Kilcast / Angus Reducing Salt in Foods

Practical Strategies
1. Auflage 2007
ISBN: 978-1-84569-304-6
Verlag: Elsevier Science & Techn.
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, 384 Seiten

Reihe: Woodhead Publishing Series in Food Science, Technology and Nutrition

Concerns have grown that consumption levels of salt are well above those needed for nutritional purposes and that this can lead to adverse effects on health, in particular cardiovascular disease. Consumers are increasingly looking to reduce their salt intake, making salt reduction a priority for food manufacturers. This is not straightforward, though, as salt plays an important role in food preservation, taste and processability. Written by a team of international experts, Reducing salt in foods provides a unique review of current knowledge in this field.This book is divided into three parts and discusses the major issues concerned with salt reduction and how it may be achieved. Part one reviews the key health issues driving efforts to reduce salt, government action regarding salt reduction and the implications of salt labelling. Consumer perception of salt and views on salt reduction and are also discussed. The second part focuses on the technological, microbiological and sensory functions of salt and strategies that can be taken to reduce salt. The final part of the book outlines strategies which have been taken to reduce salt in particular food groups: meat and poultry, seafood, bread, snack foods, dairy products and canned foods.Reducing salt in foods is an essential reference for health professionals, governments and food manufacturers. - Discusses methods to reduce salt while maintaining food sensory quality, shelf-life and processability - Provides a unique review of current knowledge in this field - An essential reference for health professionals, governments and food manufacturers

Autoren/Hrsg.

Kilcast, David

Angus, Fiona

Leseproben

2 Dietary salt, high blood pressure and other harmful effects on health
F.J. He; G.A. MacGregor    St George's University of London, UK 2.1 Introduction
Cardiovascular disease (strokes, heart attacks and heart failure) is the leading cause of death and disability worldwide. Increasing blood pressure throughout the range is the major cause of strokes and heart failure. It is also a very important cause of coronary heart disease (Lewington et al. 2002). Worldwide, 26.4% of the adult population had high blood pressure (greater than 140/90 mmHg) and the estimated total number of adults with high blood pressure was 972 million in 2000. This number is predicted to increase to a total of 1.56 billion in 2025 (Kearney et al. 2005). Salt (sodium chloride) is the primary cause of raised blood pressure and is largely responsible for the rise in blood pressure that occurs in almost all adults as they grow older. Evidence that relates salt intake to blood pressure comes from six different lines of evidence - epidemiology (Elliott et al. 1996), migration (Poulter et al. 1990), intervention (Forte et al. 1989), treatment (He and MacGregor 2002), animal (Denton et al. 1995) and genetic studies (Lifton 1996). Evidence from these different sources all suggests that salt intake is important in blood pressure regulation and a reduction in salt intake would lead to a reduction in population blood pressure, a reduction in the rise in blood pressure with age and a reduction in blood pressure in those with high blood pressure whether on or off antihypertensive treatment. Salt intake in nearly all countries around the world is between 9 and 12 g/day (INTERSALT 1988; Henderson et al. 2003). The World Health Organisation has set a worldwide target of reducing salt to 5 g/day or less for all adults (WHO 2003). The UK and US recommendations are 6 g/day or less (Whelton et al. 2002; SACN 2003). A reduction in salt intake can be achieved by a public campaign about the dangers of salt leading to less use of table and cooking salt combined with a gradual and sustained reduction in the salt concentration of all processed and catering foods. More than three-quarters of salt that is consumed in most developed countries is added by the food industry, i.e. processed, canteen, restaurant, fast and takeaway foods. Only 15% is added in cooking or at the table and 5% is naturally present in foods. Clearly, therefore, a major reduction must be made in the amount of salt added to food by the food industry in order to achieve the target of 5 to 6 g/day. If these targets were achieved, the benefits would be very large. For instance, in the UK, approximately 35,000 stroke and heart attack deaths would be saved each year (He and MacGregor 2003), as well as many people dying from heart failure. Approximately, a further 35,000 nonfatal strokes and heart attacks as well as many people suffering from heart failure would be prevented each year. A reduction in salt intake is, therefore, one of the most important strategies for improving public health and preventing people dying or suffering unnecessarily from strokes, heart attacks and heart failure. There is also increasing evidence that our current high salt intake has other harmful effects on health, which may be independent of and additive to the effect of salt on blood pressure, e.g. a direct effect on stroke (Perry and Beevers 1992), left ventricular hypertrophy (Kupari et al. 1994; Schmieder and Messerli 2000), progression of renal disease and albuminuria (Heeg et al. 1989; Cianciaruso et al. 1998; Swift et al. 2005), stomach cancer (Joossens et al. 1996; Tsugane et al. 2004), and bone demineralization (Devine et al. 1995). In this chapter, we will review the evidence that relates salt to raised blood pressure as well as the possible mechanisms whereby salt increases blood pressure. We will also briefly discuss other harmful effects of salt on health. 2.2 Definition of hypertension
The relationship between blood pressure and cardiovascular disease displays a continuous graded relationship, and there is no evidence of any threshold level of blood pressure below which lower levels of blood pressure are not associated with lower risks of cardiovascular disease (Lewington et al. 2002). Thus, any classification of people into dichotomous categories ('normotensive' and 'hypertensive') is inherently arbitrary. Nevertheless, it is useful to provide a classification of blood pressure for the purpose of identifying high-risk individuals and providing guidelines for treatment with tablets and follow-up. Geoffrey Rose suggested that 'the operational definition of hypertension is the level at which the benefits … of action exceed those of inaction'. The criteria for the classification of hypertension have changed over the past 40 years as more recent studies have shown benefit at lower levels of blood pressure (Vasan et al. 2001). The recent Seventh Joint National Committee (JNC VII) (Chobanian et al. 2003) defined individuals with blood pressure less than 120/80 mmHg as 'normal' and those with blood pressure =140 mmhg systolic or =90 mmhg diastolic as 'hypertension', whereas for those with blood pressure ranging from 120 to 139 mmhg systolic and/or 80 to 89 mmhg diastolic, the JNC VII report has introduced a new term 'prehypertension'. This new designation is intended to identify those individuals in whom early intervention by adoption of healthy lifestyles could reduce blood pressure, decrease the rate of progression of blood pressure to hypertensive levels with age, or prevent hypertension entirely. Hypertension is extremely common in Western countries. For instance, in England just under 40% of the entire adult population have hypertension (systolic =140 mmhg and/or diastolic =90 mmhg) (Primatesta et al. 2001). The prevalence of hypertension increases with age, e.g. at the age of 50-59 years, approximately 50% have high blood pressure, and at the age of 60-79 years, 70% have high blood pressure. Many treatment trials have demonstrated a clear benefit of lowering blood pressure in hypertensive individuals (Staessen et al. 2001). 2.3 Benefits of lowering blood pressure in the 'normal' range
In the general population, blood pressure is distributed in a roughly normal or Gaussian manner in a bell-shaped curve with a slight skew towards higher readings. Although the risk of cardiovascular mortality increases progressively with increase in blood pressure, for the population at large, the greatest number of strokes, heart attacks, and heart failure attributable to blood pressure occur in the upper range of normal (i.e. systolic between 130 and 140 mmhg and diastolic between 80 and 90 mmhg) because there are so many individuals who have blood pressure at these levels in the population (MacMahon 1996). Therefore, a population-based approach aimed at achieving a downward shift in the distribution of blood pressure in the whole population, even by a small amount, will have a large impact on reducing the number of strokes, heart attacks and heart failure. 2.4 Salt and blood pressure
2.4.1 History of salt
Salt is a chemical that consists of sodium and chloride and, as something added to food, is not a normal constituent of the human or any mammalian diet. For several million years the evolutionary ancestors of humans ate a diet that contained less than 0.25 g/day of salt (Eaton and Konner 1985). Sufficient sodium exists in natural foods to ensure that mammals could develop away from the sea. However, the chemical salt has played an important role in the development of civilization (MacGregor and de Wardener 1998). It was first found to have the magical property of preserving foods, probably by the Chinese around 5000 years ago, when they found that meat or fish could be preserved for a long time when they were soaked in saline solutions. This ability to preserve food allowed the development of settled communities. Salt became one of the most traded commodities in the world, as well as one of the most taxed. Salt was initially expensive to produce and was regarded as a luxury, but with the mining of salt it became much more plentiful and was added to fresh food as this food tasted bland compared to the highly salted preserved foods that most people were used to eating. It was also found that when salt was added to food that was going putrid, the bitter flavours were removed and the food became edible. Salt was seen as almost magical and became a symbol of purity in most religions. In the late nineteenth century deep freezers and refrigerators were invented and salt lost its importance as a preservative. Since that time salt intake has been gradually falling. However, with the increased consumption of processed, canteen, restaurant and fast food, which contains large amounts of hidden salt, salt intake is now increasing. More than three-quarters of salt intake in most developed countries now comes from salt added to processed foods (James et al., 1987; Nestle 2002). Evolving on a low salt diet of no more than 0.25 g/day, humans are genetically programmed to this amount of salt,...