The effect of meat products enriched with plant sterols and minerals on serum lipids and blood pressure

The purpose of the study was to investigate the effect of non-esterified plant sterol-enriched and mineral-enriched low-fat and low-salted meat products compared with control meat products, on serum total and lipoprotein lipids and blood pressure in subjects with mildly to moderately elevated serum cholesterol concentration. A randomised, placebo-controlled, single-blind, repeated measure design was used. Altogether 21 volunteers completed the study. The study began with a pre-trial period of 1-2 weeks, which was followed by three different test periods in the following order: meat products enriched with plant sterols (1.2 g/day), potassium, calcium and magnesium (MP1); meat products with no added plant sterols and minerals (control); and meat products with plant sterols (2.1 g/day), potassium, calcium and magnesium (MP2). Each test period lasted for 3 weeks. During the MP2 period, the serum total and low-density lipoprotein cholesterol concentration decreased 4.9+/-7.5% (P<0.05) and 4.6+/-11.3% (not significant), respectively, compared with the control period. No differences in the high-density lipoprotein cholesterol and total triglyceride concentrations or in systolic blood pressure and diastolic blood pressure were found among the test periods. In conclusion, the present study showed that frankfurters and cold cuts enriched with plant sterols from tall oil, potassium, calcium and magnesium, as part of habitual Finnish diet reduced the serum total cholesterol concentration in hypercholesterolemic subjects when the intake of sitosterols was 2.1 g/day, but not with the lower dose.     

Beta-carotene micellarization during in vitro digestion and uptake by Caco-2 cells is directly proportional to beta-carotene content in different genotypes of cassava

Cassava, a staple food in sub-Saharan Africa, does not provide adequate amounts of pro-vitamin A (VA) carotenoids and has been targeted for biofortification (i.e. selectively breeding cultivars of increased nutrient density with agroeconomically acceptable characteristics). However, the accessibility of pro-VA carotenoids for absorption in different cultivars of cassava remains unknown. Here, we used the coupled in vitro digestion/Caco-2 cell uptake model to screen the relative accessibility of beta-carotene (betaC) in 10 cultivars of cassava with varying concentrations of betaC. After cooking (boiled for 30 min), the betaC concentration in tubers from different cultivars ranged from less than detectable to 6.9 microg betaC/g cassava. Samples were subjected to simulated oral, gastric, and small intestinal digestion to determine stability and micellarization of betaC. All-trans betaC, 9-cis betaC, and 13-cis betaC were the most abundant carotenoids in cooked cassava and recoveries after digestion exceeded 70%. Efficiency of micellarization of total betaC was 30 +/- 2% for various cultivars with no significant difference in isomers and linearly proportional to concentration in cooked cassava (r = 0.87; P < 0.001). Accumulation of all-trans betaC by Caco-2 cells incubated with the diluted micelle fraction for 4 h was proportional (R(2) = 0.99; P < 0.001) to the quantity present in micelles. These results suggest that all-trans betaC content appears to provide the key selection marker for breeding cassava to improve VA status and that the more complicated screening procedure using in vitro digestion coupled to cell uptake does not provide additional information on potential bioavailability.     

Micellarization and intestinal cell uptake of beta-carotene and lutein from drumstick (Moringa oleifera) leaves

The leaves and pods of the drumstick tree are used as food and medicine in some Asian and African countries. Although relatively high concentrations of beta-carotene and lutein have been reported in the leaves, the bioavailability of these carotenoids from this source is unknown. We have analyzed the digestive stability and bioaccessibility of carotenoids in fresh and lyophilized drumstick leaves using the coupled in vitro digestion/Caco-2 cell model. Beta-carotene and lutein were stable during simulated gastric and small intestinal digestion. The efficiency of micellarization of lutein during the small intestinal phase of digestion exceeded that of beta-carotene. Addition of peanut oil (5% vol/wt) to the test food increased micellarization of both carotenoids, and particularly beta-carotene. Caco-2 cells accumulated beta-carotene and lutein from micelles generated during digestion of drumstick leaves in a time- and concentration-dependent manner. The relatively high bioaccessibility of beta-carotene and lutein from drumstick leaves ingested with oil supports the potential use of this plant food for improving vitamin A nutrition and perhaps delaying the onset of some degenerative diseases such as cataracts.     

Divalent minerals decrease micellarization and uptake of carotenoids and digestion products into Caco-2 cells

Carotenoids are lipophilic, dietary antioxidants with the potential to prevent chronic and age-related diseases. Prior to their availability for physiological functions, carotenoids require micellarization and intestinal uptake, both constituting marginally understood processes. Based on an in vitro digestion model coupled to Caco-2 cells, we assessed the effect of dietary abundant divalent ions on spinach-derived carotenoid micellarization and cellular uptake: Ca and Mg ranging from 7.5 to 25 mmol/L in the digesta and Zn and Fe ranging from 3.8 to 12.5 mmol/L. Both micellarization and uptake were significantly inhibited by minerals in a concentration-dependent manner, with stronger effects for Fe and Zn compared to Ca and Mg. Compared to controls (no mineral addition), fractional micellarization and uptake were decreased to the greatest extent (to 22.5 and 5.0%, respectively; P < 0.001) by 12.5 mmol/L Fe. Effects of Mg were of the least magnitude; at 25 mmol/L, only uptake was decreased significantly to 69.2% of the control value (P < 0.001). Total cellular carotenoid uptake from test meals decreased similarly compared to micellarization; however, decreased β-carotene micellarization was counterbalanced by improved fractional cellular uptakes from the micelles for all ions. Compared to controls, fractional β-carotene uptake from the micelles was greater in samples digested in the presence of Fe, Ca, and Zn, by up to 5-10 times at the highest concentrations of each ion (P < 0.001). Like for the above carotenoids, a high cellular uptake of the epoxycarotenoid conversion products neochrome (from neoxanthin) and luteoxanthin+auroxanthin (from violaxanthin) was also observed. The present results indicate that divalent ions may inhibit carotenoid micellarization and uptake.     

Plant sterols as dietary adjuvants in the reduction of cardiovascular risk: theory and evidence

Plant sterol-enriched foods are an effective dietary adjuvant in reducing cardiovascular risk by lowering total cholesterol and low density lipoprotein-cholesterol (LDL-C) in serum by up to approximately 15%. The mechanism of action of plant sterols is different from those of 3-hydroxy-3-methylglutaryl coenzyme A inhibitors (statins) and thus their effect is additive. Combining plant sterols with other dietary components known to reduce cholesterol in a portfolio approach has proven to be most effective for reduction of hypercholesterolemia and provide an alternative treatment option for clinicians. Plant sterol-enriched foods provides clinicians with a relatively cheap, safe, and effective way to help patients manage their cardiovascular risk.     

Hydrolysis of zeaxanthin esters by carboxyl ester lipase during digestion facilitates micellarization and uptake of the xanthophyll by Caco-2 human intestinal cells

Zeaxanthin (Zea) and lutein are the only dietary carotenoids that accumulate in the macular region of the retina and lens. It was proposed that these carotenoids protect these tissues against photooxidative damage. Few plant foods are enriched in Zea, and information about the bioavailability of Zea from these foods and its accumulation in ocular tissues is limited. The amounts of free Zea and its mono- and diesters were measured for several plant foods that have relatively high concentrations of this xanthophyll. Wolfberry had the greatest concentration of Zea with a diester that accounts for 95% of the total. Free, mono-, and diesters of Zea were present in orange and red peppers, whereas only Zea monoesters were detected in squash. Zea esters were partially hydrolyzed by carboxyl ester lipase (CEL) during simulated digestion. The efficiency of micellarization was dependent on speciation with combined means of free Zea, Zea monoesters, Zea diesters from the digested foods of 81 +/- 8, 44 +/- 5, and 11 +/- 4%, respectively. When exposed to micelles generated during digestion of the test foods, Zea uptake by Caco-2 cells was proportional to the medium content (11-14%). Free Zea was the most abundant form in Caco-2 cells, although Zea monoesters also were detected (<8 +/- 0.7% vs. free Zea). CEL enhanced Zea uptake from micelles (12.3-fold; P < 0.05) by hydrolyzing Zea esters. After cell uptake, concentrations of free and monoesterified Zea remained relatively stable. These data suggest that dietary Zea esters are hydrolyzed by CEL during the small intestinal phase of digestion and that this conversion enhances Zea bioavailability.     

Basal plasma concentrations of plant sterols can predict LDL-C response to sitosterol in patients with familial hypercholesterolemia

BACKGROUND: Familial hypercholesterolemia (FH) is associated with a high risk of coronary heart disease. Pharmacological treatment and diet are both essential for the management of FH. Foods rich in plant sterols (PS) may play an important role in the treatment of patients with these disorders. OBJECTIVE: To test the effect of the intake of PS on low-density lipoprotein (LDL) concentration, endothelial function (EF) and LDL particle size in 30 patients with FH. DESIGN: Randomized and crossover dietary intervention study. SETTING: Tertiary outpatient care. SUBJECTS: Thirty-eight were recruited, but only 30 were subjected to four low-fat dietary intervention periods, each of 4 weeks. METHODS: Each intervention had a different content of cholesterol (<150 or 300 mg/day) and sitosterol (<1 or 2 g/day). Lipid response, EF and LDL particle size were analysed after the intervention. RESULTS: Plasma sitosterol/cholesterol ratio was higher during both plant sterol-rich periods than during the low plant sterols periods. Basal sitosterol concentrations predicted the LDL-cholesterol response during the intake of plant sterol-enriched diets. The change in LDL-cholesterol was significantly greater in subjects in the upper and intermediate tertiles of basal plasma sitosterol concentrations (-21+/-8 mg/dl, P=0.03; -19+/-7 mg/dl, P=0.04, respectively) than in subjects in the lower tertile (8+/-5 mg/dl) when they changed from a low cholesterol diet to a low cholesterol plus plant sterol diet. CONCLUSION: Our study demonstrates that basal sitosterol values can predict hypolipidemic response in patients with FH.     

Non-esterified plant sterols solubilized in low fat milks inhibit cholesterol absorption--a stable isotope double-blind crossover study

Summary. Background: The cholesterol absorption inhibiting properties of plant sterols in milks are unknown. The milk fat globule membrane components may enhance the absorption of cholesterol and could make plant sterols less efficient in this complex matrix. Aim of the study: To evaluate in hypercholesterolemic men the cholesterol absorption inhibiting properties of verified properly solubilized, non-esterified plant sterols in partly vegetable oil containing milks. Methods: The plant sterols in milk were determined to be properly solubilized, and to have effective in vitro functionality. Sixteen hypercholesterolemic adult men (initial total cholesterol 5.8–8.6 mM) then consumed milk containing sterols (1.8 g of non-esterified pure plant sterols/d) and control milk, alternatively, during two 6-day periods in a double blind cross over design. During the trial, cholesterol absorption was evaluated from the ratio of plasma isotopic enrichment of [26, 26, 26, 27, 27, 27–²H₆]cholesterol from oral intake (35.6 ± 0.2 μmol, ± SEM) over enrichment of [23, 24, 25, 26, 27–¹³C₅]cholesterol from intravenous injection (77.9 ± 0.5 μmol). Results: Plant sterols in low fat milks contained very few crystals > 11 μm in the presence and absence of bile salts and lysophospholipids, and inhibited cholesterol uptake in Caco-2 cell. This assured that the sterols were properly solubilized prior to the clinical trial. In the clinical study, compliance of volunteers was excellent. After tracer injections (72 h), the plasma [²H] and [¹³C] isotopic enrichments changed from 0.024 ± 0.001 and 0.072 ± 0.003 MPE (control) to 0.015 ± 0.001 and 0.074 ± 0.002 MPE during sterol treatment, respectively. Cholesterol absorption was reduced from 70.1 ± 4.2 % with control to 41.1 ± 4.0 % with milks containing plant sterol (P < 0.001). Conclusions: These results demonstrate that properly solubilized non-esterified plant sterols in milks significantly inhibit cholesterol absorption in mildly hypercholesterolemic men. Received: 10 October 2002, Accepted: 8 January 2003 Correspondence to: Etienne B. Pouteau     

Plant sterol-enriched fermented milk enhances the attainment of LDL-cholesterol goal in hypercholesterolemic subjects

Background The number of hypercholesterolemic individuals who do not meet their cholesterol recommended targets is inappropriately high. The use of plant sterol-enriched foods could help in this clinical setting. Aim of the study To evaluate the efficacy and side effects of plant sterol-enriched fermented milk in reducing LDL-cholesterol and increasing the number of patients who attain their therapeutic targets. Methods This was a multicentre, randomised, double-blind, placebo-controlled, parallel clinical trial. Eighty-three hypercholesterolemic patients that were not at therapeutic goals were studied. The patients received one 100 ml serving of either plain (control) low-fat or phytosterol enriched (1.6 g of free sterol equivalents) drinkable yogurt per day along with the main meal for 42 days. The principal variables were variation on LDL cholesterol (LDL-C) concentration and the number of patients achieving therapeutic goals after intervention. Results Patients on phytosterols attained an average LDL-C reduction of more than 10% (12.2% after 3 weeks; 10.6% after 6 weeks) (P = 0.001; 95% CI: 4.03–19.00) regardless of statin therapy compared to the control group. About 50% of the subjects on phytosterols, as compared to 20% of controls, attained their LDL-C target values (<3.3 or <2.6 mmol/l for primary and secondary prevention, respectively) at the end of the study (P < 0.001). HDL-cholesterol (HDL-C) did not change and triglycerides (TG) were decreased by 14% (P < 0.018). The plasma sterols/total cholesterol ratio increased. Conclusions Plant sterol-enriched fermented milk significantly reduced LDL-C and increased the number of moderately hypercholesterolemic patients achieving therapeutic targets.     

Chicken thigh, chicken liver, and iron-fortified wheat flour increase iron uptake in an in vitro digestion/Caco-2 cell model

The objective of this study was to test meat and fortified-food combinations to identify those that optimize iron uptake in an in vitro digestion/Caco-2 cell model, a proxy for iron bioavailability. Four experiments tested combinations of meats such as chicken (blood, spleen, liver, thigh), beef (cube steak), and fish (whole-fish meal) with iron-fortified foods (rice cereal, maize-soy flour, wheat flour). Chicken liver, thigh, spleen, blood, or fish meal increased the Caco-2 cell iron uptake from these combined with rice cereal (P < .05). Chicken liver, thigh, blood, and beef increased the Caco-2 cell iron uptake from these combined with wheat flour (P < .05). Chicken liver and thigh were tested further. Compared with the liver or thigh alone, adding fortified foods to these meats did not increase the Caco-2 cell iron uptake (P ≥ .05). Adding either meat to the 3 fortified foods increased the Caco-2 cell iron uptake of the fortified foods (P < .05). Chicken liver, chicken thigh, and wheat flour were selected for an infant porridge because the combinations with the highest Caco-2 cell iron uptake were chicken thigh + wheat flour, chicken liver + wheat flour, and chicken liver + maize-soy flour, and wheat flour was the least expensive fortified food sold in the target population. Per unit of iron, the chicken thigh + wheat flour and chicken liver + wheat flour combinations resulted in the highest bioavailable iron. In the proportion of 3:1 fortified food:meat examined, meat increases the bioavailability of iron-fortified foods, but iron-fortified foods do not enhance total iron bioavailability when added to meat.     

In vitro micellarization and intestinal cell uptake of cis isomers of lycopene exceed those of all-trans lycopene

The ratio of cis and all-trans lycopene (LYC) in human and animal tissues exceeds that in foods. The basis for this difference remains unknown, although differences in their stability, transport, and metabolism have been suggested. Here, we systematically compared the digestive stability, efficiency of micellarization, and uptake and intracellular stability of cis and all-trans isomers of LYC and carotenes using the coupled in vitro digestion and Caco-2 human intestinal cell model. Aril and oil from the carotenoid-rich gac fruit (Momordica cochinchinensis Spreng) were cooked with rice to provide a natural source of LYC and carotenes. The ratio of cis:trans isomers of LYC and beta-carotene was similar before and after simulated gastric and small intestinal digestion with recovery of total carotenoids in the digesta exceeding 70%. Micellarization of cis isomers of LYC during digestion of meals with both gac aril and oil was significantly greater than that of the all-trans isomer but less than for the carotenes. Uptake of cis isomers of LYC by Caco-2 cells was similar to that of carotenes and significantly greater than all-trans LYC. Micellarized carotenoids were relatively stable in micelles incubated in the cell culture environment and after accumulation in Caco-2 cells. These data suggest that the greater bioaccessibility of cis compared with all-trans isomers of LYC contributes to the enrichment of the cis isomers in tissues and that gac fruit is an excellent source of bioaccessible LYC and provitamin A carotenoids.     

Cholesterol-lowering effects of plant sterol esters differ in milk, yoghurt, bread and cereal

OBJECTIVE: To measure the relative effects of each of four phytosterol ester-enriched low-fat foods (bread, breakfast cereal, milk and yoghurt) on serum lipids, plasma phytosterols and carotenoids. DESIGN:: Three research centres undertook a randomised, incomplete crossover, single-blind study consisting of four treatment periods of 3 weeks each, one of which was a control period. Each sterol-enriched test food provided 1.6 g/day of phytosterols as sterol esters. SETTING: General Community. SUBJECTS: In all 58, free-living men and women with mean age (s.d.) 54 (8) y, moderately elevated plasma total cholesterol 6.2 (0.7) mmol/l and body mass index 26.2 (3.0) kg/m(2). MAIN OUTCOME MEASURES: Serum lipids, plasma phytosterols and carotenoids. RESULTS: Serum total and LDL cholesterol levels were significantly lowered by consumption of phytosterol-enriched foods: milk (8.7 and 15.9%) and yoghurt (5.6 and 8.6%). Serum LDL cholesterol levels fell significantly by 6.5% with bread and 5.4% with cereal. They were both significantly less efficacious than sterol-enriched milk (P<0.001). Plasma sitosterol increased by 17-23% and campesterol by 48-52% with phytosterol-enriched milk and bread. Lipid-adjusted beta-carotene was lowered by 5-10% by sterols in bread and milk, respectively. CONCLUSIONS: This is the first study to demonstrate that cholesterol-lowering effects of plant sterol esters may differ according to the food matrix. Plant sterols in low-fat milk was almost three times more effective than in bread and cereal. Despite phytosterol-enriched cereal products resulting in lower serum cholesterol reductions compared to sterol-enriched milk, the detection of similar changes in plasma phytosterols demonstrated that such products still delivered and released phytosterols to the gut.     

Estimation of plant sterol and cholesterol intake in Finland: quality of new values and their effect on intake

The Finnish national food composition database Fineli was updated with recent analytical values for plant sterols (PS) (sitosterol, campesterol, stigmasterol, avenasterol, brassicasterols and stanols) and cholesterol. The quality of the new analytical data was assessed. The aims of the present study were: (1) to compare the effect of old and new database values on PS and cholesterol intakes based on average per capita food consumption data; (2) to estimate the current intake and major sources of these compounds in various population groups according to the national FINDIET 1997 survey data. The intake of total PS was 305 mg/d for men and 237 mg/d for women. The respective intakes for cholesterol were 284 mg/d and 201 mg/d. Women had a higher density of PS in their diets than men, whereas the cholesterol density in the diets did not differ between genders. Cereals, margarine, vegetables and vegetable oils were the main food sources of PS. Meat, meat products and eggs were the main sources of cholesterol. A 9 % greater PS intake estimate was obtained with the new PS database compared with the old PS database, probably due to minor methodological differences between the new and old analyses. Notable changes in analytical methods suggest a lower value (-19 %) for cholesterol intake calculated from the new database compared with the old one. We conclude that researchers can have confidence in the new values for PS and cholesterol, because systematic evaluation of the new analytical values showed them to be of high quality.     

In vitro screening of relative bioaccessibility of carotenoids from foods

Carotenoids are lipophilic pigments in plant foods that are of particular interest as precursors of vitamin A, a nutrient required for vision, cell differentiation, and the immune system. In order to mediate such activities, carotenoids and their metabolites must be absorbed for delivery to tissues. Unlike many other dietary lipids, the efficiency of carotenoid absorption is typically inefficient, being affected by food matrix, style of processing, other dietary components, and nutritional and physiological status. Thus, reliable prediction of carotenoid bioavailability is problematic. We have developed a relatively simple and cost effective procedure to study the potential bioavailability, i.e., the bioaccessibility, of carotenoids. The method involves simulated oral, gastric and small intestinal digestion of test samples to access the efficiency of incorporation into micelles, an obligatory step for absorption of lipophilic compounds. The model can be further expanded by adding micelles generated during small intestinal phase of digestion to monolayers of Caco-2 human intestinal epithelial cells to investigate apical uptake, cellular metabolism and transepithelial transport of carotenoids. Recent work by Borel and associates has demonstrated that the relative bioaccessibility of carotenoids observed in vitro is highly correlated with in vivo observations and results from bioavailability trials with human subjects. Results from recent studies using the in vitro model to screen relative bioaccessibility of beta-carotene in various cultivars of cassava, impact of amount and types of fatty acyl groups in triglycerides on micellarization of carotenoids, and the mechanism of digestion and intestinal cell uptake of xanthophyll esters are presented.     

Plant sterol-enriched spread enhances the cholesterol-lowering potential of a fat-reduced diet

OBJECTIVE: To determine the effect of a plant sterol-enriched spread on plasma cholesterol concentrations when replacing butter or a standard polyunsaturated spread in a diet containing 30% of energy fat. DESIGN: Parallel butter phase followed by double-blind, randomized, cross-over polyunsaturated spread phases. SETTING: General community. SUBJECTS: Volunteer sample of 50 free-living men and women with mean age (s.d.) 46.7 y (10.5), moderately elevated plasma total cholesterol 5.95 mmol/l (0.78), and body mass index 26.0 (3.9) kg/m(2). INTERVENTION: Participants ate a moderately low-fat diet (30% of energy) for the 11-week intervention. During the first 3 weeks the diet included 20 g per day of butter. Participants were then randomized to replace the butter with 25 g of polyunsaturated spread with or without 2 g of plant sterols for 4 weeks, crossing over in the last 4 weeks to the alternate spread. MAIN OUTCOME MEASURES: Plasma cholesterol and fatty acids. RESULTS: Replacing butter with a standard polyunsaturated fat spread reduced mean plasma total cholesterol concentrations by 4.6% (from 6.09 (0.82) to 5.81 (0.77) mmol/l, P<0.01) and low-density lipoprotein cholesterol by 5.5% (from 3.98 (0.76) to 3.76 (0.74) mmol/l, P<0.05). Replacing butter with a polyunsaturated spread containing plant sterols reduced plasma total cholesterol by 8.9% (from 6.09 (0.82) to 5.55 (0.76) mmol/l, P<0.01) and low density lipoprotein cholesterol by 12.3% (from 3.98 (0.76) to 3.49 (0.72) mmol/l, P<0.01). Plasma high density lipoprotein cholesterol concentration was the same on the three diets. CONCLUSION: In people with moderately raised plasma cholesterol concentrations consuming reduced-fat diets the reduction in plasma total and low-density lipoprotein cholesterol concentrations achieved by replacing butter with a polyunsaturated spread is enhanced by addition of plant sterols.     

Sitosterol reduces messenger RNA and protein expression levels of Niemann-Pick C1-like 1 in FHs 74 Int cells

Intake of plant sterols has long been shown to reduce cholesterol absorption and subsequently plasma cholesterol concentrations. Despite competition between plant sterols and cholesterol for incorporation into mixed micelles as a suggested major mechanism for the inhibition of cholesterol absorption by plant sterols, studies exist to support an alternative mechanism. For example, another mechanism may be the action of plant sterols to reduce cholesterol absorption at the cellular level. This study was undertaken to test the hypothesis that plant sterols can modulate the expression of transporters such as Niemann-Pick C1-like 1 (NPC1L1) and scavenger receptor class B, type I (SR-BI) to lower intestinal cholesterol absorption. FHs 74 Int cells, a human small intestine epithelial cell line, were used as a model of enterocytes. The cells were treated with 25α-hydroxycholesterol (25 μmol/L) or 250 μmol/L of sitosterol, stigmasterol, and cholesterol for 24 hours to measure genes involved in cholesterol absorption and metabolism by quantitative real-time polymerase chain reaction. 25α-Hydroxycholesterol, cholesterol, and sitosterol significantly reduced the messenger RNA (mRNA) expression of NPC1L1 and hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, whereas SR-BI mRNA was not altered by the sterols. Western blot analysis confirmed the reduction in NPC1L1 by sterols. Depletion of cellular cholesterol by mevinolin, a cholesterol synthesis inhibitor, increased NPC1L1 and HMG-CoA reductase mRNA; and repletion of cholesterol abolished the increase. Sitosterol, but not stigmasterol, reduced the mRNA levels of NPC1L1 and HMG-CoA reductase to a similar extent of cholesterol. In conclusion, sitosterol can inhibit the expression of NPC1L1 in the enterocytes, which could be an alternate mechanism for plant sterols to reduce intestinal cholesterol uptake.     

A spread enriched with plant sterol-esters lowers blood cholesterol and lipoproteins without affecting vitamins A and E in normal and hypercholesterolemic Japanese men and women

The objective of the study was to investigate whether different initial baseline cholesterol levels modulate the efficacy of a spread enriched with plant sterol-esters (PS) in lowering blood cholesterol in a Japanese population consuming their usual diet. Healthy adults with a mean age of 45 y and mean plasma total cholesterol (TC) level of 6.5 mmol/L were recruited to participate in a double-blind trial comprised of a run-in period of 1 wk, followed by two intervention periods of 3 wks in a 2 x 2 crossover design and a post-trial follow-up of 3 wk. Volunteers consumed two spreads, one enriched with PS (12 g/100 g plant sterols) and a control spread not fortified with PS. Recommended spread intake was 15 g/d. Effects on plasma lipids, lipoproteins, beta-carotene and vitamins A and E were assessed. Plasma TC and LDL cholesterol (LDL-C) concentrations were 5.8 and 9.1% lower, respectively, when subjects consumed the PS spread than when they consumed the control spread (P < 0.001). Subjects were divided into two groups [normal and mildly cholesterolemic (TC <5.7 mmol/L) and hypercholesterolemic (TC >/= 5.7 mmol/L)]. Reductions (P < 0.001) in TC and LDL-C due to treatment in the former group were 4.9 and 7.9%, respectively. In the hypercholesterolemic group, the reductions (P < 0.001) were 7.1 and 10.6%, respectively. The decreases did not differ between normal/mildly cholesterolemic and hypercholesterolemic subjects. Plasma apolipoprotein B (apoB) and remnant-like particle (RLP) cholesterol (RLP-C) concentrations were lower when subjects consumed the PS spread (44.3 g/L) than the control spread (49.7 g/L). Plasma beta-carotene concentration was lower (P < 0.001) in subjects consuming the PS spread than in the control. Changes in plasma vitamins A and E levels did not differ after intake of the PS and control spreads. In conclusion, consumption of a PS-enriched spread effectively lowered plasma TC, LDL-C, apoB and RLP-C regardless of baseline plasma TC at an intake of 1.8 g/d of plant sterols.     

A healthy diet rich in carotenoids is effective in maintaining normal blood carotenoid levels during the daily use of plant sterol-enriched spreads

Blood cholesterol levels are affected by diet and in particular by the type and amount of fat intake. In recent years, vegetable oil spreads containing plant sterols/stanols (as their fatty acid esters) have been developed. Numerous clinical trials on spreads with added plant sterols/stanols have shown that they have much greater cholesterol-lowering properties than conventional vegetable oil spreads. Plant sterols decrease both dietary and biliary cholesterol absorption in the small intestine, with a consequential increase in excretion of cholesterol. It is also recognized that plant sterol/stanol-enriched, cholesterol-lowering spreads, if consumed regularly, may induce a 10-20% decrease in plasma carotenoids, adjusted for changes in plasma lipids. A 10-20% decrease in plasma carotenoids falls well within the seasonal variation observed in individuals. Our current understanding of the physiological functions of carotenoids does not indicate any health risk associated with the slight decrease in their blood levels due to the intake of plant sterol/stanol. The questions that have been raised, though, are how plant sterols/stanols affect plasma carotenoid levels, and in addition, what quantity of fruits and vegetables (the richest dietary sources of carotenoids) would have to be consumed to improve plasma carotenoid levels? The current mini-review covers the cholesterol-lowering effect of plant sterols, their mechanisms of action and effect on blood carotenoids, and concludes with the potential heath benefits of daily intake of plant sterol-enriched spreads.     

Reduction in cholesterol absorption in Caco-2 cells through the down-regulation of Niemann-Pick C1-like 1 by the putative probiotic strains Lactobacillus rhamnosus BFE5264 and Lactobacillus plantarum NR74 from fermented foods

Hypercholesterolaemia is a major risk factor related to atherosclerosis, and it may be influenced by our diet. This study addresses the impact of Lactobacillus rhamnosus BFE5264 (isolated from Maasai fermented milk) and Lactobacillus plantarum NR74 (from Korean kimchi) on the control of cholesterol absorption through down-regulation of Niemann-Pick C1-like 1 (NPC1L1) expression. Caco-2 enterocytes were treated with the live, heat-killed (HK) bacteria, bacterial cell wall extracts and metabolites; mRNA level and protein expression were measured. Caco-2 cells showed lower NPC1L1 expression in the presence of the live test strains than the control, elucidating down-regulation of cholesterol uptake, and were compared well with the positive control, L. rhamnosus GG. This effect was also observed with HK bacteria and cell wall fractions but not with their metabolites. The potential of some Lactobacillus strains associated with traditional fermented foods to suppress cholesterol uptake and promote its efflux in enterocytes has been suggested from these data.     

Homogenization, lyophilization or acid-extraction of meat products improves iron uptake from cereal-meat product combinations in an in vitro digestion/Caco-2 cell model

The effect of processing (homogenization, lyophilization, acid-extraction) meat products on iron uptake from meat combined with uncooked iron-fortified cereal was evaluated using an in vitro digestion/Caco-2 cell model. Beef was cooked, blended to create smaller meat particles, and combined with electrolytic iron-fortified infant rice cereal. Chicken liver was cooked and blended, lyophilized, or acid-extracted, and combined with FeSO4-fortified wheat flour. In the beef-cereal combination, Caco-2 cell iron uptake, assessed by measuring the ferritin formed by cells, was greater when the beef was blended for the greatest amount of time (360 s) compared with 30 s (P < 0.05). Smaller liver particles (blended for 360 s or lyophilized) significantly enhanced iron uptake compared to liver blended for 60 s (P < 0.001) in the liver-flour combination. Compared to liver blended for 60 s, acid-extraction of liver significantly enhanced iron uptake (P = 0.03) in the liver-flour combination. Homogenization of beef and homogenization, lyophilization, or acid-extraction of chicken liver increases the enhancing effect of meat products on iron absorption in iron-fortified cereals.