Calcium - A fresh look at this essential micro-nutrient
Dairy is a source of calcium in the diet. Calcium is important for building and maintaining strong bones. A minimum of 3 servings a day of dairy products is recommended.
The facts
- Dairy products are a source of calcium
- Dairy calcium is particularly well absorbed therefore bioavailable
- Dietary calcium enhances the effect of physical activity on bone mass during growth
- Dairy consumption increases bone mass. Low bone mass is associated with increased fracture risk in children- just as in adults
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Important life stages
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Calcium recommendations (mg/day)
|
Suggested servings per day
|
| Newborn up to 6 months |
300 (breast milk)
400 (cow's milk) |
|
| Baby & toddler |
6 – 12 months 270
1 – 3 years 500 |
2 |
|
Children 4 – 9 years
|
800 |
2 - 3 |
|
Adolescents 10 – 19 years
|
1300 |
4 |
| Adults > 20 years |
1300 |
4 |
| Elderly 65 years |
1300 |
4 |
| PHYSICAL CONDITIONS |
|
|
| Pregnancy* |
1200 |
4 |
| Lactation |
1300 |
4 |
| Menopause |
1300 |
4 |
Calcium absorption
- The human body contains about 1200 g calcium (99% in the skeleton i.e. bones and teeth & the remaining 1% is found in blood, extracellular fluid, muscle, and other tissue).
- About 30-35% of calcium ingested from dairy products is absorbed at an intake of 400 mg /day depending on the calcium status of the individual.
- A minimum of 140 mg/day of calcium is lost through urine.
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Dietary factors that enhance calcium absorption
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Dietary factors that inhibit calcium absorption
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Stomach acids
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Lack of stomach acids
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Vitamin D and growth hormones
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Deficiency of vitamin D
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Physiological state. Calcium must be in a water-soluble form to be absorbed. Approximately one third of calcium in dairy is in a water-soluble form, thus particularly well absorbed.
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Oxalates. Calcium in plant material is absorbed to a small extent as it contains substances that render the calcium insoluble in water.
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Phosphopeptides and lactose
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High phosphorus intake
|
| |
Sodium increases calcium excretion
|
| |
High dietary fibre
|
| |
Phytates present in beans, seeds, nuts and grains
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Non-dietary factors affecting calcium metabolism
Calcium and physical exercise is important to increase bone mass
- Age and estrogen status
- Pregnancy and lactation
Benefits of physical activity and dairy consumption
- Helps to prevent fall-related fractures due to improved muscle strength, body balance and reaction time.
- The risk of hip fracture decreases by 20-40% among physically active individuals when compared to their sedentary counterparts.
- Individuals already diagnosed with osteoporosis will also benefit from physical activity – however, excessive or sudden strain should be avoided.
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SOURCES OF CALCIUM AND BIOAVAILABILITY
|
|
Food Product
|
Ca content mg/100g
|
Bio-avail Ca mg/100g
|
|
Cheddar cheese
|
788
|
236
|
|
Gouda cheese
|
806
|
242
|
|
Feta cheese
|
386
|
116
|
|
Maas
|
162
|
49
|
|
Plain yoghurt
|
149
|
45
|
|
Fruit yoghurt
|
145
|
44
|
|
Buttermilk
|
144
|
43
|
|
Low-fat milk
|
122
|
37
|
|
Full-cream milk
|
120
|
36
|
|
UHT whole milk
|
117
|
35
|
|
Cottage cheese: fat-free
|
120
|
36
|
|
Cottage cheese: full-cream
|
111
|
33
|
|
Spinach, boiled
|
109
|
5
|
|
Cauliflower, cooked
|
12
|
6
|
|
Brussel sprouts
|
47
|
24
|
|
Broccoli
|
36
|
18
|
|
Cabbage
|
29
|
15
|
|
Sardines, with bones
|
240
|
120
|
|
Sweet potatoes, boiled, no skin
|
9
|
2
|
|
Baked beans, canned
|
34
|
7
|
|
Fortified maize meal, super
|
5
|
*
|
|
Fortified maize meal, special
|
9
|
*
|
|
Fortified maize meal, sifted
|
12
|
*
|
|
Fortified white bread
|
16
|
*
|
|
Fortified brown bread
|
14
|
*
|
References
BHATIA V. 2008. Dietary calcium intake – a critical appraisal. Indian J Med Res (127)
HEANY RP, WEAVER CM. 2005. Never perspectives on calcium nutrition and bone quality. J Am College Nutr 24(6): 574S-581S
IFIC REVIEW. 2002. Physical activity, nutrition and bone health
KEEN R. 2007. Osteoporosis: strategies for prevention and management. Best Practice & Research Clinical Rheumatology 21(1)
KHAN K, MCKAY HA, HAAPASALO H, BENNELL KL, FOORWOOD MR, KANNUS P & WARK JD. 2000. Does childhood and adolescence provide a unique opportunity for exercise to strengthen the skeleton. J Science and Sports Med 3(2): 150-164
LANOU AJ; BERKOW SE & BARNARD ND. 2005. Calcium, dairy products and Bone Health in Children and young Adults: a reevaluation of the evidence. Pediatrics 115(3)
WOSJE KS, BINKLEYTL, FAHRENWALD NL & SPECKER BL. 2000. High bone mass in a female Hutterite population. J Bone Mine Res 15(8): 1429 -1436