Timothy P Carr

University of Nebraska at Lincoln, Lincoln, Nebraska, United States

Are you Timothy P Carr?

Claim your profile

Publications (77)178.49 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Grain sorghum (GS) and its co-products are a rich source of chemically diverse phytochemicals, many of which have been reported to protect against multiple human health conditions or diseases that are currently afflicting western cultures. However, due to rapid urbanization and nutrition transition, these diseases are also increasing in developing worlds, making sorghum an even more relevant food staple for these countries. Research on GS and its co-products thus is also steadily increasing but as potential functional foods or as supplements. For example, studies have demonstrated that both GS lipids and its co-product, dry distiller's grain sorghum were able to promote cardiovascular health by reducing both plasma low-density lipoprotein (LDL) and liver cholesterol levels but at different dosage levels. Grain sorghum phenols have also been shown to inhibit hepatic gluconeogenesis enzymes thereby promoting endogenous insulin sensitivity. As these results represent only a few of the health related studies cited in the literature in response to GS within the past 10. years, this manuscript reviews studies on GS and its co-products as a potential health promoting system reported between 2005 and 2015.
    Full-text · Article · Aug 2015 · Food Research International
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We previously demonstrated that Nostoc commune var. sphaeroids Kützing (NO), a blue-green alga (BGA), exerts a hypolipidemic effect in vivo and its lipid extract regulates the expression of genes involved in cholesterol and lipid metabolism in vitro. The objective of this study was to investigate whether the hypolipidemic effect of NO is attributed to an algal lipid or a delipidated fraction in vivo compared with Spirulina platensis (SP). Male C57BL/6J mice were fed an AIN-93M diet containing 2.5% or 5% of BGA (w/w) or a lipid extract equivalent to 5% of BGA for 4 weeks to measure plasma and liver lipids, hepatic gene expression, intestinal cholesterol absorption, and fecal sterol excretion. Plasma total cholesterol (TC) was significantly lower in 2.5% and 5% NO-fed groups, while plasma triglyceride (TG) levels were decreased in the 5% NO group compared with controls. However, neither NO organic extract (NOE) nor SP-fed groups altered plasma lipids. Hepatic mRNA levels of sterol regulatory element-binding protein 2, 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGR), carnitine palmitoyltransferase-1α, and acyl-CoA oxidase 1 were induced in 5% NO-fed mice, while there were no significant changes in hepatic lipogenic gene expression between groups. NO, but not NOE and SP groups, significantly decreased intestinal cholesterol absorption. When HepG2 cells and primary mouse hepatocytes were incubated with NOE and SP organic extract (SPE), there were marked decreases in protein levels of HMGR, low-density lipoprotein receptor, and fatty acid synthase. In conclusion, the nonlipid fraction of NO exerts TC and TG-lowering effects primarily by inhibiting intestinal cholesterol absorption and by increasing hepatic fatty acid oxidation, respectively.
    Full-text · Article · Jul 2015 · Journal of medicinal food
  • [Show abstract] [Hide abstract]
    ABSTRACT: Elevated concentrations of LDL cholesterol are associated with the development of atherosclerosis and therefore are considered an important target for intervention to prevent cardiovascular diseases. The inhibition of cholesterol absorption in the small intestine is an attractive approach to lowering plasma cholesterol, one that is addressed by drug therapy as well as dietary supplementation with plant sterols and plant sterol esters (PSEs). This study was conducted to test the hypothesis that the cholesterol-lowering effects of PSE require hydrolysis to free sterols (FSs). Male Syrian hamsters were fed atherogenic diets (AIN-93M purified diet containing 0.12% cholesterol and 8% coconut oil) to which one of the following was added to the diet: no PSEs or ethers (control), 5% sterol stearate esters, 5% sterol palmitate esters (PEs), 5% sterol oleate esters (OEs), 5% sterol stearate ethers (STs; to mimic nonhydrolyzable PSE), or 3% FS plus 2% sunflower oil. The treatments effectively created a spectrum of PSE hydrolysis across which cholesterol metabolism could be compared. Metabolic measurements included cholesterol absorption, plasma and liver lipid concentration, and fecal neutral sterol and bile acid excretion. The STs and the PEs and SEs were poorly hydrolyzed (1.69-4.12%). In contrast, OEs were 88.3% hydrolyzed. The percent hydrolysis was negatively correlated with cholesterol absorption (r = -0.85; P < 0.0001) and positively correlated with fecal cholesterol excretion (r = 0.92; P < 0.0001), suggesting that PSE hydrolysis plays a central role in the cholesterol-lowering properties of PSE. Our data in hamsters suggest that PSE hydrolysis and the presence of FS is necessary to induce an optimum cholesterol-lowering effect and that poorly hydrolyzed PSE may lower cholesterol through an alternative mechanism than that of competition with cholesterol for micelle incorporation. © 2015 American Society for Nutrition.
    No preview · Article · May 2015 · Journal of Nutrition
  • [Show abstract] [Hide abstract]
    ABSTRACT: The lipid fraction of the grain sorghum whole kernel (GS-WK) (i.e., phytosterol rich oil or policosanol rich wax) responsible for lowering cholesterol in hamsters fed the crude lipid (wax + oil) was determined. As expected, hamsters fed an atherogenic diet for a four week period presented with higher plasma non-HDL plasma and liver esterified cholesterol than those on the low fat diet. However, the atherogenic diet containing 5% (w/w) oil significantly lowered non-HDL plasma and liver cholesterol. Although the 5% wax supplement did not affect either plasma or liver cholesterol, excreted neutral sterol and bile acid were slightly higher than produced by the atherogenic diet. Still, cholesterol excretion negatively correlated with liver cholesterol concentration (r = −0.681, p < 0.001) across diets with the oil fraction producing the greatest impact. These combined results indicate that oil plays the most significant role in modulating cholesterol, most likely by inhibiting absorption, but subtle interactions by the wax may be involved. However, the sorghum oil would be the most potent component to serve as a possible heart health ingredient in functional foods.
    No preview · Article · Mar 2014 · Journal of Functional Foods

  • No preview · Article · Jan 2014 · Meat Science
  • [Show abstract] [Hide abstract]
    ABSTRACT: Crossbred steers (n = 64) were grazed on warm- or cool-season grasses, without or with energy supplementation of wet distillers grains with solubles (WDGS), and were finished on a corn-based diet with or without 35% WDGS. Grass type was the major contributor in determining the fatty acid profile, especially in the neutral lipid layer. Warm-season grasses decreased concentrations of most fatty acids compared to cool-season grasses. The provision of WDGS as an energy supplement while grazing dissipated any differences caused by grass type.
    No preview · Article · Jan 2014
  • Source
    Trevor J Carden · Timothy P Carr
    [Show abstract] [Hide abstract]
    ABSTRACT: Obesity rates in the United States have risen consistently over the last four decades, increasing from about 13% of the population in 1970 to more than 34% in 2009. Dietary fructose has been blamed as a possible contributor to the obesity increase, although the consumption pattern of fructose and other key nutrients during this 40 year period remains a topic of debate. Therefore, we analyzed the USDA Loss-Adjusted Food Availability Database in combination with the USDA Nutrient Database for Standard Reference (Release 24) to determine whether fructose consumption in the US has increased sufficiently to be a casual factor in the rise in obesity prevalence. Per capita loss-adjusted food availability data for 132 individual food items were compiled and analyzed. Nutrient profiles for each of these foods were used to determine the availability of energy as well as macronutrients and monosaccharides during the years 1970-2009. The percent change in energy from food groups and individual nutrients was determined by using the year 1970 as the baseline and area-under-the-curve analysis of food trends. Our findings indicate that during this 40 year period the percent change in total energy availability increased 10.7%, but that the net change in total fructose availability was 0%. Energy available from total glucose (from all digestible food sources) increased 13.0%. Furthermore, glucose availability was more than 3-times greater than fructose. Energy available from protein, carbohydrate and fat increased 4.7%, 9.8% and 14.6%, respectively. These data suggest that total fructose availability in the US did not increase between 1970 and 2009 and, thus, was unlikely to have been a unique causal factor in the increased obesity prevalence. We conclude that increased total energy intake, due to increased availability of foods providing glucose (primarily as starch in grains) and fat, to be a significant contributor to increased obesity in the US.
    Preview · Article · Sep 2013 · Nutrition Journal
  • Youngki Park · Timothy P Carr
    [Show abstract] [Hide abstract]
    ABSTRACT: Dietary consumption of phytosterols and certain fatty acids has been shown to reduce cholesterol absorption and plasma cholesterol concentrations. However, it has not been fully elucidated whether phytosterols or fatty acids can alter the expression of cholesterol transporters by functioning as signaling molecules. This study tested the hypothesis that various fatty acids and phytosterols commonly found in the food supply can modulate the expression of transporters including Niemann-Pick C1-like 1, low-density lipoprotein receptor, and scavenger receptor class B type I and 3-hydroxy-3-methylglutaryl-coenzyme A reductase in the intestine and liver. Caco-2 cells were used as models of enterocytes, and HepG2 cells were used as a model of hepatocytes. The cells were treated for 18 hours with 100 μmol/L of a fatty acid, or for 24 hours with 10 μmol/L of 25α-hydroxycholesterol, or 100 μmol/L of cholesterol, sitosterol, and stigmasterol to measure expression of genes involved in cholesterol transport using quantitative real-time polymerase chain reaction. Polyunsaturated fatty acids in Caco-2 cells and sterols in HepG2 cells significantly reduced the messenger RNA expression levels of Niemann-Pick C1-like 1, scavenger receptor class B type I, low-density lipoprotein receptor, and 3-hydroxy-3-methylglutaryl-coenzyme A reductase. Importantly, sitosterol and stigmasterol reduced the messenger RNA levels of genes to a similar extent as cholesterol. The data support the hypothesis that unsaturated fatty acid and phytosterols can act as signaling molecules and alter the expression of genes involved in cholesterol transport and metabolism.
    No preview · Article · Feb 2013 · Nutrition research
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The gastrointestinal microbiota impacts the metabolism of the mammalian host with consequences for health. However, the complexity of gut microbial communities and host metabolic pathways make functional connections difficult to unravel, especially in terms of causation. In this study, we have characterized the fecal microbiota of hamsters whose cholesterol metabolism was extensively modulated by the dietary addition of plant sterol esters (PSE). PSE intake induced dramatic shifts in the fecal microbiota, reducing several bacterial taxa within the families Coriobacteriacea and Erysipelotrichaceae. The abundance of these taxa displayed remarkably high correlations with host cholesterol metabolites. Most importantly, the associations between several bacterial taxa with fecal and biliary cholesterol excretion showed an almost perfect fit to a sigmoidal inhibitory nonlinear model describing bacterial inhibition, suggesting that host cholesterol excretion can shape microbiota structure through the antibacterial action of cholesterol. In vitro experiments suggested a modest antibacterial effect of cholesterol, and especially of cholesteryl-linoleate, but not plant sterols when included into model bile micelles. The findings obtained in this study are relevant to our understanding of gut microbiota-host lipid metabolism interactions, as they provide first evidence for a role of cholesterol excreted with the bile as a relevant host factor that modulates the gut microbiota. The findings further suggest that the connections between Coriobacteriaceae and Erysipelotrichaceae and host lipid metabolism, which have been observed in several studies, might be caused by a metabolic phenotype of the host (cholesterol excretion) affecting the gut microbiota.
    Preview · Article · Nov 2012 · Applied and Environmental Microbiology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Ninety-four, calf-fed crossbred steers were randomly allocated to three different dietary treatments (0%, 15% or 30% wet distillers grains plus solubles - WDGS - DM basis) and fed for 167 d to test the influence of different levels of WDGS on quality attributes of beef. At 48 h postmortem, marbling score, marbling texture, and marbling distribution were assessed by a USDA grader. After grading, one ribeye slice (Longissimus thoracis) about 7 mm thick was excised from each carcass, trimmed of subcutaneous fat, and analyzed for fatty acid profile and lipid content. At 7 d postmortem, 48 top blades (Infraspinatus), strip loins (Longissimus lumborum) and tenderloins (Poas major) (16 per treatment) were removed from shoulder clods and short loins and two steaks were obtained for measurement of mineral content, fatty acid profile (except strip loins), trained sensory analysis, objective color and lipid oxidation. Finishing diet did not influence the content of total lipid (P = 0.19) or marbling, marbling texture, or marbling distribution (P = 0.46, P = 0.84 and P = 0.40, respectively). Feeding WDGS created a linear increase (P < 0.01) of PUFA in all three muscles (Longissimus thoracis showed: 4.90, 5.91, and 6.23 % for 0, 15 and 30%, respectively). Similar responses were observed for 18:2(n-6) and total omega 6 fatty acids. Conversely, lower proportions of 18:1(n-7) fatty acid were observed in beef from animals fed 30% WDGS (P < 0.01). Total trans fatty acids increased linearly in strip loin and top blade steaks (P < 0.01) whereas proportions of 16:0 and 14:1(n-5) fatty acids decreased in all muscles (P < 0.01) as levels of WDGS increased. Diet did not affect mineral content of top blades or strip loins. For tenderloin steaks, sulfur concentration was lower when 30% of WDGS was fed (P = 0.05). No effects on sensory attributes and Warner Bratzler shear force were observed (P ≥ 0.50), except a minimal effect on strip loin juiciness (5.32, 4.86, and 5.52 for 0, 15, and 30%, respectively; P = 0.02). Top blade and tenderloin steaks from cattle fed 30% WDGS were significantly less red (lower a* values) on day 3 of simulated retail display (P < 0.04). Inclusion of 30% WDGS in the diet resulted in higher levels of oxidation after 7 d of retail display for top blade and strip loin steaks (P < 0.01). Feeding WDGS to calf-fed steers altered fatty acid profile, increased oxidation and decreased color stability during retail display.
    Full-text · Article · Aug 2012 · Journal of Animal Science
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Wet distillers grains contain approximately 65% moisture. A partially dried product (modified distillers grains plus solubles; MDGS) contains about 50% moisture. However, both have similar nutrient composition on a dry matter basis. The objective of this study was to investigate the effects of finishing diets varying in concentration of MDGS on marbling attributes, proximate composition, and fatty acid profile of beef. Yearling steers (n = 268) were randomly allotted to 36 pens which were assigned randomly to 0, 10, 20, 30, 40 and 50% MDGS (DM basis) and fed for 176 d prior harvest. Forty-eight h postmortem marbling score, marbling texture, and marbling distribution were assessed by a USDA grader and one ribeye slice (longissimus thoracis) 7 mm thick was collected from each carcass for proximate and fatty acid analysis. Treatments did not significantly alter marbling score or marbling distribution (P ≤ 0.05). USDA Choice slices had coarser marbling texture when compared to USDA Select. Although dietary treatment affected marbling texture no consistent pattern was evident. Diets did not influence fat content, moisture, or ash of the ribeye (P ≥ 0.05). For treatments 0, 10, 30, 40 and 50% there were positive linear relationships between marbling score and fat percentage in the ribeye (P ≤ 0.05) and all slopes were similar (P = 0.45). Feeding MDGS linearly increased stearic, linoelaidic, linoleic, linolenic, PUFA and n-6 fatty acids. As levels of MDGS increased, linear decreases were observed in all n- 7 fatty acids and cubic relationships were detected for the 18:1 trans isomers (trans-6-8-Octadecenoic acid, 6-8t, elaidic acid, 9t, trans-10-Octadecenoic acid, 10t, and trans vaccenic, 11t). No effects were observed for saturated fatty acids containing 6 to 14 carbons. Feeding MDGS resulted in increased PUFA, trans, and Omega 6 fatty acids, minimal effects on marbling texture, and no effects on the relationship of marbling to intramuscular fat content relationship.
    Full-text · Article · Aug 2012 · Journal of Animal Science
  • Mark M Ash · Jiliang Hang · Patrick H Dussault · Timothy P Carr
    [Show abstract] [Hide abstract]
    ABSTRACT: The dietary impact of specific phytosterols incorporated into phytosterol fatty acid esters has not been elucidated. Therefore, we tested the hypothesis that phytosterol esters containing different sterol moieties (sitosterol, sitostanol, or stigmasterol) but the same fatty acid moiety (stearic acid) produce different effects on cholesterol metabolism. Male Syrian hamsters were fed sitosterol, sitostanol, and stigmasterol stearate esters (25 g/kg diet) in an atherogenic diet containing cholesterol (1.2 g/kg) and coconut oil (80 g/kg). The phytosterol stearates produced no decrease in cholesterol absorption or plasma non-high-density lipoprotein cholesterol despite a reduction in liver free cholesterol in hamsters fed both sitosterol and sitostanol stearate diets. In addition, sitosterol stearate significantly increased fecal esterified and total neutral sterol excretion. Stigmasterol stearate did not differ from control in neutral sterol excretion, plasma lipids, or hepatic lipid concentration. Sitosterol stearate demonstrated the highest level of net intestinal hydrolysis, whereas sitostanol and stigmasterol stearate equivalently demonstrated the lowest. The cholesterol-lowering effect in liver-but not plasma-and the limited presence of fecal free sterols indicate that intact (unhydrolyzed) phytosterol stearates may impact cholesterol metabolism by mechanisms unrelated to the role of free phytosterols. The consumption of phytosterol esters at 2.5% of the diet elicited only modest impacts on cholesterol metabolism, although sitosterol stearate had a slightly greater therapeutic impact by lowering liver free cholesterol and increasing esterified and total neutral sterol fecal excretion, possibly due to a greater level of intestinal hydrolysis.
    No preview · Article · Jul 2011 · Nutrition research
  • [Show abstract] [Hide abstract]
    ABSTRACT: Unrefined and refined black raspberry seed oils (RSOs) were examined for their lipid-modulating effects in male Syrian hamsters fed high-cholesterol (0.12% g/g), high-fat (9% g/g) diets. Hamsters fed the refined and the unrefined RSO diets had equivalently lower plasma total cholesterol and high-density lipoprotein (HDL) cholesterol in comparison with the atherogenic coconut oil diet. The unrefined RSO treatment group did not differ in liver total and esterified cholesterol from the coconut oil-fed control animals, but the refined RSO resulted in significantly elevated liver total and esterified cholesterol concentrations. The unrefined RSO diets significantly lowered plasma triglycerides (46%; P=.0126) in comparison with the coconut oil diet, whereas the refined RSO only tended to lower plasma triglyceride (29%; P=.1630). Liver triglyceride concentrations were lower in the unrefined (46%; P=.0002) and refined (36%; P=.0005) RSO-fed animals than the coconut oil group, with the unrefined RSO diet eliciting a lower concentration than the soybean oil diet. Both RSOs demonstrated a null or moderate effect on cholesterol metabolism despite enrichment in linoleic acid, significantly lowering HDL cholesterol but not non-HDL cholesterol. Dramatically, both RSOs significantly reduced hypertriglyceridemia, most likely due to enrichment in α-linolenic acid. As a terrestrial source of α-linolenic acid, black RSOs, both refined and unrefined, provide a promising alternative to fish oil supplementation in management of hypertriglyceridemia, as demonstrated in hamsters fed high levels of dietary triglyceride and cholesterol.
    No preview · Article · May 2011 · Journal of medicinal food
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The floss and oil of the common milkweed (Asclepias syriaca L.) seeds are currently used to produce comforters/pillows and skin care products, respectively. As an outcome of these products, copious quantities co-products (pressed seed meal and pod biomass) are disposed of each year despite the presence of potential health benefitting lipids. The objective of this project was to determine the feasibility of developing the lipid fraction from of these co-products for the fast growing dietary human health market. Although certain types of lipids were affected by the extraction solvent used (hexane and diethyl ether) as were overall amounts, analysis of the each extract showed novel lipid profiles with several potential health benefitting agents present at levels comparable to or exceeding those present in other typically consumed dietary oils or food systems (vitamin E, carotenoids, sterols and unsaturated free fatty acids, particularly the both omega 7-fatty acids).
    Full-text · Article · May 2011 · Food Chemistry
  • [Show abstract] [Hide abstract]
    ABSTRACT: Cattle (n = 336; 595 ± 20 lb) were fed one of seven diets (corn/5% straw; 40% distillers grain (DG)/5% straw; 70% DG/8% straw; 70% DG/25% straw; 77.5% DG/9% straw; 77.5% DG/17% straw, and 85% DG/10% straw – DM basis) to measure effects of feeding high levels of DG on shelf life of aged beef. Except for 70% DG/25% straw, strip loins were cut into three steaks each after 20 days of postmortem aging for 0, 4, and 7 days of retail display. The treatment having 70% DG/8% straw had the greatest oxidation status. Trans fatty acids and polyunsaturated fatty acids increased significantly in the strips of cattle fed high levels of WDGS and straw. Treatments with the highest levels of DG (85% DG/10% straw) or straw (77.5% DG/17% straw) had the most discoloration and were darkest at day three and four of retail display.
    No preview · Article · Jan 2011
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Forty pigs (66.6 lb) were used in a 14-week 4-phase regime study conducted to evaluate the effect of feeding varying concentrations of DDGS to growing-finishing pigs formulated on a standardized ileal digestibility (SID) lysine (lys) basis, DDGS withdrawal at the last feeding phase, and ractopamine (RAC) supplementation 4 weeks prior to harvesting on carcass quality, and color stability and sensory characteristics of longissimus muscle (LM) of finishing pigs. Treatments consisted in 0, 15, or 40% dietary DDGS inclusion supplemented with or without RAC (4.5 ppm) 4 weeks prior harvesting. Final body weight, hot carcass weight, and dressing percentage were not affected by dietary DDGS inclusion, withdrawal or RAC supplementation (P > 0.10). Color characteristics were not affected by dietary DDGS inclusion or withdrawal (P > 0.10); however, dietary RAC supplementation reduced a* and b* at days 0 and 7 (P > 0.10). Total polyunsaturated fatty (TPUFA) acids increased and total saturated fatty acids (TSFA) were decreased in response to increased dietary DDGS inclusion (P < 0.01); however, DDGS withdrawal partially alleviated these changes in fatty acid composition by increasing TSFA and reducing TPUFA (P < 0.01). The inclusion of RAC decreased TSFA and increased total monounsaturated fatty acids concentration (P = 0.03 and 0.04, respectively). Sensory characteristics were not affected by dietary RAC, DDGS inclusion or DDGS withdrawal (P > 0.10). The results of this investigation suggest that dietary RAC, DDGS inclusion or DDGS withdrawal did not affect carcass quality as evaluated by color, chemical composition, and sensory characteristics of LM of growing-finishing pigs. Increasing the concentration of dietary DDGS altered the fatty acid profile of backfat of pigs by decreasing saturated and increasing unsaturated fatty acids. However, withdrawing DDGS, 4 weeks prior to harvesting partially alleviated the increase in PUFA, and consequently the “soft pork” problems associated with the use of DDGS.
    Full-text · Article · Jan 2011
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A study was conducted to evaluate the effect of feeding 0, 5, 10, or 15% distillers dried grains with solubles (DDGS) on carcass quality, color stability, and sensory characteristics of the longissimus muscle (LM) of finishing pigs. Two hundred forty pigs (61.7 lb) were assigned to 1 of 4 dietary treatments with varying concentrations of DDGS (0, 5, 10, and 15%). Live weight, hot carcass weight, and dressing percentage did not change in response to increased dietary DDGS (P = 0.491, 0.807, 0.316, respectively). After 7 days of retail display, yellowness changed due to DDGS inclusion (P = 0.016). No differences in shear force were observed (P = 0.06). Total polyunsaturated fatty acids increased and total saturated fatty acids decreased (P < 0.01, and 0.04, respectively) as dietary DDGS increased. Treatments did not differ in sensory characteristics (P > 0.10). The results of this investigation suggest that increasing dietary DDGS did not affect carcass quality as evaluated by color, chemical composition, and sensory characteristics of LM of finishing pigs. Increasing concentration of DDGS altered the backfat fatty acid profile of pigs by reducing saturated fatty acids and increasing unsaturated fatty acid concentration which may result in increased carcass softness.
    Full-text · Article · Jan 2011
  • [Show abstract] [Hide abstract]
    ABSTRACT: Grain sorghum (GS) lipid contains valuable phytochemicals that may have potential critical health benefits. Although the chemical composition of GS lipids varies among studies due to different extraction methods, intrinsic factors, such as variety, and the analytical methods applied, it has been consistently reported that GS lipids contain phytosterols, policosanols, unsaturated fatty acids, aldehydes and steryl/wax esters. A series of hamster studies showed that GS lipids exerted health-benefiting effects on cholesterol metabolism and intestinal microbiota. In-vitro experiment with a colon cancer cell line also showed its possible role in cancer inhibition. Exact mechanisms and bioactive compounds related to these effects have not been elucidated. Studies are in progress to understand the possible health benefitting mechanisms as well as to determine the responsible bioactive compounds.
    No preview · Article · Jan 2011 · ACS Symposium Series
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Plant sterols and stanols (phytosterols) and their esters are nutraceuticals that lower LDL cholesterol, but the mechanisms of action are not fully understood. We hypothesized that intact esters and simulated hydrolysis products of esters (phytosterols and fatty acids in equal ratios) would differentially affect the solubility of cholesterol in model bile mixed micelles in vitro. Sodium salts of glycine- and taurine-conjugated bile acids were sonicated with phosphatidylcholine and either sterol esters or combinations of sterols and fatty acids to determine the amount of cholesterol solubilized into micelles. Intact sterol esters did not solubilize into micelles, nor did they alter cholesterol solubility. However, free sterols and fatty acids altered cholesterol solubility independently (no interaction effect). Equal contents of cholesterol and either campesterol, stigmasterol, sitosterol, or stigmastanol (sitostanol) decreased cholesterol solubility in micelles by approximately 50% compared to no phytosterol present, with stigmasterol performing slightly better than sitosterol. Phytosterols competed with cholesterol in a dose-dependent manner, demonstrating a 1:1 M substitution of phytosterol for cholesterol in micelle preparations. Unsaturated fatty acids increased the micelle solubility of sterols as compared with saturated or no fatty acids. No differences were detected in the size of the model micelles. Together, these data indicate that stigmasterol combined with saturated fatty acids may be more effective at lowering cholesterol micelle solubility in vivo.
    Full-text · Article · Sep 2010 · Lipids
  • Timothy P Carr

    No preview · Article · Mar 2010 · Clinical Chemistry

Publication Stats

2k Citations
178.49 Total Impact Points

Institutions

  • 1997-2015
    • University of Nebraska at Lincoln
      • Department of Nutrition and Health Sciences
      Lincoln, Nebraska, United States
  • 1996
    • University of Minnesota Duluth
      Duluth, Minnesota, United States
  • 1992-1993
    • Wake Forest University
      • Department of Comparative Medicine
      Winston-Salem, North Carolina, United States
  • 1987-1990
    • The University of Arizona
      • Department of Nutritional Sciences
      Tucson, Arizona, United States