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Calcium, the most abundant mineral
in the human body, has several important functions. More than 99%
of total body calcium is stored in the bones and teeth where it
functions to support their structure .
The remaining 1% is found throughout the body in blood, muscle,
and the fluid between cells. Calcium is needed for muscle contraction,
blood vessel contraction and expansion, the secretion of hormones
and enzymes, and sending messages through the nervous system.
A constant level of calcium is maintained in body fluid and tissues
so that these vital body processes function efficiently.
Bone undergoes continuous remodeling, with constant
resorption (breakdown of bone) and deposition of calcium into newly
deposited bone (bone formation).
The balance between bone resorption and deposition changes as people
age. During childhood there is a higher amount of bone formation
less breakdown. In early and middle adulthood, these processes
are relatively equal. In aging adults, particularly among postmenopausal
women, bone breakdown exceeds its formation, resulting in bone
which increases the risk for osteoporosis (a disorder characterized
by porous, weak bones).
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Recommendations for calcium are provided in the
Dietary Reference Intakes (DRIs) developed by the Institute of
Medicine (IOM) of the National Academy of Sciences. Dietary
Reference Intake (DRI) is the general term for a set of
reference values used for planning and assessing nutrient intakes of
healthy people. Three important types of reference values included
in the DRIs are Recommended Dietary Allowances (RDA),
Adequate Intakes (AI), and Tolerable Upper Intake
Levels (UL). The RDA recommends the average daily intake that
is sufficient to meet the nutrient requirements of nearly all
(97-98%) healthy individuals in each age and gender group. An AI is
set when there is insufficient scientific data available to
establish a RDA. AIs meet or exceed the amount needed to maintain a
nutritional state of adequacy in nearly all members of a specific
age and gender group. The UL, on the other hand, is the maximum
daily intake unlikely to result in adverse effects. It is listed in
the section "Is there health risk of too much calcium?" of
this fact sheet.For calcium, the recommended intake is
listed as an Adequate Intake (AI), which is a recommended average
intake level based on observed or experimentally determined levels.
Table 1 contains the current recommendations for calcium for
infants, children and adults.
Table 1: Recommended
Adequate Intake by the IOM for Calcium
|Male and Female Age
||Pregnancy & Lactation|
|0 to 6 months
|7 to 12 months
|1 to 3 years
|4 to 8 years
|9 to 13 years
|14 to 18 years
|19 to 50 years
is a widespread concern that Americans are not meeting the
recommended intake for calcium. According to the Continuing Survey
of Food Intakes of Individuals (CSFII 1994-96), the following
percentage of Americans are not
meeting their recommended
intake for calcium:
- 44% boys and 58% girls ages 6-11
- 64% boys and 87% girls ages 12-19
- 55% men and 78% of women ages 20+
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the United States (U.S.), milk, yogurt and cheese are the major
contributors of calcium in the
typical diet .
The inadequate intake of dairy foods may explain why some Americans
are deficient in calcium since dairy foods are the major source
calcium in the diet.
The U.S. Department of Agriculture's Food Guide Pyramid recommends
that individuals two years and older eat 2-3 servings of dairy
products per day. A serving is equal to:
- 1 cup (8 fl oz) of milk
- 8 oz of yogurt
- 1.5 oz of natural cheese (such as Cheddar)
- 2.0 oz of processed cheese (such as American)
A variety of non-fat and reduced
fat dairy products that contain the same amount of calcium as regular dairy
products are available in the U.S. today for individuals concerned about saturated
fat content from regular dairy products. Although dairy products are the main
source of calcium in the U.S. diet, other foods also contribute to overall
calcium intake. Individuals with lactose intolerance (those who experience
symptoms such as bloating and diarrhea because they cannot completely digest
the milk sugar lactose) and those who are vegan (people who consume no animal
products) tend to avoid or completely eliminate dairy products from their
diets. Thus, it is important for these individuals to meet their calcium needs
with alternative calcium sources if they choose to avoid or eliminate dairy
products from their diet. Foods such as Chinese cabbage, kale and broccoli
are other alternative calcium sources. Although most grains are not high in
calcium (unless fortified), they do contribute calcium to the diet because
they are consumed frequently. Additionally, there are several calcium-fortified
food sources presently available, including fruit juices, fruit drinks, tofu
and cereals. Figure 1 compares the amount of food that you would need to eat
from certain food sources to get the same amount of calcium that is found
in 8 fl oz of milk. Table 2 contains additional listings of food sources of
Figure 1: Calcium Content of 8 fl oz of Milk Compared to Other
Food Sources of Calcium
Source:Table 2: Selected Food Sources of Calcium
|Yogurt, plain, low fat, 8 oz.
|Yogurt, fruit, low fat, 8 oz.
|Sardines, canned in oil, with bones, 3 oz.
|Cheddar cheese, 1 ½ oz shredded
|Milk, non-fat, 8 fl oz.
|Milk, reduced fat (2% milk fat), no solids, 8 fl oz.
|Milk, whole (3.25% milk fat), 8 fl oz
|Milk, buttermilk, 8 fl oz.
|Milk, lactose reduced, 8 fl oz.**
|Mozzarella, part skim 1 ½ oz.
|Tofu, firm, made w/calcium sulfate, ½ cup***
|Orange juice, calcium fortified, 6 fl oz.
|Salmon, pink, canned, solids with bone, 3 oz.
|Pudding, chocolate, instant, made w/ 2% milk, ½ cup
|Cottage cheese, 1% milk fat, 1 cup unpacked
|Tofu, soft, made w/calcium sulfate, ½ cup***
|Spinach, cooked, ½ cup
|Instant breakfast drink, various flavors and brands, powder prepared
with water, 8 fl oz.
|Frozen yogurt, vanilla, soft serve, ½ cup
|Ready to eat cereal, calcium fortified, 1 cup
|Turnip greens, boiled, ½ cup
|Kale, cooked, 1 cup
|Kale, raw, 1 cup
|Ice cream, vanilla, ½ cup
|Soy beverage, calcium fortified, 8 fl oz.
|Chinese cabbage, raw, 1 cup
|Tortilla, corn, ready to bake/fry, 1 medium
|Tortilla, flour, ready to bake/fry, one 6" diameter
|Sour cream, reduced fat, cultured, 2 Tbsp
|Bread, white, 1 oz
|Broccoli, raw, ½ cup
|Bread, whole wheat, 1 slice
|Cheese, cream, regular, 1 Tbsp
**Content varies slightly according to fat content; average =300 mg calcium
*** Calcium values are only for tofu processed with a calcium salt. Tofu processed
with a non-calcium salt will not contain significant amounts of calcium.Daily
Values (DV) were developed to help consumers determine if a typical serving
of a food contains a lot or a little of a specific nutrient. The DV for calcium
is based on 1000 mg. The percent DV (% DV) listed on the Nutrition Facts panel
of food labels tells you what percentages of the DV are provided in one serving.
For instance, if you consumed a food that contained 300 mg of calcium, the
DV would be 30% for calcium on the food label. A food providing 5% of the
DV or less is a low source while a food that provides 10-19% of the DV is
a good source and a food that provides 20% of the DV or more is an excellent
source for a nutrient. For foods not listed in this table, please refer to
the U.S. Department of Agriculture's Nutrient Database Web site
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As the 2000 Dietary Guidelines for Americans states, "Different
foods contain different nutrients and other healthful substances. No single
food can supply all the nutrients in the amounts you need". The following
are strategies and tips to help you meet your calcium needs each day:
- Use low fat or fat free milk instead of water in recipes such as pancakes,
mashed potatoes, pudding and instant, hot breakfast cereals.
- Blend a fruit smoothie made with low fat or fat free yogurt for a great
- Sprinkle grated low fat or fat free cheese on salad, soup or pasta.
- Choose low fat or fat free milk instead of carbonated soft drinks.
- Serve raw fruits and vegetables with a low fat or fat free yogurt based
- Create a vegetable stir-fry and toss in diced calcium-set tofu.
- Enjoy a parfait with fruit and low fat or fat free yogurt.
- Complement your diet with calcium-fortified foods such as certain cereals,
orange juice and soy beverages.
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Calcium absorption refers to the amount of calcium that is absorbed from
the digestive tract into our body's circulation. Calcium absorption can
be affected by the calcium status of the body, vitamin D status, age, pregnancy
and plant substances in the diet. The amount of calcium consumed at one
time such as in a meal can also affect absorption. For example, the efficiency
of calcium absorption decreases as the amount of calcium consumed at a meal
Net calcium absorption can be as high as 60% in infants and young children,
when the body needs calcium to build strong bones . Absorption slowly
decreases to 15-20% in adulthood and even more as one ages. Because calcium
absorption declines with age, recommendations for dietary intake of calcium
are higher for adults ages 51 and over.
- Vitamin D:
Vitamin D helps improve calcium absorption. Your body can obtain vitamin
D from food and it can also make vitamin D when your skin is exposed to
sunlight. Thus, adequate vitamin D intake from food and sun exposure is
essential to bone health.
Current calcium recommendations for nonpregnant women are also sufficient
for pregnant women because intestinal calcium absorption increases during
pregnancy. For this reason, the calcium recommendations established for
pregnant women are not different than the recommendations for women who
are not pregnant.
- Plant substances:
Phytic acid and oxalic acid, which are found naturally in some plants,
may bind to calcium and prevent it from being absorbed optimally. These
substances affect the absorption of calcium from the plant itself not
the calcium found in other calcium-containing foods eaten at the same
time. Examples of foods high in oxalic acid are spinach, collard greens,
sweet potatoes, rhubarb, and beans. Foods high in phytic acid include
whole grain bread, beans, seeds, nuts, grains, and soy isolates. Although
soybeans are high in phytic acid, the calcium present in soybeans is still
partially absorbed. Fiber, particularly from wheat bran, could also prevent
calcium absorption because of its content of phytate. However, the effect
of fiber on calcium absorption is more of a concern for individuals with
low calcium intakes. The average American tends to consume much less fiber
per day than the level that would be needed to affect calcium absorption.
Calcium excretion refers to the amount of calcium eliminated from the body
in urine, feces and sweat. Calcium excretion can be affected by many factors
including dietary sodium, protein, caffeine and potassium.
- Sodium and protein:
Typically, dietary sodium and protein increase calcium excretion as the
amount of their intake is increased. However, if a high protein, high
sodium food also contains calcium, this may help counteract the loss of
Increasing dietary potassium intake (such as from 7-8 servings of fruits
and vegetables per day) in the presence of a high sodium diet (>5100
mg/day, which is more than twice the Tolerable Upper Intake Level of 2300
mg for sodium per day) may help decrease calcium excretion particularly
in postmenopausal women.
Caffeine has a small effect on calcium absorption. It can temporarily
increase calcium excretion and may modestly decrease calcium absorption,
an effect easily offset by increasing calcium consumption in the diet.
One cup of regular brewed coffee causes a loss of only 2-3 mg of calcium
easily offset by adding a tablespoon of milk. Moderate caffeine consumption,
(1 cup of coffee or 2 cups of tea per day), in young women who have adequate
calcium intakes has little to no negative effects on their bones.
- Phosphorus: The effect of dietary phosphorus on calcium is minimal.
Some researchers speculate that the detrimental effects of consuming foods
high in phosphate such as carbonated soft drinks is due to the replacement
of milk with soda rather than the phosphate level itself.
- Alcohol: Alcohol can affect calcium status by reducing the intestinal
absorption of calcium. It can also inhibit enzymes in the liver that help
convert vitamin D to its active form which in turn reduces calcium absorption.
However, the amount of alcohol required to affect calcium absorption is
unknown. Evidence is currently conflicting whether moderate alcohol consumption
is helpful or harmful to bone.
In summary, a variety of factors that may cause a decrease in calcium absorption
and/or increase in calcium excretion may negatively affect bone health.
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Your bones are living tissues and continue to change throughout life.
During childhood and adolescence, bones increase in size and mass. Bones
continue to add more mass until around age 30, when peak bone mass is reached.
Peak bone mass is the point when the maximum amount of bone is achieved.
Because bone loss, like bone growth, is a gradual process, the stronger
your bones are at age 30, the more your bone loss will be delayed as you
age. Therefore, it is particularly important to consume adequate calcium
and vitamin D throughout infancy, childhood, and adolescence. It is also
important to engage in weight-bearing exercise to maximize bone
strength and bone density (amount of bone tissue in a certain volume of
bone) to help prevent osteoporosis later in life. Weight bearing exercise
is the type of exercise that causes your bones and muscles to work against
gravity while they bear your weight. Resistance exercises such as weight
training are also important because they help to improve muscle mass and
|Examples of weight bearing exercise
||Examples of NON-weight bearing exercise
Osteoporosis is a disorder characterized by porous, fragile bones. It
is a serious public health problem for more than 10 million Americans, 80%
of whom are women. Another 34 million Americans have osteopenia, or low
bone mass, which precedes osteoporosis. Osteoporosis is a concern because
of its association with fractures of the hip, vertebrae, wrist, pelvis,
ribs, and other bones. Each year, Americans suffer from 1.5 million fractures
because of osteoporosis. Osteoporosis and osteopenia can result from dietary
factors such as:
- chronically low calcium intake
- low vitamin D intake
- poor calcium absorption
- excess calcium excretion
When calcium intake is low or
calcium is poorly absorbed, bone breakdown occurs because the body
must use the calcium stored in bones to maintain normal biological
functions such as nerve and muscle function. Bone loss also occurs
as a part of the aging process. A prime example is the loss of bone
mass observed in post-menopausal women because of decreased amounts
of the hormone estrogen. Researchers have identified many factors
that increase the risk for developing osteoporosis. These factors
include being female, thin, inactive, of advanced age, cigarette
smoking, excessive intake of alcohol, and having a family history
In 1993 the FDA authorized a health claim for food labels on
calcium and osteoporosis in response to scientific evidence that
an inadequate calcium intake is one factor that can lead to low peak
bone mass and is considered a risk factor for osteoporosis.
The claim states that "adequate calcium intake throughout life
is linked to reduced risk of osteoporosis through the mechanism of
optimizing peak bone mass during adolescence and early adulthood and
decreasing bone loss later in life
mineral density (BMD) tests, including those that measure your
hip, spine, wrist, finger, shin bone, and heel, can help determine
mass. These tests provide a T-score which is a measure of bone
mineral density that compares an individual's BMD to an optimal
of a 30 year old healthy adult. See Figure 2 below. A T-Score of
-1.0 and above indicates normal bone density. A T-score of -1.0
-2.5 indicates that a person is considered to have low bone mass
(osteopenia). A score below -2.5 indicates osteoporosis.
Figure 2: Interpreting Bone Mineral Density
osteoporosis affects people of different races, genders and
ethnicities, women are at highest risk because their skeletons are
smaller to start with and because of the accelerated bone loss that
accompanies menopause. Adequate calcium and vitamin D intakes, as
well as weight bearing exercise are critical to the development and
maintenance of healthy bone throughout the lifecycle. Older adults
should strive to maintain recommended daily calcium intakes as well
as an adequate vitamin D intake.
studies (type of research study in
which the treatment/intervention is observed and not controlled
by the researchers) and experimental
studies (type of
research study in which the researchers control the treatments/interventions
and that are
assigned to participants) indicate that individuals who eat a
vegetarian diet high in minerals (including calcium, magnesium
and potassium) and fiber, and low in fat, tend to have reduced
from some clinical trials
(a specific type of experimental
study) used to evaluate the effects of one or more
treatments/interventions in humans) indicate that an increased
calcium intake lowers blood pressure and the risk of hypertension
(high blood pressure).
However, the results of some studies produced small and inconsistent
reductions in blood pressure. One reason for these results is
because these research studies tended to test the effect of single
nutrients rather than foods on blood pressure. To help test
the combined effect of nutrients including calcium from food on
blood pressure, a study was conducted to investigate the impact
various dietary eating patterns on blood pressure. This study titled "Dietary
Approaches to Stop Hypertension (DASH)" was reported in
1997 by the National, Heart, Lung and Blood Institute of the
National Institutes of Health. It investigated the effect of various
eating patterns on lowering blood pressure. The DASH study was
multi-center research trial where food was provided to over 450
adults. It examined the effects of three different diets on high
blood pressure: a control, "typical American" diet and two modified
diets (high fruits-and-vegetables and a combination "DASH" diet
- high in fruits, vegetables, and low fat dairy). See Table 3 for
comparison of some of the components of the three
Table 3: Comparison of the Three Diets Tested
in the "DASH" Study
||Fruit & Vegetable Servings
||Lowfat Dairy Servings
||Fat (% of total calories)
|Control "Typical American" diet
|Combination "DASH" diet
Of the three diets tested,
the combination "DASH" diet resulted in the greatest decrease in
Thus, this finding from a large and carefully executed clinical
trial helped demonstrate that the combination "DASH" diet, with
increased calcium, decreased blood pressure.
A number of further studies have been done, all showing a similar
relationship between increasing calcium intakes and decreased blood
A study conducted after the original "DASH" study, referred to
as the "DASH-Sodium" study showed that the DASH diet without sodium
restriction provided as much blood pressure reduction as did severe
sodium restriction on the control diet (1500 mg sodium/day).
Overall it appears that consuming an adequate intake of fruits
and vegetables as well as calcium from low fat dairy products plays
significant role in controlling blood pressure.
relationship between calcium intake and the risk of colon cancer
has not been conclusively determined. Observational and experimental
research studies investigating the role calcium plays in the
prevention of colon cancer show mixed results. Some studies suggest
that increased intakes of dietary (low fat dairy sources) and
supplemental calcium are associated with a decreased risk of colon
Supplementation with calcium carbonate is reported to lead to
reduced risk of adenomas (nonmalignant tumors) in the colon, a
precursor to colon cancer, but it is not known if this will
ultimately translate into reduced cancer risk.
Another study reported on the association between diet and colon
cancer history in 135,000 men and women participating in two large
health surveys, the Nurses' Health Study and the Physicians' Health
Study. The authors found that those who consumed 700 to 800 mg
calcium per day had a 40 to 50% lower risk of developing left side
However, a few other observational studies found inconclusive
evidence regarding any association of calcium intake with colon
Although some research findings indicate a protective effect of
calcium or low fat dairy foods against colon cancer, further studies
are necessary to confirm this role for calcium.Prostate
There is some evidence to suggest that higher calcium
(ranging from 600 mg to >2000 mg of calcium) and/or dairy intakes
(>2.5 servings) may be associated with the development of
However, these studies are observational in nature rather than
clinical trials and cannot establish a definite causal relationship
between calcium and prostate cancer. Other findings only show a
relationship, no relationship at all or the opposite relationship
between calcium and prostate cancer.
Thus, the relationship between calcium intake, dairy intake and
prostate cancer risk remains unclear. At the present time, it is
recommended that men ages 19 and over consume a "modest" intake
of calcium ranging from 1000-1200 mg per day and maintain an intake
below the upper tolerable limit (2500 mg).
Kidney stones are crystallized
deposits of calcium and other minerals in the urinary tract. Calcium
oxalate stones are the most common form of kidney stones in the
High calcium intakes or high calcium absorption were previously
thought to contribute to the development of kidney stones. However,
more recent studies show that high dietary calcium intakes actually
decrease the risk for kidney stones .
Other factors such as high oxalate intake and reduced fluid
consumption appear to be more of a risk factor in the formation
of kidney stones than calcium in most individuals.
Research suggests that calcium,
especially calcium derived from dairy products, may help to regulate
body fat. Laboratory and animal studies provide initial evidence
calcium's role in decreasing body fat while other studies confirm
this potential benefit for humans. At this time, lowfat dairy
products seem more beneficial than calcium supplements alone in
helping to reduce body fat and reduce weight.
However, larger studies in humans need to be conducted to help
confirm the benefit of calcium for weight loss. Currently, The
National Institutes of Health is conducting a small clinical trial
to study the effects of supplemental calcium on body weight, body
composition, blood lipids and obesity-related conditions such as
insulin sensitivity. This clinical trial will be completed in late
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intake, decreased calcium absorption, and increased calcium loss
in urine can decrease total calcium in the body, with the potential
producing osteoporosis and the other consequences of chronically
low calcium intake. If an individual does not consume enough dietary
calcium or experiences rapid losses of calcium from the body,
calcium is withdrawn from their bones in order to maintain calcium
levels in the blood.
Because circulating blood calcium levels
are tightly regulated in the bloodstream, hypocalcemia (low blood
calcium) does not usually occur due to low calcium intake, but
rather results from a medical problem or treatment such as renal
failure, surgical removal of the stomach (which significantly
decreases calcium absorption), and use of certain types of diuretics
(which result in increased loss of calcium and fluid through urine).
Simple dietary calcium deficiency produces no signs at all.
Hypocalcemia can cause numbness and tingling in fingers, muscle
cramps, convulsions, lethargy, poor appetite, and mental confusion
It can also result in abnormal heart rhythms and even death.
Individuals with medical problems that result in hypocalcemia should
be under a medical doctor's care and receive specific treatment
aimed at normalizing calcium levels in the blood. [Please note
that the symptoms described here may be due to a medical condition
other than hypocalcemia.
] It is important to consult a health
professional if you experience any of these symptoms.
Menopause often leads to increases in bone loss with
the most rapid rates of bone loss occurring during the first five
years after menopause.
Drops in estrogen production after menopause result in increased
bone resorption, and decreased calcium absorption.
Annual decreases in bone mass of 3-5% per year are often seen during
the years immediately following menopause, with decreases less
1% per year seen after age 65.
Two studies are in agreement that increased calcium intakes during
menopause will not completely offset menopause bone loss.
Hormone therapy (HT), previously known as hormone
replacement therapy (HRT), with sex hormones such as estrogen and
progesterone, helps to prevent osteoporosis and fractures. However,
some medical groups and professional societies such as the American
College of Obstetricians and Gynecologists, The North American
Menopause Society and The American Society for Bone and Mineral
Research recommend that postmenopausal women consider using other
agents such as bisphosphonates (medication used to slow or stop
bone-resorption) because of potential health risks of HT if
combination HT (estrogen and progestin) is solely being administered
to prevent or treat osteoporosis.
Postmenopausal women using combination HT to reduce bone loss should
consult with their physician about the risks and benefits of
estrogen therapy for their health. Estrogen therapy works to
restore postmenopausal bone remodeling levels back to those of
premenopause, leading to a lower rate of bone loss.
Estrogen appears to interact with supplemental calcium by increasing
calcium absorption in the gut. However, including adequate amounts
of calcium in the diet may help slow the rate of bone loss for
women. Amenorrheic Women and the Female Athlete
Amenorrhea is the condition when menstrual periods
stop or fail to initiate in women who are of childbearing age.
Secondary amenorrhea is the absence of three or more consecutive
menstrual cycles after menarche occurs (first menstrual period).
secondary type of amenorrhea can be induced by exercise in athletes
and is referred to as "athletic amenorrhea". Potential causes of
athletic amenorrhea include low body weight and low percent body
fat, rapid weight loss, sudden onset of vigorous exercise,
disordered eating and stress.
Amenorrhea results from decreases in circulating estrogen, which
then negatively affect calcium balance.
Studies comparing healthy women with normal menstrual cycles to
amenorrheic women with anorexia nervosa (a type of disordered
eating) found decreased levels of calcium absorption, a higher
urinary calcium excretion, and a lower rate of bone formation
women with anorexia.
The condition "female athlete triad" refers to the
combination of disordered eating, amenorrhea, and osteoporosis.
Exercise-induced amenorrhea has been shown to result in decreases
In female athletes, low bone mineral density, menstrual
irregularities, dietary factors, and a history of prior stress
fractures are associated with an increased risk of future stress
Stress fractures can severely impact health and cause financial
burden, especially in physically active females such women in the
Thus, it is important for amenorrheic women to maintain the
recommended Adequate Intake for calcium. Lactose
Lactose maldigestion (or "lactase
non-persistence") describes the inability of an individual to
completely digest lactose, the naturally occurring sugar in milk.
Lactose intolerance refers to the symptoms that occur when the
amount of lactose exceeds the ability of an individual's digestive
tract to break down lactose. In the US, approximately 25% of all
adults have a limited ability to digest lactose. Lactose
maldigestion varies by ethnicity, with a prevalence of 85% in
Asians, 50% in African Americans, and 10% in Caucasians .Symptoms
of lactose intolerance include bloating, flatulence, and diarrhea
after consuming large amounts of lactose (such as the amount in
quart of milk).
Lactose maldigesters may be at risk for calcium deficiency, not
due to an inability to absorb calcium, but rather from the avoidance
dairy products .
Although some lactose maldigesters avoid dairy products, others
are able to consume moderate amounts of lactose, such as the amount
an 8-oz glass of milk. Some individuals may be able to consume
two 8-oz glasses of milk a day if they do so at different meals.Symptoms
of lactose intolerance vary from individual to individual depending
on the amount of lactose consumed, history of previous consumption
of foods with lactose and the type of meal with which the lactose
Drinking milk with a meal helps reduce symptoms of lactose
intolerance substantially. In addition, regularly eating foods
(e.g. daily for 2-3 weeks) with lactose (such as milk) can help
adapt to the lactose and thus reduce symptoms of lactose intolerance.
Other dietary options for lactose maldigesters include choosing
aged cheeses (such as Cheddar and Swiss) which contain little lactose,
yogurt which contains live active cultures that aid in lactose
digestion, or lactose reduced and lactose free milk.If an
individual is a lactose maldigester and chooses to avoid dairy
products, it is important for them to include non-dairy sources
calcium in their daily diet (see Table 2 for a listing of selected
food sources of calcium) or consider taking a calcium supplement
help meet their recommended calcium
There are several types of
vegetarian eating practices. Individuals may choose to include
some animal products (ovo-vegetarian, lacto-vegetarian, lacto-ovo
vegetarian, pesco-vegetarian) or no animal products (vegan) in
diet. Calcium intakes between lacto-ovo-vegetarians (those who
consume eggs and dairy products) and non-vegetarians have been
to be similar.
Calcium absorption may be reduced in vegetarians because they eat
more plant foods containing oxalic and phytic acids, compounds
interfere with calcium absorption.
However, vegetarian diets that contain less protein may reduce
Yet, vegans may be at increased risk for inadequate intake of
calcium because of their lack of consumption of dairy products.
Therefore, it is important for vegans to include adequate amounts
of non-dairy sources of calcium in their daily diet (see Table
consider taking a calcium supplement to meet their recommended
calcium intake. Furthermore, while early studies found vegetarian
diets to be beneficial for bone health, more recent studies have
found no benefits or even the opposite effect.
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Tolerable Upper Limit (UL) is the highest level of daily intake
of calcium from food, water and supplements that is likely to pose
risks of adverse health effects to almost all individuals in the
The UL for children and adults ages 1 year and older (including
pregnant and lactating women) is 2500 mg/day. It was not possible
establish a UL for infants under the age of 1 year. While
low intakes of calcium can result in deficiency and undesirable
health conditions, excessively high intakes of calcium can also
adverse effects. Adverse conditions associated with high calcium
intakes are hypercalcemia (elevated levels of calcium in the blood),
impaired kidney function and decreased absorption of other minerals.
Hypercalcemia can also result from excess intake of vitamin D,
such as from supplement overuse at levels of 50,000 IU or higher.
However, hypercalcemia from diet and supplements is very rare.
Most cases of hypercalcemia occur as a result of malignancy - especially
in the advanced stages. Another concern with high calcium
intakes is the potential for calcium to interfere with the
absorption of other minerals, iron, zinc, magnesium, and phosphorus.
Most Americans should consider their intake of calcium from
all foods including fortified ones before adding supplements to
their diet to help avoid the risk of reaching levels at or near
UL for calcium (2500 mg). If you need additional assistance
regarding your calcium needs, consider checking with a physician
or registered dietitian.
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have the potential to interact with several prescription and over
the counter medications. Further information about these
interactions is described below. Some examples of medications that
may interact with calcium include:
- antibiotics in tetracycline family
- tiludronate disodium
- anticonvulsants such as phenytoin
- thiazide, type of diuretic
- mineral oil or stimulant laxatives
- aluminum or magnesium containing antacids
supplements may decrease levels of the drug digoxin, a medication
given to heart patients.
The interaction between calcium and vitamin D supplements and
digoxin may also increase the risk of hypercalcemia. Calcium
supplements also interact with fluoroquinolones (a class of
antibiotics including ciprofloxacin), levothyroxine (thyroid
hormone) used to treat thyroid deficiency, antibiotics in the
tetracycline family, tiludronate disodium (a drug used to treat
Paget's disease), and phenytoin (an anti-convulsant drug). In all
these cases, calcium supplements decrease the absorption of these
drugs when the two are taken at the same time.
Thiazide, and diuretics similar to thiazide, can interact
with calcium carbonate and vitamin D supplements to increase the
chances of developing hypercalcemia and hypercalciuria (elevated
levels of calcium in urine).
Aluminum and magnesium antacids can both increase urinary calcium
excretion. Mineral oil and stimulant laxatives can both decrease
dietary calcium absorption. Furthermore, glucocorticoids (for
example: prednisone) can cause calcium depletion and eventually
osteoporosis, when used for more than a few weeks.
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The 2000 Dietary
Guidelines for Americans recommend that individuals consume a
variety of foods to meet their nutrient needs since no single food
can supply all the nutrients in the amounts needed by an individual
However, for some people it may be necessary to take supplements
in order to meet the recommended intakes for calcium. In 2002,
supplements were the number one selling mineral supplement and
highest selling supplement overall in the U.S.
nutrition industry totaling approximately $877 million in sales.The
two main forms of calcium found in supplements are carbonate and
citrate. Calcium carbonate is the most common because it is
inexpensive and convenient. The absorption of calcium citrate is
similar to calcium carbonate. For instance, a calcium carbonate
supplement contains 40% calcium while a calcium citrate supplement
only contains 21% calcium. However, you have to take more pills
calcium citrate to get the same amount of calcium as you would
get from a calcium carbonate pill since citrate is a larger molecule
than carbonate. One advantage of calcium citrate over calcium
carbonate is better absorption in those individuals who have
decreased stomach acid. Calcium citrate malate is a form of calcium
used in the fortification of certain juices and is also well
Other forms of calcium in supplements or fortified foods include
calcium gluconate, lactate, and phosphate. The amount of
calcium your body obtains from various supplements depends on the
amount of elemental calcium in the tablet. The amount of elemental
calcium is the amount of calcium that actually is in the supplement.
Calcium absorption also depends on the total amount of calcium
consumed at one time and whether the calcium is taken with food
or on an empty stomach. Absorption from supplements is best in
500 mg or less because the percent of calcium absorbed decreases
as the amount of calcium in the supplement increases.
Therefore, someone taking 1000 mg of calcium in a supplement should
take 500 mg twice a day instead of 1000 mg calcium at one time.
Some common complaints of calcium supplement use are gas,
bloating and constipation. If you have such symptoms, you may want
to spread the calcium dose out throughout the day, change supplement
brands, take the supplement with meals and/or check with your
pharmacist or health care provider. Figure
compares the amount of calcium (elemental calcium) found
in some different forms of calcium supplements.
3: Comparison of Calcium Content of Various
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