Advances in Food and Nutrition Research (eBook)

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2015 | 1. Auflage
146 Seiten
Elsevier Science (Verlag)
978-0-12-802427-0 (ISBN)

Infos

Advances in Food and Nutrition Research recognizes the integral relationship between the food and nutritional sciences and brings together outstanding and comprehensive reviews that highlight this relationship. Contributions detail scientific developments in the broad areas of food science and nutrition and are intended to provide those in academia and industry with the latest information on emerging research in these constantly evolving sciences. - The latest important information for food scientists and nutritionists - Peer-reviewed articles by a panel of respected scientists - The go-to series since 1948

Inhalt

Front Cover 1
Advances in Food and Nutrition Research 4
Copyright 5
Contents 6
Contributors 8
Preface 10
Chapter One: Leveraging Agriculture for Nutrition Impact through the Feed the Future Initiative 12
1. Background 13
1.1. The nutrition narrative 13
1.2. Renewed focus: Agriculture and nutrition linkages 15
2. Linking Agriculture and Nutrition 17
2.1. Current understanding of the linkages between agriculture and nutrition 17
2.1.1. Agriculture and nutrition pathways 17
2.1.1.1. ProductionConsumption pathway 18
2.1.1.2. IncomeFood and health care purchase pathway 18
2.1.1.3. Women´s empowerment pathway 20
2.1.1.4. The enabling environment for the pathways 21
2.1.1.4.1. Food market environment 21
2.1.1.4.2. Natural resources environment 22
2.1.1.4.3. Health, water, and sanitation environment 23
2.1.1.4.4. Knowledge and norms 23
2.1.2. Guiding principles 24
2.2. The Feed the Future initiative 25
3. The Landscape Analysis of Feed the Future Activities 26
3.1. Background of landscape analysis 27
3.1.1. Objective 27
3.1.2. Scope 27
3.1.3. Frameworks for landscape analysis 27
3.1.4. Limitations of landscape analysis 28
3.2. Key findings and considerations 29
3.2.1. Activity approaches 29
3.2.2. Target populations 29
3.2.3. Value chains and the selection criteria 30
3.2.3.1. Factors behind value chain selection 30
3.2.3.2. Regional emphasis 32
3.2.4. Integration of nutrition in Feed the Future activities 32
3.2.5. Agriculture-to-nutrition pathways 33
3.2.5.1. ProductionConsumptionNutrition pathway 33
3.2.5.2. IncomeFood and health purchaseNutrition pathway 33
3.2.5.3. Women´s empowerment pathway 34
3.3. Observations and discussion 34
3.3.1. Inclusion of nutrition objectives and indicators 34
3.3.2. Monitoring intermediate steps along agriculture-to-nutrition pathways 35
3.3.3. Tackling women´s roles and gender norms 36
3.3.3.1. Women´s time and workload constraints 36
3.3.3.2. Gender roles and norms 37
3.3.4. Targeting 37
3.3.4.1. Inclusion of both men and women in agriculture and nutrition interventions 37
3.3.4.2. Working with more vulnerable beneficiaries in zones of influence 38
3.3.4.3. Communications for better coverage in co-located activities 38
3.3.5. Value chain selection 39
3.3.5.1. Investing in nutrient-dense value chains 39
3.3.5.2. Potential unintended consequences on market prices 39
3.3.6. Market access to diverse, nutrient-dense foods 40
3.3.7. Social and behavioral change along value chains and agriculture-to-nutrition pathways 40
3.3.7.1. Messaging 40
3.3.7.2. Delivery 42
3.3.8. Multisectoral coordination 42
3.4. Recommendations from landscape analysis 43
3.4.1. Design and modify interventions and indicators based on context assessments 44
3.4.2. Empower women by building a supportive family and social environment 44
3.4.3. Target social and behavioral change activities along all agriculture-nutrition pathways 44
3.4.4. Focus on opportunities for nutrition throughout the value chains 45
3.4.5. Document incremental results to build the evidence base 45
4. Moving Forward 45
4.1. Technical briefs on the connections between agriculture and nutrition 45
4.2. Understanding the connections between agriculture and nutrition in the food system 49
5. Conclusion 54
Acknowledgment 55
Disclaimer 55
References 55
Chapter Two: Health Benefits of Prebiotic Fibers 58
1. Prebiotic Fibers 58
1.1. Definitions and properties of dietary fiber 58
1.1.1. Physiological properties of dietary fibers 60
1.1.2. Effect on bowel movement 61
1.1.3. Favorable colonic fermentation 62
1.1.4. Effect on serum lipids and blood glucose 63
1.1.5. Overweight 63
1.1.6. Colon cancer 63
1.2. Definition of prebiotics 64
2. Physiological Effects of Different Prebiotic Fibers 65
2.1. Lactulose and lactitol 65
2.1.1. Lactulose 65
2.1.2. Lactitol 66
2.2. Galactooligosaccharides 66
2.2.1. Galactooligosaccharides from lactose (GOS) 66
2.2.2. Soybean galactooligosaccharides 68
2.3. Fructans 69
2.3.1. Levans 69
2.3.2. Fructooligosaccharides from sucrose 70
2.3.3. Inulin and oligofructose from chicory roots 72
2.4. Glucose-based prebiotic fibers 75
2.4.1. Iso-malto-oligosaccharides 76
2.4.2. Polydextrose 76
2.4.3. Soluble Gluco Fiber 77
2.4.4. Other resistant starches 78
2.5. Gums and other complex polysaccharides as prebiotic fibers 79
2.5.1. Guar gum 79
2.5.2. Acacia gum 79
2.5.3. Arabinoxylo-oligosaccharides and xylo-oligosaccharides 80
2.5.4. Other candidates 80
3. Nutrition and Health Claims Based on Prebiotic Fibers 81
3.1. Nutrition claims 81
3.2. Health claims for prebiotic dietary fibers 82
3.2.1. Health claims in the United States 83
4. Future Developments 85
4.1. Final remarks 88
References 88
Chapter Three: Vegetarian Diets Across the Lifecycle: Impact on Zinc Intake and Status 104
1. Introduction 105
2. Definitions of Vegetarian Diets 106
3. Zinc Intake and Bioavailability 107
3.1. Phytate, zinc, and calcium 107
4. Mechanisms of Zinc Homeostasis 109
5. Determination of Zinc Status 110
6. Vegetarian Diets and Zinc Status in Healthy Adults 111
6.1. Prevalence of vegetarian diets in adults 111
6.2. Adaptations to a vegetarian diet 112
6.3. Comparative studies of zinc status in adults 113
7. Vegetarian Diets and Zinc Status in Pregnancy and Lactation 121
7.1. Comparative studies of zinc intake in pregnancy 121
7.2. Comparative studies of zinc biomarkers in pregnancy 123
7.3. Zinc status and functional outcome in pregnancy 124
7.4. Zinc status during lactation 124
8. Vegetarian Diets and Zinc Status in Children 125
8.1. Prevalence of vegetarian diets in children 126
8.2. Comparative studies of zinc status in children 127
8.3. Infants 127
8.4. Young children 129
8.5. Adolescents 130
9. Vegetarian Diets and Zinc Status in the Elderly 131
9.1. Comparative studies of zinc status in the elderly 131
10. Limitations and Further Research 133
11. Conclusion 134
References 134
Index 144

Textauszug

Chapter Two

Health Benefits of Prebiotic Fibers

Diederick Meyer1    Sensus BV, Roosendaal, The Netherlands
1 Corresponding author: email address: [e-mail]

Abstract

This chapter describes the various compounds that can act as prebiotic fibers: their structure, occurrence, production, and physiological effects (health effects) will be presented. The basis for the description is the latest definitions for dietary fibers and for prebiotics. Using as much as possible data from human studies, both the fiber and the prebiotic properties will be described of a variety of compounds. Based on the presented data the latest developments in the area of prebiotics, fibers and gut and immune health will be discussed in more detail as they show best what the potential impact of prebiotics on health of the human host might be.

Keywords

Prebiotics

Dietary fibers

Health effects

1 Prebiotic Fibers

1.1 Definitions and properties of dietary fiber

The definition of dietary fiber has been the subject of an almost endless debate, mainly because dietary fiber is not one single chemical entity like starch or cellulose. Some based the definition on physiological features, whereas other used its chemical composition. The original description by Hipsley (1953) described dietary fiber as nondigestible constituents of plant cells walls. Later, Trowell and others expanded the description to “consisting of plant polysaccharides and lignin which are resistant to hydrolysis by digestive enzymes of man.” More importantly, these authors also came up with the dietary fiber hypothesis related to health observations (Trowell, 1972, 1976). The definition of dietary fiber was based on (one of) its physiological features, namely, its nondigestibility. Based on this feature, fiber determinations were developed mimicking the human digestion in a glass tube, to determine the fiber content of food, e.g., to assist food industry and enforcing authorities with nutritional labeling. In 1985, these efforts led to an approved AOAC method (AOAC 985.29) and in many countries it was used as a de facto definition of dietary fiber: material determined by this method is dietary fiber (AOAC 985.29, 2012). Soon it turned out that many nondigestible carbohydrates with physiological functions as dietary fiber were not assessed by this method or by other methods based on AOAC 985.29. This has led to the development of a battery of assays aimed at determining specific dietary fibers, such as AOAC 997.08 and 999.03 for fructans (AOAC 997.08, 2012; AOAC 999.03, 2012), or AOAC 2000.11 for polydextrose (AOAC 2000.11, 2012). A more detailed description of the development of dietary fiber definitions and assessments can be found in Prosky (2001) and Tungland and Meyer (2002). Figure 1 (left-hand picture) shows the situation before the latest developments that will be described below.

Figure 1 Analysis of dietary fiber before the development of AOAC 2009.01/2011.25 (left-hand side) and after (right-hand side). Reprinted with permission from Official Methods of Analysis of AOAC International. Copyright 2012 by AOAC International

The whole discussion on the definition has now led to two definitions for dietary fiber for labeling; they both are based on the nondigestibility. In the EU, dietary fiber (dietary fiber) means carbohydrate polymers (either naturally occurring or obtained by physical, enzymatic or chemical means, or synthetic polymers) that are not hydrolyzed by the digestive enzymes in the small intestine of humans. The carbohydrate polymers must have a degree of polymerization (DP) of three or more monomeric units (European Commission, 2008/100/EC) and for isolated fibers and synthetic polymers a beneficial physiological effect has to be proven based on generally accepted scientific evidence. The definition adopted by Codex Alimentarius Commission (2009; Alinorm 09/32/26) is based on the same type of carbohydrate polymers, but on those having a DP of 10 and above. However, a footnote which forms an integral part of this definition, states that the decision on whether or not to include carbohydrates from three to nine monomeric units should be left to national authorities (see also Harris & Pijls, 2009). Also this definition requires evidence for a beneficial physiological effect for carbohydrates obtained by physical, enzymatic or chemical means, and synthetic polymers. It should be stressed that from a physiological point of view, there is no reason to exclude oligomers with DP < 10 (Howlett et al., 2010).

With this definition in mind, a universal method determining all dietary fibers in food was developed (McCleary, 2007; McCleary et al., 2010). These methods are now available as validated methods (AOAC 2009.01 and AOAC 2011.25) and they can be used to assess the total dietary fiber content of food irrespective of the type of fiber present (see Fig. 1) (AOAC 2009.01, 2012; AOAC 2011.25, 2012). Not surprisingly, also these methods have their disadvantages; apart from the laborious procedure it now emerges that some fibers still partially escape detection (e.g., Zielinski, DeVries, Craig, & Bridges, 2013). In connection with the issue about the DP required to classify as dietary fiber as in the Codex definition, it should be stressed that these or any other approved analytical method cannot discriminate dietary fibers with DP < 10 from those with DP ≥ 10 (Betteridge, Caers, Lupton, Slavin, & Devries, 2012).

1.1.1 Physiological properties of dietary fibers

Dietary fiber is acknowledged worldwide for its positive effects on health and well-being. The benefits include positive effects on bowel habit, a favorable effect on fermentation in the colon, a reduction of blood (LDL-) cholesterol levels and an improvement of blood glucose and insulin levels. Moreover there are associations from epidemiological evidence mainly between a lowered risk for colon cancer and for obesity with appropriate fiber consumption (e.g., EFSA, 2010b; Health Council of the Netherlands, 2006). An overview of the effects of different kind of fibers is presented in Table 1. Some dietary fibers, such as pectins or some gums, also have physiological effects due to their influence on the rheology of the intestinal content; a high viscosity is generally connected with a delayed gastric emptying and increased small intestinal transit time. A viscous environment in the small intestine may also inhibit absorption of nutrients with its physiological consequences.

Table 1

Physiological effects of various fiber types

Gastric emptying

Lower rate

None

?

No effect

Glucose absorption curve

Flattening

Unknown

?

?

Fermentation in colon

Large extent

Hardly

Variable

Completely

Bowel habit

+

++

+

+

Blood cholesterol

Lowering

No effect

Variable

Lowering

(+)+: (strong) positive effect; ?, no or conflicting data.

It should be noted that the evidence for much of the health benefits described below comes from epidemiological associations. In many cases it is not easy to carry out trials for such benefits with isolated dietary fibers, as these trials will take too long (e.g., for the lowered risk for colon cancer, or a lowered death rate from cardiovascular disease) and thus are very costly to carry out. For many of these diseases the lack of suitable and validated biomarkers also plays an important role; as an example, whereas the serum lipid level of cholesterol is an accepted biomarker for the risk for cardiovascular disease, such markers are not available for colon cancer, or obesity.

1.1.2 Effect on bowel movement

The best known effect of dietary fiber is its influence on stool: it decreases the time for food passage through the entire gastrointestinal tract and increases fecal bulk. In fact, this feature is used by some authorities as a basis for their guidelines for fiber intake (Health Council of the Netherlands, 2006; Institute of Medicine, 2005). Moreover, these effects can also be investigated easily in intervention studies with isolated fibers. As shown in Table 1 insoluble fibers have the strongest effect on bowel habit as they act as fecal bulking agents; e.g., what bran provides from 2.6 to 4.9 g/g (Cummings, Beatty, Kingman, Bingham, & Englyst, 1996; Maki et al., 2009), whereas soluble fibers such as pectin or inulin only provide about 1–2 g/g (e.g. Den Hond, Geypens, & Ghoos, 2000; Salminen et al., 1998). Their main effect is on stool consistency and frequency of defecation as they increase the softness of fecal matter.

1.1.3 Favorable colonic fermentation

Dietary fibers reach the colon intact and there they can be fermented by specific colonic bacteria and converted into short-chain fatty acids (SCFA), lactic acid and gas. The extent of the fermentation depends very much on the type...

Produkt-Details

• Erscheint lt. Verlag: 23.1.2015
• Mitarbeit: Herausgeber (Serie): Jeya Henry
• Sprache: englisch
• Themenwelt: Medizin / Pharmazie ► Gesundheitsfachberufe ► Diätassistenz / Ernährungsberatung
• Themenwelt: Naturwissenschaften ► Biologie ► Mikrobiologie / Immunologie
• Themenwelt: Technik ► Lebensmitteltechnologie
• ISBN-10: 0-12-802427-5 / 0128024275
• ISBN-13: 978-0-12-802427-0 / 9780128024270