Adequate calcium intake is essential for the maintenance of bone
health and the preservation of bone mineral density. The lay
person believes that calcium is always good for health. Successful
marketing and various clinical practice guidelines have made
prescribing calcium supplements a billion dollar market in recent years.
The aim of this study was to scan the literature and find
out whether calcium supplements should be prescribed to all patients
with fractures so as to improve their bone healing or should
it be restricted to elderly post- menopausal females who have
osteoporotic bones. The inference drawn was that dietary calcium
is easier to absorb and may have beneficial effects as compared to
calcium supplements and it should be limited to the total daily
intake to 1000–1200 mg optimally from dietary sources. Calcium
supplementation does not significantly reduce fracture risk in
postmenopausal women but it reduces the risk of osteoporosis. It
increases the risk of urolithiasis. A favourable role of calcium has
been seen in postmenopausal women, elderly population, children and
adolescents. Calcium is a double-edged sword, which may
be both potentially crucial and perilous and hence should be prescribed
with caution.
Keywords: calcium; Osteoporosis; Dementia; Kidney stones; Constipation
Introduction
A frequently asked question by a healthy, young lady
presenting with a limb fracture being managed conservatively
with immobilisation in a plaster is “Should I take Calcium
supplementation so that my fracture heals well?.” Adequate calcium
intake is essential for the maintenance of bone health during
growing phases [1] and the preservation of bone mineral density
in elderly individuals [2]. Calcium supplementation is a widespread
practice in different age-groups and has been promoted widely to
improve bone density [3]. The lay person believes that calcium is
always good for health due to successful marketing and various
clinical practice guidelines and prescribing calcium supplements
has become a billion dollar market in recent years and has been
taken by millions of both men and women, children, adults, and the
elderly wishing to improve their skeletal health.
Aim
The aim of this review article was to find out whether calcium
supplements should be prescribed to all patients with fractures so
as to improve their bone healing or should it be restricted to elderly
post- menopausal females who have osteoporotic bones.
Discussion
A. Introduction: Osteoporosis is one of the leading causes
of disability in the elderly. Because calcium deficiency contributes
to osteoporosis, daily dietary calcium intake of 1,000–1,200 mg is
recommended [4]. Such a large calcium intake through diet alone
can be difficult; therefore, calcium supplements are widely used
[4]. Epidemiological studies have demonstrated that a significant
number of population throughout the globe fail to achieve the
recommended daily calcium intake [5]. In addition to its pivotal role
in bone metabolism, the potential role of calcium in non-skeletal
tissues has also been investigated, particularly in elderly people [6].
B. Role of Calcium: Calcium is an important and integrative
component of human body with 99% of the body’s calcium being
contained within the skeleton [7]. Calcium homeostasis plays a
major role in maintaining human life activities, such as maintenance
of the skeleton, regulation of hormonal secretion, transmission
of nerve impulses, and vascular activities [8]. The homeostasis of
calcium is mainly maintained by both parathyroid hormone (PTH)
and calcitonin [9].
Benefits of Calcium Supplementation
A. Osteoporosis: Osteoporosis is a skeletal disorder
associated with aging and characterized by compromised bone
strength due to reduced bone mass and reduced bone quality
leading to increased bone fragility thereby predisposing a person to
increased risk of fracture, notably at the vertebrae, hip, and forearm.
It is suggested that Vitamin D and calcium supplementation, either
in the form of calcium supplements or dietary calcium, plays a
positive role in prevention od osteoporosis in people of different
ages and genders. Calcium supplementation plays a protective
role for bone health, improving bone mass density (BMD) and
decreasing morbidity of osteoporosis and osteoporotic fractures in
different genders and age-groups [10].
B. Postmenopausal women: Bone remodelling is
accelerated in the peri-menopausal and postmenopausal periods
and is characterized by a decrease in estrogen production and
an increase in resorption of calcium from bone resulting in a
marked decrease in bone density. Calcium supplementation may
be recommended in postmenopausal women with a history of
osteoporotic fractures, a diagnosis of osteoporosis, vitamin D
deficiency, or a high risk for osteoporosis (eg, primary ovarian
insufficiency) [11] but are not of any proven benefit in primary
prevention of fractures in community dwelling asymptomatic
premenopausal women [12].
C. Pregnant and lactating women: Calcium
supplementation in pregnant or lactating women for the skeletal
health of foetus and mother is of doubtful benefit. In a study in
pregnant women in Gambia, West Africa, with low calcium intakes,
calcium supplement resulted in significantly lower bone mineral
content, bone area, and BMD at the hip throughout 12-month
lactation. The women also had greater decreases in bone mineral
during lactation at the lumbar spine and distal radius and had
biochemical changes consistent with greater bone mineral
mobilization [13]. In pregnant and lactating women with low
calcium intakes, calcium supplementation is recommended [14].
D. Children: For growing children, bone modeling (i.e.,
formation over resorption) is the predominant skeletal process
which requires mineralization; hence, calcium requirements
are increased, particularly during neonatal and pubertal growth
spurts. For healthy children, there has been no recommendation
for routine calcium supplementation, however children with a
high risk of osteoporosis (eg, celiac disease, inflammatory bowel
disease, or congenital bone disorder) or low calcium intake may
benefit from calcium supplementation. In a study conducted in
rural Gambian children accustomed to a low-calcium diet, calcium
supplementation resulted in higher bone mineral content and BMD
[15].
E. Cardiovascular System: A study conducted among an
elderly Chinese population indicated that dietary calcium intake
could reduce the risk of death from all causes and cardiovascular
diseases [16]. Another study conducted among postmenopausal
women revealed that high intake of dietary and supplemental
calcium were associated with a decrease in the mortality of
ischemic heart disease [17].
F. Gastrointestinal tract: A randomized, double-blind
trial performed on people with a history of colorectal adenomas,
receiving either 1,200 mg/d elemental calcium or placebo has
revealed a significant reduction in the risk of recurrent colorectal
adenomas with calcium supplementation6. Calcium carbonate is
more often associated with gastrointestinal side effects, including
constipation, flatulence, and bloating [18]. The explanation behind
those findings is the ability of calcium to combine with bile acids in
the intestines, reducing the rectal epithelial proliferation rate [19].
Adverse effects of Calcium Supplementation
A. Cardiovascular System: It is estimated by a metaanalysis (including eleven randomized controlled trials) that
calcium supplements have up to 30% increase risk for myocardial
infarction [20]. The explanation behind these findings is that
calcium supplements potentially contribute to elevated serum
calcium levels and possibly accelerated cardiovascular calcification
[21].
B. Gastrointestinal Diseases: Calcium supplements may
increase the incidence of constipation, severe diarrhoea, and
abdominal pain [22].
C. Renal Stones: A major concern regarding the safety of
calcium has been the occurrence of kidney stones. An abnormality
of urinary super-saturation is one of the main factors for the
formation of kidney stones23. Individuals who consumed any
amount of supplemental calcium had an increased risk for
kidney stones compared with individuals who did not consume
supplemental calcium [24].
D. Age Related Macular Degeneration: A recent crosssectional study found that >800 mg/d of calcium consumption in
people aged >67 years may increase the risk of age related macular
degeneration compared with those who do not take calcium [25].
E. Dementia and Alzheimer’s Disease: Some trials have
reported an association between calcium supplementation and
increased risk for vascular events [26]. Vascular risk factors are
related to vascular dementia and Alzheimer disease [27]. Calcium
supplementation might have direct toxic effects on vulnerable
neurons, because the increased calcium levels may amplify
ischemic cell death and worsen the outcome after cerebrovascular
events [19]. calcium influx and intracellular calcium overload have
a crucial role in apoptosis and necrosis [28]. The mechanism of
calcium supplements in the pathogenesis of dementia could be the
steep increase in serum calcium levels caused by the supplements
[20]. Calcium plays a central role in the mechanisms of cell death. In
necrosis, the transmembrane influx of calcium ions activates
proteases that are responsible for degrading critical proteins and
disrupting membrane function [29].
F. Dietary Calcium: Dairy products in the form of milk,
yogurt, and cheese are rich sources of calcium. About 72 percent of
calcium comes from milk, cheese and yogurt and from foods to which
dairy products have been added as in pizza, lasagna, dairy desserts.
The remaining calcium comes from vegetables (7 percent); grains
(5 percent); legumes (4 percent); fruit (3 percent); meat, poultry,
and fish (3 percent); eggs (2 percent); and miscellaneous foods (3
percent) [30].
G. Difference between Dietary Calcium and
Supplementary Calcium: The difference between dietary calcium
and calcium intake by supplements could be explained by variations
in corresponding changes in serum calcium concentration. Dietary
intake does not increase the serum calcium levels to the same
extent as supplements20. In addition, dietary calcium intake
involves simultaneous intake of all other components of calciumcontaining foods and much lower dosages of calcium than calcium
supplements.
Conclusion
Dietary calcium is easier to absorb and may have beneficial
effects as compared to calcium supplements. Calcium from food
sources has not been linked to morbidity, so limiting dietary
consumption would not be advised. The recommendation should
be to limit the total daily intake to 1000–1200 mg, optimally
from dietary sources. Different dosages of calcium may induce
different results. A favourable role of calcium has been seen
in postmenopausal women, elderly population, children and
adolescents. Calcium prevents osteoporosis but at the same time,
increases the occurrence of cardiovascular diseases and risk of
urolithiasis. Calcium supplementation does not significantly reduce
fracture risk in postmenopausal women but it reduces the risk of
osteoporosis. Calcium is a double-edged sword, which may be both
potentially crucial and perilous and hence should be prescribed
with caution. The issue of safety in people receiving calcium has
long been a matter of debate. There is an abundance of data for
beneficial effects and side effects in the literature on the role of
calcium. All taken together, it is important to balance the advantages
and disadvantages of calcium supplementation on human health
[31].
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