Effects of cholestyramine and squalene feeding on hepatic and serum plant sterols in the rat

Phytosterols: From Preclinical Evidence to Potential Clinical Applications

Phytosterols (PSs) are plant-originated steroids. Over 250 PSs have been isolated, and each plant species contains a characteristic phytosterol composition. A wide number of studies have reported remarkable pharmacological effects of PSs, acting as chemopreventive, anti-inflammatory, antioxidant, antidiabetic, and antiatherosclerotic agents. However, PS bioavailability is a key issue, as it can be influenced by several factors (type, source, processing, preparation, delivery method, food matrix, dose, time of administration into the body, and genetic factors), and the existence of a close relationship between their chemical structures (e.g., saturation degree and side-chain length) and low absorption rates has been stated. In this sense, the present review intends to provide in-depth data on PS therapeutic potential for human health, also emphasizing their preclinical effects and bioavailability-related issues.

Nutritional and other health properties of olive pomace oil

Olive-pomace oil is rich in oleic acid, and thus it can be an interesting dietary fat alternative as it can allow reaching the recommendation of consuming 20% of total diet energy in the form of monounsaturated fatty acids. In addition, olive-pomace oil also contains a wide range of minor components that may contribute to its healthy properties. The major components identified with healthy properties are triterpenic dialcohols and acids, squalene, tocopherols, sterols, fatty alcohols and phenolic compounds. The refining process, that the crude pomace-oil must undergo for commercial purposes, significantly reduces the content of phenolic compounds, while the other minor components remain at concentrations which can induce positive health effects, especially on cardiovascular health, outstanding pentacyclic triterpenes and aliphatic fatty alcohols in olive-pomace oil. Numerous in vitro and preclinical studies support that mainly the pure compounds, or extracts isolated from plant sources, play an important role in preventing cardiovascular disease and risk factors. Likewise, tocopherols, squalene and phytosterols, in addition to the minor fraction of phenolic compounds, have shown high biological activity with particular association to the cardiovascular function. In the light of the foregoing, and taking into consideration the absence of clinical studies with olive-pomace oil, it would be of great interest to develop randomized, crossover, controlled, double-blind studies to extend the knowledge and understanding on the health effects of olive-pomace olive.

Synthesis and characterization of a structured lipid from amaranth oil as a partial fat substitute in milk-based infant formula

The aim of this study was to use enzymatic interesterification techniques to modify underutilized amaranth oil as a structured lipid (SL) by increasing its palmitic acid content at the sn-2 position and incorporating docosahexaenoic acid (DHA). This SL can be partially or complementarily used in milk-based infant formulas to deliver a lipid component similar to that in breast milk. Amaranth oil was modified by enzymatic interesterification in two stages. First, the palmitic acid content was increased specifically at the sn-2 position to resemble breast milk triacylglycerols (TAGs) using Novozym 435 lipase. Then DHA was incorporated, mainly at the sn-1,3 positions using Lipozyme RM IM, a sn-1,3 specific lipase. An optimization model was developed to determine the exact parameter combinations to incorporate a specific amount of DHA (1.0-2.5%). The model suggestions were used for a gram-scale interesterification to yield the expected product. The final SL composition was as follows: palmitic acid, 33.9%; stearic acid, 2.8%; oleic acid, 23.3%; linoleic acid, 37.3%; linolenic acid, 0.7%; and docosahexaenoic acid, 1.9%. The original amaranth oil and the final SL were characterized by determining the fatty acid composition, melting profile, chemical characteristics, oxidative stability (peroxide, p-anisidine, and total oxidation values), and phytosterol, tocopherol, and squalene contents. The physical and chemical characteristics determined in this study support the potential application of DHA-containing customized amaranth oil (DCAO) as a partial fat substitute or complement for milk-based infant formula. Research on the application and stability of this SL used in an infant formula is being conducted.

Processing stability of squalene in amaranth and antioxidant potential of amaranth extract

The processing stability of squalene in amaranth and the antioxidant capacity of the oil-rich fraction of amaranth were studied. The processes investigated were continuous puffing and roasting. Puffing was carried out using a single screw extruder, while roasting was carried out in a convection oven. High-performance liquid chromatography was used to quantify squalene content before and after processing. The L-ORAC method was used to study the antioxidant activity of pure squalene and lipophilic amaranth extract containing squalene. It was found that squalene was stable during all of the processing operations with a maximum loss of 12% during roasting (150 degrees C, 20 min) and no loss during puffing. The L-ORAC test showed pure squalene to be a weak antioxidant, whereas the lipophilic extract of amaranth showed higher antioxidant activity as compared to pure squalene at the same concentration, suggesting that tocotrienols and other minor ingredients also played a role as antioxidants.

Gas and liquid chromatography of hydrocarbons in edible vegetable oils

Hydrocarbons, an important part of the minor constituents belonging to vegetable oils are reviewed. Their importance, origin, characterization and detection in edible vegetable oils are considered. The determination of some of them as a means of establishing oil quality and genuineness is also highlighted. The official methodologies, as well as the most commonly procedures used for isolation and analysis are reviewed. Furthermore, novel procedures applying new techniques for determining those compounds are also presented.

Vegetable oils high in phytosterols make erythrocytes less deformable and shorten the life span of stroke-prone spontaneously hypertensive rats

Previous studies have shown that canola oil (CA), compared with soybean oil (SO), shortens the life span of stroke-prone spontaneously hypertensive (SHRSP) rats, a widely used model for hemorrhagic stroke. SHRSP rats are highly sensitive to dietary cholesterol manipulations because a deficiency of membrane cholesterol makes their cell membranes weak and fragile. Phytosterols, abundant in CA but not in SO, can inhibit the absorption of cholesterol and also replace a part of cholesterol in cell membranes. This study was performed to determine whether the high concentration of phytosterols in CA might account for its life-shortening effect on SHRSP rats. Male, 35-d-old SHRSP rats (n = 28/group) were fed semipurified diets containing CA, SO, CA fortified with phytosterols (canola oil + phytosterols, CA + P), SO fortified with phytosterols (soybean oil + phytosterols, SO + P), corn oil (CO), olive oil (OO) or a fat blend that mimicked the fat composition of a representative Canadian diet (Canadian fat mimic, CFM; 10 g/100 g diet). These fats provided 97, 36, 207, 201, 114, 27 and 27 mg phytosterols/100 g diet, respectively. Ten rats from each group were killed after 30-32 d for blood and tissue analyses. The remaining rats (18/group) were used for determination of life span. The life span of SHRSP rats fed the high phytosterol oils (CA, CA + P, SO + P and CO) was significantly (P<0.05) shorter than that of CFM- and SO-fed rats. At 30-32 d, the groups fed the high phytosterol oils had greater levels of phytosterols and significantly (P<0.05) higher ratios of phytosterols/cholesterol in plasma, RBC, liver and kidney, and a significantly (P<0.05) lower RBC membrane deformabilty index than the groups fed oils low in phytosterols (SO, OO and CFM). The mean survival times were correlated with RBC deformability index (r(2) = 0.91, P = 0.0033) and cholesterol concentration (r(2) = 0.94, P = 0.0016), and inversely correlated with RBC phytosterol concentration (r(2) = 0.58, P = 0.0798) and phytosterols/cholesterol (r(2) = 0.65, P = 0.0579), except in the OO group. This study suggests that the high concentration of phytosterols in CA and the addition of phytosterols to other fats make the cell membrane more rigid, which might be a factor contributing to the shortened life span of SHRSP rats.

Serum and hepatic cholestanol, squalene and noncholesterol sterols in man: a study on liver transplantation

Serum noncholesterol sterols indicate overall cholesterol metabolism in a variety of experimental and clinical conditions. In patients with advanced primary biliary cirrhosis serum cholestanol, a 5 alpha-derivative of cholesterol, is markedly increased, and cholesterol precursors, which are indicators of cholesterol synthesis, are clearly reduced, as is the ratio of plant sterols (campesterol/sitosterol). Therefore these variables were studied in the livers and sera of 23 patients undergoing liver transplantation (16 patients with chronic liver disease, 4 with acute liver failure and 3 receiving second liver) and in 10 healthy controls. A most striking finding was the markedly high liver and serum levels of cholestanol in patients with chronic end-stage liver disease, a finding specific for cholestanol but not for other sterols. Of the cholesterol precursor sterols, lathosterol exhibited low contents in both the serum and liver of the cirrhotic patient group, supposedly reflecting decreased cholesterol synthesis. In contrast to the largely similar levels of noncholesterol sterols in serum and liver and the positive correlations between the two sources, the serum squalene levels were markedly lower than the hepatic levels, with a negative correlation between the serum and the liver, suggesting that serum squalene content poorly reflects cholesterol synthesis. In contrast to campesterol, serum and liver sitosterol tended to show increases, and the serum and hepatic campesterol/sitosterol ratios were lower in the chronic liver disease patients than in the controls, probably because of the more consistently impaired biliary elimination of sitosterol in those patients.(ABSTRACT TRUNCATED AT 250 WORDS)