Effects of diacylglycerol on glucose, lipid metabolism, and plasma serotonin levels in lean Japanese.
OBJECTIVE
Diacylglycerol (DAG)-rich oil has been suggested to suppress postprandial hyperlipidemia and promote negative caloric balance by increasing energy expenditure (EE), due to small intestine physiochemical dynamics that differ from triacylglycerol (TAG). We studied the effect of DAG on postprandial glucose/insulin metabolism by loading of carbohydrate with oil. Further, to reveal the mechanism for increased EE by DAG, we measured plasma serotonin, which is mostly present in the small intestine and mediates peripheral sympathetic thermogenesis.


METHODS
Randomized crossover study with 2-week wash-out interval between differing fat ingestion. Seven male, lean, Japanese students ingested DAG or TAG oil with 40 g of carbohydrate. Measurements of metabolic parameters were performed before and at 2, 4, and 6 h after fat ingestion. Plasma serotonin levels and cholesterol concentration in each lipoprotein were measured using high-performance liquid chromatography (HPLC).


RESULTS
The substitution of DAG for TAG decreased very-low-density lipoprotein-cholesterol (VLDL-C) by 45.6% at 2 h, and decreased serum insulin by 41.3% at 4 h after ingestion. The incremental area under the curve (IAUC) for VLDL-C was positively correlated with the IAUC for insulin. Concurrently, DAG elevated plasma serotonin levels by 47.3% at 2 h, while TAG did not influence.


CONCLUSIONS
This study indicates that the substitution of DAG for TAG suppresses the postprandial increase in serum VLDL-C and insulin. This study also demonstrates that DAG ingestion increases plasma serotonin, proposing a possible mechanism for a postprandial increase in EE by DAG.
Yanai
Hidekatsu
H
Department of Internal Medicine, The Jikei University School of Medicine, Chiba, Japan. yanaih@jikei.ac.jp
Yoshida
Hiroshi
H
Tomono
Yoshiharu
Y
Hirowatari
Yuji
Y
Kurosawa
Hideo
H
Matsumoto
Akiyo
A
Tada
Norio
N
D000328:Adult; D001786:Blood Glucose / Q000187:drug effects*; D015243:Cholesterol, VLDL / Q000097:blood; D018592:Cross-Over Studies; D004075:Diglycerides / Q000494:pharmacology*; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology; D007564:Japan; D050356:Lipid Metabolism / Q000187:drug effects*; D008297:Male; D012701:Serotonin / Q000097:blood*; D022722:Thermogenesis / Q000187:drug effects / Q000502:physiology; D013851:Thinness / Q000208:ethnology / Q000378:metabolism*; D014280:Triglycerides / Q000494:pharmacology
D001786:Blood Glucose; D015243:Cholesterol, VLDL; D004075:Diglycerides; D007328:Insulin; D014280:Triglycerides; D012701:Serotonin