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Showing posts with the label snapshot series
Snapshot series 8: Water soluble Vitamins
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Water-soluble vitamins perform a wide range of important functions, including the extraction of energy from food, cell signalling, synthesis of DNA and conduction of nerve impulses. Water-soluble vitamins comprise nine compounds – vitamins B1, B2, B6, B12, C, niacin, folate, biotin and pantothenic acid – distinguished by their chemistry and function. They are required regularly in small amounts in the human diet as they are not stored in the body; excess intake is removed by the kidneys. Symptoms of deficiency may occur if a diet lacks any one of these vitamins. For example, a diet lacking in vitamin C can lead to the development of scurvy, characterized by impaired wound healing, joint pain, tiredness and shortness of breath; a diet lacking in vitamin B12 may lead to anaemia and degeneration of the spinal cord. It has proved difficult to know exactly how much of each vitamin is required daily to stay healthy. Early experiments (that would be considered unethical...
Snapshot series 7: Fat soluble Vitamins
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Vitamins A, D, E and K comprise a small group of fat-soluble vitamins of disparate chemical composition which are essential for good health. Various processes are dependent on an adequate availability of these vitamins, including vision (vitamin A), growth and tissue differentiation (vitamins A and D), bone and muscle function (vitamin D), immune function (vitamin A), protection against free radicals (vitamin E) and blood clotting (vitamin K). Although fat-soluble vitamins can be stored in the body for use in times of dietary scarcity, deficiencies do occur, with profound consequences. In some regions of the world, young children are at risk of becoming blind because of inadequate vitamin A. Vitamin D deficiency, which is common worldwide, may cause bowed legs and pelvic deformities of rickets in children and muscle weakness and bone pain of osteomalacia in adults. Foods of animal origin tend to be good sources of fat-soluble vitamin...
Snapshot series 6: The minerals
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Minerals are inorganic substances that are not made by living things. Found in both soil and rocks, they are absorbed by plants that are then eaten. Minerals are largely classified as ‘major’ minerals or ‘trace’ minerals. Major minerals are those that the body requires in amounts of at least 100 mg per day, and include sodium, potassium, calcium, magnesium, sulphur, phosphorus and chloride. Trace minerals are needed in amounts of less than 100 mg per day, and some, such as iron, fluoride, zinc and manganese, have established recommended daily allowances (RDAs) or Adequate Intake (AI) limits to ensure adequacy. A third classification, known as ‘ultra-trace’ minerals, require less than 1 mg per day, and include chromium, copper, iodine, molybdenum and selenium. Minerals play a role in maintaining a healthy immune system, bone and teeth health, muscle contraction, fluid balance and overall growth. A healthy diet of fruits, vegetables, w...
Snapshot series 5: Fats
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Fat is familiar to us as a substance we eat in food and store in our body. Both have the same chemical structure known as triaclyglycerol (TAG), which, when overconsumed in food, accumulates as body fat and increases body weight. The average 70-kg (155-lb) man has about 15 kg (33 lb) of body fat, which is equivalent to 140,000 calories or 40 days of stored energy, but only 0.3 kg (10 oz) of stored carbohydrate (900 calories). The physical and chemical properties of fats (TAG) in food are determined by differences in their component fatty acids (FAs), which differ in size and number of carbon double bonds. Saturated fats are mainly derived from animal sources and are solid at room temperature due to a lack of double bonds (such as butter), while monounsaturated fats have one, and polyunsaturated fats have two or more double bonds, which turn these fats into liquid oils. These oils can be extracted from plant se...
Snapshot series 4: The dietary fibre
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Dietary fibre is the indigestible component of foods and drinks which has a bulking effect in the large intestine and provides a substrate for the colonic bacteria. Originally, ‘fibre’ was limited to non-starch polysaccharides (such as cellulose) plus lignin from plants. In recent years the definition of fibre has widened to include all food components that are not digested and absorbed in the small intestine, including the non-digestible oligosaccharides (which are between the simple sugars and the starch polymers) and resistant starch. There is also an increasing use of novel, synthetic f ibres in processed foods and drinks. Recent research suggests that a high intake of dietary fibre, particularly cereal fibre and whole grains, is associated with a reduced risk of cardiometabolic disease and colorectal cancer. Higher intakes of some fibre components are also associated with reductions in serum cholesterol and triacylglycerols as ...
Snapshot 2: About Proteins.
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Snapshot 2:- About Proteins Perhaps the ultimate building Block, protein provides all the functional and structural components of the body: skin, bone, muscle, blood and all the organs. It consists of one or more long chains of amino acids linked by peptide bonds. Essential in the diet, protein provides the amino acids that are reassembled to build new body tissue during growth, used to maintain existing protein structures and to make smaller molecules like hormones and neurotransmitters. It can also serve as a fuel for the body – with the same energy density as carbohydrates (4 kal/17 kJ per gram). Protein is present in all foods – animal and plant – but rich sources include meats, dairy, fish, eggs, grains, legumes and nuts. The key is to eat a variety of these foods, to make sure that we absorb the right balance of the nine essential and the non-essential amino acids. This can be done with plant-based diets, as evident...
Snapshot 1:- About Energy
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Snapshot 1:- Energy. Our body uses energy to fuel Cellular metabolism, especially the major organs like brain, heart, liver and gastrointestinal tract, and for physical activity. Carbohydrates and proteins each provide 17 kJ/g (4.1kcal) of metabolizable energy intake, with fats and alcohol providing 37 kJ/g and 29 kJ/g respectively. Our appetite mechanism usually allows us to match energy intake to energy expenditure so that we maintain a healthy body weight, but when we overeat, the excess energy intake is stored as fat. Overweight people should aim for an energy intake slightly less than their energy expenditure so that their energy deficit is met from their body fat, helping them to achieve a lower, healthy body weight. Our total energy expenditure (TEE) depends on the rate at which the body expends energy at rest (basal metabolic rate – BMR) and our physical activity level (PAL), and this is expressed by the relationship: TEE = PAL x B...