While we know that it plays a fundamental role in the building of our bones, Calcium’s influence goes far beyond bone health.  It plays a vital role in other processes including muscle function, nerve transmission, and even blood clotting. In other words, it helps us to maintain a well-functioning body, in addition to preventing bone diseases.

It is of equal importance to both men & women and you may be surprised to find out just how many foods contain calcium and how easy it is to take in your RDA from a balanced diet, even if you are dairy intolerant like me. 

So what is calcium?

It is the fifth most abundant element in the Earth’s crust and is the most abundant mineral in our bodies. Calcium was among the first substances known to be essential in the diet.  We store the majority of it in our skeleton, hence the focus on bone health.   

Why do we need it?

As you know, if we don’t get enough calcium, we could face health problems related to weak bones and so it is essential at all stages of life.  For example, if children aren’t eating enough calcium rich foods, they may not reach their full potential adult height and it can also lead to a condition called rickets.  Adults may have low bone mass, which is a risk factor for osteomalacia and osteoporosis. Building bone mass when we are children and young adults is essential for optimising bone health in later life.  The benefit will arise post menopause for women, because oestrogen plays a role in promoting bone formation.  So sharp declines in oestrogen will cause calcium to be taken down from the bone and into the blood, to maintain blood serum levels and so a decrease in bone mass can precipitate osteoporosis.

Of course, this can be managed with your GP with an appropriate protocol through menopause.

However, calcium is also essential for other aspects of our health. It plays a vital role in muscle function, heart health, hormonal balance, nerve transmission, and even blood clotting. It has been noted that calcium in our cells can promote lipolysis which is the breakdown of fats into fatty acids and so can help when losing weight.

So, we should think about its importance in terms of our overall health now, in addition to preventing osteoporosis in later life.  

What are the symptoms of deficiency?

Symptoms of deficiency can include frequent fractures, blood clotting problems, chronically low blood calcium, muscle cramps, twitches and symptoms of hypertension.

How do we get it?

According to the HSE, we should be able to get all the calcium we need by eating a varied and balanced diet. Dairy products are the most concentrated source but a wide variety of plant foods also contain calcium, for those of us that are lactose intolerant.

What helps absorption?

To absorb calcium, your body also needs vitamin D. A few foods naturally contain small amounts of vitamin D, such as canned salmon with bones and egg yolks. You can also get vitamin D from fortified foods and sun exposure. Also, maintaining a balanced diet with adequate magnesium and vitamin K can enhance calcium utilization.

What can prevent absorption?

Oxalates are natural compounds found in plants and animal food sources and can also be produced by our bodies.  They bind to minerals, especially calcium, and so make it more difficult for it to be absorbed.  You might be familiar with the term oxalates if you have ever had kidney stones, and they are only a problem when we accumulate too many of them.

Phytates, some medications and fat malabsorption may also decrease absorption of calcium.  Like oxalates, phytates are naturally occurring compounds and are generally only a problem if there is a build-up and guess what avoids a build up?  A varied diet and healthy gut microbiome!

How much is enough?

Calcium needs vary across age groups. Children, adolescents, women who are pregnant or lactating, and older adults have different requirements. A balanced diet and, if necessary, consultation with a healthcare professional can help tailor calcium intake to individual needs.  We can have habits which waste calcium eg diets high in animal protein, salt and caffeine, low sun exposure or vitamin d, low physical activity and so would need to ingest more in those cases.

In Ireland, our recommendations are

  • 1-10 years 800mg/d
  • Adults 11-17 1200mg/d
  • Adults 18+ 800mg/d
  • Pregnant & lactating women 1200mg/d

Adequate Calcium intake is not a guarantee of healthy bones – equally as important is avoidance of calcium wasting lifestyle factors!! 

Dairy sources include cheese, milk, yogurt, and plant sources include dark green leafy & cruciferous vegetables such as kale, brussels sprouts, broccoli, bok choy, cabbage and cauliflower, and almonds, sesame seeds, soybeans, tofu, dried figs and a good fish source is sardines. 

Example of dairy sources meeting RDA:

1 cup of milk, 2 slices of cheese and 2 tablespoons of natural yoghurt or Greek yoghurt

Example of plant sources meeting RDA:

1 cup of almond milk, 1 tablespoon of sesame seeds, 1 tablespoon chia seeds, 3 dried figs, 1 tablespoon of flaxseeds, 2 tablespoons of soy yoghurt, 1 small orange, 4 spears of broccoli, 1 cup of shredded cabbage, 1 cup of cauliflower

Who should consider calcium supplements?

You may not be consuming enough calcium if you:

  • Are lactose intolerant and don’t eat variety of plants
  • Re pregnant or lactating
  • Eat a lot of junk food or processed food
  • Have been diagnosed with low bone density
  • Have high caffeine and alcohol intake
  • Are on a high animal protein diet eg Atkins diet
  • Consume large amounts of sodium, which can cause your body to excrete more calcium
  • Are receiving long-term treatment with corticosteroids
  • Have certain bowel or digestive diseases that decrease your ability to absorb calcium, such as inflammatory bowel disease or celiac disease

In these situations, calcium supplements may help you meet your calcium requirements. Talk with your doctor or practitioner about whether calcium supplements are right for you and they will take into account any medications you are on, and health issues you might have, to recommend appropriate levels.

All varieties of calcium supplements are better absorbed when taken in small doses (500 mg or less).  The form Calcium citrate is absorbed equally well when taken with or without food and is a form recommended for individuals with low stomach acid (more common in people over 50 or taking acid blockers), inflammatory bowel disease or absorption disorders. The other forms are better absorbed when taken with food.

  • Calcium carbonate (40% elemental calcium)
  • Calcium citrate (21% elemental calcium)
  • Calcium gluconate (9% elemental calcium)
  • Calcium lactate (13% elemental calcium)

Elemental calcium is important because it is the actual amount of calcium in the supplement, so the amount of calcium your body absorbs.  

Some calcium supplements are combined with other vitamins and minerals. For example, they may also contain vitamin D or magnesium. Check the ingredient list to see which form of calcium your calcium supplement is and what other nutrients it may contain. If you are taking other supplements you may need to cross check to ensure that you are not taking too much of any nutrient.  This information is important if you have any health or dietary concerns.

Taking high doses of calcium (more than 1,500mg a day) could lead to stomach discomfort,  pain or diarrhoea.  Other side effects can include gas, constipation, bloating (generally calcium carbonate is most constipating).


The good news is that calcium is available from a wide variety of dairy and plant food. Furthermore, eating a balanced diet and exercising are beneficial for our overall health and well being. So, try to get the calcium you need from your meals, but if you are concerned or have any of the issues mentioned above, talk to your GP or health practitioner to make sure that you are supplementing the right form, in the right way.

Other Resources

Calcium and calcium supplements: Achieving the right balance – Mayo Clinic

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