TABLE OF CONTENTS
Title Page – – – – – – – – – I
Certification Page – – – – – – – – – ii
Dedication – – – – – – – – – iii
Acknowledgement – ¬- – – – – – – – iv
Abstract – – – – – – – – – v
Table of Contents – – – – – – – – – vi
List of Figures – – – – – – – – – ix
List of Tables – – – – – ¬- – – – x
CHAPTER ONE: INTRODUCTION
1.1 Processed foods – – – – – – – – 3
1.1.2 Reasons why processed foods contain salt- – – – – – – 4
1.2 Snacks – – – – – – – – – 5
1.3 Breakfast cereals – – – – – – – – 6
1.3.1 Traditional (hot) cereals – – – – – – – 6
1.3.2 Ready to- eat cereals – – – – – – – – 7
1.4 Sodium – – – – – – – – – 7
1.4.1 Sources of sodium – – – – – – – – 9
1.4.2 Sodium guidelines/acceptable nutrient claims of sodium set by NAFDAC – 9
1.5 Calcium – – – – – – – – – 9
1.6 Iron – – – – – – – – – – 10
1.7 Potassium – – – – – – – – – 10
1.7.1 Sodium-potassium interactions – – – – – – 11
1.7.2 Significance of sodium-potassium ratio – – – – – 13
1.8 Methods/strategies for sodium reduction in processed foods – – – 15
1.8.1 Role of food industries – – – – – – – – 15
1.8.1.1 Sodium reduction by stealth – – – – – – – 16
1.8.1.2 Use of salt substitutes – – – – ¬- – – – 17
1.9 Roles of government – – – – – ¬- – – 18
1.10 Roles of consumers – – – – – ¬- ¬- ¬- 20
1.10.1 Sodium restricted diets – – – – ¬- – – ¬20
1.11 Responsibilities/roles of Food and Drug Administration of Nigeria
in regulating sodium – – – – – – – – 21
1.12 Effect of sodium reduction in processed foods – – – – 23
1.13 2012 salt targets of some food categories by UK Food Standard Agency – – 24
1.14 Standard amount of sodium by NAFDAC – – – – – 25
1.15 Aims and objectives of the research – – – – – – 25
CHAPTER TWO: MATERIALS AND METHODS
2.1 Materials – ¬- – – – – – – – 26
2.1.1 Instruments – – – – – – – – – – 26
2.1.2 Chemicals – – – – – – – – – 26
2.1.3 Preparation of reagents- – – – – – – – 27
2.1.3.1Preparation of standard- – – – – – – – 27
2.2 Methods – – – – – – ¬- – – 28
2.2.1 Collection of samples – – – – – – – – 28
2.2.2 Sample digestion (wet digestion) – – ¬- – – ¬- 28
2.2.2.1Nitric-perchloric acid digestion -¬ – – – – – 28
2.2.2.2Principle of wet digestion – – – – – – – 28
2.2.3Determination of sodium and potassium ions by flame photometry method – 28
2.2.3.1Principleof flamephotometer – – – – – – ¬29
2.2.4 Determination of calcium content – – – – – – 30
2.2.4.1 Principle of complexometricmethod – – – – – – 30
2.2.5 Determination of iron content- – – – – – – 31
2.2.5.1 Principleof bathophenanthrolinemethod – – – – – 31
2.2.6Statistical analysis – – – ¬- – – ¬- – 31
CHAPTER THREE: RESULTS
3.1 Concentrationsof sodium, potassium, iron and calcium in biscuit, sausage,
cake/pastries and breakfast cereals – – – – – 32
3.2 Comparison of sodium and potassium contents in breakfast cereals – – ¬34
3.3 Comparison of sodium and potassium content of cake, doughnut
and meat pies- – – – – – – – – – 36
3.4 Percentage contribution of the food samples relative to the recommended daily allowance of sodium, potassium, iron and calcium 38
3.5 A comparisonof the sodium concentration in different categories of biscuit — 40
3.6Comparison of the sodium and potassium concentrationsin different brands of
biscuits – – – – – – – – – 42
3.7Iron content of biscuits, sausages, cakes/pastries and breakfast cereals – 44
3.8Comparison of Iron concentrations of different brands of biscuit – – 46
3.9Comparison of mean iron content in breakfast cereals- – – – 48
3.10Calcium concentrations in different brands of biscuits – – – – 50
3.11Comparison of mean calcium concentrations in breakfast cereals – – ¬- 52
3.12 Calcium concentration of biscuits, sausages, cakes/pastries
and breakfast cereals – – – – – – -54
CHAPTER FOUR: DISCUSSION
4.1 Discussion – – – – – – – – – – 56
4.2 Conclusion- – – – – – – – – – 61
4.3 Suggestions for further studies – – – – – – 61
REFERENCES – – – – – – – – – 62
APPENDICES – – – – – – – – – 75
LIST OF FIGURES
Fig1: Sources of sodium – – – – – – – – 4
Fig 2: mechanism of sodium-potassium pump – – – – – – 12
Fig3: The relationship between sodium, potassium and blood pressure
in the pathogenesis of hypertension – – – – – – 14
Fig 4: Comparison of sodium and potassium content of samples of
breakfast cereals – – – – – – – – – 35
Fig5:Sodium and potassium content of cake, doughnut
and meat pies – – – – – – – – – 37
Fig6: Percentage daily value of biscuit, sausage, cake/pastries and
breakfastcereals relative to the RDA of sodium, potassium, iron and calcium- 39
Fig 7: Sodium and potassium concentration in different brands of biscuits – – 43
Fig 8: Iron content of biscuits, sausage,cakes/pastries and breakfast cereals – 45
Fig 9: Iron content of different brands ofbiscuit- – – – – – 47
Fig10: Iron content in samples of breakfast cereals – – — ¬- – 49
Fig 11:Calcium content of samples of biscuits- – – – – – 51
Fig 12:Calcium content of samples of breakfast cereals- – – – – 53
Fig 13: Calcium concentration of biscuits, sausages, cakes/pastries
and breakfast cereals – – – – – – – 55
LIST OF TABLES
Table 1: Sodium containing ingredients and their uses – – – – 8
Table 2: Sodium guidelines by FDA – – – – – – 9
Table 3: Salt targets of food categories by UKFSA – – – – 24
Table 4:Standard amount of sodium by NAFDAC- – – – – 25
Table 5: Working standard solution for sodium and potassium determination- 31
Table 6:Sodium, potassium, iron and calcium concentration in biscuits,
sausages, cakes/ pastries and breakfast cereals – – – 33
Table 7: Sodium concentration in different categories of biscuits – – – 40
CHAPTER ONE
INTRODUCTION
Sodium occurs naturally in almost all foods including processed foods, and, is essential for normal human functioning; however, its current intake far exceeds recommendations for good health (Brown et al., 2009). This has become a common occurrence around the world (Elliot, 2007). Excess sodium consumption is now a major public health concern worldwide (Institute of Medicine, 2010) and, has been linked to numerous adverse health conditions like hypertension, which is a major cause of cardiovascular diseases (Turnbull, 2003; Dickinson and Havas9, 2007), gastric cancer (Tsugane9et al., 2004), decreased bone mineral density (Devine et al., 1995) and possibly obesity (He and MacGregor, 2008). It has been estimated that 62% of stroke and 49% of coronary heart disease is caused by high blood pressure (He and MacGregor, 2010), which rises with age (Havaset al., 2004). In recent decades, with increasing consumption of many different processed foods containing high levels of sodium (Mattes and Donnely, 1991), the perception of dietary salt has evolved to a point where it is now considered a potential health threat. In 2003, as a result of the high sodium intakes around the world, the World Health Organization( WHO) recommended a worldwide intake target of less than 5grammesof salt (or 2000 mg sodium) per day per person (World Health Organization, 2003).
Modern diet contains a high proportion of processed foods with high levels of sodium, which is inherently appealing to humans (Mattes, 1997). As seen in many developed countries, a new pattern of food intake which favours the consumption of processed foods and snacks is emerging in Nigeriadue, to the convenience of these processed foods that often encourages unhealthy eating patterns (Monteiro, 2009). This change in life style may be attributed to busy work schedule which makes dependence on these convenience foods to be on the increase. Most processed breakfast cereals have been modified in flavours and forms, thereby making them more appealing to consumers (Truswell and Brand, 1985), thus, helping manufacturers to increase sales in a highly competitive market. Also, most people have strong preference for snacks like cake, biscuit and the wholesomeness of these snacks are not important in determining their food choice,since they do not provide overall intake of nutrients (Buthrieet al., 2002).Due to the health risks associated with excessive consumption of sodium, health agencies estimated that reducing its levels in processed and restaurant food by 50% would save 150,000 lives (Havaset al., 2004). Historically hominid diets contained high potassium and low sodium concentrations due to a diet consisting largely of fruits, vegetables and whole grains (Cordainet al., 2005). The consumption of excess sodium and insufficient potassium intake that is associated with a typical modern diet has been linked to several health effects. High intake of sodium and the low intakes of potassium has been shown to produce and maintain elevated blood pressure in a big proportion of the population (Krishna, 1990; Karppanenet al., 2005).
Processed foods can be deliberately fortified with micronutrients like iron and calcium, to increase intake of these nutrients. This could reduce micronutrient deficiency and associated health conditions (Darnton-Hill and Nalubola, 2002). Low iron intake is associated with anaemia (Nielson and Nachtigall, 1998), while, low calcium consumption increases the risk of bone problems like osteoporosis (Heaney, 2006) and elevated blood pressure. Increase in dietary sodium intake has a potential to influence bone loss by increasing loss of calcium. High intake of calcium has been shown to reduce systolic and diastolic blood pressure (Griffith et al., 1999).
WHO, as part of its Global Strategy on diet, physical activity and health, organized a forum and technical meeting in 2006 to review and discuss the link between high salt consumption and health, various initiatives to reduce population-wide salt intake and the cost and effectiveness of these programs. Several countries have developed strategies for significantly reducing the sodium chloride content of many processed foods (Cobcroftet al., 2008).
Based on the realization that processed foods are major contributors to the daily sodium intake, reducing the sodium content of processed foods has therefore been recognized as a feasible and more effective strategy for reducing daily salt intake than simply reducing the amount of salt added during cooking or on the table (WHO, 2007). Unfortunately, consumers are often unaware of the salt content of some of these processed foods that they consume regularly (Nwanguma and Okorie, 2013). This so called ‘hidden salt’ has been reported to contribute up to 95% of the salt intake of some people, especially in countries where processed foods are widely consumed (Anderson et al., 2010). An international organization of experts on the health effects of salt WASH (World Action on Salt and Health) publicized the adverse effects of sodium chloride on health and work with governments and industry to reduce salt concentration in processed foods, catered foods and restaurant food, as well as salt added during cooking, and at the table. Achieving population wide reductions in salt intake is therefore, an important public health priority in many countries (Webster et al., 2011). Numerous health organizations and Government agencies have recommended a substantial reduction in sodium levels that would allow for manufacturers to reformulate foods and for consumers to adapt their tastes to lower sodium. The research was aimed at surveying sodium, potassium, calcium and iron content of selected retail samples of processed foods available in Nsukka, Enugu State South Eastern Nigeria, namely breakfast cereals, biscuits, cakes, meat pies, doughnut and sausage.
1.1 Processed foods
Food processing is the set of methods and techniques used to transform raw ingredients into food, or to transform food into other forms for consumption (Monteiro and Levy, 2010). Food processing can create products that require little or no preparation on the part of consumers (Brunner et al., 2010). It produces attractive, marketable and often long shelf-life food products. Methods used for food processing are canning, freezing, dehydration, aseptic processes (Monteiro and Levy, 2010).
Processed foods are foods that have been altered from their natural state for safety reasons or for convenience. They are designed to be less perishable, more durable and more portable than prepared foods and, often contain substantial amounts of sweeteners, preservatives and appealing ingredients such as chocolates, peanuts and specially designed flavours (such as flavoured potato chips) (Street Foods, 2006). Processed foods are major contributors to population dietary salt intake (i.e. the total number of sodium intake from all sources including sodium chloride, monosodium glutamate or any other sodium containing preservatives or additives. They account for more than three-quarters of all sodium consumed as shown in fig.1 (Mattes, 1997; FSANZ, 2007). The reduction of salt (sodium) in processed foods is therefore a major challenge for health authorities across the globe and in many cases the challenge is currently being set to the food industry to change formulations and, reduce dietary sodium consumption thereby reducing hypertension and associated risks on cardiovascular disease (Webster et al., 2010; Xing, 2012).
