ABSTRACT
Processed foods have been noted to be generally, high in sodium but, low in potassium. Some of these foods such as snacks often provide a quick bite at work and school and often do not provide the needed nutrients such as calcium and iron needed in adequate quantities. The food categories sampled were biscuits, sausages, cakes/pastries and breakfast cereals. Sodium, potassium, calcium and iron concentrations were determined within and across the above named food categories. The various foods sampled (biscuit, sausage, cake/pastries and breakfast cereals) had varying concentrations of sodium, potassium, calcium and iron. Mean sodium contents obtained by flame photometry were, 258.14±30.46 mg/100g for biscuits, 260.42± 34.41 mg/100g for sausage, 263.57±32.63 mg/100g for cakes/pastries and 265.82±35.12 mg/100g for breakfast cereals. The mean sodium content of biscuit 258.14±30.46 mg/100g was close to the target set by United Kingdom Food Standard Agency (UKFSA) (270-450mg/100g) but, lower than the value of 629mg/100g set by the National Agency for Food and Drug Administration and Control(NAFDAC). Sodium level in cake (303.03±21.69 mg/100g) was within the reference range set by UKFSA (200-400mg/100g); and was quite close to the standard set by NAFDAC (300 mg/100g). The average sodium content across food samples ranged from 231.47±5.02 mg/100g (biscuit) to 312.50±8.19 mg/100g (breakfast cereals). From the values, the consumption of 100g of biscuit, sausage, cake/pastries and breakfast cereals would contribute 10.76, 10.85, 10.99 and 11.09% respectively to the recommended daily intake (RDI) of sodium. The mean potassium concentrations were 136.51±21.06 mg/100g for biscuits, 130.11±9.71 mg/100g for sausage, 155.91±15.44 mg/100g for cakes/pastries and 157.62±29.55 mg/100g for breakfast cereals.These contributed 3.89% for biscuit, 3.71% for sausage, 4.45% for cake/pastries and 4.54% for breakfast cereals to the recommended potassium intake. The mean iron contents were1.59±0.41 mg/100g for biscuits, 2.46±1.10 mg/100g for sausage, 1.86±0.64 mg/100g for cakes/pastries, and 1.89±1.04 mg/100g for breakfast cereals. Iron content ranged from 1.14 mg/100g for biscuitto 4.08 mg/100g for fortified breakfast cereals. Mean calcium concentrations were, 116.14±58.39 mg/100g (for biscuit), 112.67±32.22 mg/100g (for sausage), 89.78±25.32 mg/100g (for cake/pastries) and 139.90±25.63 mg/100g (breakfast cereals). Calcium concentration varied widely across food samples, ranging from 42 mg/100g (biscuit) to 402 mg/100g (fortified breakfast cereals). The calcium content of biscuit showed a significant difference (p<0.05), ranging from 42±2.0 to 222.67±1.76 mg/100g, while that of breakfast cereals varied from 43±3.46 to 402±2.0mg/100g
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).
1.1.2 Reasons why processed foods contain salt
The utility of sodium has made it a crucial ingredient for many processed foods. Sodium improves the sensory properties of foods, by increasing saltiness, decreasing bitterness, and increasing sweetness and other congruent flavour effects (Keast and Breslin, 2003). Salt is added to processed foods for the following reasons:
1. Sodium chloride (salt) can prevent the development of food-borne pathogens.
It reduces water activity in foods thereby acting as a critical hurdle to control growth of pathogens and spoilage organism (Delahunty and Piggott, 1995; Hutton, 2002).Because food manufacturers and producers often want to prolong the shelf life of their products, the amount of sodium in many processed foods is increased to certain levels.
2. Sodium helps bind ingredients and enhances the colour of the food.In breakfast cereals,it plays a key flavour-blending role, added at about 1.25-
1.75% by weight.
3. Salt improves taste flavour enhancement and aids in stabilization.( Lynch et al., 2009; Taormina, 2010)
4. Salt is also responsible for fermentation control and texture in yeast-raised breads.
5. Salt plays a part in fat emulsification, thus diminishing the loss of fat and water during cooking in products such as sausages.
6. In most baked goods like biscuits, salt is used to improve product taste and flavour. Without salt, many baked goods will have an insipid taste. Salt not only sustains the “life” of the food but also, provides a more economical approach to most companies. Thus, if the food is more processed, it is likely
that the sodium content is higher. Some of the most popular leavening agents contain sodium, including baking soda (sodium bicarbonate) accounting for 95 percent of the sodium in these products.
7. Salt has been found to improve the perception of product thickness, enhance sweetness, mask metallic or chemical off-notes, and round out overall flavour while improving flavour intensity (Gillette, 1985).
8. Various sodium-containing ingredients have been known to reduce the bitterness of certain compounds found in foods, including quinine hydrochloride, caffeine, magnesium sulfate, and potassium chloride (Breslin and Beauchamp, 1995)
1.2 Snacks
Snacks are quick foods, oftentimes smaller than that of a regular meal, usually derived from one or more basic food items, and are eaten between meals. They give a feeling of satiety. Snacks come in a variety of forms including packaged and processed foods and items made from fresh ingredients at home. They can be processed from food group origin such as cereals, pulses, starchy fruits, roots and tubers, beef, dairy and poultry (Okoruwa, 1997). Processed snack foods are designed to be less perishable, more durable, and more portable than prepared foods and they often contain substantial amounts of sweeteners, preservatives, and appealing ingredients. They constitute a major meal for a handful of indigenes due to their availability, affordability and accessibility (Draper, 1996). Commonly consumed snacks in Nigeria include baked products (biscuits, cake, hamburger, meat pie and sausage rolls), fried and roasted snacks (cashew nut, doughnuts, peanuts and popcorn), and nuts. Snack food are patronized in leaps and bounds by individuals to satisfy their hunger pangs or as refreshments without giving cognizance to the preparation and packaging methods or nutritional contents in most cases.
1.3 Breakfast cereals
Breakfast cereals are foods made from processed grains and are often eaten with the first meal of the day. It is often eaten cold, usually mixed with milk (e.g. cow’s milk, so y milk, rice milk, almond milk), juice, water, or yogurt, and sometimes fruit, but may be eaten dry. They are good sources of micronutrients (Bonner et al., 1999). Fortified breakfast cereals are of great importance (McNulty et al., 1994) since they contribute significantly to iron and calcium intakes (McNulty et al., 1996). They can be categorized into, traditional (hot) cereals and ready-to-eat (cold) cereals.Traditional (hot) cereals require further cooking or heating before consumption while, cold cereals can be consumed from the box or with the addition of milk (Tribelhorn, 1991)
1.3.1 Traditional (hot) cereals
Traditional (hot) cereals are those requiring cooking or heating prior to consumption and are made from oats, farina (wheat), rice, and corn (Fast, 1990). Almost all (99 percent) of the traditional cereal market are products produced from oats (over 81 percent) and farina (approximately 18 percent). Cereals made from rice, corn (excluding corn grits), and wheat (other than farina) make up less than 1 percent of traditional cereals.
1.3.2 Ready-to-eat cereals
Ready-to-eat breakfast cereals are processed grain formulations, suitable for human consumption without further cooking in the home. They are relatively shelf- stable, lightweight, and convenient to ship and store. They are made primarily from corn, wheat, oats, or rice, usually with added flavor and fortifying ingredients. These groups are flaked cereals, extruded flaked cereals, gun-puffed whole grains, extruded gun-puffed cereals, oven-puffed cereals, shredded whole grains, extruded shredded cereals, and granola cereals (Fast, 1990).
1.4 Sodium
Sodium is an essential nutrient, the cation that performs a number of vital roles in the body including, regulating extracellular fluid volume and plasma volume, maintaining the volume of extracellular fluid, osmotic pressure, acid-base balance and transmission of nerves impulses (Geerling and Loewy, 2008). It determines membrane potential of cells, participates in the active transport of some molecules across cell membranes, facilitates absorption of nutrients such as glucose (sugar), amino acids (protein constituents) and, is essential for myriad biological processes
including fluid balance and muscle contraction (Webster et al., 2010). Sodium also occurs naturally in almost all foods and is present in processed foods due to the use of some food additives, for example, sodium bicarbonate (baking soda) used as a raising agent in cakes and biscuits. Most of the sodium in our food comes from sodium chloride (table salt) which is the major dietary source of sodium and in western diets; starchy foods are one of the major dietary contributors (e.g. breads, snacks and crisps). Sodium chloride is a commonly used food ingredient which provides many technological functions such as flavour enhancement, preservation and texture modification (Hutton, 2002).
High levels of dietary sodium have however, been linked to health conditions such as hypertension. World Health Organization (WHO) recommendations indicate that, in order to prevent chronic diseases, an adult upper daily limit intake of sodium should be less than 87 mmol Na/day (<5 g NaCl/day) (WHO, 2007). The National Research Council of the National Academy of Sciences recommends even less, 1,200 to 1,500 mg of sodium each day for adults (Institute of Medicine, 2010). However, leading scientific organizations and governmental agencies advise limiting sodium intake to 2400 mg or less daily (Dickinson and Havas, 2007).
1.4.1 Sources of sodium
Sodium is also found in many other ingredients used in food processing. Examples of sodium-containing ingredients and their uses in foods as shown in table
Compounds Uses
Baking powder leavening agent Baking soda leavening agent Monosodium glutamate flavour enhancer
Sodium benzoate preservative
Sodium caseinate thickener and binder
Sodium citrate control acidity in soft drinks and fruit drinks
Sodium nitrite curing agent in meat, provides color, prevents botulism (a food poisoning)
Sodium propionate mold inhibitor (inhibits molds in bread and cake)
Sodium phosphate emulsifier, stabilizer, buffer
Sodium saccharin artificial sweetener
Disodium phosphates quick cook cereals and processed cheeses
Sodium alginate Used inchocolate milk and ice cream;
holds chocolate in suspension
Table 1: sodium containing ingredients and their uses (Institute of
Medicine, 2012)
1.4.2 Sodium guidelines or acceptable nutrient claims of sodium by Food and
Drugs Administration (FDA).
Terms Sodium amount
Sodium – free less than 5mg per serving Very low sodium 35mg or less per serving Low sodium 140mg or less per serving Medium sodium ≥200<500mg per serving High sodium >500mg per serving
Table 2: sodium guidelines by FDA (Food Facts, 2014).
1.5 Calcium
Calcium helps build strong bones and teeth, regulates muscle contraction, including the heartbeat and makes sure blood clots normally (Heaney and Weaver,
1990). Most highsodium foods increases the risk of calcium loss(Ho et al., 2001). Concerns regarding bone health and sodium intake stem from the observation that a high salt intake is associated with increased urinary calcium excretion. It has been estimated that urinary calcium levels increase by approximately 1mmol per 100 mmol sodium intake (Nordinet al., 1993).Cutting back or eliminating these high-sodium processed foods therefore, is a great way to lower calcium excretion and risk of bone problems (Devine et al., 1995), hence, marginal deficiency of calcium may play a role in stimulating human salt intake (Tordoff, 1992). This suggest that one strategy to reduce salt liking and, perhaps intake would be to encourage increased calcium consumption, which is already strongly recommended for bone health (HHS, 2000). By encouraging milk consumption, breakfast cereals are also an excellent way of helping to ensure adequate calcium intake in both children and adults.Research has indicated that calcium intake at the recommended level (1,000-1,200 mg/day) (Ma et al., 2007), may be helpful in preventing and treating moderate hypertension(Miller et al., 2000).Recommendations however, vary for different stages of growth and reproduction (COMA, 1991).
1.6 Iron
Iron is an essential mineral that plays important roles in the body(Boldt, 1999 ; Conrad et al., 1999). The majority of functional iron within the body is present in haem proteins, such as haemoglobin, myoglobin and cytochromes, which are involved in oxygen transport or mitochondrial electron transfer. Many other enzymes also contain or require iron for their biological function(Lieu et al., 2001). Fortified breakfast cereals are an important source of iron in the diet, providing 20% of mean total iron intake. These fortifications have contributed to increased dietary iron intake and reductions in iron deficiency anaemia (Whittaker et al., 2001). Breakfast cereals fortified with vitamins and minerals provide at least 17% for iron. RDI (Recommended Daily Intake) for iron is 10-15mg/day however; recommendations vary for different stages (COMA, 1991)
1.7 Potassium
Potassium is an essential dietary micronutrient responsible for smooth muscle contractility, fluid balance, neural signal transduction and cardiac function (Wardlaw and Hampl, 2007). Adequate intake for the prevention of chronic disease for potassium is 120 mM/day (4.6g) (WHO, 2003; Champagne, 2006). The increase in potassium intake makes it possible to reduce blood pressure. This phenomenon can be explained by potassium’s capacity to increase excretion of sodium and by the vasoactive effects on blood vessels.
Potassium is present in many foods but not in large quantities. The best sources of potassium are fresh foods (fruits and vegetables) that have undergone little processing. These diets are high in potassium but low in sodium and hence, can reduce the risk of hypertension i.e., reduce blood pressure (Adrogué and Madias,
2008). Some processed foods might contain potassium but food manufacturers tend to flavour their products with a lot of sodium, and, don’t balance out the sodium additives with potassium additives.
The equilibrium between potassium (K+) and sodium (Na2+) is fundamental. Due
to the imbalance between sodium and potassium intake the kidney retains more sodium and releases potassium. Too much sodium retained in the water in the body is thus stored and it expands the body fluids, and this increases blood pressure and affects the kidney and heart functions. Hence the more processed foods one eats the more sodium intake will exceed potassium intake.
1.7.1Sodium-potassium interactions
Through a mechanism known as the “sodium-potassium” pump, as shown in fig. 2, sodium and potassium work together closely to initiate muscle contraction and nerve transmission, and to maintain the body’s normal distribution of fluid (Debska et al., 2001). Sodium potassium pump is an enzyme based mechanism of active transport driven by the energy generated by Na+,K+-ATPASE, by which sodium (Na+) is extruded from a cell and potassium (K+) is brought in, so as to maintain the low concentration of sodium and the high concentration of potassium within the cell with respect to the surrounding medium. Most of the potassium in the body is stored inside of your cells, while most of the sodium in your body is stored in the fluid that surrounds the cells (He and Macgregor, 2001). During muscle contraction and nerve transmission, potassium leaves the cell and sodium enters the cell via the “sodium-potassium pump.” (Sigworth, 2001). This transfer causes a change in electrical charge within the cell, which initiates the muscle contraction or the nerve impulse. Because sodium attracts water, once the muscle contraction or nerve impulse is initiated, the sodium is immediately pumped out of the cell to prevent water from entering the cell and causing the cell to swell or burst, and potassium is pumped back into the cell (Sobey, 2001). A high concentration of intracellular potassium is necessary for vital processes such as protein biosynthesis, certain enzyme activities, and maintenance of the membrane potential of excitable cells.
This material content is developed to serve as a GUIDE for students to conduct academic research
SURVEY OF SODIUM POTASSIUM IRON AND CALCIUM CONTENTS OF RETAIL SAMPLES OF SOME PROCESSED FOODS (BREAKFAST CEREALS AND SNACKS) SOLD IN NSUKKA ENUGU STATE
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