What does calcium do for the body?

Around 99 per cent of the body’s calcium is stored in bones and teeth, where it contributes to their strength and structure. Calcium works with phosphorus to build and maintain bone density, which is especially important for children, adolescents and older adults, particularly menopausal women, to prevent bone diseases like osteoporosis.

As well as being essential for strong bones and teeth, calcium is essential for muscle function and nerve signalling. It helps with blood clotting and supports the release of hormones and enzymes that regulate body processes. If there isn’t enough calcium in the diet, the body takes it from bones, which can weaken them over time.

Dairy is generally thought to be the highest source of dietary calcium, but it is found in other sources too. It should be relatively easy to get enough calcium from your diet, although the groups mentioned above might need a supplement, as well as vegans and people who avoid dairy.

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Best calcium supplements

Together Health Calcium

Available from: Together Health (£9.99), Superdrug (£9.99), Bodykind (£9.99)

Together Health Calcium

Price per day (recommended dose): 33p
Star rating: 4.5/5

Affordable, easy to swallow and tasteless capsules, this vegan supplement is likely to be well absorbed and scored highest across all areas. Two capsules provide 76% of the NRV and are free from listed allergens, with recyclable packaging. This supplement doesn’t contain vitamin D, which may aid absorption, but it does contain a synergistic blend of trace minerals that occur naturally from the seaweed that the product is derived from. This product also scored highly as it is free from undesirable additives.

Available from:

Cytoplan Organic Whole Food Calcium

Available from: Lifestyle Vitamins (£15.95), Cytoplan (£17), Dolphin Fitness (£17)

Cytoplan Organic Whole Food Calcium

Price per day (recommended dose): 57p
Star rating: 4/5

Another food source calcium supplement, made from calcified seaweed, in the form of a tasteless, easy to swallow capsules. This provides 50% NRV of calcium in an organic product, with no undesirable additives and is free from allergens.

Available from:

Purolabs Calcium Complex

Available from: Purolabs (£29.99)

Purolabs Calcium Complex

Price per day (recommended dose): £1
Star rating: 4/5

This is a pricier product, but is a multi nutrient, not just calcium. It is a synergetic complex of calcium, magnesium, vitamin C, zinc and vitamin D designed to support bone health. All of the nutrients come in absorbable forms and the calcium takes the form of calcium citrate. The capsules are tasteless and easy to swallow, and the product is free from undesirable additives. It provides almost 50% of the NRV which is fine if you’re getting some calcium from the diet, which most people are. It is suitable for vegetarians.

Available from:

BioCare Calcium Citrate

Available from: Nirvana Health (£19), BioCare (19.45), Revital (19.45)

BioCare Calcium Citrate

Price per day (recommended dose): 65p
Star rating: 3.5/5

This is a plain calcium citrate product in a tasteless, easy to swallow capsule. It is likely to be well absorbed by most, with or without food, providing 38% NRV. It does contain some additives (silicone dioxide and microcrystalline cellulose) which are thought to be safe in low amounts. It is free from allergens and suitable for vegans.

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How much calcium should I take per day?

The daily nutrient reference values (recommended daily intake) for calcium in the UK are as follows:

0-12 months (non-breastfed only) – 525mg
1-3 years – 350mg
4-6 years – 450mg
7-10 years – 550mg
11-18 years, boys – 1000mg
11-18 years, girls – 800mg
Adults (19+) years – 700mg
Pregnant women – 700mg
Breastfeeding women – 700mg + 550mg

The safe upper limit for adults ranges from 2,000 to 3,000mg, with pregnant and lactating women sitting at the higher end.

Very high calcium intake, or excessive calcium in the blood can pose risks to our health. These include gastrointestinal upset and digestive issues, kidney stones, cardiovascular issues, and interference with other nutrients.

When should I take calcium?

To maximise absorption and minimise side effects, it is advisable to split the dose of calcium supplementation if taking over 500mg. Calcium carbonate supplements are best taken with food. Vitamin D can support calcium absorption, while caffeine, phytates, oxalates and excessive iron or zinc may inhibit absorption if taken at the same time.

Very importantly, calcium supplements can interfere with some medications. For example those taking thyroid medication should wait at least four hours before taking calcium supplements. Those considering taking a calcium supplement who have a medical condition or take medication, should get advise from their healthcare provider before commencing.

What form of calcium should I take?

The main forms of supplemental calcium are calcium carbonate, which is the same as chalk, and calcium citrate. Food source calcium from seaweed is also available and likely to be well absorbed.

The research suggests that calcium citrate may be better absorbed than calcium carbonate, though the evidence is mixed and mostly based on small scale studies. However, we do know that calcium carbonate, which is the cheaper product to produce, can cause digestive upset for some people, and that it should be taken with food which not all supplements specify. We also know that calcium carbonate requires sufficient stomach acid to be able to be well absorbed, and that typically the people who may benefit from calcium supplementation (menopausal women, older adults and vegans) might be more prone to low stomach acid. Calcium citrate and food source calcium supplements do not need to betaken with food.

Vegans should be aware that many calcium supplements also contain vitamin D3 to aid absorption, which may not be vegan friendly.

What format of calcium supplement is best?

There’s no preference as to the delivery mechanism in the research. Mostly, any delivery is thought to be sufficient; it is more the dose, form, and biochemistry of the individual taking that makes the biggest difference.

What we looked for in calcium supplements

All supplements were tested within the same time period, with observations recorded based on the testing criteria. We included samples from various manufacturers, offering both tablets and capsules, with a range of price points to suit different budgets. The key areas we assessed were as follows:

  • Taste and flavour: is the consuming experience pleasant?
  • Nutrient profile: how much calcium per daily dose? How does this compare to the NRV?
  • Bioavailability: does the product contain forms of calcium that are easily absorbed? Does it contain any additional ingredients that might support efficacy?
  • Additives: does the product contain additives, for example: preservatives, artificial sweeteners or colourings?
  • Dietary requirements: does the product meet any specific dietary needs– is it vegetarian, vegan?
  • Value for money: how does it compare to other products on a cost-per-day basis

Vital minerals – what do I need?
Top 8 calcium-rich foods
Am I at risk of a calcium deficiency?
The best vegan calcium sources
Healthy bones recipes

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