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  1. Protein  Essential for the life of every cell and the vital functions in the body  It is essential for growth and repair and the maintenance of good health  Requirements do not change very much  Needs may increase with illness, infections, surgery, or injury  More than adequate intakes in Caribbean diets
  2. Protein  Protein is the second most abundant compound in the body, following water.  A large proportion of this will be in muscle with significant proportions being present in skin and blood.  Protein is found in all body fluids, except bile and urine.  Carbon, nitrogen, oxygen, and hydrogen are abundant elements in proteins, and there is a smaller proportion of sulfur
  3. Structure  Proteins are large molecules made up of long chains of amino acids. Amino acids are the building blocks of proteins.  There are many amino acids that combine in many different ways to form many different types of proteins.  The sequence of amino acids in each protein determines its shape and function  There are about 20 different amino acids commonly found in plant and animal proteins. For adults, 8 of these, have to be provided in the diet and are therefore defined as ‘essential’ amino acids. These are:
  4. Structure (essential amino acids) Leucine Isoleucine Valine Threonine Methionine Phenylalanine Tryptophan Lysine
  5. Quality  Proteins vary according to:  their origin (animal or plant)  their amino acid composition (particularly their relative content of the essential amino acids) and,  their digestibility  High quality proteins are those that are readily digestible and contain the dietary essential amino acids in quantities that correspond to human requirements.
  6. Quality  Proteins from animal sources have a higher biological value (they contain all the essential amino acids needed by the human body) than proteins from plant sources.  A combination of plant proteins tends to have a complementary effect boosting their overall biological value.  In most diets, different proteins tend to complement each other in their amino acid pattern, so when two foods providing vegetable protein are eaten at a meal, such as a cereal and pulses, the amino acids of one protein may compensate for the limitations of the other, resulting in a combination of higher biological value. This is known as the complementary action of proteins.
  7. Quality  Most legumes tend to be deficient in methionine. Cereals, e.g., tend to be low in lysine and tryptophan content, although they do contain sufficient methionine. Thus, the combination of different plant-based foods in dishes such as rice and beans, or peanut butter and bread, results in a complementary effect that raises the protein quality compared with either food consumed alone. Therefore, it is possible to obtain adequate amounts of high-quality protein from a vegetarian or vegan diet.  Yams are more useful as a source of protein than other root crops and the protein complements the type in cereals so a combination of yam and dumplings would also improve protein quality of the meal.
  8. Quality  Digestion and absorption should always be considered in evaluating protein quality.  A protein can be predicted as being of good quality on the basis of its amino acid score, but in practice be of only poor quality because it is poorly digested and/or absorbed.
  9. Digestion, Absorption & Utilization of Proteins  All foods are broken down in the mouth but the chemical digestion of protein begins in the stomach.  Protein digestion begins with the action of an enzyme called pepsin. Proteins are broken down into smaller peptides by the action of pepsin.  Completed in the small intestine, several enzymes from the pancreatic juice and the lining of the intestine complete the breakdown of protein into small peptides and amino acids.
  10. Digestion, Absorption & Utilization of Proteins  Absorbed amino acids pass into the liver, where a portion of the amino acids are taken up and used; the remainder pass through into the circulation and are utilized by the tissues. The hepatic portal vein is the vein that transports blood from the digestive tract to the liver.  Protein building and breakdown take place every day in the body. Urea is formed from the breakdown of protein and is carried in the bloodstream to the kidneys where it is excreted in the urine.  Most of the protein in the body is stored in muscle, and when dietary intakes are low, the body will breakdown the protein in muscle to meet its needs. When we take more protein than the body needs, the excess is broken down, some ends up as urea, the rest is used in the production of glucose.
  11. Functions  Protein is essential for many basic body functions:  Helps in growth and development, and in repair of muscles, bones, organs, blood, skin, hair  Needed for repair of damaged tissues due to illness or injury  Needed to maintain the fluid balance within and outside body cells. Proteins also help maintain the balance between acids and bases within the body fluids by accepting and releasing hydrogen ions.  Needed for blood clotting
  12. Disease Risk  Less severe deficiencies - due to low protein intake or an imbalance in amino acid intake may result in –  Reduced growth in children  Loss of lean body mass in adults  Anaemia (low Hb) in all age groups  Weakened immune system increasing risk of infection and subsequent health problems
  13. Disease Risk Protein and weight management  Including a lean source of protein with a meal can help to minimise feelings of hunger and decrease overall energy intake.  High protein, low carbohydrate diets claim to be effective at producing weight loss despite a high fat intake  Such a diet remains contradictory to current healthy eating messages. Also safety concerns about very-high- protein diets that involved cutting out other food groups and caution should therefore be exercised in promoting them
  14. Disease Risk Heart Disease  Foods rich in animal protein tend to be high in saturated fat and sodium  High intake of protein from red meat and dairy products associated with greater risk of heart disease Kidney Disease  Regular high protein intake increases work of kidneys  Not a cause of kidney disease but may worsen existing kidney disease or hasten decline in function
  15. Disease Risk Adult bone loss  High protein intake may be associated with increased urinary loss of calcium  This area of research is still controversial and the findings have not been consistent. Cancer  Protein quality seems to matter more than quantity  Eating a lot of red meat and processed meat is linked to an increased risk of stomach & colon cancer
  16. Food Sources Animal protein  Protein from animal sources contains the full range of essential amino acids  Sources include meat, fish, eggs, milk and cheese. Low fat options are preferable as some can be high in saturated fat.
  17. Food Sources Plant protein  Complementary mixtures needed  Sources: dried peas, beans, nuts, seeds and cereals; smaller amounts in dark green leafy vegetables, yam
  18. Food Sources Protein content in common foods A 3-ounce cooked serving of most meat, poultry or fish - about 18 - 21 grams of protein  1 hard/soft boiled egg – 6.3 g  1 oz of cheese – about 6-8 g  1 cup of low-fat milk - 8 g  1/2 cup of cooked dried beans – 8 g,  ½ cup cooked rice – 2 g;  1/2 cup peanuts – 18g;  1 tbsp peanut butter- 4g.
  19. Dietary recommendations Protein requirements: Caribbean RDA: The current RDA for adults (male & female) is 0.7 - 0.8 g protein/kg body weight/d with an extra 10 or 15 g recommended for pregnant and lactating women, respectively  Requirements are higher for growing children (requirement per kg body weight) and in some disease states Percentage (%) of total calories: • WHO: 10 -15% • Caribbean – Proposed: 10% (approx. 56.3 grams protein)