Nutrition in the Prevention and Treatment of Abdominal Obesity

Ronald Ross Watson

• Publisher: Academic Press
• Year: 2018
• eBook ISBN: 9780128137819
• Edition: 2
• Topic: Biological Sciences
• Subtopic: Endocrinology & Metabolism
• Index: Biological Sciences

Nutrition in the Prevention and Treatment of Abdominal Obesity, Second Edition focuses on the important role that exercise, dietary changes and foods play in promoting and reducing visceral fat. Nutritionists, dieticians and healthcare providers seeking to address the abdominal obesity epidemic will find this book to be a valuable resource in their long-term goal of preventing chronic diseases, especially heart, vascular and diabetic diseases. Chapters define a range of dietary approaches to reduce risk for the associated chronic diseases. In addition, discussions of the importance of dietary approaches to reduce abdominal obesity, along with clinical approaches, are discussed, including costs and risks.- Serves as a starting point for in-depth discussions in academic settings that will lead to revised and updated treatment options- Offers detailed, well-documented reviews outlining the various dietary approaches to visceral obesity with their benefits and failures- Includes updated research on the gut microbiome, FGF 21 and dietary foods and supplements

Section V

Micronutrients and Dietary Components in Obesity

Chapter 25

Conjugated Linoleic Acid in Human Health: Effects on Weight Control

Phoebe B. Chen; Yeonhwa Park Department of Food Science, University of Massachusetts, Amherst, MA, United States

Abstract

Since conjugated linoleic acid (CLA) was identified as an anticancer component from beef extract, CLA has shown other beneficial bioactivities. Among them, the most interesting aspect of CLA is its ability to control body fat. This chapter reviews the current knowledge of CLA supplementation in humans, with particular focus on its effects on weight and body fat control. The suggested mechanisms of CLA with regard to body fat regulation as well as consideration of age, study design, interaction between CLA and exercise and other dietary supplementations, and comparison between animal and human studies are discussed in the chapter. Other health benefits of CLA from human studies (cancer prevention, cardiovascular diseases, immune and inflammatory responses, and bone health) are reviewed. The potential adverse effects associated with CLA supplementation, such as its role in oxidative stress, glucose metabolism, milk fat depression, and liver functions, are updated and discussed in this revised chapter.

Keywords

Conjugated linoleic acid; CLA; Obesity; Conjugated trans fatty acid; Body fat

Outline

• Introduction
• Discovery and Origins of CLA
• Antiobeisty Effects of CLA
  • Overview of Human Studies for CLA
  • Mechanisms of Body Fat Regulation by CLA
  • Exercise and CLA Supplementation
  • Subject Age and CLA Supplementation
  • CLA: Other Considerations
• Other Health Benefits of CLA
  • Cancer Prevention and CLA
  • Cardiovascular Diseases and CLA
  • Bone Health and CLA
  • Immune and Inflammatory Responses and CLA
  • Health Concerns Associated With CLA Consumption
  • Oxidative Stress
  • Glucose Metabolism
  • Milk Fat Depression
  • Liver Functions
• Conclusion
• References

1 Introduction

Health concerns over the consumption of trans fatty acids compared to the known health benefits of fish oil clearly illustrate how different dietary fats contribute to our health. The trans fatty acids can be further divided into unconjugated or conjugated trans fatty acids based on their structural features. Unconjugated trans fatty acids found in foods from ruminant sources are referred to as ruminant trans fatty acids. Unconjugated trans fatty acids derived from partially hydrogenated vegetable oils are referred to as industrial trans fatty acids. These industrial trans fatty acids are known to be the major dietary source of trans fatty acids and are also considered to be a major health concern, particularly for cardiovascular diseases.^1,2

Current regulation by the US Food and Drug Administration for trans fat labeling specifically defines “all unsaturated fatty acids that contain one or more isolated double bonds (i.e., nonconjugated) in a trans configuration.”³ Based on this definition, the “conjugated” trans fatty acids, primarily conjugated linoleic acid (CLA), have been excluded from the current trans fat labeling. In addition, with current approval for CLA as generally recognized as safe (GRAS) and a food additive for use in certain types of food in the United States since 2008, the consumption of CLA associated with dietary supplements or foods is expected to rise significantly. Thus, it is important to review the current knowledge on CLA, and particularly its human health implications. This chapter primarily focuses on CLA publications involving human studies on body fat and weight control.^4,5

Discovery and Origins of CLA

As early as 1932, the existence of CLA was reported in a scientific paper although it was not until much later that its structure was identified and it was given the name “CLA.”⁶ The first report of CLA was from milk, in which increased ultraviolet absorption at 230 nm in summer milk compared with winter milk was reported, suggesting the presence of a conjugated double bond in CLA's structure.⁶ In the 1980s, Dr. Pariza's group at the University of Wisconsin-Madison investigated the relationship between mutagen formation and cooking temperature and time using cooked ground beef to expand on previous observations that eating overcooked meat can cause cancer.^7,8 They found that increased cooking temperature and time potentiated mutagen formation in cooked beef, but interestingly they also identified a beef extract fraction that inhibited mutagenesis.^7,8 The principal compound responsible for this activity was identified as a conjugated isomer of linoleic acid and thus named conjugated linoleic acid.^7,8

CLA was discovered in beef and the primary dietary source of CLA is ruminant products. CLA is derived from biohydrogenation of linoleic acid to stearic acid by rumen bacteria.⁹ Among a number of potential CLA isomers (please see below for details), the main CLA isomer from biohydrogenation is the cis-9,trans-11 isomer, a stable intermediate of biohydrogenation.⁹ This isomer is also called rumenic acid, which implies that it is produced by rumen bacteria.¹⁰ Similarly, trans-11 vaccenic acid, the other stable intermediate of biohydrogenation, escapes this process and can be converted to the cis-9,trans-11 isomer by delta-9 desaturase expressed in mammalian tissue.^11,12 This is considered an alternative source of tissue cis-9,trans-11 CLA.^11,12

Even though foods from ruminant origins are considered to be good sources of CLA, typical concentrations of cis-9,trans-11 CLA in food are relatively low, less than 10 mg CLA per g fat.¹³ CLA intake varies greatly depending on a person's dietary pattern: high CLA intake with high dairy consumption (up to 291 mg/...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributors
• Acknowledgments
• Section I: Overview of Obesity and Population Studies
• Section II: Mechanisms of Obesity
• Section III: Role of Dietary Supplements in Obesity
• Section IV: Foods and Macronutrients in Obesity
• Section V: Micronutrients and Dietary Components in Obesity
• Index