Impact of various emulsifiers on ALA bioavailability and chylomicron synthesis through changes in gastrointestinal lipolysis
Formulating healthy food rich in omega 3 fatty acids requires prior knowledge of the parameters influencing their bioavailability and their metabolic fate. In this context, we studied the effects of various emulsifiers widely used in the food industry, on the gastrointestinal lipolysis of flaxseed oil emulsions in an in vitro model and on the intestinal absorption and lymphatic secretion of alpha-linolenic acid (ALA) in rats. In vitro data showed that the emulsification of flaxseed oil with soya lecithin improved the gastric lipolysis of the oil (+30%), while the presence of Tween 80 or of sodium caseinate decreased it (−80% and −40%, respectively). The in vivo data demonstrated that the intestinal absorption and the lymphatic secretion of ALA were improved with soya lecithin (Cmax = 24 mg mL−1) and reduced in the presence of sodium caseinate (Cmax = 7 mg mL−1) compared to unemulsified flaxseed oil (Cmax = 16 mg mL−1); Tween 80 had no effect. In addition, the synthesized chylomicrons were notably larger and more numerous with soya lecithin whereas they were smaller in the presence of sodium caseinate (p < 0.05). This study shows that the intestinal bioavailability of ALA was increased by the emulsification of flaxseed oil with soya lecithin via an improved lipolysis, favouring the intestinal absorption of ALA and the secretion of many large chylomicrons in lymph.