The shift in modern dietary habits often leads to insufficient calcium intake from food sources, resulting in calcium deficiency. In such cases, supplementing calcium through calcium tablets becomes the most convenient and effective approach. There are various types of calcium supplements available in the market, including calcium carbonate, calcium citrate, and seaweed calcium, each with different absorption rates and effects. This article compiles a comparison of 7 popular calcium supplements to assist you in making an informed choice to address calcium deficiency.
What is Calcium?
“Calcium” is an essential component of bones and plays a crucial role in bone metabolism[1]. It also contributes to the stability and function of muscles and nerves. Both excessively high and excessively low calcium levels can have an impact and lead to discomfort signals such as muscle cramps, insomnia, and irritability. Most of the time, the body regulates calcium ion concentration by storing and releasing calcium from bones to maintain it within a certain range[3]. If calcium is continuously extracted from the bones without being replenished, it can result in osteoporosis over the long term.
Importance of Calcium Supplementation
In addition to maintaining bone health, calcium is involved in various physiological processes such as:
- Contraction and relaxation of muscles and blood vessels throughout the body
- Transmission of nerve signals
- Intracellular signal transmission
- Blood clotting
- Endocrine system function
Common Symptoms of Calcium Deficiency
The following signals are common symptoms of calcium deficiency:
Muscle Cramps
Calcium ions regulate muscle movement in the body. Insufficient calcium can lead to overexcitation of muscle neurons and muscle cramps.
Palpitations
Heartbeats are also regulated by nerves and muscle movements. Calcium deficiency can affect normal rhythm and lead to palpitations.
Emotional Instability and Mental Confusion
The brain is controlled and regulated by numerous neurons. Calcium ions help stabilize brain physiological functions. A lack of calcium can result in emotional instability, mental confusion, and heightened sensitivity of auditory nerves, leading to auditory hallucinations.
Poor Sleep Quality
Autonomic nervous system imbalance can impact sleep quality and result in increased dreaming.
Deterioration of Tooth Enamel and Tooth Decay
Teeth and bones are calcium storage areas. Prolonged calcium extraction without replenishment can lead to weakened, brittle teeth and tooth decay.
Increased Eye Pressure and Blurred Vision
Numerous small nerves and muscles around the eyes regulate eye movement. Calcium deficiency can affect visual and eye pressure regulation.
Numbness in Hands and Feet, Lower Back Pain
When muscle and bone metabolism is compromised, waste buildup occurs, affecting movement and sensation.
Rough Skin
Skin metabolism is affected, causing dryness, lack of moisture retention, and dry, flaky, damaged skin.
Calcium Supplement Dosage: Should You Take Less or More?
There exists an inverse relationship between calcium intake and absorption rate. For calcium obtained from food:
- Calcium intake of 200 mg/day results in an absorption rate of about 45%.
- With a calcium intake of 2,000 mg/day, the absorption rate drops to about 15%.
Age also influences calcium absorption from the diet:
- Infants and young children have an absorption rate of up to 60% as they require ample calcium for bone development.
- In adulthood, this rate decreases to around 25% and continues to decline with age[5].
In summary, for adults with a recommended calcium intake of 1000 mg, it’s advisable to supplement with around 200 mg of calcium powder/tablets between meals to achieve optimal absorption.
Further Reading: Recommended Calcium Intake and Calcium-Rich Foods
Types of Calcium Supplements
Common forms of calcium found in calcium supplements include calcium carbonate and calcium citrate. Nowadays, there are other forms of calcium ions available in the market, including seaweed calcium, calcium sulfate, calcium ascorbate, calcium gluconate, calcium lactate, and calcium phosphate, among others[7].
The dosage forms of calcium supplements are often in tablet form, but there are also powdered forms available. Powdered forms generally have a higher absorption surface area and better absorption completeness compared to tablets. For children and the elderly, powdered forms are more suitable as they can be easily mixed into beverages for consumption.
Comparison of Calcium Ion Content in Various Calcium Sources
Calcium Carbonate
Calcium ion content is about 40%. Traditional calcium supplements are often derived from sources like oysters and bones, which may be prone to heavy metal contamination. Individuals with lower stomach acid secretion may experience lower solubility of calcium carbonate, potentially reducing calcium absorption.
Calcium Citrate
Calcium ion content is about 21%. Calcium citrate’s absorption is less dependent on stomach acid secretion, and its absorption is less affected when taken without food. For individuals with conditions like low stomach acid, inflammatory bowel disease, malabsorption issues, or those taking specific medications, calcium citrate is a more effective calcium supplement. Additionally, calcium citrate has better absorption compared to calcium carbonate[6].
Seaweed Calcium
Calcium ion content is approximately 31%[10]. Seaweed calcium is primarily sourced from green and red algae with calcified skeletons.
Calcium Lactate
Calcium ion content is about 13%.
Calcium Gluconate
Calcium ion content is about 9%[8]. Due to the lower concentration of calcium in calcium gluconate and calcium lactate, they are not considered the optimal choices for calcium supplementation[10].
💡Calcium Ion Content: Calcium Carbonate > Seaweed Calcium > Calcium Citrate > Calcium Lactate > Calcium Gluconate.
Comparison of Absorption Rate and Bioavailability of Different Calcium Types
Here is a summary of human studies regarding absorption rate and bioavailability:
💡Clinical studies have found that calcium lactate has significantly higher absorption rate compared to calcium gluconate. The calcium excretion in the feces of the calcium lactate group was also significantly reduced, indicating better bioavailability of calcium lactate compared to calcium gluconate[9].
💡In premenopausal women, the calcium absorption rate of calcium citrate combined with calcium lactate and calcium phosphate was significantly higher than that of calcium lactate combined with calcium phosphate[13].
💡Other studies have shown that calcium amino acid chelates have higher calcium absorption rate and bioavailability compared to calcium carbonate[14].
💡Seaweed calcium has better bioavailability compared to calcium carbonate and is even more bioavailable than calcium citrate[11]. It is considered a favorable form of calcium supplement[12].
In conclusion, considering the same amount of different forms of calcium supplements:
Absorption Rate: Seaweed Calcium > Calcium Citrate > Calcium Carbonate > Calcium Lactate > Calcium Gluconate.
“Seaweed calcium” and “calcium citrate” have higher calcium ion content and absorption rates compared to other forms of calcium supplements, making them superior choices with higher bioavailability.
| Seaweed Calcium | Calcium citrate | Calcium carbonate | Calcium Lactate | Calcium gluconate | |
| Calcium ion content | 31% | 21% | 40% | 13% | 9% |
| Absorptivity and bioavailability | Good | Good | Medium | Poor | Poor |
How to Choose Calcium Supplements/Calcium Powder?
Comprehensive Calcium Formula: Benefits of Absorption Rate and High Calcium Content
Calcium Citrate + Seaweed Calcium Calcium citrate and seaweed calcium are calcium sources with better absorption and higher bioavailability. Choosing a comprehensive calcium powder that combines seaweed calcium and calcium citrate can enhance absorption efficiency[6].
Add Vitamin D
Vitamin D in the human body promotes the absorption of calcium ions in the intestines. It assists in opening calcium ion channels and regulating calcium transport proteins present in cellular solutes, thereby controlling calcium ion transport[15].
The US FDA also recommends that postmenopausal women combine calcium intake with vitamin D to aid calcium absorption[16]. This can help prevent osteoporosis, improve bone density, and reduce the risk of osteoporosis[17].
Add Magnesium Ion
Studies have indicated that a calcium-to-magnesium ratio of 2:1 results in the best absorption effect. This ratio enhances the attachment, proliferation, and differentiation capabilities of human osteoblasts. Therefore, if calcium supplements provide a calcium-to-magnesium ratio of 2:1, they can have more positive effects on bone health[18].
Comparison of 8 Recommended Calcium Tablets/Powders
1. Daiken Calcium + Vitamin D3
- Dosage form: powder packet
- Calcium sources: seaweed calcium, calcium citrate
- Calcium content: 500 mg
- Calcium-magnesium ratio (optimally 2:1): 2:1
- Other vitamins: vitamins A, C, D, K
- Third party inspection: Yes
- View Product >
2. SunVita Red Algae Calcium Plus+
- Dosage form: capsule
- Calcium sources: seaweed calcium
- Calcium content: 358 mg
- Calcium-magnesium ratio (optimally 2:1): 5:1
- Other vitamins: vitaminD, K2
- Third party inspection: Yes
- View Product >
3. LongWalk Ca+Mg
- Dosage form: powder packet
- Calcium sources: seaweed calcium, micron calcium
- Calcium content: 336 mg
- Calcium-magnesium ratio (optimally 2:1): 2:1
- Other vitamins: vitaminD, K2, CPP
- Third party inspection: Yes
- View Product >
4. NutriPlus Magnesium + Calcium
- Dosage form: tablet
- Calcium sources: calcium citrate
- Calcium content: 242 mg
- Calcium-magnesium ratio (optimally 2:1): 2:1
- Other vitamins: Vitamin C, D, K, Zinc, Copper, Manganese
- Third party inspection: no label
- View Product >
5. PharGoods Magnesium + Calcium
- Dosage form: capsule
- Calcium sources: seaweed calcium
- Calcium content: 625 mg
- Calcium-magnesium ratio (optimally 2:1): 3:1
- Other vitamins: Vitamin D, Vietnamese rice protein, Belgian pea protein
- Third party inspection: Yes
- View Product >
6. DRWS Algae Calcium
- Dosage form: tablet
- Calcium sources: calcium citrate
- Calcium content: 300 mg
- Calcium-magnesium ratio (optimally 2:1): 15:2
- Other vitamins: Vitamin D, Zinc, Copper, Manganese
- Third party inspection: no label
- View Product >
7. Caltrate Calcium
- Dosage form: tablet
- Calcium sources: calcium carbonate
- Calcium content: 600 mg
- Calcium-magnesium ratio (optimally 2:1): 12:1
- Other vitamins: Vitamin D, Zinc, Copper, Manganese
- Third party inspection: no label
- View Product >
8. Sentosa Ca + D3
- Dosage form: tablet
- Calcium sources: calcium carbonate
- Calcium content: 200 mg
- Calcium-magnesium ratio (optimally 2:1): 20:1
- Other vitamins: Vitamin D, Zinc, Copper, Manganese
- Third party inspection: no label
- View Product >
Comparison Table of 8 Calcium Tablets/Powders
| product | Daiken Calcium + Vitamin D3 | SunVita Red Algae Calcium Plus+ | LongWalk Ca+Mg | NutriPlus Magnesium + Calcium | PharGoods Magnesium + Calcium | DRWS Algae Calcium | Caltrate Calcium | Sentosa Ca + D3 |
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| Dosage Form | Powder pack | Capsule | Powder pack | Tablet | Capsule | Tablet | Tablet | Tablet |
| Calcium sources | Seaweed Calcium Calcium citrate |
Seaweed Calcium | Seaweed Calcium micron calcium |
Calcium citrate | Seaweed Calcium | Seaweed Calcium | Calcium carbonate | Calcium citrate |
| Calcium content (mg) | 500 | 358 | 336 | 242 | 625 | 300 | 600 | 200 |
| Calcium to Magnesium Ratio The best is 2:1 |
2:1 | 5:1 | 2:1 | 2:1 | 3:1 | 15:2 | 12:1 | 20:1 |
| Other vitamins | Vitamins A, C, D, K | Vitamin D, K2 | Vitamin D, K2, CPP | Vitamins C, D, K Zinc, Copper, Manganese |
Vitamin D Vietnamese Rice Protein Belgian pea protein |
Vitamin D Zinc, Copper, Manganese |
Vitamin D Zinc, Copper, Manganese |
Vitamin D Zinc, Copper, Manganese |
| Third Party Inspection | Yes | Yes | Yes | No label | Yes | No label | No label | No label |
Can taking too many calcium supplements cause kidney stones?
Research findings indicate that increasing calcium intake can reduce the excretion of oxalates in urine, lowering the risk of kidney stone formation[20]. Additionally, consuming an adequate amount of calcium (around 1000-1200 milligrams per day from dietary sources) can significantly decrease the oversaturation of calcium oxalate in urine and reduce the relative risk of developing high-calcium urine kidney stones[21] [23].
The Food and Agriculture Organization/World Health Organization (FAO/WHO) suggests that the risk of kidney stone formation due to “dietary” high calcium intake can be considered negligible[22].
However, consuming “excessively high doses” of calcium over the long term can lead to elevated blood calcium levels, affecting kidney function, promoting kidney stone formation, causing vascular and soft tissue calcification, high calcium in urine, and interfering with the absorption of other minerals[4].
How should calcium supplements be taken and when?
- Take calcium supplements with meals: Taking them with meals can enhance absorption efficiency.
- Divide calcium intake into small, frequent doses: Optimal absorption occurs when each dose of calcium supplement/calcium powder is around 200 mg.
- Take calcium supplements before bedtime: For individuals with poor sleep quality, taking calcium before sleep may help improve sleep. Decreased calcium ion content in brain cells is associated with sleep instability. Studies have shown that individuals with higher dietary calcium intake tend to have better sleep quality[25][26].
Further Reading: Joint Health: A Comparison of 11 Marketed UCII/UC2 Supplements!
Further Reading: When Should You Take Calcium Supplements? A Comprehensive Guide to Calcium-Rich Foods, Benefits, Recommendations, and Side Effects
