Calcium is the most abundant mineral in our body! In fact, it accounts for 2% of our total body weight!

Why Do We Need Calcium?

Calcium is essential to all cells in our body. It plays many vital roles and is required for:

• Skeletal function – mineralisation of our bones and teeth
• Muscular function – needed for muscle contraction and relaxation
• Heart function
• Blood clotting
• Immune defences
• Nervous system – nervous impulse transmission
• Activating enzyme reactions
• Cellular metabolism

99% of calcium stored in our bones and teeth, while the remaining 1% is found in our extracellular fluid (fluid surrounding our cells).

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How much do we need to consume every day?

Calcium is an essential nutrient, meaning our body does not produce calcium, so we must obtain it from food. After food is digested in the stomach, calcium is primarily absorbed in the duodenum, which is the first part of our small intestine.

Below is the amount of calcium we need to consume each day.

INFANTS:

0-6 months: 210mg/day

7-12 months: 270mg/day

CHILDREN & ADOLESCENTS

1-3 years: 500mg/day

4-8 years: 700mg/day

9-11 years: 1000mg/day

12-18 years: 1300mg/day

ADULTS

19-50 years: 1000mg/day

51-70 years: 1300mg/day

Source: Nutrient Reference Values, 2014 -https://www.nrv.gov.au/nutrients/calcium

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What Effects Our Calcium Needs?

Calcium needs vary between individuals, depending on:

• Age:
  • During puberty/adolescence, almost 40% of peak bone mass is accumulated during this period of growth, therefore requirements increase.
  • Adults over 50 years cannot absorb calcium as effectively, and more can be excreted by the kidneys, therefore, intake needs to be maintained at higher levels.
• Gender:
  • Menopausal women: decreasing oestrogen production increases bone resorption and decreases calcium absorption, thus intakes are slightly increased for women over 50.
• Bioavailability:
  • Depending on the food source of calcium, different foods have different bioavailabilities – this is the proportion of calcium in food that can be absorbed.
  • Some dietary factors work together with calcium to boost its absorption: e.g. Vitamin D, Lactose and casein phosphopeptides (found in cow’s milk).
  • Some dietary factors hinder the absorption of calcium: oxalates and phytates (found in green leafy vegetables).
• Sodium intake
  • High sodium (salt) intakes, found in high amounts in processed foods, can increase calcium excretion, leading to decreased bone mass in the long term.
• Protein intake
  • High protein diets have been found to increase calcium excretion. If calcium loss is sustained. However, its effects on calcium retention are still unclear.

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What happens when we have too much calcium?

The upper limit for calcium is 2500mg/day. High levels of urinary calcium can increase risk of developing kidney stones, or in extreme cases (over-supplementation), renal failure.

What happens when we don’t have enough calcium?

Low, or inadequate intakes of calcium can lead to hypocalcaemia (calcium deficiency), which can be associated with many health implications, including:

• Dental health – brittle teeth, tooth decay, irritated gums, numbness in the mouth, difficulty swallowing
• Weak, brittle nails
• Muscle aches, spasms, stiffening of muscles (cramping).
• Osteopenia & osteoporosis – weak brittle bones and increased risk of bone fractures.

Many factors can also reduce the calcium in our bones, and contribute to lower bone density:

• Caffeine: consumption has been associated with increased calcium excretion. Studies have shown that a total of 2-3mg of calcium is lost per cup of coffee, a small amount in relation to how much we should be consuming every day. Ensuring that you are consuming adequate amounts of calcium in your diet will ensure effects of caffeine on bone health are minor.
• Carbonated drinks: whilst there are studies that have shown carbonated drinks contribute to decreased bone density, more research needs to be conducted to determine why. It could be that soft drinks are consumed in replacement of calcium rich beverages or related to their high sodium content that poor associations are shown in terms of bone health.
• Alcohol: excessive alcohol intake interferes with the body’s calcium balance, as the stomachs absorption of calcium is impaired. Furthermore, it impairs the function of the pancreas and its absorption of calcium and Vitamin D.
• Very low body weight – a low body mass index (BMI) has been proven to be a considerable risk factor for low bone mineral density.  
• Low levels of weight bearing exercise: just like our muscles, bone tissue responds to exercise; it strengthens. Exercise elicits a physiological response in our bone structure, and adapts to the ‘load’ in which is applied. Hence, regular weight bearing exercise increases the rigidity of bone structure.
• Low Vitamin D levels: Vitamin D is a hormone which helps absorb calcium and controls calcium levels in the blood. Low levels of this vitamin thus impact on bone density, if we aren’t absorbing the calcium efficiently, bone density will decrease.  
• Smoking: studies have shown a strong relationship between smoking and decreased bone density, linking smokers to a higher risk of developing osteoporosis.

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Non-Dairy Sources of Calcium

Dairy foods are rich in calcium and have a high calcium bioavailability. However, this doesn’t mean that you need to consume dairy to meet your calcium needs.

There are many non-dairy calcium-rich foods for those who can not, or choose not, to consume dairy.

You can meet your calcium needs without dairy. Here are some non-dairy, calcium-rich food sources:

• Fish with bones (sardine, salmon) (279mg per small can)
• Nuts (almonds) (30 mg in 10 almonds)
• Calcium fortified soy, or almond milks (309mg per 250 mL, of a fortified soy milk)
• Broccoli (15mg in 2 florets)
• Brussel sprouts (42mg per 100g)
• Cauliflower (22mg per 100g)
• Leafy greens (150mg per 100g kale)
• Tofu firm (832mg per cup)
• Beans/Legumes (90mg per cup of canned chickpeas)
• Oranges (40mg per 100g)
• Calcium fortified breakfast cereals (200mg per cup of fortified cereals)
• Dried figs (160 mg in 6 figs)
• Supplements – calcium citrate or carbonate: 500-600mg doses are recommended per day.

You can keep a record of what you eat and add up the amounts of calcium to see if you are reaching your calcium requirements. If you are unsure if you are getting enough calcium, see a Dietitian to help determine this. Ensuring that you consume adequate amounts of calcium from good quality sources every day can ensure that your bones, joints, muscles and teeth stay strong!

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This article was co-written by student Nutritionist Tahlia Claringbold from the Nourish Naturally team.