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Water and Minerals

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  • 1. Water and Minerals Charles Lohman
  • 2. Water
    • Water
      • water constitutes about 60% of an adult’s body weight
      • body composition influences how much of the body’s weight is water because there is more contained in lean tissue and less in fat
      • water is an essential nutrient, more important than any others
      • the body needs more water each day than any other nutrient
      • you can survive only few days without water, where a deficiency of other nutrients may take weeks, months or even years to develop
  • 3. Water and Body Fluids
    • Water and the body’s life processes
      • water carries nutrients and waste products throughout the body
      • water maintains the structure of large molecules
      • water participates in metabolic processes
      • water acts as a lubricant and cushion
      • water aids in the regulation of body temperature
      • water maintains blood volume
  • 4. Water Balance and Recommended Intakes
    • Water Intake
      • thirst and satiety influence water intake in response to changes in the mouth, the hypothalamus and nerves
      • when there is inadequate water intake the blood becomes concentrated, the mouth becomes dry, and the hypothalamus initiates drinking behavior
      • when water intake is excessive, the stomach expands and stretch receptors send signals to stop drinking
      • when too much water is lost from the body and not replaced, dehydration develops
      • water intoxication is rare, but can occur with excessive water ingestion and kidney disorders that reduce urine production
  • 5. Water Balance and Recommended Intakes
    • Water Sources
      • obvious dietary sources of water are water itself and other beverages
      • nearly all foods contain water
      • fruits and vegetables contain about 90% water
      • meats and cheeses contain about 50% water
      • water is also generated during metabolism
    • Water Losses
      • the body must excrete at least 2 cups of water each day as urine, which is enough to carry away waste products generated by the body’s metabolic processes
      • water is also lost from the lungs as vapor and from the skin as sweat
  • 6. Water Balance and Recommended Intakes
    • Water Recommendations
      • about 8 to 12 cups which is based on a person who expends 2000 kcalories a day
      • total water includes not only drinking water, but water in other beverages and foods as well
      • people who are physically active or live in hot environments may need more
      • beverages currently represent over 20% of the total energy intake in the United States
      • most people would well to select water as their preferred beverage
      • some research suggests that people who drink caffeinated beverages lose a little more fluid than when drinking water because caffeine acts as a diuretic
  • 7. Water Balance and Recommended Intakes
    • Health Effects of Water
      • drinking water may protect against urinary stones and constipation
      • even mild dehydration seems to interfere with daily tasks involving concentration, alertness, and short term memory
      • the kind of water a person drinks may also make a difference to health; hard water vs soft water
      • hard water has high concentrations of calcium and magnesium which may benefit hypertension and heart disease
      • soft water contains sodium and potassium which may aggravate hypertension and heart disease
  • 8. The Minerals – An Overview
    • Major Minerals
      • major minerals are named so because they are present, and needed, in larger amounts in the body
      • although trace minerals are needed in smaller amounts, they are still vital to the body
    • Inorganic Elements
      • unlike organic vitamins, which are easily destroyed, minerals are inorganic elements that always retain their chemical identity
      • once they enter the body, they remain there until they are excreted, they cannot be changed into anything else
  • 9.
    • The Body’s Handling of Minerals
      • minerals also differ from vitamins in the amounts the body can absorb and in the extent to which they must be specially handled
      • some minerals such as potassium are easily absorbed and readily excreted like the water soluble vitamins
      • some minerals such as calcium need carriers to be absorbed and transported
    • Variable Bioavailability
      • some foods contain binders that combine chemically with minerals, preventing their absorption and carrying them out of the body with other wastes
      • examples of binders are phytates, which are found primarily in legumes and grains
      • another example of a binder is oxalates, which are present in rhubarb and spinach
    The Minerals – An Overview
  • 10. The Minerals – An Overview
    • Nutrient Interactions
      • the presence or absence of one mineral can affect another’s absorption, metabolism, and excretion
      • the interaction between sodium and calcium cause both to be excreted when sodium intakes are too high
      • phosphorus binds with magnesium in the GI tract, so magnesium absorption is limited when phosphorus intakes are too high
    • Varied Roles
      • all of the major minerals help to maintain the body’s fluid balance, sodium, chloride, and potassium are most noted for this role
      • other minerals have roles in bone growth and health- calcium, phosphorus, and magnesium
  • 11. Sodium
    • Sodium Roles in the Body
      • the principal cation of the extracellular fluid and the primary regulator of its volume
      • helps maintain acid-base balance and essential to nerve impulse transmission and muscle contraction
    • Sodium Recommendations
      • diets rarely lack sodium, and even when intakes are low, the body adapts by reducing sodium losses in urine and sweat
      • sodium recommendations are set low enough to protect against high blood pressure, but high enough to allow an adequate intake of other nutrients with a typical diet
      • upper level of sodium intake for adults is 2400 mg
      • the average intake of sodium in the United States exceeds the Upper Level and most adults will develop hypertension at some point in their life
  • 12. Sodium
    • Sodium and Hypertension
      • for many years high sodium intake was considered the primary factor responsible for high blood pressure
      • salt (sodium chloride) is actually the cause
      • salt has a greater effect on blood pressure than either sodium or chloride alone
      • for some individuals, blood pressure increases in response to excesses in salt intake
      • people most likely to have a salt sensitivity include those whose parents had high blood pressure, those with chronic kidney disease or diabetes, African Americans, and people over the age of 50
      • overweight people also appear to be particularly sensitive to the effect of salt on blood pressure
  • 13. Sodium
    • Sodium and Bone Loss
      • a high salt intake is also associated with increased calcium excretion, but its influence on bone loss is less clear
      • potassium may prevent the increase in calcium excretion caused by a high salt diet
    • Sodium in Foods
      • processed foods contain the most sodium, whereas unprocessed foods such as fresh fruits, vegetables, milk, and meats have the least
      • 75% of sodium in people’s diets comes from salt added to foods by the manufacturer
      • 15% comes from salt added during cooking
      • 10% comes from the natural content in foods
  • 14. Chloride
    • Chloride Roles in the Body
      • chloride maintains fluid and electrolyte balance as sodium and potassium
      • inside the stomach chloride is part of hydrochloric acid, which maintains the strong acidity of the gastric juice
    • Chloride Recommendations and Intakes
      • chloride is abundant in foods (especially processed foods) as part of sodium chloride and other salts
      • because the proportion of chloride in salt is greater than sodium, chloride recommendations are slightly higher, but still equivalent to, those of sodium
    • Chloride Deficiency and Toxicity
      • diets rarely lack chloride
      • chloride losses may occur in conditions such as heavy sweating, chronic diarrhea, and vomiting
  • 15. Potassium
    • Potassium Roles in the Body
      • potassium plays a major role in maintaining fluid and electrolyte balance and cell integrity
      • also critical to the maintenance of nerve impulse transmissions and muscle contractions
    • Potassium Recommendations and Intakes
      • potassium is abundant in all living cells, both plant and animal
      • because cells remain intact unless foods are processed, the richest sources of potassium are fresh foods
      • to meet Adequate Intake for potassium, increase fruit and vegetable intake to 5 to 9 servings daily
  • 16. Calcium
    • Calcium Roles in the Body
      • 99% of the body’s calcium is in the bones and teeth where it plays two roles
      • first it is an integral part of bone structure, providing a rigid frame that holds the body upright and serves as attachment points for muscles, making motion possible
      • second it serves as a calcium bank, offering a readily available source of the mineral to the body fluids should a drop in blood calcium occur
  • 17. Calcium
    • Calcium and Disease Prevention
      • calcium may protect against hypertension
      • for example with the DASH diet(Dietary Approaches to Stop Hypertension), which isn’t particularly low in sodium, but is rich in calcium, and as well as magnesium and potassium
      • the DASH diet, together with a reduced sodium intake, is more effective in lowering blood pressure than either strategy alone
    • Calcium and Obesity
      • calcium may also play a role in maintaining a healthy body weight
      • in particular, calcium from dairy foods, but not from supplements, seems to influence body weight
      • an adequate dietary calcium intake may help prevent excessive fat accumulation by stimulating hormonal action that targets the breakdown of stored fat
  • 18. Calcium
    • Calcium Recommendations
      • for adolescents up to the age of 18, 1300 mg of calcium a day
      • between the ages of 19 to 50, 1000mg of calcium a day
      • for older adults, over 50, a higher recommendation of calcium is given at 1200 mg a day to minimize bone loss that occurs later in life
    • Calcium in Foods
      • some cultures do not use milk in their cuisines
      • some vegetarians exclude milk as well as meat and some people are allergic to milk protein or lactose intolerant
      • others simply do not enjoy the taste of milk
      • some tofu, corn tortillas, some nuts (such as almonds), and some seeds (such as sesame seeds) can supply calcium for the person who does not use milk products
      • also vegetables, mustard and turnip greens, bok choy, kale, parsley, watercess, and broccoli are also good sources of calcium
  • 19. Phosphorus
    • Phosphorus Roles in the Body
      • phosphorus salts are found in not only in bones and teeth, but in all body cells as part of a major buffer system
      • it is also part of DNA and RNA and is therefore necessary for all growth
    • Phosphorus Recommendations and Intakes
      • phosphorus is found in almost all foods
      • foods rich in proteins are the best sources
      • research shows that displacement of milk in the diet by cola drinks, not the phosphoric acid content of the beverages, has adverse effects on bone
  • 20. Magnesium
    • Magnesium Roles in the Body
      • in addition to maintaining bone health, magnesium acts in all the cells of the soft tissues, where it forms part of the protein making machinery and is necessary for energy metabolism
    • Magnesium Intakes
      • average dietary magnesium estimates for U.S. adults fall below recommendations
      • magnesium can be found in legumes, seeds, and nuts and also in leafy green vegetables
  • 21. Sulfate
    • Sulfate
      • is the oxidized form of the mineral sulfur, as it exists in food and water
      • the body’s needs for sulfate are easily met by a variety of foods and beverages
      • in addition the body receives sulfate from the amino acids methionine and cysteine found in dietary proteins
      • because sulfate needs are easily met with normal protein intakes, there is no recommended intake for sulfate