Does spinach have calcium

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Calcium Content in Spinach: An Analysis

Calcium Presence in Spinach

Spinach (Spinacia oleracea) is known to contain calcium, but the bioavailability of this calcium is significantly lower compared to other sources like milk. Studies have shown that while spinach does contain calcium, much of it is bound to oxalates, which makes it less absorbable by the human body 126.

Calcium Absorbability and Bioavailability

Comparison with Milk

Research comparing the absorbability of calcium from spinach and milk found that calcium absorption from spinach is considerably lower. In a study involving 13 healthy adults, the mean absorption of calcium from milk was 27.6%, whereas from spinach, it was only 5.1% . This significant difference is attributed to the presence of oxalates in spinach, which bind to calcium and inhibit its absorption.

Chemical Form and Solubility

Further studies have confirmed that the calcium in spinach largely exists as calcium oxalate, a form that is not easily dissociated and thus poorly absorbed by the body. The solubility of calcium in spinach was found to be less than 2%, which parallels its low in vitro bioavailability . This low solubility and bioavailability are critical factors that limit the nutritional value of spinach as a calcium source.

Impact of Oxalates

Oxalate Binding

The presence of oxalates in spinach not only reduces calcium absorption but also poses potential health risks, such as the formation of kidney stones. The high oxalate content in spinach binds with calcium to form insoluble complexes, which are not easily absorbed by the digestive system 125.

Dietary Implications

Despite the low bioavailability of calcium from spinach, studies have shown that consuming spinach does not significantly alter the overall calcium balance in the body when part of a mixed diet. For instance, a study on children consuming 100 grams of spinach daily found no significant changes in their calcium storage rates, suggesting that spinach can be part of a balanced diet without adverse effects on calcium metabolism .

Enhancing Calcium Absorption

Processing Techniques

Research has explored various methods to improve the bioavailability of calcium from spinach. One study investigated the addition of different calcium compounds to spinach to reduce soluble oxalate levels. Calcium chloride was found to be the most effective in binding with oxalates, thereby potentially increasing the bioavailability of calcium .

Alternative Plant Sources

Comparative studies have also looked at other plant sources of calcium. For example, Moringa oleifera leaves have been found to have significantly higher calcium content and bioavailability compared to spinach, making them a better alternative for individuals seeking plant-based calcium sources .

Conclusion

While spinach does contain calcium, its bioavailability is significantly hindered by the presence of oxalates, which bind to calcium and reduce its absorption. Although spinach can be part of a healthy diet, relying on it as a primary calcium source is not advisable due to its low calcium bioavailability. Alternative plant sources like Moringa oleifera or processing techniques to reduce oxalate content may offer better options for enhancing calcium intake from plant-based foods.

Sources and full results

Most relevant research papers on this topic

Calcium absorbability from spinach.

Spinach calcium is less readily available than milk calcium, with a mean absorption rate of 27.6% compared to 5.1% in healthy adults.

RCTHighly Cited

1988·

211citations

·Robert P. Heaney et al.

Assessing Chemical Form of Calcium in Wheat, Spinach, and Kale

Knowledge of the chemical form of calcium in plants can help design processing procedures to improve calcium absorption.

1993·

13citations

·Denise A. Benway et al.

The influence of a daily serving of spinach or its equivalent in oxalic acid upon the mineral utilization of children

A daily serving of 100 grams of spinach is not harmful to growing children, and its richness in vitamins, minerals, and iron should remain alongside other green leafy vegetables.

Non-RCT

1938·

25citations

·Priscilla Bonner et al.

Influences of Calcium Deficiency and Cerium on Growth of Spinach Plants

Cerium treatment in calcium-deficient media improves spinach plant growth and photosynthesis by substituting for calcium and enhancing nitrogen metabolism.

Non-RCT

2008·

28citations

·L. Chao et al.

Mineral balances of human subjects consuming spinach in a low-fiber diet and in a diet containing fruits and vegetables.

Spinach in a high-fiber diet can negatively affect mineral balances, especially calcium and zinc, compared to cauliflower-free diets.

Highly Cited

1983·

80citations

·J. Kelsay et al.

Calcium content, in vitro digestibility, and bioaccessibility in leaves of spinach ( Spinacia oleracea ), sweet potato ( Ipomea batatas ), and drumstick tree ( Moringa oleifera )

Moringa oleifera leaves have higher calcium content and bioaccessibility than spinach and sweet potato leaves, potentially increasing calcium intake in tropical and warm temperate regions.

2014·

5citations

·Jonathan C Allen et al.

No influence of supplemental dietary calcium intake on the bioavailability of spinach carotenoids in humans

Supplemental calcium intake at high physiological concentrations does not significantly impact the bioavailability of carotenoids from a spinach-based meal in humans.

RCTVery Rigorous Journal

2017·

21citations

·J. Corte-Real et al.

Addition of calcium compounds to reduce soluble oxalate in a high oxalate food system.

Adding calcium chloride to spinach juice reduces soluble oxalate, making it safer for regular consumption and potentially preventing kidney stone development.

2017·

25citations

·Wen-Chun Bong et al.

Cerium under calcium deficiency—influence on the antioxidative defense system in spinach plants

Cerium addition to spinach plants in calcium-deficiency media improves plant growth and enhances oxidative stress-resistance, despite calcium deficiency symptoms.

2009·

35citations

·L. Chao et al.

Arsenic accumulation and physiological attributes of spinach in the presence of amendments: an implication to reduce health risk

EDTA and calcium amendments can reduce arsenic accumulation and toxicity in spinach, reducing human health risks and enhancing chlorophyll contents.

2017·

52citations

·M. Shahid et al.

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