Transcript minerals__2008

MINERALS
classification
Major minerals
• needed in the body in the largest amounts
requirements >100 mg/day
calcium, sodium, potassium, phosphorus
• There are many more minerals and trace elements,
however, we will be focusing on the ones that are the
most problematic in human nutrition and those which are
important for chronic disease prevention.
Calcium
Main functions:
– bone/tooth formation
– regulation of nerve transmission, blood clotting,
contraction of muscles
– helps maintain normal blood pressure
Stored in:
– 99% of the total calcium in the body is stored in the
bones
– 1% of the total calcium in the body is found in the
blood
• Calcium stored in the bones serves as a reservoir of
calcium. Its there to help maintain blood calcium levels
when intake of calcium is low.
• A chronically poor intake of calcium, over a number of
years, causes a lot of calcium to removed from the bones
to supply the blood (which is used for more immediate
needs like muscle contraction, nerve transmission, etc).
• Eventually, calcium loss from the bones results in reduced
bone density and this condition is known as osteoporosis.
We will discuss osteoporosis in a bit.
• Calcium has a low bioavailability so anything that you
can do to enhance, and therefore, improve calcium
absorption is important.
• These are factors which enhance calcium’s
bioavailability:
– Vitamin D:
• fortunately one of the best sources of calcium (milk) also contains
Vitamin D. Women taking calcium supplements should also consider
taking a calcium supplement that has some Vitamin D to help with
absorption.
– Lactose:
• again, milk, our best calcium source also contains lactose. (What is
lactose?)
– Gastric acid:
• is the acid secreted in your stomach for digestion; calcium absorption is
enhanced in an acidic environment—since acid is secreted whenever
you eat food, its best to take a calcium supplement with food.
– Need:
• any time you body needs more calcium, during pregnancy and periods
of active growth such as infancy and adolescence, for example, our
bodies can absorb more calcium
Factors which decrease Calcium absorption
– Too much fiber in the diet
• >35 gms/day
• for most Americans, this is not a problem, since the average fiber
intake is ~10-15 gms/day
– Age
• As we age, we produce less gastric acid
– Excess use of laxatives
– Too much phosphorus in the diet
• Our main source of phosphorus is soda—and we drink a lot of
soda, especially children and teens—which could be putting thier
bones at risk, especially when they substitute soda for milk
– Vitamin D deficiency
– Too much coffee, tea
Osteoporosis
– a chronic, degenerative disease
– characterized by:
• bone loss
• decrease in bone density
– 2001:
• 1.5 million fractures annually
• costs $17 billion/yr ($47 million per day)
– prevention is key
Normal bone
.
Bone loss from
osteoporosis
Bone loss occurs primarily in the
hips, spine and wrist
A DEXA scan is used to measure
bone density
• Osteoporosis is a major public health threat for an estimated 44 million
Americans
• In the U.S. today, 10 million individuals are estimated to already have
the disease and almost 34 million more are estimated to have low bone
mass, placing them at increased risk for osteoporosis.
• Of the 10 million Americans estimated to have osteoporosis, eight
million are women and 2 million are men.
• 34 million Americans, or 55% of the people 50 years of age and older,
have low bone mass, which puts them at increased risk of developing
osteoporosis and related fractures.
• Significant risk has been reported in people of all ethnic backgrounds.
• While osteoporosis is often thought of as an older person's disease, it
can strike at any age
• 80% of those affected by osteoporosis are women.
• 20% of those affected by osteoporosis are men.
• One in two women and one in four men over age
50 will have an osteoporosis-related fracture in
their lifetime.
• Osteoporosis is responsible for more than 1.5
million fractures annually, including:
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300,000 hip fractures; and approximately
700,000 vertebral fractures,
250,000 wrist fractures; and
300,000 fractures at other sites.
Osteoporosis Risk Factors
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Increased age
Being female
Small boned, thin women
People with a history of
anorexia nervosa
• Caucasian/Asian women
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Family history
Sedentary lifestyle
Smoking, heavy drinking
Long term use of certain
medications such as
prednisone
• Remember what a risk factor is??
– It is something that increases the chances of
developing a medical condition
• The more risk factors one has, the higher the
chance of developing the medical condition.
Having one or even 2 risk factors does not
necessarily mean one will definitely develop a
problem, just that the chances are higher.
Preventing Osteoporosis
• Consume adequate calcium and vitamin D in your
diet-- throughout life
• Get regular physical activity, especially weight
bearing exercise
• Be moderation in alcohol/caffeine consumption
• Prevention is key because currently, there is no cure
Treatment
• Hormone replacement therapy (estrogen)
• Calcium, vitamin D supplements
• Drugs
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Bisphosphonates
Alendronate (brand name Fosamax®)
Risedronate (brand name Actonel®)
Calcitonin (brand name Miacalcin®)
Raloxifene
• Bisphosphonates are a family of drugs used to prevent and
treat osteoporosis.
– alendronate (Fosamax ®)
– etidronate (Didrocal ®)
– risedronate (Actonel ®).
• How do they work?
– Bisphosphonates bind permanently to the surfaces of
the bones and slow down the osteoclasts (bone-eroding
cells). This allows the osteoblasts (bone-building cells)
to work more effectively.
• How effective are they?
– Bisphosphonates increase bone density and prevent
fractures of the spine (vertebral fractures).
Calcium Needs
Women
age 19-50 1000 mg
> age 51
1200 mg
pregnancy 1000 mg
Men
age 19-50 1000 mg
Current average intake: 500-600 mg per day--only about half of what needs are
Food sources
milk, cheese, yogurt
foods made with milk/cheese
(pudding, pizza)
Calcium fortified orange juice
Calcium fortified soy milk
Calcium supplements
– Who should take them?
• people with lactose intolerance,
• people who dislike milk
• any one with a milk allergy (not the same thing as being
lactose intolerant)
– Side effects of calcium supplements
• constipation, gas
• decreases iron absorption
– if you take an iron supplement for iron deficiency anemia, or to
prevent anemia, take your calcium supplement and iron
supplement at different times of the day
Tips for improving bioavailability from calcium
supplements
calcium citrate is highly bioavailable (eg: Citracal)
take chewables (Tums with Calcium, Viactiv)
split your doses (take only 500 mg at a time)
take with food
don’t take more than 1500 mg/day
avoid oyster shell calcium, dolomite, bone meal,
coral calcium
Phosphorus
Main functions:
– assists many enzymes/vitamins to extract energy from
ATP—adenosine triphosphate
– component of cell membranes
– bone structure
Requirements
– same as calcium
– excess phosphorus, esp. combined with poor calcium intake,
may contribute to bone loss
• Teens, or anyone, who drink a lot of soda and little or no milk are
increasing the risk of bone loss…a real problem in the US
Deficiency
– None— we have problems with excessive intake in U.S.
Food sources
– Soft drinks, milk, cheese, baked goods, meat, food additives
Sodium (Na+)
Sodium chloride (NaCl) known as “table salt”
Main functions:
– fluid/water balance
– conduction of nerve impulses
– glucose transport/absorption
– acid-base balance
Physiological requirements: 500 mg/day
– This is the amount we need every day to prevent a
deficiency
Average U.S intake: 5000-8000 mg/day
Recommended intake for good health
<2400 mg/day
How does this compare with the average
intake in the US?
A grain of salt
Food sources
Table salt:
1 tsp = 2250 mg
Naturally occurring Na
Food
milk
meat (raw)
fruits
vegetables
serving size
Na+ (mg)
1 cup
120
3 oz
50
---<10
½ cup
5-50
Sodium is naturally present in almost all foods—so it is
impossible to have a sodium free diet
Sodium Added During Processing
Food
serving size
ham
bologna
canned soup
cottage cheese
McDonalds shake
dill pickle
soy sauce
3 oz
2 slices
1 can
1 cup
medium
1 whole
1 tbsp
Na (mg)
1200
580
800-1000
920
300
850
1029
• We get most of our sodium from salt added
during processing…not from the salt we add at
the table to foods.
• Remember what your physiological
requirements are….if you eat one can of soup
(not the low sodium kind) you are already
consuming twice your needs and 1/3 of what is
recommended for an entire day.
Sodium content of select foods
Taco bell bean burrito (1)
McD. Quarter Pounder w/cheese
Pizza Hut Stuffed
Crust Pizza (2 slices)
Chicken wings (12)
Kraft Mac and cheese
(1 cup, prepared)
Taco Bell Taco (1)
American cheese (1 slice)
BK Whopper
1100 mg
1300mg
2850 mg
1750 mg
750 mg
330 mg
300 mg
900 mg
Sodium: major food sources
canned, cured, smoked meats
– bologna, salami, pepperoni, sausage, ham
canned soups
canned vegetables
Bouillon, Ramen noodles
olives, sauerkraut, anchovies
chips, crackers
seasonings (garlic salt, celery salt), MSG
(monosodium glutamate)
some frozen dinners
Hypertension (high blood pressure)
Blood pressure
– the measurement of how hard your heart has to
work to pump blood from your heart to the rest of
your body
– Optimal blood pressure:
systolic
diastolic
<120
<80
Hypertension
Causes of hypertension:
1. No known cause
this type of hypertension occurs in 90-95% of
people diagnosed with hypertension
2. Kidney disease
kidney disease is the cause of hypertension in only
5-10% of people with hypertension
• The cause of high blood pressure is unknown in the majority
of cases….there are many risk factors, but the exact cause is
not known. For a small percentage of the US population,
kidney disease causes their high blood pressure.
Symptoms
– None until significant organ damage has occurred
• Headaches, visual problems
• Hypertension is called the “silent killer” because there are
no symptoms and therefore, most people do not know
they have hypertension
Long term complications of uncontrolled
hypertension
– stroke
– kidney disease
– blindness/impaired vision
– heart failure
• Hypertension is known as “the silent killer”
because you can have high blood
pressure for years and years and yet
never know it because there are no
outward signs or symptoms.
• That is why regular monitoring is
important, especially if you are at high risk.
You can have your blood pressure
checked free of charge at most
supermarkets and pharmacies.
Hypertension
Risk Factors
– older age
• as we age, our blood
pressure increases
– smoking, heavy alcohol
intake
– African-American descent
– family history
– obesity
• usually develop high BP at an
earlier age and it can be more
severe
– heart disease
– diabetes/insulin resistance
• Type 1 or 2
Hypertension: Prevention
low to moderate sodium consumption
lose weight if overweight
eat a diet high in fruits, vegetables
consume low fat dairy products, whole grains
emphasize poultry, fish, nuts; eat less red meat
get some exercise
The DASH diet
• The DASH diet is a plan that has been clinically proven
to help reduce blood pressure
• Information regarding the DASH diet is available at the
following website.
– http://www.nhlbi.nih.gov/health/public/heart/hbp/dash/
– (Or download the pdf file about the dash diet linked
on the syllabus)
• Read the article available at the CSPI website:
– http://www.cspinet.org/nah/dash.htm
Potassium
Main functions:
– conduction of nerve impulses
– critical in maintaining the heartbeat
– fluid and electrolyte balance
Deficiency:
– 90% we eat is absorbed
• potassium has a high bioavailability
– Low blood levels may be caused by:
• excessive vomiting, prolonged diarrhea, certain diuretics,
laxative abuse
Potassium
Toxicity
– can occur with potassium supplements (KCl)
Food sources
leafy greens (spinach)
oranges, orange juice, broccoli, bananas,
tomatoes