Lipid Bioaccessibility Research Articles

Emulsification of algal oil with soy lecithin improved DHA bioaccessibility but did not change overall in vitro digestibility.

Oil emulsification facilitates digestive lipolysis and subsequent lipid bioaccessibility. This study aimed to understand the effects of emulsification on DHA-rich algal oil digestion and bioaccessibility. An oil/water emulsion (50 : 44 : 6 oil-water-soy lecithin) was subjected to an in vitro digestion model with gastric pH 1.6 or 4.0 and particle size distributions, duodenal stage lipolysis and DHA bioaccessibility were determined. The emulsion was destabilized at gastric pH 1.6, with subsequent slow duodenal lipolysis. With gastric pH 4.0, the emulsion structure remained intact, initial lipolysis proceeded rapidly and DHA bioaccessibility was higher than for bulk oil, a mixture of oil, water and soy lecithin, and the gastric pH 1.6 destabilized emulsion (p < 0.05). However, the extent of lipolysis was not affected by emulsification or gastric pH. Therefore, the presence of an intact emulsion at the start of duodenal digestion, while not impacting the extent of lipolysis, did impact the initial lipolysis and DHA bioaccessibility.

Evaluation of the risk/benefit associated to the consumption of raw and cooked farmed meagre based on the bioaccessibility of selenium, eicosapentaenoic acid and docosahexaenoic acid, total mercury, and methylmercury determined by an in vitro digestion model

The bioaccessibility of total lipids, EPA, DHA, Se, Hg, and MeHg in raw and cooked meagre (Argyrosomus regius) was studied by using an in vitro digestion method. A risk–benefit assessment of raw and cooked meagre on the basis of the bioaccessibility data was carried out. The bioaccessibility of total lipids was generally high in raw and cooked meagre with exception of grilled fish. For EPA and DHA, bioaccessibility percentages were low never surpassing the 50% in raw, boiled, and grilled meagre. The bioaccessibility percentage of Se was equal or higher than 82% (grilling treatment). Likewise, for Hg and MeHg, high bioaccessibility values were determined with exception of grilled meagre, displaying lower values of 54% and 64%, respectively. The risk–benefit probabilistic assessment brought about a recommendation of a maximum consumption of two weekly meals for boiled or roasted meagre and three weekly meals for grilled meagre.

The bioaccessibility of eicosapentaenoic acid was higher from phospholipid food products than from mono- and triacylglycerol food products in a dynamic gastrointestinal model.

The bioaccessibility of eicosapentaenoic acid (EPA) in the forms of monoacylglycerol (EPA-MAG), triacylglycerol (EPA-TAG), and phospholipid (EPA-PL) during gastrointestinal passage was compared in this study using a dynamic gastrointestinal model (TIM system). The TIM system simulated the average upper gastrointestinal tract conditions of healthy human adults after intake of a meal (fed state conditions). In this study, the three EPA-rich oils were separately homogenized with full fat milk to obtain oil-in-water emulsions. Plain yogurt was added into the mixture at an emulsion/yogurt ratio of 4:1 (w/w) as the food matrix of the test products. The results show that the test meals containing EPA-PL left the stomach compartment most efficiently in comparison with the gastric emptying of EPA-MAG and EPA-TAG. The PLs also showed a significantly (P < 0.05) higher bioaccessibility of EPA (75–80%) in comparison with MAG (30%) and TAG (38%). The better gastric emptying of EPA-PL was likely related to the more stable emulsion of EPA-PL in the test meal. EPA-PL was delivered within the meal matrix into the duodenum instead of floating on the top of the test meal matrix. EPA-MAG had the highest amount of EPA that did not leave the stomach (68% of the test meal). The results from this work indicate that EPA-PL is a more effective form of EPA for a higher lipid bioaccessibility than MAG and TAG under the test conditions.

Influence of Emulsifier Structure on Lipid Bioaccessibility in Oil–Water Nanoemulsions

The influence of several nonionic surfactants (Tween-20, Tween-40, Tween-60, Span-20, Span-60, or Span-80) and anionic surfactants (sodium lauryl sulfate, sodium stearoyl lactylate, and sodium stearyl fumarate) showed drastic differences in the rank order of lipase activity/lipid bioaccessibility. The biophysical composition of the oil and water interface has a clear impact on the bioaccessibility of fatty acids (FA) by altering the interactions of lipase at the oil-water interface. It was found that the bioaccessibility was positively correlated with the hydrophilic/lipophilic balance (HLB) of the surfactant and inversely correlated to the surfactant aliphatic chain length. Furthermore, the induction time in the jejunum increased as the HLB value increased and decreased with increasing aliphatic chain length. The rate of lipolysis slowed in the jejunum with increasing HLB and with increasing aliphatic chain length.

The role of dietary fiber in regulating lipid bioaccessibility of almonds during mastication

Almonds contain phytochemicals and nutrients that potentially have positive health benefits in relation to heart disease, diabetes and obesity. One important mechanism associated with these benefits is the bioaccessibility (release) of lipids from the almond tissue during mastication and digestion. Indeed, it has been reported that in human subjects on almond‐rich diets, a significant proportion of lipid remains undigested, mainly caused by the entrapment of lipid by intact cell walls (dietary fiber). However, the bioaccessibility of almond lipid has not yet been quantified. We have studied this by performing a mastication trial in healthy human volunteers (n = 15). The particle size distribution of chewed almonds was measured using mechanical sieving and laser diffraction methods. Lipid release from ruptured almond cells was estimated using a theoretical model based on the particle size of the chewed almond tissue and the diameter of the lipid‐rich cells. Our results showed that laser diffraction was the most reliable and efficient method. Lipid release from masticated almonds was estimated to be ~30% of total lipid and originated from the ruptured cells of the fractured tissue. This indicates that the majority of almond lipid is unavailable for the early stages of digestion. Further work will extend to studies of lipid release and digestion at more distal sites of the gastrointestinal tract. This work was funded by the BBSRC, UK (DRINC; BB/H004866/1).

Encapsulation of lipid by alginate beads reduces bio-accessibility: An in vivo13C breath test and MRI study

This paper describes an in vivo study of the use of encapsulation to alter lipid bio-accessibility in the gastro-intestinal (GI) tract. The hypothesis that encapsulation would delay the accessibility of lipid in the GI tract was tested using subjects (N=11) who consumed either 30g of 13C-labelled sunflower oil encapsulated within 70g alginate gel particles, or unencapsulated ‘free’ sunflower oil and alginate-only particles (control). Lipid accessibility was determined by the appearance of the 13C label in breath carbon-dioxide (CO2), and the particles behaviour in the GI tract was investigated using non-invasive magnetic resonance imaging (MRI).Despite apparently faster gastric emptying, encapsulation of lipid resulted in a mean 47min delay in the time to peak of the 13C label reaching the breath and a reduction in the initial slope of the 13C breath curve (both p<0.05). Furthermore the gall bladder ejection fraction measured from MRI data was significantly smaller for the encapsulated lipid meal. We suggest this was due to delayed accessibility of the lipid for its digestion to the free fatty acids which are required to stimulate duodenal receptors and the release of cholecystokinin (CCK). This would account for both the smaller gall bladder response and faster gastric emptying observed with the encapsulated lipid meal.This study showed that encapsulation is an effective strategy to control the GI fate of lipids. It also showed that multimodal studies including MRI are powerful tools for investigating how the body handles food components and may aid in the design of food products with controlled functionality.

Manipulation of lipid bioaccessibility influences postprandial vitamin E concentrations in healthy human subjects: implications for inflammation, oxidative stress and vascular responses.

Postprandial lipemia is associated with an acute elevation in oxidative stress, inflammation and impaired vascular function, which is attenuated by the presence of antioxidant vitamins. We previously reported that slow release (low bioaccessibility) of lipid from whole almonds (WA) during digestion, compared with free oil from almond (AO) or sunflower (SO) seeds, reduced postprandial lipemia (over 8h), but no effects on oxidative stress and vascular function were found1. Subjects (n=20, aged 18‐40y) were fed test meals containing 50g fat provided as WA, AO or SO in a randomised cross‐over design, with 1‐wk washout. Additional analysis to investigate the effects of differences in lipid bioaccessibility on changes in plasma vitamin E and interleukin 6 (IL‐6; inflammatory marker) concentrations are presented. Plasma vitamin E concentrations were lower (mean incremental area under curve with 95% CI) following the WA meal (69 (25, 113)) vs. the AO (150 (211, 88)) and CO (137 (190, 84)) meals; P=0.003. IL‐6 concentrations increased significantly from fasting following the test meals (P=0.023), but did not differ between meals. The concomitant increase in plasma vitamin E with postprandial lipemia from the free oils may counterbalance the deleterious effects of exaggerated lipemia on oxidative stress, inflammation and vascular function.1Berry et al. Am J Clin Nutr 2008;88:922‐9

Application of a duplex PCR approach for the specific and simultaneous detection of Bifidobacterium spp. and lactobacillus spp. in duodenum, jejunum, ileum and cecum of broilers

Bifidobacterium spp. and Lactobacillus spp genera are useful and important microbiota which affect poultry performance. These bacteria are natural inhabitants of the intestine of broilers. These bacteria have a unique hexose metabolism that occurs via the phosphoketolase pathway. Bifidobacterium spp. produces the vitamins B1, B2, B6, B12, nicotinic acid and folic acid. Enzymatic hydrolysis by Bifidobacterium spp. increases bioaccessibility of lipids and proteins. Lactobacillus spp. exhibit properties which include the ability to adhere to cells, persist and multiply and produce acids, hydrogen peroxide and bacteriocidal and bacteriostatic agents. The ability of Lactobacillus to inhibit bacterial pathogens including E. coli and Salmonella species and to influence parasitic infection including Cryptosporidium parvum, Eimeria acervulina, and Giardia intestinalis (Seidavi et al. 2008). The aim of this study was to develop a method for the direct and simultaneous detection of Bifidobacterium spp. and Lactobacillus spp.in the intestine by multiplex PCR.

Mastication of almonds: effects of lipid bioaccessibility, appetite, and hormone response

Background: Epidemiologic and clinical data indicate that nuts can be incorporated into the diet without compromising body weight. This has been attributed to strong satiety properties, increased resting energy expenditure, and limited lipid bioaccessibility.Objective: The role of mastication was explored because of evidence that the availability of nut lipids is largely dependent on the mechanical fracture of their cell walls.Design: In a randomized, 3-arm, crossover study, 13 healthy adults (body mass index, in kg/m2: 23.1 ± 0.4) chewed 55 g almonds 10, 25, or 40 times. Blood was collected and appetite was monitored during the following 3 h. Over the next 4 d, all foods were provided, including 55 g almonds, which were consumed under the same chewing conditions. Complete fecal samples were collected.Results: Hunger was acutely suppressed below baseline (P < 0.05), and fullness was elevated above baseline longer (P < 0.05) after 40 chews than after 25 chews. Two hours after consumption, fullness levels were significantly lower and hunger levels were significantly higher after 25 chews than after 10 and 40 chews (P < 0.05). Initial postingestive glucagon-like peptide-1 concentrations were significantly lower after 25 chews than after 40 chews (P < 0.05), and insulin concentrations declined more rapidly after 25 and 40 chews than after 10 chews (both P < 0.05). Fecal fat excretion was significantly higher after 10 chews than after 25 and 40 chews (both P < 0.05). All participants had higher fecal energy losses after 10 and 25 chews than after 40 chews (P < 0.005).Conclusion: The results indicate important differences in appetitive and physiologic responses to masticating nuts and likely other foods and nutrients. This trial was registered at clinicaltrials.gov as NCT00768417.

Manipulation of lipid bioaccessibility of almond seeds influences postprandial lipemia in healthy human subjects

Background: Plant cell walls are known to influence the rate and extent of lipid release from plant food tissues during digestion; however, the effect of cell wall structure on postprandial lipemia is unknown.Objective: The objective was to investigate the effects of lipid release (bioaccessibility) on postprandial lipemia by comparing lipid encapsulated by cell walls with lipid present as free oil.Design: A randomized crossover trial (n = 20 men) compared the effects of 3 meals containing 54 g fat provided as whole almond seed macroparticles (WA), almond oil and defatted almond flour (AO), or a sunflower oil blend as control (CO) on postprandial changes in oxidative stress (8-isoprostane F2α concentrations), vascular tone (peripheral augmentation index), and plasma triacylglycerol, glucose, and insulin concentrations.Results: The postprandial increase in plasma triacylglycerol was lower [74% and 58% lower incremental area under curve (iAUC)] after the WA meal than after the AO and CO meals (P < 0.001). Increases in plasma glucose concentrations (0–180 min) were significantly higher after the WA meal (iAUC: 114; 95% CI: 76, 153) than after the AO meal (iAUC: 74; 95% CI: 48, 99) (P < 0.05), but no significant differences from the CO meal were observed (iAUC: 88; 95% CI: 66, 109). The peak reductions in peripheral augmentation index after the WA, AO, and CO meals (−9.5%, −10.1%, and −12.6%, respectively, at 2 h) were not significantly different between meals. Plasma 8-isoprostane F2α and insulin concentrations did not differ significantly between meals.Conclusions: The bioaccessibility of lipid in almond seeds, which is regulated by the structure and properties of cell walls, plays a primary role in determining postprandial lipemia.

Manipulation of lipid bioaccessibility of almonds influences postprandial lipemia in healthy human subjects

An exaggerated postprandial lipemic response is associated with increased risk of coronary heart disease, due to acute effects on lipids, oxidative stress, hemostatic factors and vascular function. Lipid released slowly from a complex food matrix during digestion may attenuate postprandial lipemia1. The present study therefore investigates the effects of lipid release (lipid bioaccessibility (LB)) on postprandial changes (over 8h) in plasma triacylglycerol (TAG) concentration, oxidative stress (measured by 8‐isoprostane F2α) and vascular function (measured by peripheral augmentation index (PAIx)). Subjects (n = 20, aged 18–40y) were fed test meals containing 50g fat of low LB (intact whole almonds; WA), high LB (almond oil + defatted almond flour; AO) or as a control meal (CO) in a randomised cross‐over design, with 1‐wk washout. The postprandial increase in plasma TAG was significantly lower (74% &amp; 58% lower incremental area under curve) following the WA vs. the AO and CO meals, respectively (P&lt;0.001). The peak reduction in PAIx (by −9.5%, −10.1% &amp; −12.6% at 2h following WA, AO and CO meals respectively, time effect; P&lt;0.001) was not significantly different between meals. There were no changes in plasma 8‐isoprostane F2α concentrations. Reducing LB of almonds beneficially influences postprandial lipemia.This study was funded by the Almond Board of California

The effect of mastication on appetite and lipid bioaccessibility

The effect of mastication on appetite and lipid bioaccessibility

Mathematical modelling of lipid bioaccessibility in almond seeds

Mathematical modelling of lipid bioaccessibility in almond seeds

Effect of Partially Hydrolyzed Guar Gum (PHGG) on the Bioaccessibility of Fat and Cholesterol

The addition of a compound that lowers the intestinal uptake of fat and cholesterol might be an interesting strategy to reduce the risk of vascular disease. Partially hydrolyzed guar gum (PHGG) has been shown to have this effect in healthy volunteers after intake of a yogurt drink with 3 to 6% PHGG. In the present study a yogurt drink with 3% sunflower oil and 4% egg yolk was tested with 3% and 6% PHGG, and compared to a control without PHGG. Experiments were performed in a multi-compartmental model of the gastrointestinal tract, equipped to study the digestion and availability for absorption (bioaccessibility) of lipids. The results show that PHGG decreases the bioaccessibility of both fat and cholesterol in a dose-dependent manner. The bioaccessibility of fat was 79.4+/-1.7%, 70.8+/-2.5% and 60.1+/-1.1% for the control experiments and the experiments with 3% and 6% PHGG respectively. The bioaccessibility of cholesterol was 82.2+/-2.0%, 75.4+/-1.2% and 64.0+/-4.3% for the control and the experiments with 3% and 6% PHGG respectively. Additional experiments indicated that PHGG reduces bioaccessibility through the depletion flocculation mechanism. Depletion flocculation antagonizes the emulsification by bile salts and thus decreases lipolytic activity, resulting in a lower bioaccessibility of fat and cholesterol. Depletion flocculation with polymers might be an interesting mechanism, not described before, to reduce fat and cholesterol absorption.

Role of cell walls in the bioaccessibility of lipids in almond seeds

Certain nutrients and phytochemicals in almonds may confer protection against cardiovascular disease, but little is known about factors that influence their bioavailability. A crucial and relevant aspect is the amount of these dietary components available for absorption in the intestine, which is a concept referred to as bioaccessibility. We investigated the role played by cell walls in influencing the bioaccessibility of intracellular lipid from almond seeds. Quantitative analyses of nonstarch polysaccharides (NSPs) and phenolic compounds of cell walls were performed by gas-liquid chromatography and HPLC, respectively. In a series of experiments, the effects of mechanical disruption, chewing, and digestion on almond seed microstructure and intracellular lipid release were determined. In the digestibility study, fecal samples were collected from healthy subjects who had consumed diets with or without almonds. Almond seeds and fecal samples were examined by microscopy to identify cell walls and intracellular lipid. Cell walls were found to be rich in NSPs, particularly arabinose-rich polysaccharides, with a high concentration of phenolic compounds detected in the seed coat cell wall. During disruption of almond tissue by mechanical methods or chewing, only the first layer of cells at the fractured surface was ruptured and able to release lipid. In fecal samples collected from subjects consuming the almond diet, we observed intact cotyledonary cells, in which the cell walls encapsulated intracellular lipid. This lipid appeared susceptible to colonic fermentation once the cotyledonary cell walls were breached by bacterial degradation. The cell walls of almond seeds reduce lipid bioaccessibility by hindering the release of lipid available for digestion.