to 28 but not in normal-weight or obese participants.
Randomized controlled trial; two daily liquid-formula drinks adding 1040 kJ and about 20 g of fat a day as structured MLCT (about 10 percent medium-chain fatty acids, made from rapeseed oil) or soybean oil, for 12 weeks, on a usual diet; two of four authors from Nisshin Oil Mills (Matsuo et al. 2001, Asia Pac J Clin Nutr)
13 healthy male students aged 18 to 20 without a daily exercise habit; 7 received MLCT and 6 the control drink.
Body weight rose slightly in both groups with no significant difference (1.83 versus 0.91 kg). Body fat percentage rose less on MLCT (2.16 versus 4.30 percent change, significant across the 12 weeks), and fat mass rose 2.01 versus 2.79 kg. Blood biochemistry did not differ. The control fat was soybean oil rather than the rapeseed base of the MLCT.
Double-blind crossover; one 500 kcal liquid meal with 14 g of MLCT (about 12 percent medium-chain fatty acids) or 14 g of canola oil, at least 2 days apart, with energy expenditure by indirect calorimetry for 6 hours; 4 of 7 authors from The Nisshin OilliO Group, which prepared the test food (Ogawa et al. 2007, J Oleo Sci)
20 healthy young adults (9 men, 11 women), average age 24, average BMI 21.7.
Diet-induced thermogenesis over 6 hours was 47.9 kcal after MLCT versus 34.4 kcal after canola oil (p < 0.05), about 14 kcal more. Oxygen consumption and respiratory quotient curves were similar. This was a single-meal marker study and did not measure weight or body fat.
Randomized, double-blind, placebo-controlled crossover; a test food with 14 g of MLCT (11.6 percent medium-chain fatty acids) or 14 g of rapeseed oil daily for 4 weeks each, 5 week washout; outcome was oxidation of carbon-13 labeled triolein over 4 hours; registered UMIN000046604; funded by The Nisshin OilliO Group, and four of five authors are its employees (Nosaka et al. 2023, Front Nutr)
30 sedentary Japanese adults (14 men, 16 women) with BMI 25 to under 30, average age 50.5.
Cumulative oxidation of the labeled fat over 4 hours was 2.3 percent of the dose after MLCT versus 1.8 percent after rapeseed oil, a difference of 0.5 percentage points (p < 0.05). Energy and fat intake did not differ between periods. No adverse events were attributed to the MLCT food; two people reported digestive complaints while on the control food.
Double-blind, randomized, placebo-controlled parallel trial; a mint-flavored structured MLCT supplement made with vegetable oils such as rapeseed and palm, taken in two daily doses (the methods give about 10 g/day) for at least 6 days around 300 maximal eccentric knee-extensor contractions; primary outcomes were rapid and peak torque, muscle ultrasound and soreness; funded by Bunge Loders Croklaan USA, which could review the manuscript before submission (Velasquez et al. 2025, Nutrients)
40 recreationally active women, average age 22; 20 per group.
No condition by time interaction for strength recovery, with trends only for torque at 25 ms (p = 0.06) and peak torque (p = 0.05), and none for muscle size or echo intensity, soreness and pain ratings, thigh circumference, leg volume or vertical jump. The authors concluded the supplement did not significantly influence the rate of muscle strength recovery.