Lupin protein isolate versus casein modifies cholesterol excretion and mRNA expression of intestinal sterol transporters in a pig model

Abstract

BackgroundLupin proteins exert hypocholesterolemic effects in man and animals, although the underlying mechanism remains uncertain. Herein we investigated whether lupin proteins compared to casein modulate sterol excretion and mRNA expression of intestinal sterol transporters by use of pigs as an animal model with similar lipid metabolism as humans, and cellular cholesterol-uptake by Caco-2 cells.MethodsTwo groups of pigs were fed cholesterol-containing diets with either 230 g/kg of lupin protein isolate from L. angustifolius or 230 g/kg casein, for 4 weeks. Faeces were collected quantitatively over a 5 d period for analysis of neutral sterols and bile acids by gas chromatographically methods. The mRNA abundances of intestinal lipid transporters were analysed by real-time RT-PCR. Cholesterol-uptake studies were performed with Caco-2 cells that were incubated with lupin conglutin γ, phytate, ezetimibe or albumin in the presence of labelled [4-14C]-cholesterol.ResultsPigs fed the lupin protein isolate revealed lower cholesterol concentrations in total plasma, LDL and HDL than pigs fed casein (P < 0.05). Analysis of faeces revealed a higher output of cholesterol in pigs that were fed lupin protein isolate compared to pigs that received casein (+57.1%; P < 0.05). Relative mRNA concentrations of intestinal sterol transporters involved in cholesterol absorption (Niemann-Pick C1-like 1, scavenger receptor class B, type 1) were lower in pigs fed lupin protein isolate than in those who received casein (P < 0.05). In vitro data showed that phytate was capable of reducing the uptake of labelled [4-14C]-cholesterol into the Caco-2 cells to the same extend as ezetimibe when compared to control (−20.5% vs. −21.1%; P < 0.05).ConclusionsData reveal that the cholesterol-lowering effect of lupin protein isolate is attributable to an increased faecal output of cholesterol and a reduced intestinal uptake of cholesterol. The findings indicate phytate as a possible biofunctional ingredient of lupin protein isolate.

The health benefits of sweet lupin seed flours and isolated proteins

“…Another model applied to narrow-leaf lupin was the hyperlipidaemic pig, initially in 2005 (Martins, Riottot, de Abreu, Viegas-Crespo, Lança, Almeida, et al, 2005) and then again in 2014 (Radtke, Geissler, Schutkowski, Brandsch, Kluge, Duranti, et al, 2014). In both researches, significant decreases of total and LDL-cholesterol were observed: in the former the changes in total cholesterol and LDL-C were -29.2% and -37.9%, respectively, in the latter the changes were -32.6% and -28.9%, respectively.…”

“…In both researches, significant decreases of total and LDL-cholesterol were observed: in the former the changes in total cholesterol and LDL-C were -29.2% and -37.9%, respectively, in the latter the changes were -32.6% and -28.9%, respectively. The observed reductions of total cholesterol and LDL-C concentrations were explained with an increased faecal cholesterol output (Radtke, et al, 2014). …”

Additive effects of lupin protein and phytic acid on aortic calcification in ApoE deficient mice

“…The crude components of the dietary proteins were determined by official methods [20] and are shown in Supplementary Table S1 . The amino acid contents of the proteins were analyzed as described elsewhere [14] , and are shown in Table 1 . Total phosphate and Mg 2+ concentrations were determined after digestion in HNO 3 for 8 h at 170 °C using inductively coupled plasma optical emission spectrometry (ICP-OES) (Ultima 2, Horiba Jobin Yvon S.A.S, Longjumeau, France).…”

“…Single peptides and amino acids, but also plant compounds associated with the plant proteins are suggested to have an impact on plasma cholesterol (reviewed in 10 , 11 , 12 ). Lupin protein isolates are associated with 14–25 g/kg of phytic acid 13 , 14 . Although phytic acid is considered as an antinutritive component due to its mineral binding [15] , there has been increasing evidence for beneficial effects of phytic acid in the body.…”

Proteomics for exploiting diversity of lupin seed storage proteins and their use as nutraceuticals for health and welfare

“…Recently, Radtke et al [59] also confirmed that L. angustifolius γ-conglutin (200 g/kg) exerts a beneficial impact on serum cholesterol in apoE-deficient mice, a model of atherosclerosis, but this did not result in any obvious atheroprotective effect. The only study made in other animal models apart from rodents, was the one conducted by Radtke et al [60] using pigs fed with a chow containing either a L. angustifolius protein isolate or casein as a control. The lupin protein reduced plasma cholesterol concentration and increased the cholesterol output in feces.…”