Calcium in Supplements and Food: The Complete Guide

Calcium is a nutrient that is essential for healthy bones, teeth and various bodily functions.

In this blog article, you will learn about the benefits of calcium, how to get enough of it, and how to recognize and resolve a potential calcium deficiency.

Calcium is a mineral that plays a fundamental role in the structure and strength of your bones and teeth. It also helps your muscles and nerves function properly and plays a role in your body's metabolism.

Calcium is a very versatile mineral that has several benefits for the human body.

Supports bones and teeth:

• Calcium contributes to strong teeth and the maintenance of strong bones;
• In women, it helps reduce bone mineral loss during menopause (low bone mineral density is a risk factor for osteoporotic fractures); and
• In children, calcium is needed for normal growth and development of bones

Good for body cells and blood:

• In addition, calcium plays a role in the process of cell division and differentiation; and
• Supports blood clotting

Supports energy levels and muscles:

• Calcium contributes to normal muscle function and heart muscle function; and
• Activates your natural energy in the body

Good for digestion and the nervous system:

• Calcium supports digestion and;
• Is important for the nervous system

When you get calcium from supplements or food, it's usually bound to other substances, such as calcium phosphate (especially in dairy), calcium carbonate , and calcium citrate (especially in supplements).

These calcium compounds consist of:

1. The pure amount of calcium available to your body ( elemental calcium )
2. Another substance (such as phosphate , carbonate , or citrate )

Calcium supplements are often available in the forms of calcium carbonate and calcium citrate.

Both types of calcium have advantages and disadvantages. The best type depends on your personal situation and the properties that are important to you.

This table shows the main differences between calcium carbonate and calcium citrate so you can compare them properly:

A 1999 meta-analysis found that calcium citrate (27%) is absorbed slightly more easily by the body than calcium carbonate (22%). However, a recent study (2022) found that both calcium carbonate and calcium citrate are absorbed about equally well (around 24%).

It is important to take calcium carbonate supplements with meals, as this helps them to be better absorbed.

Calcium citrate, on the other hand, is well absorbed both with and without food. This makes this form of calcium suitable for people with reduced stomach acid production, for example.

Elemental calcium is the pure amount of calcium available to your body. You could also call it the unbound form of calcium. Calcium carbonate contains a high concentration of elemental calcium (about 40%) compared to calcium citrate (21%) and other salts.

It's important to know how much elemental calcium you're taking, because this is the actual amount of calcium your body uses. For example, a 500 mg calcium carbonate tablet contains approximately 200 mg of elemental calcium.

It's best to consume nutrients in their natural form . Synthetic forms, which are created entirely in laboratories, are generally less well absorbed by your body.

So, if you're looking for a calcium supplement, choose one that contains calcium from a natural source. This ensures optimal absorption and the supplement is most effective.

Aquamin® Calcium is a good example. This natural calcium supplement is extracted from red algae. The benefits of calcium from red algae are:

• In addition to calcium, it also contains other minerals (such as trace elements)
• Natural origin
• High bioavailability

Calcium is found in the body in the bones (99%) and in the serum (the liquid part of blood that remains after the blood cells have been removed).

In the bones

1. In the storage form of calcium, hydroxyapatite
2. Provides strength to the skeleton and serves as a reservoir for calcium in the blood serum

Three forms of calcium occur in the serum :

• Bound to proteins – 40%, unavailable for use by tissues
• Ionized (free) – 51%, essential for body functions
• Chelated – 9%, helps with calcium absorption and transport[6]

Ionized calcium is considered the best form because it is immediately available and active in the body.

How much calcium you need daily depends on your age and individual needs. These are the guidelines according to the Health Council and the Nutrition Centre:

Calcium deficiency can occur in various at-risk groups, including children, women aged 50 and older, and men aged 70 and older. It is also relatively common among vegans.

If children have a calcium deficiency of less than 125 milligrams per day, these symptoms may occur:

1. Incomplete bone formation, resulting in skeletal deformities (rickets)
2. Muscle cramps

Due to reduced calcium absorption in this group, calcium deficiency can lead to:

1. Slow decalcification of bones , which can lead to an increased risk of bone fractures
2. Faster bone loss in postmenopausal women ^[8]
3. Muscle cramps

Whether you are at risk of developing a calcium deficiency depends on factors such as your diet, absorption and changing needs.

1. Elderly – With increasing age, the efficiency of calcium absorption decreases
2. Women during and after menopause – Hormonal changes reduce calcium absorption and increase bone loss
3. Not eating dairy , due to veganism, lactose allergy or cow's milk allergy
4. People with certain medical conditions - Conditions such as celiac disease, inflammatory bowel disease (e.g., Crohn's disease), and cystic fibrosis can interfere with calcium absorption in the intestines ^[9]

Calcium works with other nutrients, such as vitamin D. They aid in the absorption and activation of calcium in the body, which is beneficial for bone health. Other substances, however, inhibit this absorption.

These are the main interactions:

1. Vitamin D plays a crucial role in the absorption of calcium in the intestines and in the storage of calcium in the bones.
2. Oxalic acid and phytic acid , found in certain vegetables and grains, can reduce calcium absorption . However, consuming these products is not a problem as long as your diet contains sufficient calcium and you eat a varied diet.

Calcium is found in various products. Dairy products, such as milk, cheese, and yogurt, are rich in calcium. Leafy greens, legumes, nuts, seeds, and certain types of fish are also good sources of dietary calcium.

Here are some examples of foods containing calcium:

When the concentration of calcium in the blood is too high, it's called hypercalcemia. Your kidneys can no longer properly process the large amount of calcium and excrete it through your urine. This can lead to the formation of kidney stones. Calcification of the kidneys and blood vessel walls can also occur ^[10] .

If you consume more than 2500 milligrams of calcium per day for an extended period, your kidneys will be under strain. And that's more than double the RDA for the group with the highest need (1200 mg for men and women over 70)!

For calcium, the tolerable upper limit has been set at 2500 mg (2.5 grams) per day for adults ^[11] .

You're unlikely to exceed 2500 mg through diet. But with supplements, be careful not to get more calcium than you need!

Too much calcium in the blood can cause the following symptoms:

1. Fatigue
2. Muscle weakness
3. Nausea
4. Decreased appetite
5. Yield
6. Constipation
7. Cardiac arrhythmias
8. Calcium deposition in soft tissues
9. Weight loss

High blood calcium levels can cause too much calcium to enter the urine, which can lead to:

1. Kidney stones
2. Kidney function problems ^[12]

Besides taking too many calcium supplements, there are a number of other possible causes of high calcium.

In adults, vitamin D and the parathyroid hormones regulate calcium balance:

• Too much vitamin D - Excessive vitamin D intake can lead to high calcium levels in the blood. This can only occur with prolonged excessive supplementation (at doses of 100+ mcg/day). You don't run the risk of vitamin D overdose through diet or prolonged exposure to sunlight.
• Parathyroid Problems – The parathyroid gland produces a number of hormones that regulate the amount of calcium in your body. If there are problems in this gland, this mechanism does not work properly and too much calcium can enter the blood ^[13] .

Here's what you can do to lower calcium levels:

• Drinking Water - Drinking enough water helps both prevent the first kidney stone and reduce the risk of recurring stones ^[14]
• Eat foods rich in phytic acid (grains, nuts, seeds, etc.) and oxalic acid (spinach, beets, rhubarb, etc.) – These substances inhibit the absorption of calcium
• Stop high-dose vitamin D – above 100 mcg per day.
• Eat less dairy - dairy is rich in calcium

Vitamins D3 and K2 are important for calcium metabolism . They work together to ensure that calcium is efficiently absorbed from food.

When you take calcium tablets with vitamin D3 and K2, you help your body with:

1. Better absorption of calcium from food
2. Transporting calcium to the right places in your body
3. Improving vessel elasticity (at optimal levels of both vitamin D and vitamin K) ^[15]

The majority of studies found that taking both vitamin D and vitamin K promotes optimal bone health. This combined effect was stronger than when the vitamins were taken separately [16]

To properly absorb calcium from food, you need enough vitamin D3 (cholecalciferol). Without enough vitamin D, your body only absorbs a small amount (10-15%) of calcium, but with sufficient vitamin D, your body absorbs much more calcium (30-40%). Vitamin D is therefore essential for effective calcium absorption! ^[17]

Calcium is primarily used to support bone health. However, you also need additional minerals and vitamins. The calcium supplement Bone Strength Premium contains everything you need to support healthy bones.

It contains, among other things, a natural form of calcium extracted from seaweed, together with Biocell® Collagen, Zinc, Magnesium, Vitamin D3 and Vitamin K2-MK7.

Of all these ingredients, the most absorbable forms have been selected, which the body can use immediately.

Reference list

1. https://pubmed.ncbi.nlm.nih.gov/11329115/
2. https://pubmed.ncbi.nlm.nih.gov/11329115/
3. https://ods.od.nih.gov/factsheets/Calcium/HealthProfessional/
4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8746734/
5. https://www.ncbi.nlm.nih.gov/books/NBK562303/
6. https://www.ncbi.nlm.nih.gov/books/NBK482128/ 
7. https://www.voedingscentrum.nl/encyclopedie/calcium.aspx)#blokwaarvoor-heb-je-calcium-nodig ?
8. https://www.voedingscentrum.nl/encyclopedie/calcium.aspx)#blokwaarvoor-heb-je-calcium-nodig ?
9. https://pubmed.ncbi.nlm.nih.gov/33491051/
10. https://www.voedingscentrum.nl/encyclopedie/calcium.aspx)#blokwat-zijn-de-gevolgen-van-te-veel-calcium ?
11. https://www.voedingscentrum.nl/encyclopedie/calcium.aspx)#blokwat-zijn-de-gevolgen-van-te-veel-calcium ?
12. https://voedingscentrum.nl/
13. https://www.ncbi.nlm.nih.gov/books/NBK430714/ 
14. https://www.mdpi.com/2571550
15. https://edepot.wur.nl/440347
16. https://edepot.wur.nl/440347
17. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2669834/