Calcium
Calcium is the most abundant mineral in the body and nearly all of it (99%) is
in the bones, teeth, soft tissues and blood. It accounts for about 2% of body
weight.
Calcium is an essential nutrient for strong bones and healthy teeth but is
equally vital as a regulator in most of our body tissues, helping nerves and
muscles
to work properly.
All calcium required for bones and teeth comes from our diet. Milk and milk
products are the major source in the British diet. White and brown bread (by law
fortified with calcium), cereal products, vegetables and hard water also provide
significant amounts. A healthy balanced diet should provide all the calcium we
need.
How much calcium do we need?
We should ensure we have an adequate intake of calcium throughout our life.
Calcium is a vital mineral which helps our bodies function, as well as being a
'bone builder' in the early years of our lives.
Peak bone mass is reached at the age of about 30-35 years. It is the stage at
which bone is strongest. After this age bone mass gradually decreases. Achieving
a good peak bone mass is important in reducing the risk of osteoporosis in
later
life because it means that bones are strong before loss begins.
The Recommended Daily Allowance (RDA) for calcium is 800 mg. but older people
may require more.
Surveys show that adults generally take in satisfactory levels of calcium but
the intakes of 16-24 year olds are significantly lower than those of people aged
over 35.
A survey of British schoolchildren aged 10-15 showed that the intakes of both
boys and girls (intakes for boys were greater) were considerably lower than
recommended (National Diet & Nutrition Survey). In particular the intakes of
some
girls who consumed very little milk or cereal products were less than 300
mg per
day. This is a cause for concern. Young people whose intake is regularly
as low
as 300 mg per day are not getting sufficient calcium at a crucial age
for the
development of bones and teeth.
Consumption of vegetables in the UK is relatively low and accounts for less than
15% of calcium intake. Vegans, who do not consume milk or milk products and who
often prefer wholemeal bread, have lower calcium intakes, consuming an average
537 mg calcium per day mainly from vegetable sources. Calcium from wholemeal
bread and some vegetable sources is not as easily absorbed by the body.
Bread
By law white and brown flours are fortified with calcium so that white or brown
breads are preferable to wholemeal for people whose calcium intake may be
inadequate.
Osteoporosis
Osteoporosis is a condition in which the density of bones is reduced. This is
due to a loss of both protein and calcium from the bone. Because of the
osteoporosis the bones are weaker and break more easily.
Osteoporosis occurs usually as a result of the ageing process, in both men and
women, and in the years following menopause for women as a result of oestrogen
deficiency.
Calcium deficiency has been implicated in the development of osteoporosis
through failure to achieve an adequate peak bone mass during early years (usually by
the age of 30-35), or an increased rate of bone loss in later life. There does
not appear to be any relationship between current calcium intake and present
bone
mass.
Bone loss following the menopause cannot be prevented by extra calcium alone.
However, calcium supplements may reduce the dose of oestrogen necessary to
prevent bone loss. Regular weight bearing exercise, such as brisk walking or
dancing,
reduces the risk of osteoporosis.
Calcium Amounts in Bread
Six Slices, Brown or White Bread
White 110 mg per 100g
Brown 100 mg per 100g
Wholemeal 55 mg per 100g
Six medium slices of white bread per day would provide 238 mg of calcium, more
than 30% of the RDA.