Absorption Of Palmitic Acid Research Articles

A Concept Formula With Large, Milk Phospholipid‐Coated Lipid Droplets Enriched With Milk Fat Decreases Palmitic Acid and Calcium Levels in Stools of Healthy, Term Infants

AbstractThis study evaluates the impact of an infant formula comprising large, dairy milk phospholipid‐coated lipid droplets containing a vegetable‐dairy lipid mixture (Concept‐Mix) with 6% of fatty acid (FA) as sn‐2 palmitic acid (PA) on infant stool characteristics. Stool samples from infants fed Concept‐Mix or standard formula with 97% vegetable lipids with 2% of FA as sn‐2 PA (Control‐Veg) are evaluated at baseline, 13 and 52 weeks of age. Overall, mean stool fat content decreases from 8 to 10 w% at baseline to <2 w% at 52 weeks. At 13 weeks, PA and Calcium (Ca) content, as well as FA sum are lower in Concept‐Mix than Control‐Veg stools, with values closer to breastfed infants. The increased dietary sn‐2 PA content is regarded as instrumental for this fecal PA reduction. Indeed, in their proof of principle study in rats fed formula‐based diets using Control‐Veg, Concept‐Mix, or Concept formula with 95% vegetable lipids (Concept‐Veg) comprising 2%, 6%, and 2% of FA as sn‐2 PA, they demonstrate that PA absorption is the highest for Concept‐Mix. Hence, a concept formula with large, milk phospholipid coated lipid droplets enriched with milk fat beneficially affects PA and Ca absorption in infants, likely due to its increased sn‐2 PA content.Practical applications: The results of these studies show the merit with regard to sn‐2 palmitic acid (PA) and Calcium absorption of increasing the sn‐2 PA content in the fat blend of infant formula by including dairy milk fat.

The mechanism of increased intestinal palmitic acid absorption and its impact on hepatic stellate cell activation in nonalcoholic steatohepatitis

Dietary palmitic acid (PA) promotes liver fibrosis in patients with nonalcoholic steatohepatitis (NASH). Herein, we clarified the intestinal absorption kinetics of dietary PA and effect of trans-portal PA on the activation of hepatic stellate cells (HSCs) involved in liver fibrosis in NASH. Blood PA levels after meals were significantly increased in patients with NASH compared to those in the control. Expression of genes associated with fat absorption and chylomicron formation, such as CD36 and MTP, was significantly increased in the intestine of NASH model rats compared with that in the controls. Plasma levels of glucagon-like peptide-2, involved in the upregulation of CD36 expression, were elevated in NASH rats compared with those in the controls. Furthermore, portal PA levels after meals in NASH rats were significantly higher than those in control and nonalcoholic fatty liver rats. Moreover, PA injection into the portal vein to the liver in control rats increased the mRNA levels associated with the activation of HSCs. Increased intestinal absorption of diet-derived PA was observed in NASH. Thus, the rapid increase in PA levels via the portal vein to the liver may activate HSCs and affect the development of liver fibrosis in NASH.

The Hepatotoxicity of Palmitic Acid in Zebrafish Involves the Intestinal Microbiota

Palmitic acid (PA) is the main saturated fatty acid naturally occurring in animal fats and vegetable oils. In recent decades, palm oil, an alternative lipid source containing high amounts of PA, has been widely used to replace fish oil in aquafeed. We investigated the hepatotoxicity of PA in zebrafish and the underlying mechanism. One-month-old zebrafish fed a high-fat diet (HFD) containing 16% soybean oil and 3 PA-incorporated HFDs [4%, 8%, and 12% PA (12PA)] for 2 wk (experiment 1) and 4 wk (experiment 2) were used to evaluate PA-induced liver damage and endoplasmic reticulum (ER) stress. Germ-free (GF) zebrafish fed low-fat, high-fat, or 12PA diets for 5 d were used to study the direct effects of PA on liver damage (experiment 3). GF zebrafish colonized with HFD or 12PA microbiota for 48 h were used to elucidate the indirect effects of PA-altered microbiota on liver damage (experiment 4). Last, GF zebrafish colonized with HFD or 12PA microbiota were used to evaluate the effects of different microbiotas on PA absorption (experiment 5). In experiment 1, the proportion of PA in the liver linearly increased as its percentage in dietary lipid increased (r2=0.83, P<0.05). In experiment 2, the expression of glucose-regulated protein 78 (Grp78) and C/EBP-homologous protein (Chop) was higher in the 12PA group than in the HFD group (2.2- and 2.7-fold, respectively; P<0.05). The activity of caspase-12 was increased by 61.1% in the 12PA group compared with the HFD group (P<0.05). In experiment 3, caspase-12 activity was higher in the 12PA group than in the HFD group (P<0.05). In experiment 4, GF zebrafish colonized with PA-altered microbiota had higher caspase-12 activity (P<0.05) than those colonized by HFD microbiota. In experiment 5, PA-altered microbiota promoted PA absorption (P<0.05) and aggravated ER stress and liver damage in the context of high-PA feeding. The PA-altered microbiota indirectly induced ER stress and liver damage in zebrafish. Moreover, the PA microbiota promoted the absorption of PA, leading to enhanced PA overflow into the liver and aggravated hepatotoxicity of PA in zebrafish.

Biotechnological and Novel Approaches for Designing Structured Lipids Intended for Infant Nutrition

AbstractHuman milk fat (HMF) is a perfect nutritional source that includes all the required ingredients which are necessary for the growth of infants up to 6 months. Although its composition may differ among mothers or during lactation stage, its unique triacylglycerol (TAG) structure remains constant which is characterized by the presence of palmitic acid (PA) at the sn‐2 position. Previous reports provided convincing information of higher PA and calcium absorption and efficient use of dietary energy when at this specific position in the TAG moiety than when PA is at the sn‐1,3 positions. During the design of structured lipids (SLs) intended for infant nutrition, this unique property is taken into consideration. Human milk fat substitutes (HMFS) enriched with important fatty acids such as omega‐3 and omega‐6 fatty acids are intended to better mimic the functions of HMF as well as provide associated health benefits. The use of microencapsulation technology and novel technologies such as ultrasound technology in conjunction with SL production and enzyme‐catalyzed reactions are evolving and ongoing issues in infant formula production. Therefore, further studies should be directed towards new process improvements in order to increase the functional properties and oxidative stabilities of HMFS. Novel technologies in lipid biotechnology related to HMFS preparation should also be explored.

Upregulated absorption of dietary palmitic acids with changes in intestinal transporters in non-alcoholic steatohepatitis (NASH).

Palmitic acid is an important risk factor for the pathogenesis of non-alcoholic steatohepatitis (NASH), but changes in palmitic acid intestinal absorption in NASH are unclear. The aim of this study was to clarify changes in palmitic acid intestinal absorption and their association with the pathogenesis of NASH. A total of 106 participants were recruited to the study, of whom 33 were control subjects (control group), 32 were patients with NASH Brunt stage 1-2 [early NASH (e-NASH)], and 41 were patients with NASH Brunt stage 3-4 [advanced NASH (a-NASH)]. 13C-labeled palmitate was administered directly into the duodenum of all participants by gastrointestinal endoscopy. Breath 13CO2 levels were measured to quantify palmitic acid absorption, and serum Apolipoprotein B-48 (ApoB-48) concentrations were measured after a test meal to quantify absorbed chylomicrons. Expressions of fatty acid (FA) transporters were also examined. The associations of breath 13CO2 levels with hepatic steatosis, fibrosis and insulin resistance was evaluated using laboratory data, elastography results and liver histology findings. Overall, 13CO2 excretion was significantly higher in e-NASH patients than in the control subjects and a-NASH patients (P<0.01). e-NASH patients had higher serum ApoB-48 levels, indicating increased palmitic acid transport via chylomicrons in these patients. Jejunal mRNA and protein expressions of microsomal triglyceride transfer protein and cluster of differentiation 36 were also increased in both NASH patient groups. The 13CO2 excretion of e-NASH patients was significantly correlated with the degree of hepatic steatosis, fibrosis and insulin resistance (P=0.005, P<0.001, P=0.019, respectively). Significantly upregulated palmitic acid absorption by activation of its transporters was evident in patients with NASH, and clinical progression of NASH was related to palmitic acid absorption. These dietary changes are associated with the onset and progression of NASH.

Detection of impaired intestinal absorption of long-chain fatty acids: validation studies of a novel test in a rat model of fat malabsorption

Classic fat balance studies detect fat malabsorption but do not discriminate between the potential causes of malabsorption, such as impaired intestinal lipolysis or reduced uptake of fatty acids. We aimed to validate a novel test for the specific, sensitive detection of impaired intestinal uptake of long-chain unesterified fatty acids in an appropriate rat model of fat malabsorption. The absorption and appearance in plasma of [(13)C]palmitic acid were determined in control rats and in rats with fat malabsorption due either to chronic bile deficiency (permanent bile diversion) or to oral administration of the lipase inhibitor orlistat (200 mg/kg diet). [(13)C]Palmitic acid results were compared with the percentage absorption of ingested dietary fat determined by fat balance. Between 1 and 6 h after intraduodenal administration, plasma [(13)C]palmitate concentrations in control rats were 4-10-fold higher than in bile-deficient rats (P < 0.05) but were not significantly different between orlistat-supplemented rats and their controls. In control and bile-deficient rats, plasma [(13)C]palmitate concentrations allowed complete discrimination between normal (>92%) and reduced (<92%) fat absorption, whereas the percentage absorption of [(13)C]palmitate over 48 h appeared to be highly correlated with the percentage absorption of ingested dietary fat (r = 0.89, P < 0.001). The [(13)C]palmitic acid absorption test detects impaired intestinal absorption of long-chain fatty acids selectively and sensitively in a rat model of fat malabsorption due to bile deficiency. Our data strongly support the use of the [(13)C]palmitic acid absorption test for the diagnosis of clinical fat malabsorption syndromes.

Effect of cafeteria diet on intestinal absorption of palmitic acid in rats

The effect of a hypercaloric cafeteria diet on the accumulative ability of small intestine palmitic acid transport in female Wistar rats was studied using everted intestinal slices. Cafeteria diet decreased jejunal and ileal absorption of palmitic acid per intestinal mass after obesity had developed. A link between gastrointestinal functions, feeding behavior, and the development of obesity induced by cafeteria diet is suggested.

Differential intestinal absorption of two fatty acid isomers: elaidic and oleic acids.

The absorption of 14C-labeled oleic acid and 14C-labeled elaidic acid was studied in bile- and pancreatic juice-diverted adult rats. In some cases these acids were compared with 14C-labeled palmitic acid absorption. Sodium taurocholate-emulsified test infusates containing an equimolar mixture of monopalmitin and two fatty acids (oleic and elaidic or palmitic), one of which was 14C labeled, were infused through a duodenal canula. The chyle was collected from the mesenteric lymphatic vessel by plastic tubing. Among the three fatty acids studied, oleic acid exhibited the highest lymphatic recovery rate (43-50%). Elaidic and palmitic acids appeared more slowly and in lesser amounts (10-17%). Simultaneously, the highest amount of chylomicrons was observed when the lipid emulsion contained oleic acid alone; the lowest was observed when elaidic acid was the only unsaturated fatty acid. Experimental data have also shown that compared with elaidic acid, oleic acid is preferentially incorporated into the lymph triglycerides. We can conclude from the data presented that the enterocytic enzymes involved in the absorption of lipids show a high degree of specificity related to the fatty acid isomery, since the absorption of elaidic acid differs markedly from its isomer oleic acid.

Does carnitine have a role in fat absorption?

The effect of D-carnitine and tetradecylglycidic acid (TDGA), an inhibitor of carnitine palmitoyltransferase, on intestinal absorption of palmitic acid was determined. The proximal intestinal segment was ligated in adult male rats and filled with 0.5 μCi of 14C-palmitic acid alone or with either D-carnitine or TDGA. Thirty minutes later the radioactivity was determined in the intestinal lumen, intestinal wall and plasma. The absorption of palmitic acid was decreased in the presence of D-carnitine (10 mg/ml) as evidenced by significantly lower levels of radioactivity in the gut wall and the plasma and by significantly greater residual radioactivity in the lumenal contents. L-carnitine had no effect on plasma radioactivity but if D- and L-carnitine were given together the effect of D-carnitine was still in evidence. TDGA also inhibited intestinal absorption of palmitic acid.

Effect of Micelle Formation on the Absorption of Neutral Fat and Fatty Acids by the Chicken

Experiments were conducted to determine the absorption of various dietary fatty acids and glycerides singly and in mixtures. Chickens with or without cannulated bile ducts or ligated pancreatic ducts were used to evaluate the absorption of fatty acids or mixtures of fatty acids and the absorption patterns of several classes of lipids and their effect on the absorption of palmitic acid under in vivo conditions. In spite of wide melting point differences, isomers of various monoglycerides or 18-carbon unsaturated fatty acids exhibited identical absorption and solubility patterns. A homologous series of saturated monoglycerides showed a maximum absorption value for the monoglycerides with fatty acids of 12 and 14 carbons. Absorption decreased with increasing chain lengths of the fatty acid in the monoglyceride. Conversely, the absorption of palmitic acid when fed with the various monoglycerides progressively increased to a maximum in the mixture containing monomyristin and then decreased when fed with monopalmitin or monostearin.

Triglyceride Configuration and Fat Absorption by the Human Infant

A metabolic balance study was performed with 11 newborn infants fed formulas identical except for the type of fat. Five infants received a formula containing natural lard (palmitic acid primarily in the 2-position of the triglyceride molecule) while six infants received a formula containing randomized lard (palmitic acid equally distributed among the 1-, 2-, and 3-positions of the triglyceride molecule). Excretion of fat by infants fed the formula containing natural lard averaged 0.30 g/kg per day (range 0.15 to 0.50) while that by infants fed randomized lard averaged 1.79 g/kg per day (range 1.09 to 3.11). All of the fatty acids of the natural lard were absorbed better, but this was most marked in the case of palmitic and stearic acids. The greater absorption of palmitic acid from lard is believed to result from the greater content of 2-monopalmitin and the lower content of free palmitic acid present in the intestine after hydrolysis. Although there is no obvious mechanism to explain the greater absorption of stearic acid from lard, it may be due to a more rapid rate or greater extent of micellization in the presence of greater amounts of 2-monopalmitin.

The effect of unabsorbed sucrose- or mannitol-induced accelerated transit on absorption in the human small intestine.

The absorption of arginine, xylose, and palmitic acid was studied by a perfusion method in a 50 cm segment of proximal small intestine of three children during normal and accelerated passage of a test solution through the segment. Accelerated transit was induced by substituting sucrose for 150 mmoles/1 of glucose in the test solution in a child with congenital sucrose-isomaltose malabsorption and mannitol in two children with normal intestines. The findings were similar in the normal children and the patient. The transit time through the test segment was shortened by 50–70%, and the absorption of palmitic acid, xylose, and arginine was reduced by an average of 42, 35, and 9.5%, respectively. These findings suggest that the slight generalized malabsorption observed in patients with congenital disaccharide malabsorption is due to the hurried passage of intestinal content through the small intestine.

The absorption of tristearin and stearic acid and tripalmitin and palmitic acid: Studies on the rate-limiting steps in rats

1. 1. In free feeding experiments in rats the absorption of labelled tristearin was poor. It remained constant over a wide dose range, but fell with a high dose. The absorption in bile fistula rats was diminished. 2. 2. The addition of triolein increased the absorption of labelled tristearin in control rats but not in bile fistula rats, suggesting that poor solubility in bile salt solution is an important step hindering the absorption of tristearin and that triolein stimulates absorption by increasing this solubility. 3. 3. Jejunal segments incubated in a micellar solution of equal concentration of labelled stearic acid and oleic acid in 10 mM sodium taurocholate took up stearic acid at a slightly faster rate than oleic in a ratio of 0.84, but incorporation into triglyceride was greater for oleic acid in the ratio of 1.3. 4. 4. When a micellar solution of equal concentration of labelled oleic and stearic acids were infused into the duodenum the content of oleic acid in lymph triglyceride was greater than that of stearic acid in a ratio of 1.35. 5. 5. When equal weights of labelled oleic and stearic acids were fed, mixed with bran, the content of oleic acid in lymph triglyceride was much greater than that for stearic acid, in a ratio of 8.9 in the first hour, falling to 4.5 by the fourth hour. These ratios are much greater than those during lymphatic absorption from equimolar micellar solution. 6. 6. We conclude that micellar solubilisation is a major rate-limiting step in the absorption of tristearin and stearic acid, that mucosal cell uptake is not rate-limiting and that esterification is only a minor rate-determining step. 7. 7. The absorption of palmitic acid by control rats was slightly increased by a large dose of triolein added to the feed, but that of tripelmitin was unaltered. Reasons for the difference in behaviour between tripalmitin and tristearin are discussed.

Pathway and form of absorption of palmitic acid in the chicken

The ratio of lipid C14 in plasma of portal vein blood to that in plasma of systemic blood was determined in chickens killed 30, 60, 90, and 150 min after injection of palmitic acid-1-C14 into their gizzards. In other experiments other ratios were determined: (a) lipid C14 in plasma of pancreaticoduodenal blood to that in portal vein blood in chickens killed 30 min after fatty acid administration; and (b) lipid C14 in jejunal vein to that in portal vein plasma in birds killed 90 and 150 min after the injection. The results demonstrated that the portal system is a significant pathway for the absorption of fatty acid from the intestines of the bird, and that during the early period absorption from the duodenum takes place. Measurement of the C14 remaining in the digestive tract contents indicated that up to 96% of the injected labeled palmitic acid was absorbed in 90 min. Analysis of ultracentrifugally-separated plasma lipoproteins in blood drawn from the pancreaticoduodenal vein half an hour after introduction of the labeled palmitic acid into the gizzard revealed that the palmitic acid was absorbed from the intestines into the bloodstream principally as triglycerides in the very low density (Sf > 20) lipoproteins.

Effect of Oleic and Linoleic Acids on the Absorption of Saturated Fatty Acids in the Chick

Palmitic and stearic acids, which are utilized very poorly by the chick when fed singly, are absorbed to a significant degree when fed in a mixture of fatty acids such as hydrolyzed lard. Experiments were conducted with chicks to determine whether oleic and linoleic acids are specifically required for absorption of the saturated fatty acids. Increasing the amount of oleic acid (O) in relation to palmitic acid (P) resulted in a linear increase in absorption of the palmitic acid. A significant improvement was detected with an oleic to palmitic acid ratio (O:P) of 0.1:1. The absorb-ability of palmitic acid was increased to 80% when the O:P ratio was 0.8:1, and maximal absorption of 85 to 90% was obtained with an O:P ratio of 1.34:1. The effect of linoleic acid (L) was less dramatic. The maximal improvement in absorption of palmitic acid was 20% with the highest levels of linoleic acid. Mixtures containing a ratio of linoleic to palmitic acid (L:P) of 1:1 or more were no better than a ratio of L:P of 0.4:1. Palmitic and stearic acids when fed together tended to depress the absorption of each other. In mixtures of these 2 saturated fatty acids, high levels of oleic acid were required for 50% absorption of each of the saturated fatty acids. When linoleic acid was fed with oleic acid and a mixture of the 2 saturated fatty acids, maximal absorption of the saturated fatty acids was obtained with lower levels of both of the unsaturated fatty acids. Oleic acid appears to play a direct role in facilitating the absorption of the saturated fatty acids. It is not known whether this effect is exerted in the lumen or in the mucosal cells of the intestine.