α-Lactalbumin Peptide Asp-Gln-Trp Ameliorates Hepatic Steatosis and Oxidative Stress in Free Fatty Acids-Treated HepG2 Cells and High-Fat Diet-Induced NAFLD Mice by Activating the PPARα Pathway.

SCOPE: Dietary intervention has emerged as a promising strategy for the management of nonalcoholic fatty liver disease (NAFLD). The aim of this study is to investigate the ameliorative effects of the α-lactalbumin peptide Asp-Gln-Trp (DQW) against NAFLD and the underlying mechanism. METHODS AND RESULTS: The models of lipid metabolism disorders are established both in HepG2 cells and in C57BL/6J mice. The results demonstrate that DQW activates peroxisome proliferator-activated receptor α (PPARα) and subsequently ameliorates lipid deposition and oxidative stress in vitro. Interestingly, GW6471 markedly attenuates the modulatory effects of DQW on the PPARα pathway in HepG2 cells. Moreover, results of in vivo experiments indicate that DQW alleviates body weight gain, dyslipidemia, hepatic steatosis, and oxidative stress in high-fat-diet (HFD)-induced NAFLD mice. At the molecular level, DQW activates PPARα, subsequently enhances fatty acid ß-oxidation, and reduces lipogenesis, thereby ameliorating hepatic steatosis. Meanwhile, DQW may ameliorate liver injury and oxidative stress via activating the PPARα/nuclear-factor erythroid 2 (Nrf2)/heme-oxygenase 1 (HO-1) pathway. CONCLUSION: Those results indicate that α-lactalbumin peptide DQW may be an effective dietary supplement for alleviating NAFLD by alleviating lipid deposition and oxidative stress.

Applications for α-lactalbumin in human nutrition.

α-Lactalbumin is a whey protein that constitutes approximately 22% of the proteins in human milk and approximately 3.5% of those in bovine milk. Within the mammary gland, α-lactalbumin plays a central role in milk production as part of the lactose synthase complex required for lactose formation, which drives milk volume. It is an important source of bioactive peptides and essential amino acids, including tryptophan, lysine, branched-chain amino acids, and sulfur-containing amino acids, all of which are crucial for infant nutrition. α-Lactalbumin contributes to infant development, and the commercial availability of α-lactalbumin allows infant formulas to be reformulated to have a reduced protein content. Likewise, because of its physical characteristics, which include water solubility and heat stability, α-lactalbumin has the potential to be added to food products as a supplemental protein. It also has potential as a nutritional supplement to support neurological function and sleep in adults, owing to its unique tryptophan content. Other components of α-lactalbumin that may have usefulness in nutritional supplements include the branched-chain amino acid leucine, which promotes protein accretion in skeletal muscle, and bioactive peptides, which possess prebiotic and antibacterial properties. This review describes the characteristics of α-lactalbumin and examines the potential applications of α-lactalbumin for human health.

Role of continuous phase protein, (-)-epigallocatechin-3-gallate and carrier oil on ß-carotene degradation in oil-in-water emulsions.

The chemical instability of ß-carotene limits its utilization as a nutraceutical ingredient in foods. In this research, the effect of continuous phase alpha-lactalbumin (α-LA) and (-)-epigallocatechin-3-gallate (EGCG) on ß-carotene degradation in medium chain triacylglycerol (MCT)- and corn oil-in-water emulsions was examined. EGCG significantly inhibited ß-carotene degradation in both MCT and corn oil-in-water emulsions in a dose dependent manner. α-LA was not able to protect ß-carotene in MCT emulsions and the combination of EGCG and α-LA had a similar effect as EGCG alone. EGCG had no effect on lipid oxidation in corn oil-in-water emulsions but can protect ß-carotene. ß-Carotene was more stable in corn oil emulsions stabilized by α-LA compared to emulsions stabilized by Tween 20. These results show that EGCG is effective at protecting ß-carotene in different emulsion systems without negatively impacting lipid oxidation suggesting that it could be utilized to increase the incorporation of ß-carotene into food emulsions.

Bovine milk-derived α-lactalbumin inhibits colon inflammation and carcinogenesis in azoxymethane and dextran sodium sulfate-treated mice.

Cyclooxygenase-2 is expressed early in colon carcinogenesis and plays crucial role in the progress of the disease. Recently, we found that α-lactalbumin had anti-inflammatory activity by inhibiting cyclooxygenase-2. In experiment 1, we investigated the effects of α-lactalbumin on the colon carcinogenesis initiated with azoxymethane (AOM) followed by promotion with dextran sodium sulfate (DSS) in mice. Dietary treatment with α-lactalbumin decreased fecal occult blood score at 3 days after DSS intake. α-Lactalbumin also decreased the colon tumor at week 9. In experiment 2, AOM-treated mice were sacrificed at 7 days after DSS intake. The plasma and colon prostaglandin E2 (PGE2) levels in AOM/DSS-treated mice were higher than those in the DSS-treated mice without initiation by AOM. α-Lactalbumin decreased PGE2 in both plasma and colon. These results suggest that α-lactalbumin effectively inhibited colon carcinogenesis, and the inhibition may be due to the decreased PGE2 by inhibiting cyclooxygenase-2 at cancer promotion stages.

Milk-derived proteins and peptides in clinical trials.

Clinical trials are reviewed, involving proteins and peptides derived from milk (predominantly bovine), with the exception of lactoferrin, which will be the subject of another article. The most explored milk fraction is α-lactalbumin (LA), which is often applied with glycomacropeptide (GMP) - a casein degradation product. These milk constituents are used in health-promoting infant and adult formulae as well as in a modified form (HAMLET) to treat cancer. Lactoperoxidase (LCP) is used as an additive to mouth hygiene products and as a salivary substitute. Casein derivatives are applied, in addition, in the dry mouth syndrome. On the other hand, casein hydrolysates, containing active tripeptides, found application in hypertension and in type 2 diabetes. Lysozyme is routinely used for food conservation and in pharmaceutical products. It was successfully used in premature infants with concomitant diseases to improve health parameters. When used as prophylaxis in patients with scheduled surgery, it significantly reduced the incidence of hepatitis resulting from blood transfusion. Lysozyme was also used in infected children as an antimicrobial agent showing synergistic effects in combination with different antibiotics. Proline-rich polypeptide (PRP) was introduced to therapy of Alzheimer's disease patients. The therapeutic value of PRP was proved in several clinical trials and supported by studies on its mechanism of action. Concentrated immunoglobulin preparations from colostrum and milk of hyperimmunized cows showed efficacy in prevention of infections by bacteria, viruses and protozoa. A nutrition formula with milk-derived TGF-ß2 (Modulen IBD®) found application in treatment of pediatric Crohn's disease. In conclusion, the preparations containing milk-derived products are safe and effective measures in prevention and treatment of infections as well as autoimmune and neoplastic diseases.

Sensitization of Staphylococcus aureus to methicillin and other antibiotics in vitro and in vivo in the presence of HAMLET.

HAMLET (human alpha-lactalbumin made lethal to tumor cells) is a protein-lipid complex from human milk with both tumoricidal and bactericidal activities. HAMLET exerts a rather specific bactericidal activity against some respiratory pathogens, with highest activity against Streptococcus pneumoniae, but lacks activity against most other bacterial pathogens, including Staphylococci. Still, ion transport associated with death in S. pneumoniae is also detected to a lower degree in insensitive organisms. In this study we demonstrate that HAMLET acts as an antimicrobial adjuvant that can increase the activity of a broad spectrum of antibiotics (methicillin, vancomycin, gentamicin and erythromycin) against multi-drug resistant Staphylococcus aureus, to a degree where they become sensitive to those same antibiotics, both in antimicrobial assays against planktonic and biofilm bacteria and in an in vivo model of nasopharyngeal colonization. We show that HAMLET exerts these effects specifically by dissipating the proton gradient and inducing a sodium-dependent calcium influx that partially depolarizes the plasma membrane, the same mechanism induced during pneumococcal death. These effects results in an increased cell associated binding and/or uptake of penicillin, gentamicin and vancomycin, especially in resistant stains. Finally, HAMLET inhibits the increased resistance of methicillin seen under antibiotic pressure and the bacteria do not become resistant to the adjuvant, which is a major advantageous feature of the molecule. These results highlight HAMLET as a novel antimicrobial adjuvant with the potential to increase the clinical usefulness of antibiotics against drug resistant strains of S. aureus.

A molecular complex of bovine milk protein and oleic acid selectively kills cancer cells in vitro and inhibits tumour growth in an orthotopic rat bladder tumour model.

UNLABELLED: WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: Novel intravesical therapies are needed for superficial bladder cancer that reduce the risk of infection associated with Bacillus Calmette-Guérin (BCG) and further destabilization of the urothelium associated with cytotoxic chemotherapy. Experimental therapies to date have included photodynamic therapy, oncolytic viruses, gene therapy (antisense oligonucleotides and silencing RNA), cytokine therapy, death receptor agonists (tumour-necrosis-factor-related apoptosis-inducing ligand and anti-DR5 monoclonal antibody), naturally occurring substances (curcumin and deguelin) and human α-lactalbumin made lethal to tumour cells (HAMLET). HAMLET, a natural occurring product in milk, induces apoptosis in urothelial cancer cells but has limitations in clinical application because of its human source. A previous study in patients with bladder cancer has demonstrated that intravesical HAMLET (daily for 5 days before tumour resection) caused selective apoptotic tumour cell death. BAMLET, the bovine equivalent of HAMLET, is a complex of bovine α-lactalbumin and oleic acid (bLAC) that has been shown in vitro to accumulate in the endolysosomal compartment of tumour cells and induce leakage of lysosomal cathepsins into the cytosol followed by activation of the pro-apoptotic protein Bax. This is the first in vivo study to show that BAMLET (bLAC) induces apoptosis in urothelial cancer cells and controls the growth of high risk urothelial cancer in a syngeneic rat orthotopic model. This same bladder cancer model system has been used to test other novel therapies, including BCG, and therefore provides a relative comparison of its effectiveness with other intravesical therapies. OBJECTIVE: To investigate the efficacy of a complex of bovine α-lactalbumin and oleic acid (bLAC) to kill urothelial cancer cells in vitro and inhibit tumour growth and progression in a high risk bladder tumour model. MATERIALS AND METHODS: The cytotoxicity of bLAC to a large panel of urothelial cell cancer (UCC) cells was tested by the MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) assay, using bLA, the folded α-lactalbumin without oleic acid, as a control. The mechanism of bLAC-inducing cell death was evaluated by annexin V staining, TUNEL (terminal deoxynucleotidyl transferase mediated nick end labelling) assay and sub-G1 DNA analysis. The selective bLAC cytotoxicity was examined using multicellular spheroids consisting of UCC and non-transformed fibroblasts. Rats bearing orthotopic tumour received intravesical instillations (twice weekly, for 3 weeks) of bLAC, bLA, BCG or saline, starting 6 days after UCC (AY-27) cell inoculation. Animals were monitored for survival, toxicity and tumour growth control. RESULTS: A dose-dependent bLAC-inducing apoptotic-like cell death was shown in UCC cells tested, including cells refractory to classic apoptosis-inducing agents, whereas bLA showed little cytotoxicity. bLAC selectively destroyed cancer cells in spheroids. Intravesical bLAC therapy demonstrated marked reduction in tumour growth/progression and significantly prolonged animal survival vs saline instillations (P = 0.004, log-rank test) and showed comparable efficacy with BCG (standard) therapy. CONCLUSION: The findings identify bLAC as a new candidate for UCC therapy and suggests that topical administration of bLAC alone or with BCG to prevent progression of bladder cancer warrants further exploration.

In vitro adventitious shoot regeneration via indirect organogenesis from inflorescence explants and peroxidase involvement in morphogenesis of Populus euphratica Olivier.

The inflorescences as explants for rapid propagation in vitro remained unknown in Populus euphratica Olivier. Here, we reported that multiple shoots were initiation from calli of both male and female inflorescences. The optimum medium for shoot induction from male inflorescences was lactose sulfite medium containing 1.0 mg L(-1) 6-benzylaminopurine (BA) and 0.5 mg L(-1) α-naphthalene acetic acid (NAA) or Murashige and Skoog (MS) medium containing 0.5 mg L(-1) BA and 0.2 mg L(-1) NAA. The optimum medium of shoot induction from female inflorescence calli was the MS medium containing 0.5 mg L(-1) BA and 0.2 mg L(-1) NAA. Rooting of regenerated shoots was obtained on 1/2 MS medium supplemented with 0.5∼1.0 mg L(-1) indole-3-butyric acid (IBA) and the highest frequency rooting was on medium containing 0.5 mg L(-1) IBA. No shoots were obtained on medium without BA and NAA. Peroxidase (POD) activity was measured by polyacrylamide gel electrophoresis during shoot induction and differentiation stages. The results showed that two bands of POD (2a and 2b) activity appeared lowest during the early 8 days at the dedifferentiation phase of leaves inducing calli, whereas POD 2a, 2b activity appeared to be increasing at the homeochronous dedifferentiation phase of inflorescence. Five most intensive bands, POD 1a, 1b, 1c, 2a, and ab, appeared in 8th and 28th days at the redifferentiation phase during shoot morphogenesis. These results demonstrated that the POD was involved in shoot morphogenesis from both leaf and inflorescence explants of Populus euphratica.

Exploring a new jellyfish collagen in the production of microparticles for protein delivery.

A microparticulate protein delivery system was developed using collagen, from the medusa Catostylus tagi, as a polymeric matrix. Collagen microparticles (CMPs) were produced by an emulsification-gelation-solvent extraction method and a high loading efficiency was found for the entrapment of lysozyme and α-lactalbumin. CMPs were cross-linked with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). The uncross-linked CMPs were spherical, rough-surfaced, presenting an estimated median size of 28 µm by laser diffraction. Upon cross-linking, particle size (9.5 µm) and size distribution were reduced. CMPs showed a moderate hydrophobic behaviour and a positive surface charge. Cross-linking also resulted in greater stability in water, allowing a slow release, as shown by in vitro experiments. The assessment of lysozyme's biological activity showed that the protein remained active throughout the encapsulation and cross-linking processes. In summary, the work herein described shows the potential use of a marine collagen in the production of microparticles for the controlled release of therapeutic proteins.

Effects of different fractions of whey protein on postprandial lipid and hormone responses in type 2 diabetes.

BACKGROUND/OBJECTIVES: Exacerbated postprandial lipid responses are associated with an increased cardiovascular risk. Dietary proteins influence postprandial lipemia differently, and whey protein has a preferential lipid-lowering effect. We compared the effects of different whey protein fractions on postprandial lipid and hormone responses added to a high-fat meal in type 2 diabetic subjects. SUBJECTS/METHODS: A total of 12 type 2 diabetic subjects ingested four isocaloric test meals in randomized order. The test meals contained 100 g of butter and 45 g of carbohydrate in combination with 45 g of whey isolate (iso-meal), whey hydrolysate (hydro-meal), α-lactalbumin enhanced whey (lac-meal) or caseinoglycomacropeptide enhanced whey (CGMP-meal). Plasma concentrations of triglyceride, retinyl palmitate, free fatty acid, insulin, glucose, glucagon, glucagon-like peptide 1 and glucose-dependent insulinotropic peptide were measured before and at regular intervals until 8-h postprandially. RESULTS: We found no statistical significant differences between meals on our primary variable triglyceride. The retinyl palmitate response was higher after the hydro-meal than after the iso- and lac-meal in the chylomicron-rich fraction (P=0.008) while no significant differences were found in the chylomicron-poor fraction. The hydro- and iso-meal produced a higher insulin response compared with the lac- and CGMP-meal (P<0.001). Otherwise no significant differences in the hormone responses were found in the incremental area under the curve over the 480-min period. CONCLUSIONS: A supplement of four different whey protein fractions to a fat-rich meal had similar effects on postprandial triglyceride responses in type 2 diabetic subjects. Whey isolate and whey hydrolysate caused a higher insulin response.

α-Lactalbumin and casein-glycomacropeptide do not affect iron absorption from formula in healthy term infants.

Iron absorption from infant formula is relatively low. α-Lactalbumin and casein-glycomacropeptide have been suggested to enhance mineral absorption. We therefore assessed the effect of α-lactalbumin and casein-glycomacropeptide on iron absorption from infant formula in healthy term infants. Thirty-one infants were randomly assigned to receive 1 of 3 formulas (4 mg iron/L, 13.1 g protein/L) from 4-8 wk to 6 mo of age: commercially available whey-predominant standard infant formula (standard formula), α-lactalbumin-enriched infant formula (α-LAC), or α-lactalbumin-enriched/casein-glycomacropeptide-reduced infant formula (α-LAC/RGMP). Nine breast-fed infants served as a reference. At 5.5 mo of age, (58)Fe was administered to all infants in a meal. Blood samples were collected 14 d later for iron absorption and iron status indices. Iron deficiency was defined as depleted iron stores, iron-deficient erythropoiesis, or iron deficiency anemia. Iron absorption (mean ± SD) was 10.3 ± 7.0% from standard formula, 8.6 ± 3.8% from α-LAC, 9.2 ± 6.5% from α-LAC/RGMP, and 12.9 ± 6.5% from breast milk, with no difference between the formula groups (P = 0.79) or all groups (P = 0.44). In the formula-fed infants only, iron absorption was negatively correlated with serum ferritin (r = -0.49; P = 0.005) and was higher (P = 0.023) in iron-deficient infants (16.4 ± 12.4%) compared with those with adequate iron status (8.6 ± 4.4%). Our findings indicate that α-lactalbumin and casein-glycomacropeptide do not affect iron absorption from infant formula in infants. Low serum ferritin concentrations are correlated with increased iron absorption from infant formula.

α-Lactoalbúmina como ingrediente de fórmulas infantiles

La α-lactoalbúmina es la principal proteína del lactosuero en la leche materna, alcanzando una concentración de 2,44 g/L en la leche madura. Su principal función es la síntesis de lactosa a partir de glucosa y galactosa en la glándula mamaria, aunque posee además otros efectos beneficiosos sobre la salud del lactante debido a su elevada proporción de aminoácidos esenciales (triptófano y cisteína). Según diversos estudios parece influir positivamente en la absorción de hierro en el intestino del niño, y en experimentos in vitro, unida al ácido oleico (complejo HAMLET), es efectiva frente a tumores celulares como el papiloma humano. El complejo HAMLET también presenta un claro efecto antimicrobiano frente a Streptococcus pneumoniae, Haemophilus influenzae, cepas enteropatógenas de Escherichia coli y Salmonella thypimurium, sin embargo no se ha demostrado que durante la digestión de la leche materna se forme dicho complejo en el tracto digestivo del lactante. El desarrollo de fórmulas infantiles destinadas a la alimentación del niño durante el primer año de vida ha mejorado considerablemente en las últimas décadas intentando no sólo adecuar la concentración de nutrientes a los requerimientos del lactante, sino también adicionando compuestos bioactivos de diferente naturaleza, como la α-lactoalbúmina, con el objetivo de alcanzar los efectos funcionales que se producen en los niños alimentados con leche materna.

α-Lactalbumin as an ingredient of infant formula. α-lactalbumin is the main whey protein in human milk rising 2,44 g/L in mature milk. It has a key function in the synthesis of lactose from glucose and galactose in the mammary gland although this compound has also other beneficial effects on the infant health due to the high proportion of essential aminoacids (tryptophan and cysteine). It seems also to increase iron absorption in the digestive track, and in in vitro experiments, linked to oleic acid (HAMLET complex), has shown anticarcinogenic effects against cellular tumor such as human papilloma. In addition, this complex has been reported to exhibit antimicrobial properties against Streptococcus pneumoniae,Haemophilus influenzae, enteropathogenic strains of Escherichia coli and Salmonella thypimurium. However, the in vivo synthesis of HAMLET complex during milk digestion has not been proved yet. Infant formula have been improved considerably during the last decades not only adapting nutrient concentrations to infants requirements but also by the addition of new bioactive ingredients such as α-lactalbumin, to have the same functional effect as in breast fed babies.

[Alpha-Lactalbumin as an ingredient of infant formula]. / Alpha-Lactoalbúmina como ingrediente de fórmulas infantiles.

Alpha-Lactalbumin is the main whey protein in human milk rising 2,44 g/L in mature milk. It has a key function in the synthesis of lactose from glucose and galactose in the mammary gland although this compound has also other beneficial effects on the infant health due to the high proportion of essential aminoacids (tryptophan and cysteine). It seems also to increase iron absorption in the digestive track, and in in vitro experiments, linked to oleic acid (HAMLET complex), has shown anticarcinogenic effects against cellular tumor such as human papilloma. In addition, this complex has been reported to exhibit antimicrobial properties against Streptococcus pneumoniae, Haemophilus influenzae, enteropathogenic strains of Escherichia coli and Salmonella thypimurium. However, the in vivo synthesis of HAMLET complex during milk digestion has not been proved yet. Infant formula have been improved considerably during the last decades not only adapting nutrient concentrations to infants requirements but also by the addition of new bioactive ingredients such as alpha-lactalbumin, to have the same functional effect as in breast fed babies.

Effects of whey protein supplements on metabolism: evidence from human intervention studies.

PURPOSE OF REVIEW: Epidemiological studies indicate that the consumption of milk and dairy products is inversely associated with a lower risk of metabolic disorders and cardiovascular diseases. In particular, whey protein seems to induce these effects because of bioactive compounds such as lactoferrin, immunoglobulins, glutamine and lactalbumin. In addition, it is an excellent source of branch chained amino acids. This review summarizes recent findings on the effects of whey protein on metabolic disorders and the musculoskeletal system. RECENT FINDINGS: We identified 25 recently published intervention trials examining chronic and/or acute effects of whey protein supplementation on lipid and glucose metabolism, blood pressure, vascular function and on the musculoskeletal system. Whey protein appears to have a blood glucose and/or insulin lowering effect partly mediated by incretins. In addition, whey protein may increase muscle protein synthesis. In contrast there are no clear-cut effects shown on blood lipids and lipoproteins, blood pressure and vascular function. For bone metabolism the data are scarce. SUMMARY: In summary, whey protein may affect glucose metabolism and muscle protein synthesis. However, the evidence for a clinical efficacy is not strong enough to make final recommendations with respect to a specific dose and the duration of supplementation.

Effects of an acute alpha-lactalbumin manipulation on mood and food hedonics in high- and low-trait anxiety individuals.

Serotonergic hypofunction is associated with a depressive mood state, an increased drive to eat and preference for sweet (SW) foods. High-trait anxiety individuals are characterised by a functional shortage of serotonin during stress, which in turn increases their susceptibility to experience a negative mood and an increased drive for SW foods. The present study examined whether an acute dietary manipulation, intended to increase circulating serotonin levels, alleviated the detrimental effects of a stress-inducing task on subjective appetite and mood sensations, and preference for SW foods in high-trait anxiety individuals. Thirteen high- (eleven females and two males; anxiety scores 45.5 (sd 5.9); BMI 22.9 (sd 3.0)kg/m(2)) and twelve low- (ten females and two males; anxiety scores 30.4 (sd 4.8); BMI 23.4 (sd 2.5) kg/m(2)) trait anxiety individuals participated in a placebo-controlled, two-way crossover design. Participants were provided with 40 g alpha-lactalbumin (LAC; l-tryptophan (Trp):large neutral amino acids (LNAA) ratio of 7.6) and 40 g casein (placebo) (Trp:LNAA ratio of 4.0) in the form of a snack and lunch on two test days. On both the test days, participants completed a stress-inducing task 2 h after the lunch. Mood and appetite were assessed using visual analogue scales. Changes in food hedonics for different taste and nutrient combinations were assessed using a computer task. The results demonstrated that the LAC manipulation did not exert any immediate effects on mood or appetite. However, LAC did have an effect on food hedonics in individuals with high-trait anxiety after acute stress. These individuals expressed a lower liking (P = 0.012) and SW food preference (P = 0.014) after the stressful task when supplemented with LAC.

Effects of a breakfast yoghurt, with additional total whey protein or caseinomacropeptide-depleted alpha-lactalbumin-enriched whey protein, on diet-induced thermogenesis and appetite suppression.

Previous studies have shown effects of high-protein diets, especially whey protein, on energy expenditure and satiety, yet a possible distinction between the effects of whey or alpha-lactalbumin has not been made. The present study assessed the effects of the addition of total whey protein (whey) or caseinomacropeptide-depleted alpha-lactalbumin-enriched whey protein (alpha-lac) to a breakfast yoghurt drink on energy expenditure and appetite suppression in human subjects. A total of eighteen females and seventeen males (aged 20.9 (sd 1.9) years; BMI 23.0 (sd 2.1) kg/m2) participated in an experiment with a randomised, three-arm, cross-over design where diet-induced energy expenditure, respiratory quotient and satiety were measured. Breakfasts were isoenergetic and subject-specific: a normal-protein (NP) breakfast consisting of whole milk (15, 47 and 38 % energy from protein, carbohydrate and fat, respectively), a high-protein (HP) breakfast with additional whey or a HP breakfast containing alpha-lac (41, 47 and 12 % energy from protein, carbohydrate and fat, respectively). Resting energy expenditure did not differ between the three conditions. HP breakfasts (area under the curve: whey, 217.1 (se 10.0) kJ x 4 h; alpha-lac, 234.3 (se 11.6) kJ x 4 h; P < 0.05) increased diet-induced thermogenesis more compared with a NP yoghurt at breakfast (179.7 (se 10.9) kJ x 4 h; P < 0.05). Hunger and desire to eat were significantly more suppressed after alpha-lac (hunger, - 6627 (se 823); desire to eat, - 6750 (se 805) mm visual analogue scale (VAS) x 4 h; P < 0.05) than after the whey HP breakfast (hunger, - 5448 (se 913); desire to eat, - 5070 (se 873) mm VAS x 4 h; P < 0.05). After the HP breakfasts, a positive protein balance occurred (alpha-lac, 0.35 (sd 0.18) MJ/4 h; whey, 0.37 (sd 0.20) MJ/4 h; P < 0.001); after the NP breakfast a positive fat balance occurred (1.03 (sd 0.29) MJ/4 h; P < 0.001). In conclusion, consumption of a breakfast yoghurt drink with added whey or alpha-lac increased energy expenditure, protein balance and decreased fat balance compared with a NP breakfast. The alpha-lac-enriched yoghurt drink suppressed hunger and the desire to eat more than the whey-enriched yoghurt drink.

Novel functions of bovine milk-derived alpha-lactalbumin: anti-nociceptive and anti-inflammatory activity caused by inhibiting cyclooxygenase-2 and phospholipase A2.

Milk whey proteins contain major components of alpha-lactalbumin (alphaLA) and beta-lactoglobulin (betaLG), and a minor component of lactoferrin (LF). It has been reported that LF reduces nociception and inflammation in various animal models. However, the efficacy of alphaLA and betaLG has not been clarified. This study aimed to assess the efficacy of alphaLA and betaLG in various animal models such as acetic acid-induced writhing, carrageenan-induced paw inflammation, and adjuvant induced-arthritis. Orally administered alphaLA showed (i) inhibition of writhing induced by acetic acid in mice; (ii) suppression of nociception and inflammation in rat footpads caused by carrageenan in rat; and (iii) therapeutic effects on the development of adjuvant-induced pain and inflammation in rat. In contrast, betaLG had no effects in these animal models. To clarify the anti-nociceptive and anti-inflammatory mechanisms of alphaLA, we examined the levels of interleukin (IL)-6 and prostaglandin (PG)E(2) in carrageenan-injected paw exudates. The administration of alphaLA 1 h before carrageenan injection inhibited the increased formation of IL-6 and PGE(2) in paw exudates. Next, we demonstrated in vitro enzyme-inhibition assay; cyclooxygenase (COX), phospholipase A(2), and 5-lipoxygenase. alphaLA inhibited COX and phospholipase A(2) activities. alphaLA inhibited COX and phospholipase A(2) activities. Moreover, alphaLA showed selectivity on COX-2 as compared with COX-1. However, 5-lipoxygenase activity was not affected by alphaLA. These results suggest that alphaLA is a safe and useful natural drug for patients that require anti-inflammatory drugs, as alphaLA is contained in dairy food and is frequently ingested as daily food.

Lupin (Lupinus albus) protein isolate (L-ISO) has adequate nutritional value and reduces large intestinal weight in rats after restricted and ad libitum feeding.

BACKGROUND: A protein isolate from white lupin (Lupinus albus; L-ISO) has potential as a novel human food ingredient, but its nutritional effects are unknown. METHODS: We evaluated protein quality and effects on body composition in rats of isoenergic diets of L-ISO, lactalbumin, or casein with both restricted (10-day) and ad libitum (28-day)intake. The diets were equivalent in protein per se, but supplementation was used to balance essential amino acid levels. RESULTS: In both studies, the rats consumed similar amounts of each diet, and no effect of diet on the gain:feed ratio was observed--though gain:N ratio and net protein utilization were slightly lower for the L-ISO diet. Lower large intestinal weights after the L-ISO than after the lactalbumin diet were observed in both studies. The L-ISO diet resulted in lowered body fat percentage in the 10-day study but in an elevated level in the 28-day study. Liver composition (DNA, RNA, glycogen, and fat) and plasma levels of some amino acids (His, Thr, Ala, Pro, Tyr, Val and Met) were affected by diet, but no effects on plasma lipid, glucose, or uric acid were observed. CONCLUSION: The L-ISO diet did not affect feed intake and has adequate nutritional quality in rats whilst modifying large intestinal weight in a potentially beneficial manner--suggesting potential for this protein in human nutrition.

Diet rich in alpha-lactalbumin improves memory in unmedicated recovered depressed patients and matched controls.

Depression is associated with reduced brain serotonin (5-hydroxytryptamine; 5-HT) function and with cognitive dysfunctions. A diet rich in alpha-lactalbumin protein has been found to increase the ratio tryptophan /large neutral amino acids (Trp/SigmaLNAA), and to improve cognitive functioning in individuals with high neuroticism scores. Since cognitive dysfunctions sometimes persist after remission of depression, the present study investigated the effects of alpha-lactalbumin-enriched diet on cognition in recovered depressed patients. Twenty-three recovered depressed patients and 20 healthy matched controls without a history of depression consumed meals rich in alpha-lactalbumin or casein protein in a double-blind crossover design. Mood, cognitive function and plasma amino acids were assessed at both sessions before and after dietary intake. Alpha-lactalbumin protein had no effect on mood, but improved abstract visual memory and impaired simple motor performance. These effects were independent of history of depression. Supplements of lactalbumin may be useful for nutrition research in relation to age- or disease-related memory decline. The present findings should be further examined in different (e.g. medicated) samples. The long-term effects of alpha-lactalbumin should also be investigated.

Alpha-lactalbumin-enriched diets enhance serotonin release and induce anxiolytic and rewarding effects in the rat.

Among food proteins, alpha-lactalbumin (LAC) has the highest ratio of tryptophan (Trp) over its competitor amino acids. Consequently, contrary to casein (CAS), LAC ingestion increases Trp access to the brain leading to enhanced serotonin (5-HT) synthesis. As an index of serotonergic activity, we assessed extracellular 5-HT in response to LAC ingestion, using microdialysis, and performed behavioural tests in rats in order to characterise the suggested improvements of mood observed in humans after ingestion of this protein. Rats were fed with diets enriched either in LAC or CAS as control, acutely (30 min meals) or chronically (3 and 6 days). A 30 min LAC meal significantly increased 5-HT release in the medial hypothalamus. This effect disappeared after 3 and 6 days of diet. The basal premeal 5-HT levels were increasingly enhanced by the LAC diet. Compared to a CAS meal, LAC increased the percentage of time spent on the open arms of the elevated plus maze and the number of visits to the centre of the open field, suggesting an anxiolytic-like effect. A single LAC meal decreased sucrose consumption, while 3 or 6 days diets enhanced it, reflecting an appetitive and/or rewarding action. In conclusion, LAC ingestion induces anxiolytic-like and rewarding effects possibly related to serotonergic activation. Shifting transiently, the commonly consumed CAS-enriched to LAC-enriched diets may induce beneficial effects on mood.