Transcript Water and Minerals

Water
Water’s Functions
• Carries nutrients and waste products
• Actively participates in chemical
reactions
• Serves as a solvent for minerals,
vitamins, amino acids glucose, and
other small molecules
Water’s Functions
• Serves as a lubricant and cushion
around joints
• Acts as a shock absorber(eyes, spinal
column, amniotic sac)
• Aids in maintaining body’s
temperature
Body’s Water Balance
• Water makes up about 60 % of the body’s
weight
• A change in the body’s water can bring a
change in the body weight
– Sweating: water loss during exercise
– Edema: water retention during pregnancy
Water Balance
• Water loss necessitates water intake
– Urine, sweat, exhalation, feces
• Dehydration can have serious
consequences
RECOMMENDATIONS - 2004
• No rule of thumb regarding # of glasses
– AI - 91 oz for women, 125 oz for men
– Water, juice, milk, coffee, tea, soda, fruits,
vegetables and other foods and beverages
• Let thirst be your guide
– Physical activity
– Heat exposure
Figure 10.6 The consequence of a difference in osmotic pressure
(a) A solute such as NaCl is more concentrated outside the cell than inside. (b) Water
flows by osmosis out of the cell until the concentrations are equal. Neurons in certain
brain areas detect their own dehydration and trigger thirst.
Water Recommendations and
Sources
• Hard water is high in calcium and
magnesium
• Soft water is high in sodium
– It also dissolves cadmium and lead from pipes
• If a person has lead pipes, this can be a problem
with long term use
Electrolytes
• Electrolytes (sodium, potassium, chloride)
help keep fluids in the proper
compartments
– Intracellular water
– Extracellular water
Electrolytes
• Enable nerves to respond
• Signal muscles to contract
Primary electrolytes-major
minerals
• More than 0.1 grams (or 100 mg) required
per day in the diet
• These include:
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Chloride
Phosphorus
Potassium
Sodium
Sodium: + ion of table salt (NaCl)
• No known human diet lacks sodium
• Minimum requirement about 500 mg/day
– estimated safe and adequate Daily intake
• Average intake in US for men = 3300
mg/day(equal to 8 grams of salt/day)
Calcium
• Roles:
– 99% in bones and teeth
– 1%
• Cell membranes: regulates transport of ions into
and out of cells
– Nerve to nerve transmission
» Nerve to muscle transmission
• Helps hold cells together
• Blood Clotting
• Co-factor for several enzymes
Calcium: Blood Levels Highly
Regulated: 4 ways
• 1. Protein-bound Ca released to become
available for use by cells
• 2. Increased Calcium absorption from gut
through activation of Vitamin D
• 3.Increased Calcium released from the
bone through parathyroid hormone
activation of Vitamin D
• 4. Kidneys conserve Calcium
Calcium RDA 1000-1200 mg/day
for Adults
• Foods rich in Calcium:
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1 cup milk:
1 oz cheese:
1/2 cup spinach:
1 orange
1 cup Yogurt
(fat free or low fat)
300 mg
200 mg
106 mg
52 mg
350-400mg
Calcium Deficiency
• Rickets: in children. Same as Vitamin D
deficiency
– Bow legs, poor bone formation
• Osteomalacia: in adults. Same as Vitamin D
deficiency
– poor bone formation
• Osteoporosis: Multiple causes
Calcium and Osteoporosis
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Low Calcium intake
Poor Vitamin D status
female
family history
small skeleton
menopause
smoking
high animal protein
drinking alcohol bed rest
white/Asian
• Vitamin D improves symptoms of knee osteoarthritis
Trace Minerals: Micro minerals
• One definition: less than 0.1 gram(100
mg/day) need in the diet
– Some trace minerals:
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Iron (Fe)
Iodine(I)
Zinc(Zn)
Fluoride(F)
Iron
• Component of hemoglobin and myoglobin
– hemoglobin carries oxygen in blood
– myoglobin stores oxygen in muscle cells
• Deficiency:
– RDA set at 18 mg/day for females and 8 mg/day
for males
– If iron stores exhausted, iron deficiency
anemia
• microcytic, hypochromic anemia
• reduced Hemoglobin synthesis, RBCs are small and
Megaloblastic anemia
Iron Absorption
• Most iron we eat doesn’t get absorbed
– What helps?
• vitamin C
• MFP factor: some factor in meat, fish and poultry
helps absorb iron
• need for iron
– What hurts absorption?
• tea
coffee
• Calcium and Phosphorus
• phytates and fiber and oxalates
Factors Affecting Iron Absorption
• Increase
• Decrease
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Gastric Acid
Heme iron
Demand
Low body stores
MPF
Vitamin C
Phytic Acid
Oxalic Acid
Polyphenols
Full body stores
Excess of other min.
Reduced gastric acid
Some antacids
Iron: Method of Absorption
• Iron in food
– Absorbed into cells that line GI tract
– If blood levels of iron are low
• iron picked up from cells by the blood and carried
to places where RBCs are made
– If blood levels of iron are ok
• iron stays in cells lining the GI tract
– In 3 to 5 days the cells are worn out and fall into the
lumen of the GI tract and mix with the remains of
digestion
Iron Overload
• 2 Types of Overload
– 1. Hereditary Defect: Hemochromatosis
• Very efficient absorption
• High circulating Fe which is laid down in tissues of
liver, heart and causes damage
– 2. High Iron ingestion: Hemosiderosis
• Even with control of absorption, high intake can
result in toxic side effects
• We don’t have a good mechanism of getting rid of
absorbed iron
Iron Sources
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4 oz of lean roast = 3 mg
4 oz liver = 7 mg
1/2 cup beans = 4.15 mg
1 cup broccoli = 1.12 mg
1 slice mixed grain bread = 0.8 mg
1 cup raisins = 3.12 mg
Zinc
• Part of nearly 100 enzymes
• Role in immune function
• Absorption affected by zinc status,
phytates, iron
• Hinders absorption of copper and iron
• Sources: red meats, eggs, vegetables
Zinc Deficiency
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Growth delay
Altered digestive function
Impairs immune response
Vitamin deficiencies
Loss of appetite
Slow wound healing
Iron and Zinc Deficiency in
School-age Children
80
60
%40
20
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Selenium
• Functions
– Antioxidant system
– Thyroxine and immune function
• Deficiency
– Keshan disease
– Impaired immune response, cognitive
function, muscle pain, wasting
– The Link between Selenium and
Chemoprevention: A Case for Selenoproteins
-- Diwadkar-Navsariwala and Diamond 134
(11): 2899 -- Journal of Nutrition
Selenium – RDA 55 mg/day
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Sources
Nuts
Seafood
Pasta
Fluoride
• Becomes part of crystalline deposits in
bones and teeth
– In teeth, resistant to tooth decay (dental
caries)
– 1 part per million in water supply optimum
resistance
– Higher than that can result in tooth mottling
• Brown coloration on teeth
– Much higher (18 ppm) can result in fluoridosis
• Bone malformation
Copper
• Coenzyme
– Part of ceruloplasmin
• Deficiency
• Toxicity