Effects of milk phospholipid on memory and psychological stress response
Identifieur interne : 001C09 ( Istex/Corpus ); précédent : 001C08; suivant : 001C10Effects of milk phospholipid on memory and psychological stress response
Auteurs : Juliane Hellhammer ; Alireza Waladkhani ; Torsten Hero ; Claudia BussSource :
- British Food Journal [ 0007-070X ] ; 2010-09-28.
Abstract
Purpose Phosphatidylserine PS extracted from both bovine cortex and soya beans has been previously reported to positively affect cognitive functioning, mood, and the capacity to cope with stress. The present paper aims to investigate whether the daily intake of phospholipid concentrate PL rich in phosphatidylserine PS and sphingomyelin SM has similar beneficial effects on working memory, allostastic load and the acute stress response. Designmethodologyapproach A total of 46 healthy men average 41.5 years received either placebo or 13.5g per day PL over a threeweek period. On the 21st day of PL intake, subjects' working memory performance and their psychological and endocrine responses to the Trier Social Stress Test TSST were tested. Findings Compared to placeboexposed individuals, there was a tendency for shorter reaction times in the working memory task, suggesting better performance in PLtreated subjects. The two treatment groups did not significantly differ in their endocrine stress response. However, PLtreated subjects with a higher stress load showed a blunted psychological stress response. Practical implications Results of the present study show beneficial effects of PL intake on cognitive performance. Under acute stress, benefits of PL may only be visible in chronically stressed subjects. Originalityvalue This paper provides new information for practitioners, academics and food supplement industries interested in possible beneficial effects of a milk phospholipid product on memory and mental stress.
Url:
DOI: 10.1108/00070701011080258
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ISTEX:A946577710A52D0DA12C501751CF37CC69D26CB0Le document en format XML
<record><TEI wicri:istexFullTextTei="biblStruct"><teiHeader><fileDesc><titleStmt><title xml:lang="en">Effects of milk phospholipid on memory and psychological stress response</title><author><name sortKey="Hellhammer, Juliane" sort="Hellhammer, Juliane" uniqKey="Hellhammer J" first="Juliane" last="Hellhammer">Juliane Hellhammer</name><affiliation><mods:affiliation>DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany</mods:affiliation></affiliation></author><author><name sortKey="Waladkhani, Alireza" sort="Waladkhani, Alireza" uniqKey="Waladkhani A" first="Alireza" last="Waladkhani">Alireza Waladkhani</name><affiliation><mods:affiliation>FPP Center for Psychobiology and Psychosomatic Research, University of Trier, Trier, Germany</mods:affiliation></affiliation></author><author><name sortKey="Hero, Torsten" sort="Hero, Torsten" uniqKey="Hero T" first="Torsten" last="Hero">Torsten Hero</name><affiliation><mods:affiliation>DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany</mods:affiliation></affiliation></author><author><name sortKey="Buss, Claudia" sort="Buss, Claudia" uniqKey="Buss C" first="Claudia" last="Buss">Claudia Buss</name><affiliation><mods:affiliation>DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany</mods:affiliation></affiliation></author></titleStmt><publicationStmt><idno type="wicri:source">ISTEX</idno><idno type="RBID">ISTEX:A946577710A52D0DA12C501751CF37CC69D26CB0</idno><date when="2010" year="2010">2010</date><idno type="doi">10.1108/00070701011080258</idno><idno type="url">https://api.istex.fr/document/A946577710A52D0DA12C501751CF37CC69D26CB0/fulltext/pdf</idno><idno type="wicri:Area/Istex/Corpus">001C09</idno><idno type="wicri:explorRef" wicri:stream="Istex" wicri:step="Corpus" wicri:corpus="ISTEX">001C09</idno></publicationStmt><sourceDesc><biblStruct><analytic><title level="a" type="main" xml:lang="en">Effects of milk phospholipid on memory and psychological stress response</title><author><name sortKey="Hellhammer, Juliane" sort="Hellhammer, Juliane" uniqKey="Hellhammer J" first="Juliane" last="Hellhammer">Juliane Hellhammer</name><affiliation><mods:affiliation>DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany</mods:affiliation></affiliation></author><author><name sortKey="Waladkhani, Alireza" sort="Waladkhani, Alireza" uniqKey="Waladkhani A" first="Alireza" last="Waladkhani">Alireza Waladkhani</name><affiliation><mods:affiliation>FPP Center for Psychobiology and Psychosomatic Research, University of Trier, Trier, Germany</mods:affiliation></affiliation></author><author><name sortKey="Hero, Torsten" sort="Hero, Torsten" uniqKey="Hero T" first="Torsten" last="Hero">Torsten Hero</name><affiliation><mods:affiliation>DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany</mods:affiliation></affiliation></author><author><name sortKey="Buss, Claudia" sort="Buss, Claudia" uniqKey="Buss C" first="Claudia" last="Buss">Claudia Buss</name><affiliation><mods:affiliation>DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany</mods:affiliation></affiliation></author></analytic><monogr></monogr><series><title level="j">British Food Journal</title><idno type="ISSN">0007-070X</idno><imprint><publisher>Emerald Group Publishing Limited</publisher><date type="published" when="2010-09-28">2010-09-28</date><biblScope unit="volume">112</biblScope><biblScope unit="issue">10</biblScope><biblScope unit="page" from="1124">1124</biblScope><biblScope unit="page" to="1137">1137</biblScope></imprint><idno type="ISSN">0007-070X</idno></series><idno type="istex">A946577710A52D0DA12C501751CF37CC69D26CB0</idno><idno type="DOI">10.1108/00070701011080258</idno><idno type="filenameID">0701121007</idno><idno type="original-pdf">0701121007.pdf</idno><idno type="href">00070701011080258.pdf</idno></biblStruct></sourceDesc><seriesStmt><idno type="ISSN">0007-070X</idno></seriesStmt></fileDesc><profileDesc><textClass></textClass><langUsage><language ident="en">en</language></langUsage></profileDesc></teiHeader><front><div type="abstract">Purpose Phosphatidylserine PS extracted from both bovine cortex and soya beans has been previously reported to positively affect cognitive functioning, mood, and the capacity to cope with stress. The present paper aims to investigate whether the daily intake of phospholipid concentrate PL rich in phosphatidylserine PS and sphingomyelin SM has similar beneficial effects on working memory, allostastic load and the acute stress response. Designmethodologyapproach A total of 46 healthy men average 41.5 years received either placebo or 13.5g per day PL over a threeweek period. On the 21st day of PL intake, subjects' working memory performance and their psychological and endocrine responses to the Trier Social Stress Test TSST were tested. Findings Compared to placeboexposed individuals, there was a tendency for shorter reaction times in the working memory task, suggesting better performance in PLtreated subjects. The two treatment groups did not significantly differ in their endocrine stress response. However, PLtreated subjects with a higher stress load showed a blunted psychological stress response. Practical implications Results of the present study show beneficial effects of PL intake on cognitive performance. Under acute stress, benefits of PL may only be visible in chronically stressed subjects. Originalityvalue This paper provides new information for practitioners, academics and food supplement industries interested in possible beneficial effects of a milk phospholipid product on memory and mental stress.</div></front></TEI><istex><corpusName>emerald</corpusName><author><json:item><name>Juliane Hellhammer</name><affiliations><json:string>DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany</json:string></affiliations></json:item><json:item><name>AliReza Waladkhani</name><affiliations><json:string>FPP Center for Psychobiology and Psychosomatic Research, University of Trier, Trier, Germany</json:string></affiliations></json:item><json:item><name>Torsten Hero</name><affiliations><json:string>DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany</json:string></affiliations></json:item><json:item><name>Claudia Buss</name><affiliations><json:string>DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany</json:string></affiliations></json:item></author><subject><json:item><lang><json:string>eng</json:string></lang><value>Cognition</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Food additives</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Personal health</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Proteins</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Memory</value></json:item></subject><language><json:string>eng</json:string></language><originalGenre><json:string>research-article</json:string></originalGenre><abstract>Purpose Phosphatidylserine PS extracted from both bovine cortex and soya beans has been previously reported to positively affect cognitive functioning, mood, and the capacity to cope with stress. The present paper aims to investigate whether the daily intake of phospholipid concentrate PL rich in phosphatidylserine PS and sphingomyelin SM has similar beneficial effects on working memory, allostastic load and the acute stress response. Designmethodologyapproach A total of 46 healthy men average 41.5 years received either placebo or 13.5g per day PL over a threeweek period. On the 21st day of PL intake, subjects' working memory performance and their psychological and endocrine responses to the Trier Social Stress Test TSST were tested. Findings Compared to placeboexposed individuals, there was a tendency for shorter reaction times in the working memory task, suggesting better performance in PLtreated subjects. The two treatment groups did not significantly differ in their endocrine stress response. However, PLtreated subjects with a higher stress load showed a blunted psychological stress response. Practical implications Results of the present study show beneficial effects of PL intake on cognitive performance. Under acute stress, benefits of PL may only be visible in chronically stressed subjects. Originalityvalue This paper provides new information for practitioners, academics and food supplement industries interested in possible beneficial effects of a milk phospholipid product on memory and mental stress.</abstract><qualityIndicators><score>9.64</score><pdfVersion>1.3</pdfVersion><pdfPageSize>519 x 680 pts</pdfPageSize><refBibsNative>true</refBibsNative><keywordCount>5</keywordCount><abstractCharCount>1532</abstractCharCount><pdfWordCount>5004</pdfWordCount><pdfCharCount>30642</pdfCharCount><pdfPageCount>14</pdfPageCount><abstractWordCount>220</abstractWordCount></qualityIndicators><title>Effects of milk phospholipid on memory and psychological stress response</title><refBibs><json:item><author><json:item><name>D. Benton</name></json:item><json:item><name>R.T. 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The present paper aims to investigate whether the daily intake of phospholipid concentrate PL rich in phosphatidylserine PS and sphingomyelin SM has similar beneficial effects on working memory, allostastic load and the acute stress response. Designmethodologyapproach A total of 46 healthy men average 41.5 years received either placebo or 13.5g per day PL over a threeweek period. On the 21st day of PL intake, subjects' working memory performance and their psychological and endocrine responses to the Trier Social Stress Test TSST were tested. Findings Compared to placeboexposed individuals, there was a tendency for shorter reaction times in the working memory task, suggesting better performance in PLtreated subjects. The two treatment groups did not significantly differ in their endocrine stress response. However, PLtreated subjects with a higher stress load showed a blunted psychological stress response. Practical implications Results of the present study show beneficial effects of PL intake on cognitive performance. Under acute stress, benefits of PL may only be visible in chronically stressed subjects. Originalityvalue This paper provides new information for practitioners, academics and food supplement industries interested in possible beneficial effects of a milk phospholipid product on memory and mental stress.</p></abstract><textClass><keywords scheme="keyword"><list><head>keywords</head><item><term>Cognition</term></item><item><term>Food additives</term></item><item><term>Personal health</term></item><item><term>Proteins</term></item><item><term>Memory</term></item></list></keywords></textClass><textClass><keywords scheme="Emerald Subject Group"><list><label>cat-PPEM</label><item><term>Public policy & environmental management</term></item><label>cat-FN</label><item><term>Food & nutrition</term></item></list></keywords></textClass></profileDesc><revisionDesc><change when="2010-09-28">Published</change></revisionDesc></teiHeader></istex:fulltextTEI><json:item><extension>txt</extension><original>false</original><mimetype>text/plain</mimetype><uri>https://api.istex.fr/document/A946577710A52D0DA12C501751CF37CC69D26CB0/fulltext/txt</uri></json:item></fulltext><metadata><istex:metadataXml wicri:clean="corpus emerald not found" wicri:toSee="no header"><istex:xmlDeclaration>version="1.0" encoding="UTF-8"</istex:xmlDeclaration><istex:document><!-- Auto generated NISO JATS XML created by Atypon out of MCB DTD source files. Do Not Edit! --><article dtd-version="1.0" xml:lang="en" article-type="research-article"><front><journal-meta><journal-id journal-id-type="publisher-id">bfj</journal-id><journal-id journal-id-type="doi">10.1108/bfj</journal-id><journal-title-group><journal-title>British Food Journal</journal-title></journal-title-group><issn pub-type="ppub">0007-070X</issn><publisher><publisher-name>Emerald Group Publishing Limited</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.1108/00070701011080258</article-id><article-id pub-id-type="original-pdf">0701121007.pdf</article-id><article-id pub-id-type="filename">0701121007</article-id><article-categories><subj-group subj-group-type="type-of-publication"><compound-subject><compound-subject-part content-type="code">research-article</compound-subject-part><compound-subject-part content-type="label">Research paper</compound-subject-part></compound-subject></subj-group><subj-group subj-group-type="subject"><compound-subject><compound-subject-part content-type="code">cat-PPEM</compound-subject-part><compound-subject-part content-type="label">Public policy & environmental management</compound-subject-part></compound-subject><subj-group><compound-subject><compound-subject-part content-type="code">cat-FN</compound-subject-part><compound-subject-part content-type="label">Food & nutrition</compound-subject-part></compound-subject></subj-group></subj-group></article-categories><title-group><article-title>Effects of milk phospholipid on memory and psychological stress response</article-title></title-group><contrib-group><contrib contrib-type="author"><string-name><given-names>Juliane</given-names> <surname>Hellhammer</surname></string-name><aff>DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany</aff></contrib><x></x><contrib contrib-type="author"><string-name><given-names>Ali‐Reza</given-names> <surname>Waladkhani</surname></string-name><aff>FPP – Center for Psychobiology and Psychosomatic Research, University of Trier, Trier, Germany</aff></contrib><x></x><contrib contrib-type="author"><string-name><given-names>Torsten</given-names> <surname>Hero</surname></string-name><aff>DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany</aff></contrib><x></x><contrib contrib-type="author"><string-name><given-names>Claudia</given-names> <surname>Buss</surname></string-name><aff>DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany</aff></contrib></contrib-group><pub-date pub-type="ppub"><day>28</day><month>09</month><year>2010</year></pub-date><volume>112</volume><issue>10</issue><fpage>1124</fpage><lpage>1137</lpage><permissions><copyright-statement>© Emerald Group Publishing Limited</copyright-statement><copyright-year>2010</copyright-year><license license-type="publisher"><license-p></license-p></license></permissions><self-uri content-type="pdf" xlink:href="00070701011080258.pdf"></self-uri><abstract><sec><title content-type="abstract-heading">Purpose</title><x> – </x><p>Phosphatidylserine (PS) extracted from both bovine cortex and soya beans has been previously reported to positively affect cognitive functioning, mood, and the capacity to cope with stress. The present paper aims to investigate whether the daily intake of phospholipid concentrate (PL) rich in phosphatidylserine (PS) and sphingomyelin (SM) has similar beneficial effects on working memory, allostastic load and the acute stress response.</p></sec><sec><title content-type="abstract-heading">Design/methodology/approach</title><x> – </x><p>A total of 46 healthy men (average 41.5 years) received either placebo or 13.5 g per day PL over a three‐week period. On the 21st day of PL intake, subjects' working memory performance and their psychological and endocrine responses to the Trier Social Stress Test (TSST) were tested.</p></sec><sec><title content-type="abstract-heading">Findings</title><x> – </x><p>Compared to placebo‐exposed individuals, there was a tendency for shorter reaction times in the working memory task, suggesting better performance in PL‐treated subjects. The two treatment groups did not significantly differ in their endocrine stress response. However, PL‐treated subjects with a higher stress load showed a blunted psychological stress response.</p></sec><sec><title content-type="abstract-heading">Practical implications</title><x> – </x><p>Results of the present study show beneficial effects of PL intake on cognitive performance. Under acute stress, benefits of PL may only be visible in chronically stressed subjects.</p></sec><sec><title content-type="abstract-heading">Originality/value</title><x> – </x><p>This paper provides new information for practitioners, academics and food supplement industries interested in possible beneficial effects of a milk phospholipid product on memory and mental stress.</p></sec></abstract><kwd-group><kwd>Cognition</kwd><x>, </x><kwd>Food additives</kwd><x>, </x><kwd>Personal health</kwd><x>, </x><kwd>Proteins</kwd><x>, </x><kwd>Memory</kwd></kwd-group><custom-meta-group><custom-meta><meta-name>peer-reviewed</meta-name><meta-value>yes</meta-value></custom-meta><custom-meta><meta-name>academic-content</meta-name><meta-value>yes</meta-value></custom-meta><custom-meta><meta-name>rightslink</meta-name><meta-value>included</meta-value></custom-meta></custom-meta-group></article-meta><ack><p>This study was supported by Arla Foods Ingredients amba, Denmark. The authors greatly acknowledge scientific advice from Michael Schneider.</p></ack></front><body><sec><title>1. Introduction</title><p>Phosphatidylserine (PS) has been shown in 21 double‐blind trials to improve memory, learning, attention, word choice, and other cognitive measures as well as mood and the capacity to cope with stress (<xref ref-type="bibr" rid="b19">Monteleone <italic>et al.</italic>, 1992</xref>; <xref ref-type="bibr" rid="b4">Cenachhi <italic>et al.</italic>, 1993</xref>; <xref ref-type="bibr" rid="b6">Crook, 1998</xref>; <xref ref-type="bibr" rid="b9">Hellhammer <italic>et al.</italic>, 2004</xref>). Single (50 and 75 mg) as well as repeated intake (800 mg per day for ten days) of PS has been reported to reduce ACTH and cortisol secretion in response to physical stress (<xref ref-type="bibr" rid="b18 b19">Monteleone <italic>et al.</italic>, 1990, 1992</xref>). <xref ref-type="bibr" rid="b1">Benton <italic>et al.</italic> (2001)</xref> demonstrated a positive effect of three‐month treatment with 300 mg/day PS on perceived stress during a stressful mental arithmetic task. In line with these results, we recently showed that daily intake of 400 mg phosphatidic acid and phosphatidylserine complex (PAS) over a three‐week period significantly dampens the endocrine stress response (<xref ref-type="bibr" rid="b9">Hellhammer <italic>et al.</italic>, 2004</xref>): compared to placebo, subjects exposed to 400 mg PAS had significantly lower levels of ACTH, serum cortisol and salivary cortisol (the biological active, free steroid fraction) in response to the Trier Social Stress Test (TSST; <xref ref-type="bibr" rid="b12">Kirschbaum <italic>et al.</italic>, 1993</xref>), a well‐validated laboratory protocol (<xref ref-type="bibr" rid="b7">Dickerson and Kemeny, 2004</xref>).</p><p>Furthermore, results from a clinical trial in elderly patients suggest that bovine cortex PS (BC‐PS) acts as an antidementia agent that may improve behaviour and cognitive performance without any side effects (<xref ref-type="bibr" rid="b4">Cenachhi <italic>et al.</italic>, 1993</xref>). Animal findings showed that soy PS has similar effects on cognitive performance as bovine PS (<xref ref-type="bibr" rid="b21">Sakai <italic>et al.</italic>, 1996</xref>; <xref ref-type="bibr" rid="b2">Blokland <italic>et al.</italic>, 1999</xref>; <xref ref-type="bibr" rid="b25">Suzuki <italic>et al.</italic>, 2001</xref>) and this has been confirmed in human studies (<xref ref-type="bibr" rid="b6">Crook, 1998</xref>; <xref ref-type="bibr" rid="b1">Benton <italic>et al.</italic>, 2001</xref>). Suggested mechanisms of how PS enhances memory performance implicate its involvement in the maintenance of the neuron membrane and its promoting dendritic branching and neurotransmitter release (<xref ref-type="bibr" rid="b17">McDaniel <italic>et al.</italic>, 2003</xref>).</p><p>In sum, there is preliminary evidence for a possible role of phospholipids in buffering the mental and bodily response to psychological stress and enhancing cognitive functioning.</p><p>The main objective of this single‐centre, placebo‐controlled, double‐blind study was to investigate and evaluate effects of milk phospholipid concentrate (PL) on cognition as well as on chronic stress, and psychobiological responses to acute laboratory stress (Trier Social Stress Test; TSST). Thus, we hypothesized that, when compared to placebo, the administration of PL over three weeks dampens the endocrine and psychological stress response and exerts memory‐enhancing effects.</p></sec><sec><title>2. Methods and materials</title><p>The study was approved by the Ethical Committee of the State's Medical Association of Rhineland‐Palatinate (Landesärztekammer Rheinland‐Pfalz), Germany and was performed in accordance with ethical standards of the Helsinki Declaration of 1975, as revised in 1983.</p><sec><title>2.1 Subjects</title><p>A total of 46 adult males (aged between 30 and 55 years) were recruited via e‐mail at the local university, newspaper ads and flyers to participate in this study. Pre‐screening and introduction to the study were done by phone. Only healthy subjects were included in this study. Health was verified by a medical examination/ interview, questionnaires, and a hemogram. Subjects provided a urine sample that was checked for recent drug consumption by application of the multi‐drug screen panel (Biorad Tox/See, Bio‐Rad Laboratories, Hercules, California). Furthermore, the following conditions lead to exclusion from study participation: smoking more than five cigarettes a day, familiarity with the TSST, mental illness, medication intake affecting endocrine or behavioral measures, and contra‐indications of intake of PL (e.g. lactose intolerance). Finally, only subjects who gave written informed consent for study participation were included in the study.</p><p>Subjects were randomly assigned to one of the two experimental groups, but matched on age and socio‐economic status. Randomization was conducted by an assistant of the main investigator. Group 1 received 21 small containers of 0.325L milk drinks containing PL (13.5 g) and group 2 was given 21 containers containing 0.325L of a placebo compound for daily intake during the 21 days before stress exposure (TSST) in our laboratory. Subjects were instructed to consume the product in the morning 30 minutes before breakfast.</p><p>At the time of testing and data analysis, the principal investigators were blind to which group received PL and which group received placebo. As indicated in <xref ref-type="fig" rid="F_0701121007006">Table I</xref>, the two groups did not differ in age, anthropometric variables, or three‐week nutritional intake as monitored by a nutrition diary and quantified by a computerized program (Ebis‐Diata, E+D Partner, Neu‐Anspach, Germany) (<xref ref-type="bibr" rid="b3">Bohm and Bitsch, 1999</xref>).</p></sec><sec><title>2.2 Substance</title><p>PL is a milk phospholipid concentrate on protein carrier with 19 per cent phospholipids (5 per cent sphingomyelin, 5 per cent phosphadityl choline, 4 per cent phosphadityl ethanolamine, 2.3 per cent phosphatidylserine, 1.5 per cent phosphadityl inositol).</p></sec><sec><title>2.3 Study protocol</title><p>Subjects underwent a physical examination when they first attended the laboratory. If all inclusion criteria were fulfilled, they received 21 small containers of 0.325L milk drinks containing either PL or placebo and were instructed to drink the contents of one container every day in the morning about 30 minutes before breakfast.</p><p>On day 21, after subjects consumed their last drink in the morning, they came to the laboratory in the afternoon and the TSST was performed. An overview of the test procedure is shown in <xref ref-type="fig" rid="F_0701121007001">Figure 1</xref>. Subjects received an indwelling catheter in a forearm vein for the collection of blood samples 45 minutes prior to the stress test. This was followed by a resting phase, which was necessary to exclude potential activation of the hypothalamic‐pituitary‐adrenal axis (HPA) that could possibly confound later response to the TSST. A detailed protocol of the TSST has been described elsewhere by <xref ref-type="bibr" rid="b12">Kirschbaum <italic>et al.</italic> (1993)</xref>. Before the TSST, each subject was shown the testing room and instructed to stand behind a microphone in front of a two‐man committee. The subject was informed that the whole session would be video and tape‐recorded, and that the committee was trained in behavioural observation. The experimenter instructed the subject to deliver a five‐minute speech, which was preceded by a three‐minute preparation phase. After the speech, the subject participated in five minutes of mental arithmetic as an additional stressor.</p></sec><sec><title>2.4 Psychometric assessment</title><p>At their first visit, study subjects were asked to fill in a set of psychological questionnaires, including the Trier Inventory of Chronic Stress (<xref ref-type="bibr" rid="b22">Schulz <italic>et al.</italic>, 2004</xref>), the trait version of the State‐trait Anxiety Inventory (<xref ref-type="bibr" rid="b13">Laux <italic>et al.</italic>, 1981</xref>), and the German Version of the Patient Health Questionnaire (<xref ref-type="bibr" rid="b14">Löwe <italic>et al.</italic>, 2002</xref>).</p><p>The state version of the STAI and the MDBF (“Der Mehrdimensionale Befindlichkeitsfragebogen”; <xref ref-type="bibr" rid="b24">Steyer <italic>et al.</italic>, 1997</xref>) were completed immediately before and after the TSST in order to assess changes in psychological well‐being in response to stress exposure.</p><p>Twice during the TSST, subjects were asked to rate their subjective perception of the stress test. The first evaluation took place after preparing for the speech during the TSST and the second evaluation took place at the end of the 15‐minute period after the arithmetic task. On five visual analogue scales (VAS), subjects were asked to rate on bipolar dimensions the degree of perceived stress load, controllability, predictability, the strain of the situation, and the personal relevance of the situation. Ratings were made with a 10 cm visual analogue scale VAS) with endpoints of “low” to “high.”</p></sec><sec><title>2.5 Cognitive testing</title><p><italic>2.5.1 Working memory task.</italic> Working memory was measured using an item‐recognition task that has been shown to assess memory capacity of the central executive processor of working memory in humans (<xref ref-type="bibr" rid="b10">Kahnemann, 1973</xref>; <xref ref-type="bibr" rid="b23">Shiffrin and Schneider, 1977</xref>; <xref ref-type="bibr" rid="b8">Fisk and Rogers, 1991</xref>). The task included a series of discrete trials. Each condition consisted of the presentation of three to four uppercase letters, followed by a recognition display of two to four uppercase letters, to which participants responded yes (present‐target trials) or <italic>no</italic> (absent‐target trials). By pressing one of two buttons on the computer keyboard, subjects indicated whether or not one of the targets was identical to one of the stimuli in the recognition display. There was only one possible target present in the display on present‐target trials. Each condition comprised 20 trials. Processing load, was determined by the number of comparisons, which the participant had to make in order to answer a specific item‐recognition trial. The experiment was controlled by a computer, which presented stimuli, and recorded errors and reaction times.</p><p>The subjects' working memory performance was recorded at baseline (20 minutes before exposure to the TSST) to assess potential effects of PL intake.</p></sec><sec><title>2.6 Endocrine assessment</title><p><italic>2.6.1 Adrenocorticotropic hormone (ACTH).</italic> For determination of ACTH, blood samples were drawn at two time points (two minutes before and one minute after the TSST) in EDTA‐coated tubes (Monovette, Sarstedt, Germany), which were immediately stored on ice. After centrifugation for ten minutes at 6°C, 1,200 g plasma aliquots were frozen at −80°C until analysis. For determination of human ACTH 1‐39, a two‐site enzyme‐linked immunosorbent assay (ELISA, Biometrica, Newport Beach, California, USA) was used. The sensitivity of the assay is 0.46pg/ml. The intra‐assay variation was between 3.1‐4.2 per cent, the inter‐assay variation between 5.8‐6.2 per cent, respectively.</p><p><italic>2.6.2 Determination of serum cortisol.</italic> Blood samples for determination of serum cortisol were collected in EDTA‐coated tubes (Monovette, Sarstedt, Germany) two minutes prior to the TSST and 1, 10, 20, 30, 45, and 60 minutes thereafter. After drawing the blood, samples were immediately stored on ice. Following centrifugation for ten minutes at 6°C, 1,200 g, serum aliquots were frozen at −20°C until analysis. For determination of cortisol in serum, a competitive enzyme amplified sensitivity immunoassay (ELISA, Immuno Biological Laboratories, Hamburg, Germany) was applied. Lower detection threshold of this assay is above 6.9 ng/ml. Intra‐assay variation was between 3.2 and 8.1 per cent and the inter‐assay variation range was between 6.5 and 7.7 per cent.</p><p><italic>2.6.3 Determination of free cortisol in saliva.</italic> Saliva samples were collected for assessment of free cortisol concentrations, since salivary cortisol represents the unbound, biologically active hormone fraction (<xref ref-type="bibr" rid="b11">Kirschbaum and Hellhammer, 1994</xref>). Subjects collected saliva in polypropylene tubes (Sarstedt, Nümbrecht, Germany) at the following time points: 50, 20, ten and two minutes prior to the TSST and one, ten, 20, 30, 45 and 60 minutes thereafter. Until analysis, saliva samples were stored at −20°C. After thawing, saliva samples were centrifuged at 1,200 g for five minutes resulting in a clear supernatant of low viscosity. Free saliva cortisol levels were determined employing a luminescence immunoassay (LIA, IBL, Hamburg, Germany) based on the competition principle (see previous). Intra‐assay variation of this assay ranged between 4.5 to 7.7 per cent and the inter‐assay variation ranged between 6.2 to 11.5 per cent.</p></sec><sec><title>2.7 Statistical analyses</title><p>General linear models (GLMs) were applied to assess the repeated measures effect time, the between‐subjects effect group (PL versus placebo), and the time×group interaction for endocrine and psychological responses to TSST exposure. GLMs were furthermore performed to test for working memory performance (<xref ref-type="bibr" rid="b26">Tabachnick and Fidell, 2007</xref>) differences between treatment groups. Results were adjusted with the Greenhouse‐Geisser correction for degrees of freedom (<italic>ϵ</italic>‐values reported).</p><p>For analysis of endocrine parameters, several variables were calculated. As an indicator of total hormonal secretion, the area under the curve ground (AUC<sub>g,</sub>) for ACTH, serum cortisol, and saliva cortisol was calculated. The Area under the curve increase (AUC<sub>i</sub>) for the same hormones was considered a measure of HPA responsiveness (<xref ref-type="bibr" rid="b20">Pruessner <italic>et al.</italic>, 2003</xref>). Additional measures of HPA responsiveness included the maximum increase for ACTH, serum cortisol and saliva cortisol (difference between the pre‐TSST value (TSST‐2), and the highest value after the TSST). The mean increase for serum cortisol and saliva cortisol (difference between the value prior to the TSST (TSST‐2) and the mean of all values measured post TSST) as well as the percent maximum increase for ACTH, serum cortisol and saliva cortisol. For analyses of group differences in these aggregated endocrine measures, single t‐tests were applied. <italic>P</italic>‐values of < 0.05 are considered to reflect statistical significance, and <italic>p</italic>‐values < 0.10 are reflective of statistical trends.</p></sec></sec><sec><title>3. Results</title><sec><title>3.1 Substance</title><p>The drink was well accepted from all study participants and no side effects were reported.</p></sec><sec><title>3.2 Psychological parameters</title><p>The two treatment groups did not differ in measures of perceived stress (assessed by the TICS; <italic>F</italic><sub>(10,33)</sub>=0.25, <italic>p</italic>=0.99), depression (assessed by the PHQ‐D; <italic>F</italic><sub>(1,44)</sub>=0.25, <italic>p</italic>=0.92), or trait anxiety (assessed by the STAI; <italic>F</italic><sub>(1,43)</sub>=0.04, <italic>p</italic>=0.85), before study entry.</p><p>The two treatment groups did not differ in overall state anxiety levels (effect of group: <italic>F</italic><sub>(1,44)</sub>=0.15, <italic>p</italic>=0.69) or in changes in state anxiety induced by TSST exposure (effect time x group: <italic>F</italic><sub>(1,44)</sub>=0.05, <italic>p</italic>=0.83).</p><p>After stress exposure, MDBF measures revealed that TSST exposure resulted in the expected higher levels of alertness (effect of time: <italic>F</italic><sub>(1,43)</sub>=5.75, <italic>p</italic>=0.02) and lower levels of tiredness (effect of time: <italic>F</italic><sub>(1,43)</sub>=4.25, <italic>p</italic>=0.05), suggesting that the subjects were more awake and agitated after the TSST.</p><p>No significant differences between the treatment groups in the ratings of well‐being were observed (main effect of group: <italic>F</italic><sub>(1,43)</sub>=0.25, <italic>p</italic>=0.62). The non‐significant interaction between group (placebo v. PL) and time (pre and post TSST) indicated that the groups did not differ in the way the TSST affected well‐being (<italic>F</italic><sub>(1,43)</sub>=0.15, <italic>p</italic>=0.71). This was true for all three scales of the MDBF, which was indicated by a non‐significant triple interaction between group, time and MDBF scales (<italic>F</italic><sub>(2,86)</sub>=0.07, <italic>p</italic>=0.93, <italic>ϵ</italic>=0.88).</p><p>For exploratory purpose, follow‐up <italic>t</italic>‐tests were conducted for the mood scale for the two treatment groups separately to test for distinct group effects of the TSST as suggested descriptively. These analyses indicated a trend for a worsening of mood after the TSST in the placebo group (<italic>t</italic><sub>(22)</sub>=1.9, <italic>p</italic>=0.07) but not in the PL group (<italic>t</italic><sub>(21)</sub>=0.76, <italic>p</italic>=0.45).</p><p>During the TSST, subjects twice rated their perception of the situation on five visual analogue scales, once after the preparation period and once at the end of the task after the mental arithmetic. The interaction between time of rating and VAS scales showed with progression of the TSST the perception of the situation changed in regard to some but not all scales of the VAS (<italic>F</italic><sub>(4,176)</sub>=14.36, <italic>p</italic>=0.00, <italic>ϵ</italic>=0.57). The trend for the triple interaction between time of rating, VAS scales and treatment group suggests that the way the perception on some scales changed during the TSST differed with respect to pre‐treatment (<italic>F</italic><sub>(4,176)</sub>=2.24, <italic>p</italic>=0.11, <italic>ϵ</italic>=0.57). Thus, follow‐up separate analyses were conducted for each of the five scales.</p><p>Strikingly, subjects rated their <italic>g</italic>eneral stress perception higher at the end of the TSST than at the beginning as indicated by a main effect of time (<italic>F</italic><sub>(1,44)</sub>=8.58, <italic>p</italic>=0.005). Although the interaction between time and group was not significant (<italic>F</italic><sub>(1,44)</sub>=1.98, <italic>p</italic>=0.17), paired t‐tests were conducted for the two groups separately to explore if the general stress perception changed in the one group but not in the other. In fact, these post hoc analyses revealed that an increase of general stress is only observed in the placebo group (<italic>t</italic><sub>(22)</sub>=−3.1, <italic>p</italic>=0.01) but not in the PL group (<italic>t</italic><sub>(22)</sub>=−1.06, <italic>p</italic>=0.3), as apparent in <xref ref-type="fig" rid="F_0701121007002">Figure 2</xref>.</p><p>The significant time effect for controllability suggests a lack of control in the course of the TSST (<italic>F</italic><sub>(1,44)</sub>=27.34, <italic>p</italic>=0.00). The interaction between time and group suggested that this is mainly driven by the placebo group that experienced a change in loss of control (<italic>F</italic><sub>(1,44)</sub>=5.43, <italic>p</italic>=0.02). Thus, PL may dampen perceived uncontrollability in stressful situations.</p><p>Predictability of the situation did not change over the course of the TSST (<italic>F</italic><sub>(1,44)</sub>=1.85, <italic>p</italic>=0.18). The trend for a main group effect though suggested that the PL group rated the situation as more predictable at both time points as compared to the placebo group (<italic>F</italic><sub>(1,44)</sub>=2.98, <italic>p</italic>=0.09). Since pre‐test measures are likely to be affected by anticipatory stress, PL effects on predictability may primarily become visible at this time point.</p><p>Strain due to the situation was rated higher at the end of the TSST in both groups (<italic>F</italic><sub>(1,44)</sub>=13.26, <italic>p</italic>=0.001), but no significant interaction with treatment group was observed. The same was true for the rating of the perceived subjective relevance of the situation, which was rated higher at the end of the TSST in both groups (<italic>F</italic><sub>(1,44)</sub>=4.86, <italic>p</italic>=0.03) without any significant association with treatment group.</p></sec><sec><title>3.3 Cognitive testing</title><p><italic>3.3.1 Working memory performance.</italic> After three weeks of substance intake, there was a tendency for the PL group presenting with improved working memory performance as verified by a trend for lower reaction times (<italic>F</italic><sub>(1,44)</sub>=3.01, <italic>p</italic>=0.09). Controlling for interindividual variation in cortisol concentration, which has been shown to affect working memory performance (<xref ref-type="bibr" rid="b15">Lupien <italic>et al.</italic>, 1999</xref>), slightly increases the variance in reaction time that is explained by the treatment group (<italic>F</italic><sub>(1,41)</sub>=3.7, <italic>p</italic>=0.06).</p></sec><sec><title>3.4 Biological parameters</title><p><italic>3.4.1 ACTH.</italic> The TSST induced a significant increase in ACTH concentrations (<italic>F</italic><sub>(1,41)</sub>=47.5, <italic>p</italic>=0.00, see <xref ref-type="fig" rid="F_0701121007003">Figure 3</xref>). No differences between the two treatment groups in ACTH responses was observed (effect of group: <italic>F</italic><sub>(1,41)</sub>=0.01, <italic>p</italic>=0.95), either before or after the TSST as indicated by a non‐significant interaction between time of testing and treatment group (<italic>F</italic><sub>(1,41)</sub>=1.16, <italic>p</italic>=0.29). As summarized in <xref ref-type="fig" rid="F_0701121007007">Table II</xref>, group comparisons of aggregated ACTH measures did not reveal any significant differences.</p><p><italic>3.4.2 Serum cortisol.</italic> Exposure to the TSST induced a significant increase in serum cortisol secretion as indicated by a significant time effect (<italic>F</italic><sub>(6,240)</sub>=74.54, <italic>p</italic>=0.00, <italic>ϵ</italic>=0.54). The two treatment groups did not differ in overall serum cortisol secretion (<italic>F</italic><sub>(1,40)</sub>=0.07, <italic>p</italic>=0.8). The interaction between treatment group and measuring time was close to suggesting a tendency (<italic>F</italic><sub>(6,240)</sub>=3.23, <italic>p</italic>=0.13, <italic>ϵ</italic>=0.54), which was probably driven by slightly higher serum cortisol concentration in the PL group before the TSST. Data are shown in <xref ref-type="fig" rid="F_0701121007004">Figure 4</xref>.</p><p>Group comparisons for aggregated measures of serum cortisol secretion are summarized in <xref ref-type="fig" rid="F_0701121007008">Table III</xref>. Tendencies for a lower AUCi in the PL group as well as for a lower mean increase were again related to the group's slightly higher serum cortisol concentrations before TSST exposure, which serves as a baseline for these increase measures.</p><p><italic>3.4.3 Free cortisol in saliva.</italic> Exposure to the TSST induced a significant increase in free cortisol concentration (<italic>F</italic><sub>(6,246)</sub>=30.92, <italic>p</italic>=0.00, <italic>ϵ</italic>=0.49). Significant group differences were not observed for means of free cortisol levels (<italic>F</italic><sub>(1,41)</sub>=0.12, <italic>p</italic>=0.74; see <xref ref-type="fig" rid="F_0701121007005">Figure 5</xref>) and the interaction between time and group was not significant (<italic>F</italic><sub>(6,246)</sub>=1.81, <italic>p</italic>=0.15, <italic>ϵ</italic>=0.49).</p><p>Group comparisons for aggregated measures of salivary cortisol concentrations are summarized in <xref ref-type="fig" rid="F_0701121007009">Table IV</xref>. A tendency for a blunted percent maximum increase in the PL group could be observed (<italic>p</italic>=0.06).</p></sec></sec><sec><title>4. Discussion</title><p>The findings suggest that daily intake of 13.5 g PL over a three week period has a positive, but moderate impact on working memory performance and dampens the psychological stress response. The endocrine stress response, though, was not found to be generally‐affected by PL intake.</p><p>Interestingly, an almost significant group difference among the endocrine measures was only observed for a lower percentual increase of salivary cortisol in the TSST. Due to its low molecular weight (362 Dalton) and high lipophilicity, cortisol passively diffuses through the lipid‐rich membranes of virtually all cells in the body (<xref ref-type="bibr" rid="b11">Kirschbaum and Hellhammer, 1994</xref>). Thus, lower stimulated cortisol levels in saliva may particularly refer to PL effects on the membrane of acini cells. If so, it may be worth to include the investigation of protective effects on target cells in future studies.</p><p>Memory benefits in association with PS intake have been reported in other human studies (<xref ref-type="bibr" rid="b6">Crook, 1998</xref>). Those studies focused on age‐related memory impairment, and the beneficial effects of PS were attributed to its involvement in the maintenance of the neuron membrane as well as its promoting impact on dendrite branching (<xref ref-type="bibr" rid="b17">McDaniel <italic>et al.</italic>, 2003</xref>). With the current study, we extend these findings and show that after a three‐week intake of PL, middle‐aged subjects without memory complaints had a tendency to have faster reaction times in an item‐recognition task than the placebo‐exposed group. This is interesting considering that working memory is responsible for the temporary storage and manipulation of information in memory and thus is the basis for performing higher cognitive functions such as language comprehension and reasoning. Considering that this conclusion is based on a marginally significant effect, replication is needed. Still, the marginally significant group effect suggests that PL intake might generally increase cognitive functioning in non‐impaired individuals. An even greater benefit might be gained in individuals with cognitive impairment, which remains to be investigated. However, further studies are necessary to clarify if PS or SM account for this effect.</p><p>The TSST induced an increase of state anxiety, negative mood, higher alertness, and agitation in subjects of both groups. Taking a closer look at these effects, however, reveals that subjects of the PL group were relatively protected against such effects, suggesting that perceived stress was less pronounced in the PL group. An increase in perceived stress over the course of the stress task was observed in the placebo group, but not in PL pre‐treated subjects. In addition, the situation was experienced as less controllable for the placebo group. Furthermore, the PL group experienced the stress task as more predictable than subjects of the placebo group. These data provide further support to the findings of <xref ref-type="bibr" rid="b1">Benton <italic>et al.</italic> (2001)</xref> and <xref ref-type="bibr" rid="b9">Hellhammer <italic>et al.</italic>(2004)</xref> on dampening effects of phospholipids on perceived stress.</p><p>We also explored the possibility that stressed individuals would benefit from PL intake to a greater‐extent than non‐stressed individuals. Thus, for exploratory purposes, subjects were assigned to a high vs. low stress group, and distinct analyses for treatment effects were performed for these two groups. The group median was used to assign the subjects to either the low or high stress group according to their TICS scores. Distinct analyses of ACTH levels in the high and low stressed subjects revealed no interaction between time of testing (pre vs post TSST) and treatment group in the low stressed group (<italic>F</italic><sub>(1,16)</sub>=0.39, <italic>p</italic>=0.54). Among the high stressed individuals, however, the percent ACTH increase in response to the TSST significantly differed between the treatment groups with higher values in the placebo group (<italic>t</italic><sub>(22)</sub>=2.46, <italic>p</italic>=0.02), while no such treatment effect could be observed in the low stress group (<italic>t</italic><sub>(16)</sub>=−0.63, <italic>p</italic>=0.54). Distinct repeated ANOVA for serum cortisol in the two stress groups did not indicate treatment effects in the low stress group as indicated by non‐significant treatment group effects (<italic>F</italic><sub>(1,15)</sub>=0.09, <italic>p</italic>=0.76) and non‐significant interactions between time of testing and treatment group (<italic>F</italic><sub>(6,90)</sub>=0.47, <italic>p</italic>=0.71, <italic>ϵ</italic>=0.53). In high stressed individuals though, a trend for a treatment effect was observed (<italic>F</italic><sub>(6,132)</sub>=2.45, <italic>p</italic>=0.09, <italic>ϵ</italic>=0.39), which was accompanied by a tendency towards higher mean cortisol increases in placebo treated subjects of the high stress group when compared to the high stressed PL treated subjects (<italic>t</italic><sub>(23)</sub>=1.9, <italic>p</italic>=0.07), while no such treatment effects were observed in the low stressed group <italic>t</italic><sub>(15)</sub>=0.18, <italic>p</italic>=0.86). In terms of salivary cortisol levels, distinct repeated ANOVA for the two stress groups did not show treatment effects in the low stress group. In high stressed individuals however, a treatment effect was evident by a significant interaction between time of testing and treatment group (<italic>F</italic><sub>(6,138)</sub>=3.12, <italic>p</italic>=0.05, <italic>ϵ</italic>=0.39) with lower salivary cortisol concentrations in the PL group.</p><p>In sum, we could confirm our hypothesis that PL has a slight memory enhancing effect, while a dampening of the endocrine and psychological stress response could only be observed in highly stressed individuals. There is preliminary evidence for PL treatment being more effective in dampening the endocrine stress response in subjects with a higher stress load. Thus, future studies should address PL effects on stress reactivity in a population of highly stressed individuals. Given possible PL effects on cell membranes of target tissues, such studies may include effects on several mental and physical diseases, such as depression, subtypes of abdominal obesity and the metabolic syndrome, which are all associated with a stress induced activation of the HPA axis (e.g. <xref ref-type="bibr" rid="b5">Chrousos, 2000</xref>).</p></sec><sec><fig position="float" id="F_0701121007001"><label><bold>Figure 1<x> </x></bold></label><caption><p>General overview and study flow chart of the TSST protocol after a three‐week intake of PL or placebo</p></caption><graphic xlink:href="0701121007001.tif"></graphic></fig></sec><sec><fig position="float" id="F_0701121007002"><label><bold>Figure 2<x> </x></bold></label><graphic xlink:href="0701121007002.tif"></graphic></fig></sec><sec><fig position="float" id="F_0701121007003"><label><bold>Figure 3<x> </x></bold></label><caption><p>ACTH concentration pre and post TSST for the placebo group (<italic>n</italic>=21) and the PL group (<italic>n</italic>=22)</p></caption><graphic xlink:href="0701121007003.tif"></graphic></fig></sec><sec><fig position="float" id="F_0701121007004"><label><bold>Figure 4<x> </x></bold></label><caption><p>Serum cortisol concentrations pre and post TSST for the placebo group (<italic>n</italic>=20) and the PL group (<italic>n</italic>=22)</p></caption><graphic xlink:href="0701121007004.tif"></graphic></fig></sec><sec><fig position="float" id="F_0701121007005"><label><bold>Figure 5<x> </x></bold></label><caption><p>Salivary cortisol pre and post TSST for the placebo group (<italic>n</italic>=21) and the PL group (<italic>n</italic>=22)</p></caption><graphic xlink:href="0701121007005.tif"></graphic></fig></sec><sec><fig position="float" id="F_0701121007006"><label><bold>Table I<x> </x></bold></label><caption><p>Group descriptives</p></caption><graphic xlink:href="0701121007006.tif"></graphic></fig></sec><sec><fig position="float" id="F_0701121007007"><label><bold>Table II<x> 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type="personal"><namePart type="given">Juliane</namePart><namePart type="family">Hellhammer</namePart><affiliation>DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">AliReza</namePart><namePart type="family">Waladkhani</namePart><affiliation>FPP Center for Psychobiology and Psychosomatic Research, University of Trier, Trier, Germany</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">Torsten</namePart><namePart type="family">Hero</namePart><affiliation>DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">Claudia</namePart><namePart type="family">Buss</namePart><affiliation>DAaCRO, Diagnostic Assessment and Clinical Research Organization, Trier, Germany</affiliation><role><roleTerm type="text">author</roleTerm></role></name><typeOfResource>text</typeOfResource><genre type="research-article" displayLabel="research-article"></genre><originInfo><publisher>Emerald Group Publishing Limited</publisher><dateIssued encoding="w3cdtf">2010-09-28</dateIssued><copyrightDate encoding="w3cdtf">2010</copyrightDate></originInfo><language><languageTerm type="code" authority="iso639-2b">eng</languageTerm><languageTerm type="code" authority="rfc3066">en</languageTerm></language><physicalDescription><internetMediaType>text/html</internetMediaType></physicalDescription><abstract>Purpose Phosphatidylserine PS extracted from both bovine cortex and soya beans has been previously reported to positively affect cognitive functioning, mood, and the capacity to cope with stress. The present paper aims to investigate whether the daily intake of phospholipid concentrate PL rich in phosphatidylserine PS and sphingomyelin SM has similar beneficial effects on working memory, allostastic load and the acute stress response. Designmethodologyapproach A total of 46 healthy men average 41.5 years received either placebo or 13.5g per day PL over a threeweek period. On the 21st day of PL intake, subjects' working memory performance and their psychological and endocrine responses to the Trier Social Stress Test TSST were tested. Findings Compared to placeboexposed individuals, there was a tendency for shorter reaction times in the working memory task, suggesting better performance in PLtreated subjects. The two treatment groups did not significantly differ in their endocrine stress response. However, PLtreated subjects with a higher stress load showed a blunted psychological stress response. Practical implications Results of the present study show beneficial effects of PL intake on cognitive performance. Under acute stress, benefits of PL may only be visible in chronically stressed subjects. Originalityvalue This paper provides new information for practitioners, academics and food supplement industries interested in possible beneficial effects of a milk phospholipid product on memory and mental stress.</abstract><subject><genre>keywords</genre><topic>Cognition</topic><topic>Food additives</topic><topic>Personal health</topic><topic>Proteins</topic><topic>Memory</topic></subject><relatedItem type="host"><titleInfo><title>British Food Journal</title></titleInfo><genre type="journal">journal</genre><subject><genre>Emerald Subject Group</genre><topic authority="SubjectCodesPrimary" authorityURI="cat-PPEM">Public policy & environmental management</topic><topic authority="SubjectCodesSecondary" authorityURI="cat-FN">Food & nutrition</topic></subject><identifier type="ISSN">0007-070X</identifier><identifier type="PublisherID">bfj</identifier><identifier type="DOI">10.1108/bfj</identifier><part><date>2010</date><detail type="volume"><caption>vol.</caption><number>112</number></detail><detail type="issue"><caption>no.</caption><number>10</number></detail><extent unit="pages"><start>1124</start><end>1137</end></extent></part></relatedItem><identifier type="istex">A946577710A52D0DA12C501751CF37CC69D26CB0</identifier><identifier type="DOI">10.1108/00070701011080258</identifier><identifier type="filenameID">0701121007</identifier><identifier type="original-pdf">0701121007.pdf</identifier><identifier type="href">00070701011080258.pdf</identifier><accessCondition type="use and reproduction" contentType="copyright">© Emerald Group Publishing Limited</accessCondition><recordInfo><recordContentSource>EMERALD</recordContentSource></recordInfo></mods></metadata><serie></serie></istex></record>Pour manipuler ce document sous Unix (Dilib)
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