Delta- and gamma-tocotrienols are more effective than alpha-tocotrienol and alpha-tocopherol in attenuating metabolic syndrome, suggests a recent study in diet-induced obese rats
Delta-tocotrienol – with more modest effects shown by gamma-tocotrienol and minimal changes with alpha-tocopherol and alpha-tocotrienol – improved inflammation, heart structure and function, and liver structure and function, in obese rats, according to findings published in the European Journal of Nutrition.
The study also reported the oral absorption and distribution of alpha-tocopherol, alpha-, gamma-, and delta-tocotrienol to plasma, heart, liver and adipose tissue.
'Increasing intake of delta-tocotrienol, and to a lesser extent, gamma-tocotrienol may serve as a complementary dietary strategy in managing metabolic syndrome,' concluded the researchers, led by Lindsay Brown of the University of Southern Queensland, Australia.
Vitamin E is a family of eight separate but related molecules: four tocopherols (alpha, beta, gamma, delta) and four tocotrienols (alpha, beta, gamma, delta). Although alpha-tocopherol is found in most multivitamins and is supplemented in foods, a growing base of evidence suggests that this popular vitamin E interferes with the uptake and function of tocotrienols.
Tocotrienols are derived from three major sources, including rice, palm and annatto. The current study used alpha-tocopherol provided by Sime Darby, alpha- and gamma-tocotrienol from DavosLife Naturale3 supplied by Davos Life Sciences, and delta-tocotrienol from DeltaGold 70 supplied by American River Nutrition.
Obesity – marked by chronic low-grade inflammation – is associated with increased morbidity and mortality owing to hypertension, dyslipidaemia, cardiovascular disease and liver disease. According to the World Health Organisation, 300 million worldwide are obese, and in the US, more than two-thirds of US adults are overweight or obese (69%) and more than one-third are obese (36%).
In the study, researchers gave rats a high carb high fat diet to induce obesity with accompanying cardiac remodelling, insulin resistance, hypertension and fatty liver. Animals then received oral alpha-tocopherol, alpha-, gamma-, or delta-tocotrienol at 85mg/kg/day, corresponding to a 60kg human dose of ~800mg/day.
Results showed that, while all isomers reduced collagen deposition and inflammatory cell infiltrates in the heart, only delta- and gamma-tocotrienol improved cardiovascular function and systolic blood pressure. Delta-tocotrienol normalised eccentric hypertrophy shown by lower left ventricular internal diameter (during diastole), stroke volume and cardiac output.
Furthermore, only delta-tocotrienol affected important markers of metabolic syndrome and diabetes by enhancing glucose metabolism and improving insulin sensitivity, while reducing lipids and abdominal adiposity. The mechanism of action appears to be reduction in organ inflammation, especially of the heart, liver and abdominal fat.
Notably, the study measured vitamin E isomers in the plasma, heart, liver and adipose tissue. Although alpha-tocopherol and alpha-tocotrienol were the only isomers found in the plasma, all isomers were found in vital organs, with tocotrienol concentrations being highest in the adipose tissue. The researchers noted that 'delivery of oral tocotrienols to vital organs is the key determinant of the overall efficacy of oral tocotrienols in these tissues, rather than the concentration in plasma.'
Commenting on the research, Dr Barrie Tan, president of American River Nutrition Inc., said: 'The uniqueness of this study is the availability of individual isomers supplemented to animals to distinguish their distinct properties, and apply them to a very current concern of obesity and metabolic syndrome.'
'This study found that delta-tocotrienol had the strongest effect and to a lesser extent, gamma-tocotrienol with little effect for alpha-tocotrienol and alpha-tocopherol; these effects were described as markedly, modest and minimal, respectively,' Tan added.