The health benefits of lupin : ten years of successful investigations

State of art and aim: The approval of the health claim on soy protein and hypercholesterolemia prevention in 1999 has represented an important milestone for a widespread awareness of the importance of consuming more plant proteins in replacement of animal proteins for cardiovascular prevention (Sirtori et al, 2007). During the following years, different grain legumes have been investigated, among which lupin that is a specific competitor of soy also for its high protein content and technological features. This review has the objective of discussing the main experimental and clinical studies on the hypocholesterolemic and hypotensive activity of lupin, considering either whole seed or separate ingredients, such as protein and fiber. Results and discussion: Among domesticated lupin species, only Lupinus albus and Lupinus angustifolius have been investigated in detail for their cholesterol-lowering activity. Five experimental works were performed with the rat model of hypercholesterolemia, one each with rabbit, pig or hamster models (Arnoldi et al, 2015). In all these studies, the decrease of total and LDL-cholesterol of the animals fed the lupin diet were significantly lower than those of the control animals fed a milk protein diet. The rabbit experiment permitted also to highlight the anti-atherogenic activity of lupin protein (Marchesi et al., 2008). The published clinical studies are nine, all but one on L. angustifolius: three are on foods from whole seeds, two on model foods containing purified lupin fiber and four on model foods containing purified lupin protein. The studies involving hypercholesterolemic subjects showed a significant decrease of total or LDL-cholesterolemia in respect to the base-line values and generally also in respect to the control diet, whereas those on normocholesterolemic subjects were inactive. The most impressive results were obtained when improved lupin foods were used indicating the critical importance of a perfect compliance (Bähr, Fechner, Kiehntopf, & Jahreis, 2014). The mechanism of action of the lupin protein is linked to a modulation of the cholesterol metabolism by peptides encrypted in the protein sequences (Lammi, Zanoni, Scigliuolo, D'Amato, & Arnoldi, 2014), whereas the fiber reduces the cholesterol absorbance in the intestine. A few experimental and clinical studies showed also a potential hypotensive activity that has encouraged studies on the ACE-inhibitory activity of peptide mixtures obtained by the hydrolysis of lupin protein with suitable enzymes (Boschin, Scigliuolo, Resta, & Arnoldi, 2014). Considering all these data, it seems possible to affirm that lupin may be considered an ingredient for functional foods.