Current Nutrition & Food Science

ISSN: 1573-4013

Current Nutrition & Food Science
Volume 4, Number 1, February 2008

Contents

Editorial Pp. 1


Beneficial Actions of Polyunsaturated Fatty Acids in Cardiovascular Diseases: But, How and Why? Pp. 2-31
Undurti N. Das
[Abstract]


Regulation of Ingestive Behavior, the Upper Gastrointestinal Motility and Gastric Acid Secretion by Ghrelin in Mammals Pp. 32-40
Chih-Yen Chen, Mineko Fujimiya, Akihiro Asakawa, Shou-Dong Lee and Akio Inui
[Abstract]


Use of Total Parenteral Nutrition in Severe Anorexia Nervosa Complicated by a Gastrointestinal Illness Pp. 41-43
Philip S. Mehler
[Abstract]


Screening Strategy for Iron Enhancers: Increasing Iron Bioavailability Pp. 44-52
Silvia Miret, Bernd van Buuren, Guus Duchateau and Werner Klaffke
[Abstract]


Dietary Factors Influencing Magnesium Absorption i Humans Pp. 53-72
Torsten Bohn
[Abstract]




Abstracts


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Editorial

The third year of Current Nutrition & Food Science has been completed after the publication of 4 issues in 2007 with a total number of 32 manuscripts + 4 editorials. We have followed the standard publication procedure consisting of one issue per trimester but this year with three special issues. We are very happy and thankful for the support received from our Editorial Advisory Board members as well as from many other scientists that have trusted our journal, either by submitting manuscripts for publication or by collaborating in the review of submitted manuscripts, a very important and essential task to guarantee the high scientific quality of the journal. I also wish to thank Miss Samreen Laeeq, the Manager Publications, for her continuous dedication to the journal. We are trying to keep a high scientific excellence level of the published manuscripts since it is essential to consolidate the reputation and scientific impact of CNF.

Current Nutrition & Food Science has published in 2007 a good number of reviews on topics of interest in nutrition and food science. It has also included 3 special issues of relevant interest in the field. The special issue (no. 2, May) on “Dietary determinants of the metabolic syndrome" had Prof. Luc Tappy, Dr. Jacques Delarue and Dr. Kim-Anne-Lê as guest editors. The special issue (no. 3, August) on “Oxidative stress in disease” had Prof. Alessandro Laviano as Guest Editor and the third special issue (no. 4, November) on the ”Role of food and nutritional factors in metabolic syndrome X, cancer and cardiovascular diseases” that had Prof. Undurti N. Das as guest editor. I take this opportunity to thank the guest editors for providing interesting manuscripts written by excellent scientists and for their kind collaboration in editing these special issues.

At this moment, Current Nutrition & Food Science is already indexed in Chemical Abstracts, EMBASE, Scopus, and EMNursing and is now under re-review process for its inclusion in important databases like PubMed, Medline and ISI. Current Nutrition & Food Science provides reviews on different topics of interest in nutrition and food science, trying to provide an updated state-of-the-art and latest novelties on each focused topic. Our final objective is the dissemination of updated and rigorous scientific information on nutrition and food science and making them available to all interested scientists and technical staff in academia, research centers, hospitals, nutrition and diet services, food and pharmaceutical industry and regulatory agencies.


Prof. Fidel Toldrá, Ph.D.
Editor-in-Chief
Department of Food Science
Instituto de Agroquimica y
Tecnologia de Alimentos (CSIC)
Apt. 73, 46100 Burjassot
(Valencia)
Spain
E-mail: ftoldra@iata.csic.es


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Beneficial Actions of Polyunsaturated Fatty Acids in Cardiovascular Diseases: But, How and Why?
Undurti N. Das

Omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and to a limited extent ω-6 fatty acids: arachidonic acid (AA), γ-linolenic acid (GLA) and dihomo-GLA (DGLA), prevent cardiovascular disease, thrombosis and atherosclerosis, reduce cardiac arrhythmias, lower plasma cholesterol and triglycerides, lower high blood pressure and improve endothelial function. These beneficial actions of the fatty acids could be attributed to their ability to augment endothelial nitric oxide generation, inhibit HMG-CoA reductase and angiotensin converting enzyme (ACE) activities, block the production of pro-inflammatory cytokines, and modulate telomerase activity. AA, EPA, and DHA form precursors to anti-inflammatory molecules: lipoxins and resolvins that help in wound healing, inhibit the actions of pro-inflammatory eicosanoids, and suppress the production of free radicals and enhance nitric oxide (NO) generation. In addition, these fatty acids react with NO and NO-derived reactive nitrogen species to form nitroalkene derivative of fatty acids called as nitrolipids. Nitrolipids serve as potent ligands for peroxisome proliferator activated receptors (PPARs), inhibit platelet activation through elevation of cyclic AMP levels; suppress superoxide generation, degranulation, and integrin expression by human neutrophils, and induce vasorelaxation in a concentration dependent manner by releasing NO. Nitrolipids are formed at the sites of inflammation in significant amounts and increased by oxidative inflammatory reactions. Furthermore, ω-3 and ω-6 fatty acids interact with each other to enhance the formation of prostaglandin E₁ (PGE₁), prostacyclin (PGI₂), and PGI₃, which are potent platelet anti-aggregators and vasodilators. Thus, GLA, DGLA, AA, EPA, and DHA when present in optimum amounts in the tissues, especially in endothelial cells, myocardium, platelets, and neutrophils, may aid in the prevention of cardiovascular diseases.


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Regulation of Ingestive Behavior, the Upper Gastrointestinal Motility and Gastric Acid Secretion by Ghrelin in Mammals
Chih-Yen Chen, Mineko Fujimiya, Akihiro Asakawa, Shou-Dong Lee and Akio Inui

Ghrelin, a novel 28-amino acid peptide, was recently identified as the first endogenous ligand for growth-hormone secretagogue receptors (previously known as orphan receptors), and discovered by “reverse pharmacology”. The ghrelin peptide features a unique post-translational modification of O-n-octanoylation at serine 3, and is secreted from X/A cells in gastric oxyntic glands into the blood circulation. Two major molecular forms of ghrelin are found in the stomach and plasma: acyl ghrelin with O-n-octanoylated serine in the position 3, and des-acyl ghrelin. Among dozens of enzymes, hormones and other factors secreted by the gastrointestinal tract in response to food in the lumen, acyl ghrelin is the only gastrointestinal signal to increase meal size.

Acyl ghrelin stimulates food intake both in free-feeding (naturally fed) and food-deprived (fasted) rodents, and induces adiposity. Also, acyl ghrelin ameliorates cancer cachexia in nude mice, and alleviates ingestive behavior induced by cancer chemotherapy-related dyspepsia in normal rats. However, des-acyl ghrelin counteracts the metabolic but not the neuroendocrine response to acyl ghrelin. Transgenic mice overexpressing des-acyl ghrelin have been shown small phenotype. In addition, des-acyl ghrelin inhibits food intake in food-deprived mice and rats. Acyl ghrelin stimulates gastrointestinal motor activity and accelerates gastric emptying in rats, but not in dogs. On the contrary, des-acyl ghrelin has been shown to disrupt gastric motility in rats, and delay gastric emptying in mice and rats. For the majority of experiments, acyl ghrelin stimulates gastric acid secretion in rats, however, different results exist.


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Use of Total Parenteral Nutrition in Severe Anorexia Nervosa Complicated by a Gastrointestinal Illness
Philip S. Mehler

At present there is no consensus on how to refeed patients with severe anorexia nervosa. Staged progressive oral feeding programs, enteral feedings and total parenteral nutrition have been utilized to facilitate recovery. Although most patients with anorexia nervosa should be refed with a dietary program which is based on progressive increases in oral calories, total parenteral nutrition should be judiciously considered for the select patient with severe anorexia nervosa who also has medical comorbidities which preclude the usage of this standard approach. This alternative mode of refeeding may afford a meaningful recovery to a subset of patients with anorexia nervosa for whom the overall prognosis is guarded. However, the usage of total parenteral nutrition in this population is fraught with multiple potential complications which must be averted. Herein is described two patients with severe anorexia nervosa, and comorbid gastrointestinal issues which necessitated a trial of total parenteral nutrition to effectuate weight restoration.


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Screening Strategy for Iron Enhancers: Increasing Iron Bioavailability
Silvia Miret, Bernd van Buuren, Guus Duchateau and Werner Klaffke

Iron deficiency is the most common nutritional disorder in the world. It is estimated that 2 billion people are anaemic. Approximately 50% of infants, school-age children and women of reproductive age suffer from iron deficiency anaemia in some countries of South Asia, compared to about 25% in Latin America and 10% in the industrialised countries of Europe.

Iron deficiency is a result of the imbalance between the amount of iron absorbed and iron excreted. Such an imbalance may be the result of low iron intake due to low iron content of the diet or to low bioavailability of the dietary iron to compensate for the losses. Certain compounds such as ascorbic acid are well known for increasing iron bioavailability. However, not many other compounds have been found with a similar effect. In this review, we evaluate the methods employed in the search for compounds that could enhance iron bioavailability from iron fortified foods. All the methods are designed to screen for natural compounds that can form complexes with iron to guarantee product stability and acceptable taste, but still able to increase the concentration of soluble iron in the proximity of the intestinal brush border membrane, allowing for efficient iron uptake into the intestinal cells.

When used as a prelude of human trials, this screening strategy might enable improved design and productivity of the more expensive human experiment. Applications of this model include product development, but also screening of plant cultivars for improved bioavailability, development of improved supplements and studies of the precise factors that promote iron uptake.


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Dietary Factors Influencing Magnesium Absorption in Humans
Torsten Bohn

Decreased Mg intake and low Mg status have been associated with a number of major health concerns such as diabetes mellitus type II, coronary heart disease, and osteoporosis. While information on Mg intake is available, relatively little is known on dietary factors influencing Mg bioavailability. While it is established that Mg absorption is based on a combination of a non-saturable and a saturable pathway, the nature of especially the latter mechanism is not well understood. Recently, stable isotopes have improved techniques available for the determination of Mg absorption from single test meals or supplements. Some inorganic Mg forms such as MgO seem of limited solubility in the intestine, suggesting low bioavailability. Recent studies have further added evidence that some commonly consumed dietary compounds, such as phytate and oxalate, can inhibit Mg absorption, presumably via complexation, preventing absorption from the small intestine. Phytate for example has been shown to decrease Mg absorption by up to 60%, in a dose dependent manner. On the other hand, fermentable dietary fibre, such as fructo-oligosaccharides, have been demonstrated to increase Mg absorption in humans by 10-25%, even though the underlying mechanisms remain to be elucidated. Future studies to investigate factors impacting Mg absorption are warranted.