Benefits of Calcium & RDI
Calcium is the most abundant mineral in the human body. More than 99% of the body’s calcium is found in the bones and teeth. The remaining 1% is found throughout the body in blood, muscle, and the fluid within our cells.1
Bone is not a static tissue, it is dynamic. While the bones have an obvious structural role, they also serve as the body’s reservoir (reserves pool) for calcium. If calcium levels in our blood drop, the body undergoes a process to remove calcium from the bones to support this. Once our blood calcium levels are restored then calcium is returned to the bones to be rebuilt. The balance of these two activities determines whether bone is being added or lost in any particular person at any particular time.
When the bones lose minerals more quickly than the body can replace them, this causes the bones to become less dense, brittle and fragile. They are less resistant to normal stresses, leading to a higher risk of fractures and breaks. Calcium provides rigidity and strength in bones and may help in the prevention of broken bones.
Calcium is also an essential mineral required for proper functioning of numerous cellular processes, including2:
- muscle contraction
- nerve conduction
- blood coagulation
- hormone release
- energy production
- maintenance of the immune system
Your gender, age, health status, and diet all play significant roles in helping determine how much calcium you need. Below are the recommended daily allowances for calcium from the NHMRC (National Health and Medical Research Centre – Nutrient Reference Values for Australia and New Zealand).
|0–6 months*||200 mg||200 mg|
|7–12 months*||260 mg||260 mg|
|1–3 years||700 mg||700 mg|
|4–8 years||1,000 mg||1,000 mg|
|9–13 years||1,300 mg||1,300 mg|
|14–18 years||1,300 mg||1,300 mg||1,300 mg||1,300 mg|
|19–50 years||1,000 mg||1,000 mg||1,000 mg||1,000 mg|
|51–70 years||1,000 mg||1,200 mg|
|71+ years||1,200 mg||1,200 mg|
|Table 1: Recommended Dietary Allowances (RDIs) for Calcium|
*Adequate Intake (AI)
Calcium is predominantly found in dairy foods such as cheese, yoghurt, milk and ice cream. Dairy and fish with bones, such as salmon and sardines, has the highest concentration per serving of calcium.4 Other calcium sources include dark green vegetables, amaranth, beans, blackstrap molasses, broccoli, collard greens, dandelion leaves, figs, high-calcium mineral water, kale, nuts and seeds (like almonds and sesame), okra, rutabaga, quinoa, seaweeds (kelp, wakame, hijiki), fortified products (orange juice, soy milk, almond milk).3
Refer to the table below for various foods and their calcium content.4
|Food||Std Serving Size||Calcium (MG)||Kilojoules|
|Rump Steak (lean)||100g||5||883|
|Apples||1 medium 156g||7||323|
|Lamp Chop (lean)||100g||8||1000|
|Bread – mixed grain||30g (slice)||15||272|
|Bread – wholemeal||30g (slice)||16||282|
|Chicken – roasted no skin||100g||16||783|
|Strawberries||1 cup (145g)||19||118|
|Eggs – boiled||1 large (48g)||21||303|
|Oranges||1 medium (122g)||35||190|
|Apricots – dried||50g||35||410|
|Soy beans (boiled)||100g||76||540|
|Tofu (calcium set)||100g||150||479|
|Salmon – tinned, red||100g||220||814|
|Sardines – canned||100g||380||951|
|Cheese – mild||40g piece||300||676|
|Cheddar reduced fat||40g 2 slices||323||548|
|Cheddar Cheese||40g 2 slices||327||575|
|Yoghurt – Low fat||200g (std tub)||316||738|
|Yoghurt – plain||200g (std tub)||390||716|
|Milk – regular||250ml (std glass)||285||698|
|Milk – reduced fat||250ml (std glass)||352||525|
|Milk – skim||250ml (std glass)||320||377|
|Milk – calcium fortified||250ml (std glass)||353||523|
|Who needs to eat what?||
How many serves of calcium rich foods?
Children 5-9 years
2-3 serves per day
Children and adolescents 9-18 years
3 serves per day
Adults up to the age of 51 years
2 serves per day
3 serves per day
Adults over 70 years
Approximately 4 serves
|Table 2: Who Needs to Eat What?4|
How do I know if I am deficient in calcium?2
Calcium is an essential mineral which means it cannot be manufactured in the body. We therefore must consume it through the diet or risk becoming deficient. Many diets, including vegan where animal foods are omitted, may be deficient in calcium.3 Low levels of calcium may lead to symptoms of muscle pain or spasms or bone pain, but the symptoms of deficiency are often asymptomatic (meaning there are no symptoms) until they reach a more serious condition such as osteomalacia (bone softening) or osteoporosis (bone thinning).2 If you think you are at risk, or have any concerns a discussion with your healthcare professional is recommended.
There are some lifestyle factors that interfere with calcium levels. If you smoke, consume caffeinated drinks regularly, or have a diet low in calcium (are a vegan or are lactose intolerant) you may have an increased need for calcium. A lack of exercise and familial history can also increase calcium requirements.
Calcium is essential to bone growth and development. Children and adolescents may require additional calcium to meet maximal bone growth. Calcium is required for bone strength and mass which predominantly occurs during childhood and adolescence. This increase in bone mineral density in teenagers is responsibly for reducing the risk on bone thinning and weakness in late adulthood. Children and adolescents may require additional calcium to meet maximal bone growth.
There are stages through life when you may have an increased need for calcium. Pregnancy is one of these. At this time extra calcium is required for foetal skeletal growth. Maternal vitamin D requirements can also increase up to 4 to 5-fold to facilitate the availability of extra calcium requirements.5
After menopause there is a fall in oestrogen. This puts our bones at risk because oestrogen helps to keep calcium within bone. With menopause there is a decrease in oestrogen, an increase in bone resorption (break down) and a decrease in calcium absorption into bone.
Taking extra calcium at this time may reduce the loss of calcium from bone. Importantly, vitamin D intake needs to be adequate also as it is enhances calcium’s absorption.
The elderly have an increased need too because as we age we absorb calcium less efficiently from our foods.
An excessively high level of calcium in the blood is known as Hypercalciuria. This affects about 5-10% of the population.5 Eating a healthy balanced diet ensures you will be receiving a variety of nutrients whilst avoiding too much of any one, including calcium. The important thing is balance.
If you are using a supplement, use only as directed on the label and if you have any concerns, contact your healthcare professional.
Some medications may deplete calcium levels.2 However, before starting any supplements, it’s important that you discuss your health situation and concerns with your healthcare professional.
There are many forms of calcium available on the market and this can easily cause confusion. Two popular forms of calcium in supplements are carbonate and citrate.7 Calcium carbonate is more commonly available and is both inexpensive and convenient.7 Due to its dependence on stomach acid for absorption, calcium carbonate is absorbed most efficiently when taken with food, whereas calcium citrate is absorbed equally well when taken with or without food. Calcium citrate is also useful for people with low stomach acid, or absorption disorders.7 Other calcium forms in supplements or fortified foods include gluconate, lactate, and phosphate.