Food and Nutrition Basics Module 3 Vitamins Minerals and Water PDF

Food and Nutrition Basics Module 3 / Vitamins, Minerals and Water  Module 3 / Vitamins, Minerals and Water Vitamins Module 3 - Vitamins Objectives When you finish this...

Food and Nutrition Basics Module 3 / Vitamins, Minerals and Water  Module 3 / Vitamins, Minerals and Water Vitamins Module 3 - Vitamins Objectives When you finish this section, you should be State the definition of vitamins able to: Name the two categories of vitamins and the specific vitamins they include State the difference in storage and excretion patterns between the two categories of vitamins Give the main symptons of vitamin A deficiency Explain the importance of folic acid in public health Give three important reasons why food fortification is important 2/ 3 Additional Information Notes: Vitamins – The word vitamin was coined by the Polish bio- chemist Funk, because he believed that vitamins were “vital” for life and that all were, chemically speaking, “amines”. Funk’s first belief is correct but it is now known that most of the vitamins are, in fact, not amines. Scurvy – The classical symptoms of vitamin C deficiency include swollen and inflamed gums, loosening of teeth, loss of hair and dry itchy skin. Today, occurrence of overt scurvy is rare, but may still occur in people who consume a diet devoid of fruits and vegetables. Beriberi – The name of the nutritional disease caused by vitamin B1 deficiency. Beriberi is traditionally found among those populations in which white, polished rice is a dietary staple, e.g., in Asia (brown rice, which has its bran and germ layers intact, is a good source of vitamin B1). Beriberi affects the nervous, muscular, cardio- vascular and gastrointestinal systems. Pellagra – The nutritional disease caused by the lack of niacin and characterised by dermatitis, diarrhoea and dementia. It gave, for instance, rise to epidemic proportions in the U.S. during the early 1900s in regions where maize – a poor source of absorbable niacin – became a major element of the diet. B complex – Although chemically not related to each other, the B complex vitamins are often considered together because they frequently occur in the same foods such as cereals, grains and certain vegetables.  Module 3 / Vitamins, Minerals and Water Vitamins Micronutrients Vitamins Nutrients can be classified into two major By definition, vitamins are organic sub- groups – macronutrients and micronutrients. stances found in food which the body requires Macronutrients are those that form the bulk in small quantities for ensuring normal meta- of our diets, i.e., carbohydrates, fats, protein bolism and physiological function. The body and water. These are present in large amounts either cannot synthesise them in amounts (gram quantities) in our food. Micronutrients, sufficient to meet its needs or not at all. on the other hand, are dietary substances required only in very small amounts (milli- Vitamins can be classified into two distinct gram or microgram quantities). Vitamins, groups based on their solubility: together with most minerals and all trace elements, are classified as micronutrients. Fat-Soluble Vitamins – vitamins A, D, E and K. Chemically speaking, they are lipid-like The possibility that minor substances in molecules and can be stored in either the food have significant effects on health had liver or adipose tissue (the body fat deposits) been suspected for several hundred years. when their intake is in excess of needs. Each However, it was not until 1747 that firm, consists of a number of closely related com- scientifically documented evidence of this pounds with similar physiological properties. relationship was obtained. Captain James Lind, a British naval surgeon, investigated Water-Soluble Vitamins – vitamin C and sailors suffering from scurvy (a potentially those of the so-called B complex (vitamins fatal disease, now known to be caused by B1, B2, B6, B12, niacin, biotin, folic acid and a severe deficiency of vitamin C). His study panthothenate). Unlike the fat-soluble vitamins, showed that by giving sailors suffering from the water-soluble ones are not stored in the scurvy two oranges and one lemon per body to any appreciable extent. Excess intake day (i.e., foods which contain large amounts of leads to their excretion in urine. vitamin C), their disease could be completely cured. With four notable exceptions, vitamins are essential (indispensable) nutrients, i.e., they Although James Lind discovered a dietary must be present in the diet. The four exceptions cure for scurvy, the discovery of vitamin C are vitamin A, which can be synthesised in the and understanding its direct relationship to body by converting ß-carotene; vitamin D, scurvy, was not made until the early 1930s. which can be synthesised from a cholesterol metabolite (7-dehydrocholesterol) by the action The situation for other vitamins was similar. of sunlight on the skin; niacin, for which the Diseases related to dietary deficiencies (e.g., requirement can be met in part by its synthesis beriberi and pellagra) were suspected, but the in the body from the amino acid tryptophan; vitamins responsible for these diseases were and vitamin K, which can be produced by only isolated and characterised during the first bacteria in the large intestine (colon). half of the 20th century. 4/ 5 Additional Information Notes: Antivitamins – Antivitamins, or vitamin antagonists, are substances which, when consumed, either in food or taken as pharmaceutical drugs, interact with a vitamin and prevent it from functioning normally. There are, for example, a number of drugs (isoniazid, oestrogens and penicillamine) which interfere with the normal metabolic functioning of vitamin B6. Similarly, anticancer drugs (e.g., aminopterin and methothrexate) are potent inhibitors of folic acid. Vitamin D and Calcium – The nutritional disease caused by vitamin D deficiency in the young is called rickets (rachitis). Poor calcium and phosphorus deposition results in weak, malformed bones, which bow under pressure (e.g., bowed legs). Rickets in adults is called osteomalacia, which means “soft bones”.  Module 3 / Vitamins, Minerals and Water Vitamins Provitamins fat replacers are present in food. Fat replacers – such as sucrose polyesters – are designed to These are substances in food, which are not be poorly absorbed. Therefore, products con- themselves vitamins but are capable of being taining significant amounts of fat replacers converted into vitamins in the body. Examples should be fortified with vitamins A, D, E and K of provitamins are the first three of those given (and carotenoids). in the previous paragraph, namely β-carotene, 7-dehydrocholesterol and tryptophan which are converted, respectively, into vitamin A, Toxicity vitamin D and niacin. Because water-soluble vitamins are rapidly excreted in urine, the risk of them becoming Absorption of Vitamins toxic is low. In contrast, the fat-soluble vitamins A and D, whose levels can accumu- Generally speaking, all vitamins are well late in the body (mainly in the liver), can give absorbed. Vitamins can, however, be associ- rise to toxic symptoms. This is referred to ated with other dietary components which as hypervitaminosis. If untreated, vitamin A themselves are poorly absorbed or are not and D over-consumption can result in death. taken up by the body at all. If this occurs then the associated vitamins will also be poorly absorbed. Vitamin D and Calcium The classical example is that of biotin Vitamin D regulates calcium metabolism (a B vitamin), and a protein (avidin), which is in several ways: it increases absorption of found in raw egg white. A diet rich in raw calcium (and phosphorus) from the small eggs is an inevitable way to become biotin intestine; it reduces their excretion from the deficient because avidin binds very strongly to kidneys; and it helps to regulate calcium and biotin and prevents its absorption into the phosphorus deposition in the bones. body. Cooking eggs destroys avidin. Another example is niacin in cereals, especially maize. Here niacin is in a bound, unabsorbable form. Vitamin C and Iron It can, however, be liberated by treatment with alkali. This technique has been, and still is, Vitamin C enhances iron absorption from used extensively in Central America where the small intestine. In high concentrations it maize is a staple diet (tortillas are made from can also counter the action of certain food maize treated with lime water and sweetcorn components that may inhibit iron absorption, is roasted in hot ashes). The absorption of the e.g., phytic acid. fat-soluble vitamins (A, D, E and K) can also be markedly decreased if they are dissolved in a fat, which is not absorbed by the body. This is seen when significant amounts of some 6/7 Additional Information Notes: DNA (deoxyribonucleic acid) – Every cell in the human body performs a specialised job. A cell’s master plan for work and for the necessary tools to do that work is all encoded into the cell's genetic material, the DNA. It acts as a blueprint for synthesising specific pro- teins, often enzymes, required to perform specific tasks. Even though most cells in an organism contain the same DNA information, cells through- out the body are programmed differently. As the embryo forms, different parts of the DNA become active in different cell types. For example, the intestinal cells make digestive enzymes, while in the bone marrow, cells that make the oxygen- carrying protein haemoglobin become active.  Module 3 / Vitamins, Minerals and Water Vitamins Vitamins as Antioxidants (the first two are iron and iodine). The best- defined function of vitamin A is in vision. Oxygen is vital to life, yet evidence suggests It is estimated that about half a million pre- oxidative reactions play a key role in, e.g., heart school-age children become blind as a result disease, ageing, cancer, and cataracts. This is of severe vitamin A deficiency. Vitamin A because free radicals of oxygen are normally (retinol) is involved with rhodopsin, a protein formed in the body all the time. They are highly in the retina of the eye that is responsible reactive fragments of oxygen molecules that for vision in low intensity light. It is for this can permanently damage other important reason that one of the initial symptoms of molecules in the body such as lipids, nucleic severe vitamin A deficiency is night blindness. acids (e.g., DNA) and protein. If this occurs Of much more serious consequence is the extensively, it can give rise to heart disease thickening of the cornea of the eye, which (damage to low density lipoproteins gives rise occurs in severe vitamin A deficiency. This to plaque formation in arteries), to cancer is irreversible and gives rise to total loss of (damage to DNA), and to cataracts and vision. Other important functions of vitamin A arthritis (damage to specific proteins). are in cell differentiation, development of the embryo and in the response of the immune Antioxidants are present in the body to system. protect fats, DNA, protein and other molecules against free radical damage. They do this by reacting directly with the free radicals and in Vitamins of the B Complex and doing so neutralise their effect. In the process Intermediary Metabolism the antioxidants themselves are damaged and either have to be restored (by other anti- Intermediary metabolism is a collective term oxidants) or be replenished. for certain general metabolic reactions that commonly occur in the body. Many of them are Most antioxidants are obtained through concerned with the generation of energy. the diet. Vegetables and, to a lesser extent, fruits are good sources. Two of the most impor- Vitamins of the B complex are intimately tant antioxidants are vitamins – vitamin E involved with intermediary metabolism, be- and vitamin C (another important antioxidant cause they act as co-factors for a number of is β-carotene, the precursor of vitamin A). the enzymes involved. These are extremely important in the body because they act as the first line of defence Because of their involvement in general against free radical damage. metabolism, deficiencies of the B complex vitamins give rise to a wide variety of symp- toms in many parts of the body. These are Vitamin A and vision much less specific than those of the fat- soluble vitamins. However, the most common The third most frequent micronutrient manifestation, not suprisingly, is that of deficiency in the world is that of vitamin A muscle weakness and general fatigue. 8/9 Additional Information Notes: Fortification –The list below gives examples of food fortification with minerals and vitamins: Vehicle Nutrients Countries Wheat Flour B vitamins UK, USA Maize Flour Iron, calcium Canada Sugar Vitamin A, iron Central America Salt Iodine, iron India / Asia Margarine Vitamins A & D Most countries MSG * Vitamin A Philippines Curry Powder Iron South Africa Tea Leaves Vitamin A India Breakfast Cereals B Vitamins, minerals Western nations * MSG = Monosodium glutamate In some countries certain foods have to be fortified by law. Often these are staple foods or foods that make up a significant amount of the diet. These foods are selected, as this is an easy way to increase the intake of a particular nutrient in the population as a whole.  Module 3 / Vitamins, Minerals and Water Vitamins Functions of Folic Acid (Folate) Fortification of Foods There is a great deal of interest in folic acid Fortification is the act of adding nutrients, because of its potential in improving public most often vitamins but also minerals and health – in particular, reducing the risk of trace elements, to a food. There are a number birth defects (neural tube defects) and heart of reasons for doing this. Three are particularly disease (cardiovascular disease). important: Neural tube defects occur when the brain Restoration – replacing vitamins that are or spinal cord of a foetus is malformed; the lost during production, normal storage and/or best known defect being spina bifida. The handling of food, to ensure that their levels defects are thought to occur as a result are equal to those originally present. Examples of folic acid deficiency in mothers during are the restoration of B vitamins (and iron) the first 4-6 weeks of their pregnancy. lost when cereals undergo extrusion and Consequently, adequate folic acid intake by the replacement of vitamin C destroyed by women of child-bearing age is considered very the action of oxygen during the processing of important. orange juice. The association of folate and heart disease Enrichment – increasing the amount of concerns the build up of an amino acid one or more vitamins in a food above the – homocysteine – in the body (reflected by an level normally (naturally) found in that food. increase of this amino acid in the blood). The This is frequently done for products designed reason for the accumulation is believed to be to perform specific functions. An example is a folic acid deficiency. Here again folate forti- a meal replacement. Enrichment is necessary fication of the diet is seen as a way to reduce in such a case because the natural levels in the levels of homocysteine, and thereby the the basic ingredients of the product are risk of heart disease. frequently insufficient to meet all require- ments for vitamins that would normally be Foods rich in folic acid, unfortunately, are met by a complete meal. those which are not popular – such as spinach, broccoli and liver. It is believed that, because Substitution – when a food product is of this, the incidence of folate deficiency in designed to resemble a common everyday many populations may be relatively high. component of the diet in appearance, texture, Fortification, nevertheless, needs to be done flavour and odour, and is intended to be with care and attention because over- used as a complete or partial replacement for fortification with folic acid can lead to the food it resembles. An example of sub- masking of symptoms related to a deficiency stitution is the addition of vitamins A and D of vitamin B12. As in many nutrition-related to margarine as a replacement for butter. problems, a balanced approach is necessary. 10/11 Additional Information Notes: RE (Retinol Equivalent) – For vitamin A the unit of measurement is the retinol equivalent (RE). Retinol is the most important of a group of analogue components closely related to vitamin A. In this system 1RE = 1µg of vitamin A. For β-carotene (provitamin A): 6 µg β-carotene = 1µg of vitamin A NE (Niacin Equivalent) – The RDA for niacin is expressed as niacin equivalent (NE) in order to account for the niacin from the diet as well as that synthesised by the body from tryptophan. In this system, 60 mg of tryptophan = 1 mg of niacin. ESSADI – The U.S. Food and Nutrition Board set estimated safe and adequate daily dietary intakes (ESADDI’s) for those micronutrients for which available scientific data were insufficient to establish a RDA. Therefore, ESADDI’s are shown as ranges, which indicate that at least upper and lower limits of safety should be observed.  Module 3 / Vitamins, Minerals and Water Vitamins Vitamins: U.S. RDA’s for Adults, Sources and Main Functions Fat-Soluble Vitamins Name RDA Sources (Examples) Main Functions Vitamin A M: 1,000 RE Dairy products, meat, liver, Healthy membranes, (Retinol) F: 800 RE red and green vegetables, vision in dim light yellow or orange fruits (Deficiency: night blindness) Vitamin D 5 µg Fish liver oils, dairy products, meat Healthy bones and teeth (Calciferol) (Also by the action of sunlight on skin) (Deficiency = rickets) Vitamin E M: 10 mg Vegetable oils, eggs, Biological antioxidant (Tocopherol) F: 8 mg multi-grain cereal products Vitamin K M: 80 µg Green leafy vegetables, fruits, Assists in blood clotting (Phylloquinone) F: 65 µg dairy and grain products (Deficiency = Hypothrombianaemia) (M = Male, F = Female) Water-Soluble Vitamins Name RDA Sources (Examples) Main Functions Vitamin C 60 mg Fruits and vegetables Collagen synthesis, (Ascorbic acid) (e.g. potatoes and peppers) biological antioxidant (Deficiency = scurvy) Vitamin B1 M: 1.7 mg Whole grains, yeast, Intermediary metabolism (Thiamin) F: 1.3 mg fortified cereals, liver Vitamin B2 M: 1.7 mg Whole grains, yeast, Intermediary metabolism (Riboflavin) F: 1.3 mg fortified cereals, eggs and milk Niacin M: 19 mg NE Meat, whole grains, dairy products, Intermediary metabolism (Nicotinamid) F: 15 mg NE fortified cereals, potatoes, eggs Vitamin B6 M: 2.0 mg Meat, fish, eggs, whole grains, Intermediary metabolism (Pyridoxine) F: 1.6 mg dried beans, bananas, avocados (especially amino acids) Vitamin B12 2.0 µg Meat, seafood and dairy products Red blood cells formation, (Cobalamine) DNA metabolism (Deficiency = pernicious anaemia) Pantothenic acid 4-7 mg Animal products, whole grains, Intermediary metabolism (Pantothenate) (ESADDI) legumes, vegetables and fruits Biotin 30 - 100 µg Liver, cereal/grain products, Intermediary metabolism (ESADDI) egg yolk, dairy products, yeast, liver, legumes Folic Acid M: 200 µg Green leafy vegetables, liver Intermediary metabolism (Folate) F: 180 µg (Deficiency = neural tube defects) 12/13 Additional Information Notes: Vitamins – Sensitivity of vitamins to heat, oxygen, light and pH Vitamins Heat O2 Light pH7 A ✓ ✓ ✓ ✓ D ✓ ✓ ✓ ✓ E ✓ ✓ ✓ K ✓ ✓ ✓ C ✓ ✓ ✓ ✓ ✓ B1 ✓ ✓ ✓ ✓ B2 ✓ ✓ B6 B12 ✓ ✓ Biotin Folic Acid ✓ ✓ ✓ Niacin Pantothenate ✓ ✓ ✓ Source: Killeit, 1988  Module 3 / Vitamins, Minerals and Water Vitamins Progress Check A Give the definition of vitamins B What are the two categories of vitamins, and which vitamins are included in each category? 1 2 C Match each of the following terms with its description: 1 Water-soluble vitamins A Excess stored in the liver and adipose tissue 2 Fat-soluble vitamins B Excess eliminated in the urine D Give the main symptons of vitamin A deficiency. E Give two reasons why folic acid is potentially important for public health. 1 2 F What are the three particularly important reasons for fortifying foods? 1 2 3 Answers on the following page 14 /15 Progress Check Answers A Vitamins are essential organic substances found in tiny amounts in the diet for normal function, growth and maintenance of body tissues B 1 Fat-soluble vitamins: A, D, E, and K 2 Water-soluble vitamins: Vitamin C and those belonging to the B complex C 1 B Water-soluble vitamins 2 A Fat-soluble vitamins D Night blindness (if untreated, severe vitamin A deficiency can lead to a thickening of the cornea of the eye and irrevocable loss of total vision). E 1 Reducing the risk of birth defects (neural tube defects) 2 Reducing the risk of heart diseases (cardiovascular disease) F 1 Restoration 2 Enrichment 3 Substitution If you have correctly answered all these questions, proceed to the Objectives Page for the Section on Minerals, otherwise please read this Section carefully again. 16  Module 3 / Vitamins, Minerals and Water Minerals Module 3 - Minerals Objectives When you finish this section, you should be Name the two groups of minerals according able to: to the amounts required by the body Give examples of substances enhancing or inhibiting mineral absorption State the best dietary source of minerals Name the most common nutrient deficiency in the world Explain what is osteoporosis and name the main nutrient implicated in it 17 Additional Information Notes: Minerals – Minerals occur in the body and in food mainly in their ionic form. Metals such as sodium, potassium and calcium form positive ions (cations); non- metals form negative ions (anions). The latter include chlorine, iodine, fluorine and phosphorus (as phosphate). Salts such as sodium chloride and calcium phosphate dissociate in solution and thus are found in the body fluids as Na+1, Cl-1, Ca+2 and H2PO4-1. Substances that dissociate into positively and negatively charged ions are also referred to as electrolytes. Major minerals and trace elements – Shown below are the approximate amounts of major minerals and trace elements in a healthy adult male weighing 70 kg Major minerals · Calcium (Ca) 1,100 g · Phosphorus (P) 500 g · Potassium (K) 140 g · Sodium (Na) 100 g · Chlorine (Cl) 95 g · Magnesium (Mg) 19 g Trace elements · Iron (Fe) 4.2 g · Fluorine (F) 2.6 g · Zinc (Zn) 2.3 g · Copper (Cu) 0.07 g · Selenium (Se) 0.02 g · Manganese (Mn) 0.01 g · Iodine (I) 0.01 g · Molybdenum (Mo) 0.005 g · Chromium (Cr) 0.005 g · Cobalt (Co) 0.0007 g  Module 3 / Vitamins, Minerals and Water Minerals Definition and Classification The trace elements, whose role and essentiality has been largely elucidated, are When burnt, every organism and every shown below: food leaves behind a small quantity of ash composed of minerals, i.e., inorganic elements that cannot be decomposed to simpler sub- Trace elements: stances. Minerals are essential to life and are - Iron - Fluorine supplied to living organisms by their diet in - Zinc - Copper order to support adequate growth, reproduc- - Selenium - Manganese tion and health throughout the life cycle. - Iodine - Molybdenum Similar to vitamins, the required health-sus- - Chromium - Cobalt taining quantities of minerals are measured in milligrams or even micrograms. Minerals represent around 5% of body Overview Functions weight, the remaining 95% being water, fats, proteins and carbohydrates. Minerals are essential in the diet and each plays a unique and often multi-factorial role Minerals may be divided into two groups and they act at all levels of the body – cells, according to the amounts required by the tissues, organs, and the whole organism. body: major minerals (or simply minerals) and Examples: calcium and phosphorus help trace elements. build and maintain strong bones and teeth; manganese, chromium and zinc are trace Major minerals – generally speaking, if elements that enable enzymes to function; 100mg (1/50 of a teaspoon) or more per day of a others, e.g., selenium, act as antioxidants or mineral is required, it is referred to as a major are key components of important body com- mineral. pounds. Iodine, for example, is a component of the thyroid hormones (important for growth and metabolic rate control), and iron is a component of haemoglobin in red blood Major minerals: cells. - Calcium - Chlorine - Phosphorus - Sodium Some minerals such as sodium, potassium, - Potassium - Magnesium calcium and chloride function in the trans- mission of nerve impulses and muscle con- traction, and aid in the regulation of the body’s water and electrolyte balance. Finally, several vitamins require specific minerals to act as key Trace elements – a mineral is considered a components in their structure and function. trace element when it is required in amounts For example, vitamin B12 requires cobalt in its less than 100mg/day. structure to function efficiently. 18/19 Notes:  Module 3 / Vitamins, Minerals and Water Minerals Mineral Absorption Food Sources of Minerals Variations in the bioavailability of minerals In general the best dietary sources of many in different foods make it difficult to determine minerals come from animal foods (e.g., meat, exactly how much, in a specific, food can be fish, poultry and milk products). This is mainly absorbed by the body. The bioavailability of a because minerals are more concentrated in particular mineral – that is, its ability to be animal tissues than in plant tissues. As an absorbed from the diet – depends on many animal eats plants year after year, minerals factors, for example: from the plants concentrate in the animal’s body tissues (likewise, sea animals like clams, The physiological need oysters, and shrimp concentrate the minerals A significant factor determining the degree found in seawater; seafood is, therefore, to which a mineral may be absorbed is the particularly rich in minerals). Minerals in physiological need for that mineral at the time animal foods are also better absorbed than of consumption. Iron absorption, for example, those in plant foods because there are fewer increases in people who are in the state of mineral-binding substances in animal foods iron deficiency. (e.g. phytic acid, oxalic acid). Factors enhancing absorption Calcium absorption is enhanced by vitamin Toxicity D, that of iron by vitamin C. Certain proteins present in meat increase the absorption of Excess mineral intakes can lead to toxicity. minerals such as zinc and iron. Miners, for instance, have suffered from the effect of excessive mineral intake (breathing Factors inhibiting absorption in the dust, migration through the skin), Phytic acid, for example, a substance found especially of manganese. Toxic side effects in grain fibres and certain legumes (soy), are also well documented, e.g., for excessive binds minerals such as iron, zinc and calcium, selenium intakes. Mineral toxicity can also be therefore, limiting their absorption. related to impaired renal function (excretion). Another substance limiting mineral bio- Potassium, for example, can accumulate in availability is oxalic acid, found e.g., in spinach the blood and compromise heart function. and other vegetables. Although spinach If untreated, this can be fatal, as the heart contains calcium, only about 5% of it can be eventually stops beating. absorbed because of the vegetable’s high oxalic acid concentration. 20/21 Additional Information Notes: Iron – Iron is found in every living cell and total body content is about 5g (~1 teaspoon). As iron forms part of the haemoglobin in red blood cells, it has an important role in the transport of respiratory oxygen as well as carbon dioxide. Iron is also a co-factor for several enzymes, e.g., those involved in the synthesis of collagen and of various neurotransmitters (e.g. adrenaline and dopamine). In addition, iron is needed for proper immune function. Iron in foods occurs in several forms, which differ in their absorption by the body. Iron that is part of the haemoglobin in animal meat, called haem iron, is absorbed much better than ionic iron, referred to as non-haem iron. Non-haem iron is present e.g. in vegetables, grains, and plant foods. Consequently, foods containing high amounts of haem iron, e.g., liver and red meat, are rich sources of this mineral in a bioavailable form. Goitre - The thyroid gland actively accumulates and traps iodine from the bloodstream to support its hormone synthesis. These hormones (e.g. thyronine and triiodothyronine) help regulate the metabolic rate and promote growth and development throughout the body, including the brain. If a person’s iodine intake is insufficient, the thyroid gland enlarges as it attempts to take up more iodine from the blood, this enlargement eventually results in a goitre. Goitre has been described as far back as 3000 B.C., usually in women. Simple goitre is a painless condition, but if uncorrected it can lead to pressure on the trachea (windpipe), which may cause difficulty in breathing.  Module 3 / Vitamins, Minerals and Water Minerals Main Health Aspects of Minerals Iron deficiency anaemia The current estimate of more than 1.5 billion Iron deficiency anaemia is the most people worldwide is spread between Asia common of all nutrient deficiency diseases and West Pacific (909 million), Africa and the in both developing and developed countries, Middle East (354 million), the Americas affecting an estimated 30% of the world’s (168 million) and Europe (141 million). The areas population. Groups with a particular high risk affected are primarily those where the soil are young children, and pregnant women. This and water are iodine deficient. is because during periods of rapid growth, as seen in infancy and pregnancy, blood volume Goitre (enlargement of the thyroid gland) expands and consequently extra iron is is the most obvious manifestation in adults. In needed to be incorporated in the red blood addition, babies born to women with inade- cells. When these increased iron requirements quate iodine intake during the early months of are not met by adequate dietary intake or pregnancy may show short stature (dwarfism) supplements, iron deficiency anaemia will and mental retardation, a condition referred to unavoidably develop. as cretinism. In fact, iodine deficiency is the leading cause of mental impairment world- Other causes include blood losses (e.g. from wide. bleeding ulcers, injuries, parasitic infections or in women during menstruation) and in- adequate diets containing either little iron Prevalence of Nutrition Deficiencies or iron in a poorly absorbable form. The table below shows the populations at risk and affected by iron, iodine and vitamin A Iron deficiency anaemia may result in deficiencies in different regions of the world. impairment of muscle and neurological functions, leading to decreased work per- Region Iron Iodine Vitamin A formance and behavioural changes such as Deficient or At risk and At risk and fatigue or inattention. Other consequences anaemic affected (goitre) affected (children ≤5) include impaired immune function and, for pregnant women, increased maternal and Asia + West Pacific 1,674 909 167 foetal morbidity as well as a higher risk of Africa/Middle Easst 355 354 68 premature births. Americas 94 168 16 Europe 27 141 n.a. Iodine deficiency Iodine deficiency is the second most pre- Total (in millions) 2,150 1,572 251 valent nutritional disease after iron (while Source: DeMaeyer & Adiels-Tegman. WHO Statistics Quarterly 1985. vitamin A deficiency ranks third). 22/23 Notes:  Module 3 / Vitamins, Minerals and Water Minerals Main Health Aspects of Minerals (Cont’d) Some vegetables (e.g. broccoli, green cab- bage, leek, fennel) can be considered good Calcium and Osteoporosis sources of bioavailable calcium if consumed Osteoporosis is an age-related skeletal regularly in large quantities. Some mineral disease, characterised by a low bone mass, in waters contain high levels of calcium, for which the bones typically becomes thinner example, 1 litre of CONTREX contains 464 mg and more porous. This leads to enhanced bone of calcium, a quantity comparable to 2 large fragility and, consequently, an increased risk glasses (= 400ml) of cow’s milk. of fractures, generally at the lower spine, upper thigh or wrist. Sodium and blood pressure Table salt (sodium chloride - NaCl) has Calcium is the main nutrient implicated played an important role in the human diet in osteoporosis. If dietary intake of calcium is since earliest times. However, as consump- too low, bones release calcium into the tion of dietary salt often exceeds physiologi- blood stream to maintain other important cal needs, concerns have been raised that body functions. If this process continues excessive intakes may be associated with indefinitely, skeletal strength will be seriously high blood pressure (hypertension). compromised. The relationship between low calcium intake and osteoporosis is now well Although research has linked salt intake recognised and it is acknowledged that higher to variations in blood pressure, definitive calcium intakes help to prevent osteoporosis. conclusions are still under debate. Recent studies, for instance, showed that only It is important to note that bone mass is for certain people – described as being “salt built up during childhood and adolescence. sensitive” – who have high blood pressure, Some studies show that bone mass acqui- high intakes of salt are linked to their sition is almost complete by the age of 16 in condition. girls and in boys by the age of 18. Since bone loss is reported to begin as early as Therefore, sodium in the diet is not a 30 years of age, sufficient dietary intake of problem for everyone. As it is not always calcium in young people is, therefore, of possible to tell who is “salt sensitive” and, critical importance, to prevent osteoporosis because salt is the major source of sodium later in life. Genetics, physical activity, certain in the diet, it makes sense to consume salt hormones and age also represent critical in moderation as part of a healthy, well- factors. balanced diet. Dairy products are the major sources of calcium in the diet. These include all milks (consumed alone or added, e.g., to breakfast cereals or chocolate drinks), yoghurt, milk- based desserts, ice cream and cheese. 24/25 Additional Information Notes: Revision of RDAs in the United States and Canada – In August 1997, the first of seven NAS (US National Academy of Sciences) reports was issued, with involvement of Health Canada, to update and expand the Recommended Daily Allowances. This revision of the RDAs, which is the first since 1989, makes joint recommendations for the US and for Canada. The first report reviews the bone-building nutrients: calcium, phosphorus, magnesium, vitamin D and fluoride. The remainining reports will be issued over the next two years for completion in 2000 and will review folate, the E vitamins, antioxidants, macronutrients, trace elements, electrolytes and water, and other food components. Until that time the 1989 RDAs are the reference. The new Dietary Allowances are part of a broader category that has been termed “Dietary Reference Intakes” (RDI). In addition to RDAs, the RDI category includes “adequate intake” (AI), “estimated average requirements” (EAR) and “tolerable upper intake level” (UL). The report is unique in that it sets, for the first time, guidelines for maximum intake limits to reduce the risk of adverse health effects from over-consumption of a nutrient.  Module 3 / Vitamins, Minerals and Water Minerals Minerals: U.S. RDA’s for Adults, Sources and Main Functions Major Minerals Name RDA Sources (Examples) Main Functions Calcium 800 mg Milk and milk products, dried pulses, Bone and tooth formation, small canned fish (with bones) blood clotting (Deficiency: osteoporosis) Phosphorus 800 mg Meat, poultry fish, milk products, Bone and tooth formation, whole grain cereals, dried fruit acid - base balance Potassium 2000 mg Meat, vegetables and fruits (dates, Water and acid - base balance, apricots, bananas and citrus) nerve function Chloride 700 mg Table salt and salty foods Water and acid - base balance, Formation of gastric juice Sodium 500 mg Cured meats (ham, bacon), Water and acid - base balance, cheese, soups, table salt blood pressure regulation Magnesium M: 350 mg Whole grain cereals, nuts and Activation of enzymes, F: 280 mg green vegetables muscle contractions Trace Elements Name RDA Sources (Examples) Main Functions Iron M: 10 mg Lean meat, dried fruits, cereals, Component of haemoglobin F: 15 mg green vegetables (Deficiency = anaemia) Fluorine 1.5 - 4 mg Fluorided water, tooth paste, tea Prevention of dental caries (ESADDI) ZInc M: 15 mg Seafood, meat, whole grain cereals, Immune system, growth, sexual F: 12 mg eggs, pulses maturation, activation of enzymes Copper 1.5 - 3 mg Meat, shellfish, cocoa, drinking- Activation of enzymes (ESADDI) water Seleniun 55 -70 µg Meat, eggs, seafood, certain Biological antioxidant (ESADDI) mushrooms and cereals Manganese 2 - 5 mg Tea, widely available in various foods Growth of bones and tendons, (ESADDI) carbohydrate and protein metabolism Iodine 150 µg Ocean fish, seafood, cod liver oil Normal function of thyroid gland (Deficiency: goitre, cretinism) Molybdenum 75 - 250 mg Milk, dried legumes, liver, kidney, Activation of enzymes (ESADDI) cereals Chromium 50 - 200 µg Spices, wheat, raw sugars, yeast, Glucose and energy metabolism (ESADDI) fats, peanuts Cobalt - Meats, seafood and milk products Constituent of vitamin B12 26/27 Notes:  Module 3 / Vitamins, Minerals and Water Minerals Progress Check A 1. How is a mineral of which the body requires 100 mg or more per day referred? 2. How is a mineral of which the body requires less than 100 mg per day referred? B 1. Give examples of substances which enhance mineral absorption. 2. Give examples of substances which inhibit mineral absorption. C What are the best dietary sources of minerals? D Iron deficiency anaemia is the most common of all nutrient deficiency diseases. True False E 1. What is osteoporosis? 2. What is the major source of calcium in the diet? Answers on the following page 28/29 Progress Check Answers A 1. It is referred to as a major mineral 2. It is referred to as a trace element B 1. Vitamin D (enhances calcium absorption); vitamin C (enhances iron absorption); certain meat proteins (they enhance the absorption of, e.g., zinc and iron) 2. Phytic acid and oxalic acid (they inhibit the absorption of, e.g., iron and calcium) C Animal foods (e.g., meat, seafood, poultry, milk products) D x True False E 1. Osteoporosis is an age-related skeletal disease, characterised by a low bone mass, in which the bones typically become thinner and more porous. Therefore, the risk of fractures increases 2. Dairy products If you have correctly answered all these questions, proceed to the Objectives Page for the Section on Water, otherwise please read this Section carefully again. 30  Module 3 / Vitamins, Minerals and Water Water Module 3 - Water Objectives Upon completion of this section, you should Name the two main fluid compartments be able to: of the body State the major functions of water in the body State how much water an healthy adult should consume each day Name the main factors influencing water requirements Explain the role of water in the diet 31 Additional Information Notes: Body fluids – The list below shows the water content (percentage of weight) in some body tissues and fluids Water content Saliva, sweat 99.5 % Brain 85 % Heart 79 % Lungs 79 % Muscles 73 % Skin 72 % Liver 70 % Bones 22 % Teeth 10 % – Body water is not chemically pure, but a solution, i.e., a fluid in which minerals, glucose, amino-acids, vitamins and many other substances are dissolved. Extracellular fluid – Blood (79% water): consists of cells (red and white blood cells, platelets), suspended in an aqueous fluid called plasma in the approximate proportion of 45 parts of corpuscules (cells) to 55 parts of plasma. – Lymph (96% water): the clear, watery liquid found in tissue space from where it is collected by a special vascular system (lymphatic system), conveyed and eventually returned to the bloodstream. Main functions: to remove bacteria by the action of white blood cells (lymphocytes) and to transport the absorbed fat before it reaches the bloodstream. – Cerebrospinal fluid (98.5% water): the fluid acting as a shock absorber around the brain and the spinal cord.  Module 3 / Vitamins, Minerals and Water Water Importance of Water to Life Extracellular fluid is further divided into interstitial fluid – water between cells and intra- Water is more critical to the maintenance of vascular fluid – water in the bloodstream. The life than food, i.e., although humans can live sizes (in litres) of the different compartments without food for weeks and even months are shown below. (depending on fat stores), without water death occurs within days. In fact, water is the only substance necessary to all life. Many Intracellular Fluid 25 litres total (35.7% of BW*) organisms can live without air, but none can Extracellular Fluid 17 litres total (24.3% of BW*) live without water. - Interstitial (Examples) -14 litres fluid in eyes and joints Water is the largest single component of the amniotic fluid body. In an adult male, weighing 70kg, it lymph gastrointestinal fluids amounts to 60% of the body weight (i.e., 42 cerebrospinal fluids litres). In women, the value is slightly lower (around 55%). This results from the fact that - Intravascular -3 litres blood (plasma) women have more body fat (adipose tissue) than men and fat contains very little water Total Body Fluid 42 litres (60% of BW) (around 10% by weight). Therefore, in general, * (BW = bodyweight) as the fat content of the body increases, the water decreases. The proportion of body water varies with age, being at 94% in a five month old foetus, at 70% in an infant, and at 50-55% in Functions the elderly. Loss of more than 20% of body The body fluids contained in the different water may cause death, and a loss of only 8% compartments perform the following impor- may lead to severe disorders and illness. This tant functions: is not because water is more important than Carry nutrients and waste products. the other nutrients, but because water as such Vital to the life and shape of every cell. is not stored in the body, nor can the body con- Participate actively in many important bio- serve it to a sufficient degree; regular intake, chemical reactions of digestion and metabolism. therefore, is mandatory to compensate for Assist with temperature regulation, i.e., daily losses and to maintain body functions. cooling the body by evaporation from the skin as perspiration (sweating). Act as a lubricant around joints. Intracellular and Extracellular Serve as a shock absorber, e.g., for the brain Water and the spinal cord or inside the eyes; in pregnancy, the amniotic fluid around the There are two main fluid compartments growing foetus provides protection against in the body: the intracellular and the extra- shock. cellular compartments. When functioning Serve as a solvent for minerals, vitamins, inside cells, water is known as intracellular amino acids, glucose and many other small fluid. When outside cells, water is known as molecules. extracellular fluid. 32/33 Additional Information Notes: Thirst – Although thirst acts to provide needed water, it lags behind the body’s need, i.e., when one feels thirsty dehydration already took place to a more or less important degree. Consequently, water intake as a preventive measure is important for people who are at risk of dehydration. Those are primarily infants, young children, sportsmen/women (e.g., long distance runners) and the elderly.  Module 3 / Vitamins, Minerals and Water Water Water Balance In healthy adults, total body water remains The body is equipped with a number of remarkably constant. An increase or decrease mechanisms for regulating body water with- in water intake brings about an appropriate in narrow limits. Important among these increase or decrease in water output to main- mechanisms are nerve centres in the brain, tain the balance. which control the sensation of thirst and water output by the kidneys. Stimulation of the thirst Primarily water enters the body through centre creates the desire for water, while food and directly by drinking liquid. Some stimulation of other centres causes the water is produced in the body by metabolic release of antidiuretic hormone (ADH) from processes (e.g., during the breakdown of the pituitary gland. Release of ADH results in energy nutrients such as fat and carbohy- the excretion of smaller volumes of highly drates). concentrated urine by the kidneys, thereby conserving body water. Water is lost from the body mainly through urine and by respiration (lungs) and sweating In addition, as fluid volume drops in the (skin). Faeces normally contain only little water bloodstream, blood pressure falls. This fall (around 3-4% of total excretion). initiates a sequence of events which finally trigger the adrenal glands to release the The example below refers to an healthy hormone aldosterone. This hormone signals adult living in a temperate climate. In the state the kidneys to retain more water. of water balance approximately 2,500 ml (2.5 l) per day are required to maintain body These mechanisms cannot work by them- functions. The same volume (2,500 ml) is selves to maintain water balance unless a excreted through the previously mentioned person drinks enough water. This is because routes. the body must excrete a minimum of about 400 ml of water each day as urine, i.e., enough to carry away the waste products generated Water in Water out by a day’s metabolic activities. Source Amount (ml/day) Source Amount (ml/day) Therefore, under ordinary conditions, intake Water/liquids ≈1,500 Respiration, of water should amount to about 1.5 litres per sweating ≈1,000 day for healthy adults. But as much as 10 litres Water in foods ≈700 Urine ≈1,400 per day may be needed during strenuous Metabolic water ≈300 Faeces ≈100 exercises in hot climates. Total ≈2,500 Total ≈2,500 34/35 Additional Information Notes: Water requirements – The table below gives the daily water allowances for infants and children of different age groups. (Premature and term infants receive their water from breast milk or infant formula) Age Water needed per kg BW per day Prematures 150 - 180 ml Newborn > 3 days 120 - 150 ml Infants Between 3 and 6 months 140 - 150 ml Infants Between 6 months and 1 year 120 - 130 ml Children Between 1 and 6 years 90 - 100 ml Children Between 7 and 10 years 70 - 85 ml Adolescents Between 11 and 18 years 40 - 50 ml Source: Guy Puttet in Hydration Throughout Life, 1998.  Module 3 / Vitamins, Minerals and Water Water Factors Influencing Water rapidly result in dehydration. In this context, Requirements special attention must be given to those populations which are at a higher risk of The main factors are age, body temperature, dehydration, such as infants, young children environment, illness and injury, as well as and the elderly. In major injuries, adequate natural physiological conditions such as preg- fluid provision is essential since massive nancy and lactation. dehydration may occur due to blood losses or from wound secretions. Age – Elderly people need to monitor water intake carefully to prevent dehydration be- Pregnancy and Lactation – A pregnant cause ageing diminishes the sensation of woman needs extra water to maintain her thirst. Infants and young children, on the other increased blood volume and to provide the hand, are at risk of dehydration and have spe- amniotic fluid in which the foetus swims. cial water requirements for several reasons: Lactation demands increased fluid intake for first, their bodies contain, on a percentage of the production of breast milk. body weight basis, morer water than the bod- ies of adults. Second, the surface-to-volume ratio in children is larger than in adults, allow- Effects of Dehydration ing for greater water losses from the skin. Third, they excrete a more diluted urine and, When fluid losses are not replaced, dehy- therefore, more water than adults. Compound- dration occurs and results in a series of symp- ing these problems is the inability of infants toms which may be summarised as follows: and very young children to communicate their sensation of thirst. By the time losses equal about 1% of body weight, a person will be thirsty. Body temperature and environment – Be- At around 3%, muscles undergo a significant cause the body uses water as a coolant, drop in strength and endurance. any condition that increases body tempera- Once body weight is reduced by 10-12%, ture, such as physical activity, fever or high heat tolerance decreases and the person feels environmental temperature, simultaneously very weak. increases the need of water. Finally, death may occur when about 20% of body weight is lost. For instance, water needs for individuals living in hot climates may be increased by 50 - 100%. The combination of high tempera- ture and increased physical activity may, how- ever, increase water losses from the skin and lungs threefold to tenfold. Illness and injury – Illness in which fever, vomiting, and/or diarrhoea are present, can 36/37 Additional Information Notes: Water Intoxication – When water intake is more rapid than urine formation, the extracellular compartment fluid is diluted and water moves into the cells causing them to swell. The swelling, e.g., of the cells of the brain causes drowsiness and weakness, convulsions, and eventually death. Natural mineral water – Mineral water, for instance in Europe, is a commodity regulated by a common legislation adopted and applied within the EU since 1980 (Council Directive 80/777/EEC of July 15th, 1980). Mineral waters are recognised or defined as such by the competent national authorities. These waters must have their original characteristics preserved from the spring to the bottle. Natural mineral water means microbiologi- cally wholesome water and is clearly distinguished from ordinary drinking water by a constant mineral and trace element composition throughout the year. As each mineral water has a different composition, a classifica- tion has been established according to their mineralisa- tion. This classification (see table below) is part of the aforementioned EEC Council Directive and helps the consumer to make his/her choice among the different natural mineral waters available. Classification of natural mineral water (80/777/EEC Directive) Components Content (mg/l) Description TDS* TDS < 50 very low mineral content TDS 50 < TDS < 500 low mineral content TDS TDS < TDS 1,500 rich in mineral salt HCO3-1 content > 600 contains bicarbonate SO4-2 content > 200 contains sulfate Ca content > 150 contains calcium Mg content > 50 contains magnesium Cl content > 200 contains chloride F content > 1 contains fluoride Na content > 200 contains sodium Fe content > 1 contains iron CO2 free CO2 > 250 Acidic * TDS = Total Dissolved Solids  Module 3 / Vitamins, Minerals and Water Water Water in the Diet Potable Water Water not only relieves thirst, but it also The total quantity of potable or fresh water lubricates foods for easy swallowing (saliva), on the earth exceeds all present and future dissolves flavouring compounds – thereby needs. However, much of the fresh water is enhancing the taste of some foods – and also inaccessible, or unevenly distributed from dilutes noxious substances which may be place to place or season to season. Global accidentally ingested. Water is used in cook- reserves of fresh water add up to enough to fill ing to soften and make foods eatable (e.g., the Mediterranean ten times over, but more rice, potatoes) and to facilitate blending than three-fourths of this water is bound up in of ingredients. The table below shows the glaciers and polar ice where it is beyond the water content as percentage of weight of reach of current technology. Hence the main some common foods and beverages: sources of supply are the waters of the lakes and rivers, or of the waters found deeper in the earth in the form of subterranean rivers or Food / Beverage Water content water tables (aquifers). These sources make up about 1% of the total fresh water. Water 87 - 100% Fruit juices Soft drinks The earth’s supply of water, however, Wine is limited because new water cannot be Beer created; it is simply recycled through the Tea/Coffee continuous process of evaporation (primarily Milk from the oceans) and precipitation (e.g., in the form of rain, snow or hail). Fresh fruits 75 - 96% Vegetables Raw tubers 65 - 75% Mineral Water Potatoes Cassava Water originating from precipitations per- Sweet potatoes colates through different layers of soil before reaching the subterranean aquifers or water Meat 40 - 65% tables. Therefore, this groundwater contains Fish the naturally occurring minerals found in the Poultry area. It may reappear on the surface as a spring Baked products 25 - 36% or be accessed via a bore. The denomination Raw legumes 9 - 15% natural mineral water requires that it is free Raw cereals 9 - 14% of chemical pollution, is bacteriologically safe, Biscuits 2 - 6% and has a constant mineral composition. 38/39 Additional Information Notes: Natural mineral waters and health Research has shown that minerals present in natural mineral water play an important role in nutri- tion and health. Examples: Calcium from mineral waters is very well absorbed and utilised by the body, i.e., it is bioavailable. There- fore, calcium-rich waters can contribute substantially to the daily total calcium intake (adequate calcium intake is particularly important, e.g., during childhood and adolescence). Studies have demonstrated that 30% of the daily calcium intake may originate from water without modifying the existing dietary pattern. Examples of natural mineral waters with high calcium content are Contrex, Hépar, Quézac, Vittel, Perrier, San Pellegrino and Rietenauer. Magnesium intake seems to decrease in Western societies because dietary habits are changing (in France, for example, about 70% of both men and women have magnesium intakes below the RDA). Mineral waters rich in magnesium may contribute to more than 20% of the total dietary intake. The magnesium from mineral waters is rapidly absorbed and well utilised. Hépar, San Pellegrino, Rietenauer and Contrex are examples of natural mineral waters rich in magnesium. Sulfur in the form of sulfate (SO4-2) is commonly found in waters and foods. Sulfate plays an important role in the elimination of drugs and catabolites; more recently, it was demonstrated that sulfates are important in the prevention of kidney stones. Hépar, Vittel and Contrex are examples of waters with high sulfate content. The role of fluorine in the prevention of tooth decay is well documented and it has, therefore, been added to the drinking water of many communities. An example of a fluorine-rich natural mineral water is Quézac.  Module 1 / Nutrition, Metabolism and Digestion Section 1 Progress Check A Which are the main two fluid compartments in the body? B Which of the following functions do body fluids serve: 1 carry nutrients and waste products 2 vital to the life and shape of every cell 3 participate actively in many biochemical reactions 4 assist with temperature regulation 5 serve as a shock absorber (e.g., for the brain and the spinal cord) 6 act as a lubrificant around joints 7 serve as a solvent for, e.g., minerals, amino acids, glucose and other small molecules C 1. Under ordinary conditions, how much water should an healthy adult consume per day? 2. How much during strenuous exercises in hot climates? D Name the main factors influencing water requirements E Describe the role of water in the diet Answers on the following page 40/41  Progress Check Answers Progress Check Answers A The intracellular and extracellular fluid compartments B Body fluids serve all the seven functions mentioned: 1 x carry nutrients and waste products 2 x vital to the life and shape of every cell 3 x participate actively in many biochemical reactions 4 x assist with temperature regulation 5 x serve as a shock absorber (e.g., for the brain and the spinal cord) 6 x act as a lubrificant around joints 7 x serve as a solvent for e.g., minerals, amino acids, glucose and other small molecules C 1. Around 1.5 litres per day 2. As much as 10 litres per day may be needed D Age, body temperature, environment, illness and injury E Lubricates food for easy swallowing (saliva), dissolves flavouring compounds, dilutes noxious substances. In cooking, water is used to soften and make foods eatable and to facilitate blending of ingredients. 42 Food and Nutrition Basics Printed in Switzerland Developed by the CV 4221 GB E.-RR-LU Nutrition Strategic Business Division © 1998 Nestec Ltd.