Calcium Rich Diet by Sue Kira

by sue

Calcium Rich Diet

by Sue Kira, Naturopath & Clinical Nutritionist

About calcium

Benefits of calcium

Rich sources of calcium

What do I need to eat to get all my calcium?

About calcium

The essential mineral calcium is the most readily abundant mineral in the body because our bones are primarily comprised of calcium and our bones make up around 15% of our body weight (unless we are overweight). One percent of all calcium is used in the body for blood clotting processes, nerve and muscle stimulation, parathyroid hormone function, and metabolism of vitamin D; the other 99% is deposited in our bones and teeth.

Other important functions of calcium in the body are: to regulate the heartbeat; ease insomnia; for acid/alkaline balance; for muscle growth and contraction; and for nerve stimulation. Calcium also aids the body’s utilisation of iron, helps to activate specific enzyme pathways needed for metabolism, and regulates the passage of nutrients in and out of the cell wall.

To function properly, calcium must be accompanied by certain vitamins and minerals including magnesium, phosphorus, and vitamins A, C, D, K, boron, and E, all in the right ratio to each other. In nature, the foods we eat already organise this ratio, so calcium deficiency only becomes an issue if the diet is nutrient deficient, or you have an incorrect balance of supplements.

Calcium absorption and inhibitors to absorption

Not all the calcium we consume is absorbed. It is normal for some of the calcium from our food to be excreted unused. Certain factors can lead to an abnormally low level of calcium absorption from your diet and should be discussed with your doctor or health practitioner. These include:

  • Low vitamin D levels and other nutrients
  • Certain medical conditions e.g. coeliac disease, kidney disease
  • Certain medicines e.g. prednisone, prednisolone
  • Lack of exercise. Exercise is considered to be one of the most important factors towards the laying down of calcium in bones. Weight bearing exercises stimulate the body to put more calcium into the bone structures to make us stronger to cope better with exercise. Our body then builds stronger bones for survival so we are more equipped to ‘run away from danger’, which means our body can support us better with less chance of breakages from brittle bones.

Calcium absorption in the body is generally very inefficient because calcium needs to go through a three step ‘calcium-binding protein’ process requiring certain nutrients such as Vitamin D to make it all happen.

Some research says that we ‘need’ to get loads of calcium from our diet to have strong healthy bones, yet other research says almost the opposite by suggesting that we get stronger bones from exercise, vitamin D, phosphorus, magnesium and other nutrients, and calcium has very little to do with it, even though our bones are made predominantly from calcium (and magnesium etc).

These scientists say that extra calcium causes more harm in the body than good and the recommended amount of calcium to eat may create all sorts of havoc in the body.

Well the verdict at this stage is still out, but I feel there is far too much emphasis on eating dairy products to get our calcium, when countries that have low or no dairy in their diet (especially years ago before western foods got to their shores) had no or very low levels of osteoporosis. There is more information in the Dairy Free Diet article under the heading ‘Calcium from dairy foods?’

Other factors that affect absorption of calcium include:

  • Dairy sources of calcium tend to have a large percentage of the calcium excreted in the urine and some through stool waste, and a small amount excreted via the skin. Absorption of calcium happens mostly in the duodenum (just after the stomach). Calcium absorption depends on the presence of enough hydrochloric acid in the stomach, or it will not dissolve the calcium from our food and can then build up in tissues and joints instead of going where it is really needed.
  • When large amounts of fat are combined with calcium rich foods, an insoluble compound is formed which cannot be easily absorbed (such as in dairy).
  • When oxalic acid, found in chocolate, spinach, rhubarb and kale, is combined with calcium (e.g. milk) it makes another insoluble compound that may form stones in the kidneys and gall bladder for some people if there is already a predisposed weakness (genetics). So a glass and a half of full cream milk in a block of chocolate (as advertised) may not be that good for us after all.
  • Phytic acid found in grains can also inhibit the absorption of calcium. On the other hand, too much calcium can decrease the body’s absorption of zinc, a vital nutrient needed for our immune system and healthy hormones.
  • Friendly bacteria also play a role in calcium absorption. If your friendly bacteria are ‘happy’ they can digest fermentable fibre such as pectins, which can stimulate the release of calcium from your foods.
  • On the other-hand non-fermentable fibres such as cellulose, similar to those found in wheat bran, can increase the bulk of intestinal contents and decrease the transit time, which then decreases calcium absorption from your meals.
  • Caffeine (300-400 mg a day) increases urinary calcium excretion (0.35 mmol or 10 mg per day)
  • Some nutrients interact with calcium to inhibit absorption (see calcium antagonists below). These include a high protein intake or high phosphorous diet, potassium, alcohol, and fatty acids. It’s interesting to know that if you have low levels of calcium intake, you could have high accumulation of lead in your blood and organs.
  • There are many other things that can affect the absorption of calcium; some of these include fluoride, diuretics, thyroxine, and glucocorticoids.

What Impairs the Absorption of Calcium?

Certain things can affect calcium absorption, so you may need to either consume more calcium rich foods or avoid some of things that impair absorption. Some of these are:

  • Corticosteroids used for asthma and many inflammatory conditions including prednisone, if taken for more than six weeks require more calcium due to the steroids depleting calcium. 300-500 milligrams a day of extra calcium should be consumed while taking steroids.
  • Sodium (salt) increases the amount of calcium that is excreted in the urine, so if you eat foods high in salt, you need to consume more calcium. Better still – eat less salt.
  • Excess protein produces sulphate. Sulphate increases the amount of calcium excreted in the urine, which decreases the amount of calcium in the body.
  • Oxalate binds with calcium and increases the loss of calcium through faecal excretion. Oxalate is found in some foods and beverages, such as spinach, chard, berries, chocolate, and tea.
  • Phosphorous (also known as phosphoric acid) and phosphate can interfere with calcium absorption. Phosphorous can be found in cola drinks as well as many processed foods.
  • Insoluble fibre, such as the type in wheat bran, reduces calcium absorption.
  • Alcohol inhibits the enzymes that convert inactive vitamin D to active vitamin D. Vitamin D is crucial for calcium absorption.
  • Caffeine, in excess of 300-400 mg a day, can increase the excretion of calcium via urine and stools. As a guide, 1 cup (8 fl oz) of brewed coffee contains around 135 mg of caffeine.
  • Smoking, stress, and lack of exercise can all contribute to the body’s inability to absorb calcium as efficiently.

There are certain vitamin and minerals that are considered antagonistic to absorbing calcium. What this means is that too much of the vitamins and minerals listed below can block the absorption of calcium. In particular, toxic lead can sit in the body and block calcium without you even knowing about it. Lead and other heavy metals can be picked up via a hair mineral analysis. Speak to your naturopath or health practitioner about testing if you suspect toxicity.

Vitamins: A, C, B1, B3, B6, E
Minerals: iron, potassium, magnesium, sodium, phosphorus, zinc
Metals: lead

Processed foods and certain supplements can throw out the balance, as can eating too much of one type of food that was not intended for us, such as dairy products – made for calves, not humans.

And not to mention that all animals wean their young after a short period of time, as we do with breast milk, which is why the lactase enzyme required for digesting lactose in mother’s milk (and cow’s milk alike) is no longer produced by infants after the age of two years.

Excessive calcium issues

Too much calcium is reported to cause muscle pain, severe fatigue, nausea, vomiting, diarrhea, abdominal pain, kidney stones, and mood disorders such as depression. Excessive calcium may also cause an irregular heartbeat, dangerously low blood pressure, and increase your risk for heart attack and stroke.

Deficiency symptoms and effects

If you are deficient in calcium you may have some of the following signs or symptoms: agitation, brittle nails, impaired cognition, convulsions, delusions, depression, eczema, heart palpitations, hyperactivity, hypertension, increase levels of parathyroid hypertensive factor, insomnia, laryngospasm, limb numbness, lower back pain, muscular cramps, osteoporosis, paraesthesia (numbness), hyperplasia, periodontal disease, rickets, sciatica, spinal curvature, stunted growth, tooth decay and loss.

However, please note that having some of these signs or symptoms is definitely not conclusive of your diagnosis, so seek professional advice.

A calcium deficiency can also lead to muscle cramps, numbness, tingling in the arms and legs. Bone problems such as rickets in children, osteomalacia in adults, osteoporosis, porous bones/teeth, insomnia, irritability of nerves/muscles and slow blood clotting.

When there is not enough calcium in the body, the output of estrogen also decreases.

Benefits of calcium

  • Apart from assisting with the prevention, relief and treatment of the above conditions, calcium can also help in the treatment of certain cardiovascular disorders and for the treatment of sunburn. Calcium as well as vitamin A both are great for keeping skin healthy.
  • Calcium is often used for arthritis and menopausal symptoms such as insomnia, irritability, headaches, and backache.
  • Calcium activates the action of insulin, calcitonin, thyroid hormones, and aids in the secretion of these hormones.
  • Supports cell membrane permeability and cell division.
  • Aids the function of the heart to regulate the heartbeat.
  • Has a huge role in the enzyme system. Some of these enzymic pathways are for the bones, kidneys, endocrine, muscles, and digestion.
  • A high intake of calcium has been shown to protect against the harmful effects of strontium 90, a radioactive substance commonly used in medical studies to trace/find things in the body and is also used in cancer treatment for bone pain.

Now after reading the above information, you might be confused about whether you should have more, or less, calcium in your diet and how much you really need to have to be healthy. The best way to find out is through testing.

If tests show you are low in calcium, then by all means increase calcium in your diet, or even take supplements if you need an extra boost for a while. However, long term use of supplements may not be good for you unless prescribed. Having said that, it is also important to look at WHY you are low in calcium or have osteoporosis if this is your situation.

When we eat a normal healthy nutritiously balanced diet, the foods rich in calcium are naturally balanced with the other nutrients the body needs for absorption and utilisation of calcium in the body and any excess is generally safely excreted. The issues mentioned above that can occur from excessive calcium are more inclined to happen with supplementation than from the diet.

However, overeating certain foods such as dairy products may cause problems for some people. More about this in the article about the Dairy Free Diet.

Rich sources of calcium

Dairy products are normally considered to be the ‘go to’ food for calcium. However, while the dairy corporation recommends that we need to consume 1000 to 2000mg a day from dairy products and other foods, many people cannot tolerate or even digest dairy products.

There are many calcium rich foods that are great alternatives to dairy products, considered by many health practitioners to be more bio-available (absorbable) forms of calcium. For example, green veggies are very bio-available, meaning they are easy to digest and thus it’s easy for the body to absorb their calcium.

It is also hypothesised that the amount of calcium suggested by the dairy corporation per day is excessive as much of the calcium from dairy products is excreted from the body.

The following list shows the quantity of calcium in various foods:

  • Green veggies contain around 100mg calcium per 100g (however spinach, beet greens and chard contain oxalic acid that binds to calcium making it poorly absorbed, so veggies like broccoli are a better choice)
  • Shellfish e.g. shrimp/prawns 70mg calcium per 100g
  • Nuts and seeds (Tahini from sesame seeds is particularly rich). 1Tbs of tahini contains nearly 64mg of calcium and easy to add to a salad dressing; almonds have 265mg calcium per 100g, Brazil nuts have 100mg per ½ cup
  • Chia seeds contain 630mg calcium per 100g
  • Seaweeds contain 134 mg calcium per cup
  • Egg yolk contains 130mg calcium per 100g
  • Tofu & Soybeans contain 375mg calcium per 100g
  • Sardines (and other tinned fish with bones) contain 100mg calcium per 2 sardines
  • Fresh fish contain around 75-100mg calcium per 100g
  • Dried herbs such as Basil, Thyme, Marjoram, Rosemary and Dill contain around 106mg calcium per tablespoon. Fresh herbs are also rich sources of calcium
  • Dairy products contain around 113mg calcium per 100g (listed here as a comparison, but not a recommendation)

What do I need to eat to get all my calcium?

It’s important to eat a variety of meals to get all your nutrients, but to focus on calcium, consider meals such as:

  • plenty of green vegetables, sprinkled with any green herbs like coriander parsley etc for extra calcium
  • fish or seafood for dinner
  • some chia seeds along with other nuts and seeds for breakfast with almond milk
  • a salad with lunch sprinkled with few nuts and seeds and seaweed flakes.

If you add some Tahini mixed with lemon juice and water and use it as a salad or vegetable dressing, then you will get quite a lot of calcium without even needing to focus on the other foods.

There may be days that you don’t wish to eat seafood/fish so then the Tahini dressing comes in handy to top up your calcium for the day. Tahini mixed with maple syrup makes a great ‘caramel’ tasting sauce to add to fruit for a change.


Before you commence your diet, see your medical or health care professional for qualified guidance about what foods and supplements are best for your body. While on the diet do not stop any medications or supplements previously prescribed unless advised otherwise by your medical or health care professional.

During the early stages of a new diet, you may experience symptoms such as fatigue, headaches or body aches, which may occur because your body is detoxifying. However, if you are unsure about a symptom at any time, check immediately with your medical or health care professional.


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