Effects of plant sterols and stanols on intestinal cholesterol metabolism: Suggested mechanisms from past to present

Abstract

Plant sterols and stanols are natural food ingredients found in plants. It was already shown in 1950 that they lower serum low-density lipoprotein cholesterol (LDL-C) concentrations. Meta-analysis has reported that a daily intake of 2.5 g plant sterols/stanols reduced serum LDL-C concentrations up to 10%. Despite many studies, the underlying mechanism remains to be elucidated. Therefore, the proposed mechanisms that have been presented over the past decades will be described and discussed in the context of the current knowledge. In the early days, it was suggested that plant sterols/stanols compete with intestinal cholesterol for incorporation into mixed micelles as well as into chylomicrons. Next, the focus shifted toward cellular processes. In particular, a role for sterol transporters localized in the membranes of enterocytes was suggested. All these processes ultimately lowered intestinal cholesterol absorption. More recently, the existence of a direct secretion of cholesterol from the circulation into the intestinal lumen was described. First results in animal studies suggested that plant sterols/stanols activate this pathway, which also explains the increased fecal neutral sterol content and as such could explain the cholesterol-lowering activity of plant sterols/ stanols.

Hypolipidemic Effect of the Autoclaved Extract Prepared from Pea (<i>Pisum sativum</i> L.) Pods In Vivo and In Vitro

“…It corresponds to 2.5 mm. Consequently, dietary cholesterol was excreted in the feces by plant sterol (40). Nevertheless, cholesterol excretion in feces of the AE group did not significantly increase.…”

Conjugated and free sterols from black bean (Phaseolus vulgaris L.) seed coats as cholesterol micelle disruptors and their effect on lipid metabolism and cholesterol transport in rat primary hepatocytes

“…However, more studies are needed to understand whether the phytosterols are able to alter the LXR phosphorylation state. Nonetheless, it is known that systemic LXR activation increases hepatic fatty acid synthesis and steatosis (De Smet et al 2012), and therefore, phytosterols of black bean seed coats can potentially be used to reduce or prevent these abnormalities.…”

Factors Affecting Intestinal Absorption of Cholesterol and Plant Sterols and Stanols

“…3 Role of plant sterols on cholesterol absorption 3.1 Inhibition of cholesterol absorption by plant sterols It is well established that dietary plant sterols have hypocholesterolemic activity in experimental animals and humans 5 . Because being fed a diet of plant sterols increases fecal excretion of cholesterol and its metabolites, it is thought that plant sterols inhibit cholesterol absorption in the intestine.…”

“…Therefore, we concluded that sitosterol does not influence post-micellization processes of cholesterol absorption. Recently, Smet et al summarized the proposed mechanisms responsible for the effects of plant sterols and stanols on intestinal cholesterol metabolism 5 . Although many other interesting mechanisms regulating cholesterol absorption by plant sterols have been suggested, the authors concluded that suppression of micellar solubility of cholesterol by plant sterols is the only equivocally established effect.…”

“…Plant stanols are not major constituents of plant products, but they are obtained by hydrogenation of plant sterols. It has been well established that plant sterols and stanols have hypocholesterolemic activity by inhibiting cholesterol absorption in the intestine 5 . Plant sterols and stanols are generally less absorptive than cholesterol 4 .…”