                            VegSocUK Information Sheet
                              THE VEGETARIAN SOCIETY


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                                    CALCIUM

   Calcium is the most abundant mineral in the human body. Of the body's total
   calcium, about 99% is in the bones and teeth where it plays a structural
   role. The remaining 1% is present in body tissues and fluids where it is
   essential for cell metabolism, muscle contraction and nerve impulse
   transmission.

  FUNCTIONS

   The main function of calcium is structural. The skeleton of a young adult
   male contains about 1.2 kg of calcium. There is continuous movement of
   calcium between the skeleton and blood and other parts of the body. This is
   finely controlled by hormones. Metabolites of Vitamin D are important in
   this, increasing reabsorption of calcium by bones.

   Calcium also plays a role in cell biology. Calcium can bind to a wide range
   of proteins altering their biological activity. This is important in nerve
   impulse transmission and muscle contraction. Calcium is also needed for blood
   clotting, activating clotting factors.

   Vitamin D is needed for absorption of dietary calcium and so calcium
   deficiency may be linked with rickets in children. In adults, calcium
   deficiency may lead to osteomalacia (softening of bones). This may be related
   to repeated pregnancy with lengthy breast feeding.

   Osteoporosis can be due to calcium deficiency. This involves loss of calcium
   from the bones and reduced bone density. This causes bones to be brittle and
   liable to fracture. Bone loss occurs with age in all individuals. This
   usually occurs after 35-40 years and involves the shrinking of the skeleton.
   Bone loss is greatest in women following the menopause. This is due to
   reduced levels of the hormone, oestrogen. Postmenopausal women are
   particularly at risk from osteoporosis.

   Some research has indicated vegetarian women are at less risk of osteoporosis
   than omnivorous women. This is thought to be due to animal protein increasing
   calcium loss from bones. However, other research has found no difference
   between vegetarians and omnivores.

   The risk of osteoporosis may be altered by factors other than diet. Lack of
   exercise, being underweight, smoking and alcohol can all increase the risk.

   A low level of calcium in the blood and tissues can cause hypocalcaemia. This
   involves sensations of tingling and numbness and muscle twitches. In severe
   cases muscle spasms may occur. This is called tetany. It is more likely to be
   due to a hormonal imbalance in the regulation of calcium rather than a
   dietary deficiency.

   Excess calcium in the blood can cause nausea, vomiting and calcium deposition
   in the heart and kidneys. This usually results from excessive doses of
   vitamin D and can be fatal in infants.

  DIETARY SOURCES

   Calcium is present in a wide range of foods. Dairy products, leafy green
   vegetables, nuts and seeds (almonds, brazils, sesame seeds), tofu, and dried
   fruit are all good sources of calcium for vegetarians. Most flour is
   fortified with calcium carbonate so cereals can also be a good source. Hard
   water may also provide calcium. Meat is a very poor source of calcium.

   Calcium balance can be affected by a range of other factors. Vitamin D is
   essential for absorption of calcium from the gut. This is because calcium is
   transported into the body by a special carrier protein which requires vitamin
   D for its synthesis.

   A number of substances can inhibit the absorption of calcium. Phytic acid,
   found in bran, whole cereals and raw vegetables is one of these. Uronic acid,
   a component of dietary fibre, and oxalic acid, found in certain fruits and
   vegetables can also bind calcium. However, diets habitually high in these
   acids are not thought to have a major effect on calcium absorption. Saturated
   fats can also lessen calcium absorption.

   Calcium is lost in the faeces, urine and sweat. Calcium loss is roughly equal
   to dietary calcium in adults. Calcium loss is reduced if dietary calcium is
   low. Adaptation to both high and low calcium intakes occur. Reduced intake
   leads to increased efficiency of absorption. In infants and children calcium
   is retained for new bone growth. Calcium is also lost during lactation in
   breast milk.

    Good sources of calcium (single servings).

Broccoli, boiled (95g or 3 1/2 oz)  72 mg
Spinach, boiled (130g or 5 oz)     208 mg
Chick peas, boiled (200g or 8 oz)   92 mg
Baked beans (200g or 8 oz)          90 mg
Tofu (60g or 2 oz)                 304 mg
Dried figs (4 figs)                168 mg
Sesame seeds (15g or 1/2 oz)        20 mg
Brazil nuts (9 nuts, 30 g)          54 mg
Cows milk (1/3 pint)               234 mg
Cheddar cheese (slice, 40 g)       288 mg
Soya cheese (slice, 40 g)          180 mg

    Fair sources

Brown bread (2 slices)              70 mg
Dried apricots (8 apricots)         46 mg
Cottage cheese (45g or 1 1/2 oz)    33 mg
French beans, boiled (100g)         41 mg

    Poor sources

Spaghetti, boiled (100g or 3 1/2 oz) 7 mg
Brown rice (190g or 8 oz)            7 mg

  REQUIRED INTAKES

   The old Recommended Daily Amounts (RDAs) have now been replaced by the term
   Reference Nutrient Intake (RNI). The RNI is the amount of nutrient which is
   enough for at least 97% of the population.

   Reference nutrient intakes for calcium, mg/day.

Age                      RNI

0  to 12 months          525 mg
1  to  3 years           350 mg
4  to  6 years           450 mg
7  to 10 years           550 mg
11 to 18 years, male    1000 mg
11 to 18 years, female   800 mg
19 + years               700 mg

Breast feeding women    1250 mg

   During pregnancy, calcium absorption from the gut increases and no additional
   calcium is generally needed. Pregnant adolescents are an exception to this,
   having particularly high calcium needs.

   Breast feeding women need an extra 550 mg of calcium. A lactating women can
   lose up to 300 mg a calcium/day in breast milk.

   Calcium absorption decreases with age so it is important the elderly have
   adequate dietary calcium.

  MEAL PLAN

   Sample one day's meal plan to meet the RNI of 700 mg for an adult

Breakfast

Muesli                          114 mg
Soya milk, unfortified           15 mg

Lunch

2 slices of brown bread toast   140 mg
Baked beans (200g or 8 oz)       90 mg

Evening meal

Tofu (60g) with broccoli (95g)  376 mg
Brown rice, boiled (165g)         7 mg

Total calcium intake            742 mg


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//
This article is copyright to the Vegetarian Society (UK), but may be freely
copied for non-commercial use provided it is kept intact, not altered
and these lines are included.

For futher information contact: The Vegetarian Society, Parkdale, Dunham Road,
Altrincham, Cheshire WA14 4QG, England. Tel: (England) 061 928 0793
email: vegsoc@vegsoc.demon.co.uk
//



[The text of this file was obtained from the Vegetarian Society (UK) in
March 1995.]

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