534
bone mass in adults and it doesn’t stop there, calcium slows the physiological ageassociated reduction of the measure of the bone mineral mass.
Genetic, hormonal factors and insufficient physical activity may aggravate calcium deficiency in humans. The metabolism of calcium is made possible by the
presence of vitamin D, and lack of this vitamin can be as a result of calcium deficiency and when these happen, the outcome depletes mineralization of the bone
matrix. Children with calcium deficiency may have rickets (Allen and Kerstetter
2005). Milk and its derivatives which contain about 50% of this mineral, with cereals and vegetables (each constituting 11%) are the major sources of calcium
(Lombardi-Boccia et al. 2003). Calcium bioavailability for these food sources varies considerably, with milk and its derivatives and mineral water having the highest
levels of bioavailability. Contrarily, fibre and phytate-rich vegetables have bioavailability levels that are quite low. The measure of calcium in the body is affected by
the effectiveness of calcium absorption from foods and this is constant in adolescents and adults, there is however, a decrease in calcium absorption by 2% every
10 years in post-menopausal women (Allen and Kerstetter 2005).
Calcium is a critical mineral in the developmental stages of a fetus, and its demand
is highly increased during pregnancy, which is usually an increase from a daily dosage of 50 mg/day at the halfway point, to 330 mg/day at the end and also during
lactation which is due to the movement of calcium from the maternal skeleton to the
fetus, a greater efficiency of intestinal absorption and an amplified increase in renal
retention (Theobald 2005). Adequate calcium consumption is associated with high
birth weight, effective blood pressure control and a diminished risk of premature
delivery. The placental movement of calcium from the maternal compartment to the
fetus is achieved as a result of the presence of active transport agents in the epithelium of the placenta. The amount of calcium circulated in the fetus is higher in the
20th week of pregnancy than those detected in the maternal plasma. Recommended
daily calcium intake varies between countries to countries, and the daily dose for
pregnant and breastfeeding women also varies between countries. The Italian RDA
indicate calcium value of 1.2 gram per day in the gestational period, while the WHO
recommends 1.5–2.0 gram per day from the 20th week until the end of pregnancy,
particularly for women at risk of gestational hypertension. Risks of developing gestational hypertension and pre-eclampsia in pregnant women can be reduced by a
low-dose calcium supplementation as recommended (Hofmeyr et al. 2014).
It should be noted, however, that hypercalcemia, i.e. calcium levels above normal
range is associated with a high risk of developing Hemolysis, Elevated Liver
enzymes and Low Platelets (HELLP) Syndrome. Interestingly, the measure of calcium secreted daily in breast milk varies considerably (150–300 mg/day), and this
depends largely on the active transportation of calcium from the bones and reduced
urinary secretions. The restoration of calcium stored in the maternal bones is
achieved after the weaning and resumption of ovarian function (Olausson et al.
2012). Studies have shown that the secretion of calcium in milk gland does not
depend on its dietary intake and supplementation. Hence, the daily calcium intake
during lactation is nothing different from that of the healthy adult female population
which is 1.0 g/day. Moreover, high risk of calcium deficiency during breastfeeding
S. Hassan et al.
bone mass in adults and it doesn’t stop there, calcium slows the physiological ageassociated reduction of the measure of the bone mineral mass.
Genetic, hormonal factors and insufficient physical activity may aggravate calcium deficiency in humans. The metabolism of calcium is made possible by the
presence of vitamin D, and lack of this vitamin can be as a result of calcium deficiency and when these happen, the outcome depletes mineralization of the bone
matrix. Children with calcium deficiency may have rickets (Allen and Kerstetter
2005). Milk and its derivatives which contain about 50% of this mineral, with cereals and vegetables (each constituting 11%) are the major sources of calcium
(Lombardi-Boccia et al. 2003). Calcium bioavailability for these food sources varies considerably, with milk and its derivatives and mineral water having the highest
levels of bioavailability. Contrarily, fibre and phytate-rich vegetables have bioavailability levels that are quite low. The measure of calcium in the body is affected by
the effectiveness of calcium absorption from foods and this is constant in adolescents and adults, there is however, a decrease in calcium absorption by 2% every
10 years in post-menopausal women (Allen and Kerstetter 2005).
Calcium is a critical mineral in the developmental stages of a fetus, and its demand
is highly increased during pregnancy, which is usually an increase from a daily dosage of 50 mg/day at the halfway point, to 330 mg/day at the end and also during
lactation which is due to the movement of calcium from the maternal skeleton to the
fetus, a greater efficiency of intestinal absorption and an amplified increase in renal
retention (Theobald 2005). Adequate calcium consumption is associated with high
birth weight, effective blood pressure control and a diminished risk of premature
delivery. The placental movement of calcium from the maternal compartment to the
fetus is achieved as a result of the presence of active transport agents in the epithelium of the placenta. The amount of calcium circulated in the fetus is higher in the
20th week of pregnancy than those detected in the maternal plasma. Recommended
daily calcium intake varies between countries to countries, and the daily dose for
pregnant and breastfeeding women also varies between countries. The Italian RDA
indicate calcium value of 1.2 gram per day in the gestational period, while the WHO
recommends 1.5–2.0 gram per day from the 20th week until the end of pregnancy,
particularly for women at risk of gestational hypertension. Risks of developing gestational hypertension and pre-eclampsia in pregnant women can be reduced by a
low-dose calcium supplementation as recommended (Hofmeyr et al. 2014).
It should be noted, however, that hypercalcemia, i.e. calcium levels above normal
range is associated with a high risk of developing Hemolysis, Elevated Liver
enzymes and Low Platelets (HELLP) Syndrome. Interestingly, the measure of calcium secreted daily in breast milk varies considerably (150–300 mg/day), and this
depends largely on the active transportation of calcium from the bones and reduced
urinary secretions. The restoration of calcium stored in the maternal bones is
achieved after the weaning and resumption of ovarian function (Olausson et al.
2012). Studies have shown that the secretion of calcium in milk gland does not
depend on its dietary intake and supplementation. Hence, the daily calcium intake
during lactation is nothing different from that of the healthy adult female population
which is 1.0 g/day. Moreover, high risk of calcium deficiency during breastfeeding
S. Hassan et al.