The Best (& Worst!) Animal-free Sources of Calcium.

There is a great deal of confusion about which animal-free foods are good sources of calcium. The main problem: low calcium plant-based foods are routinely promoted as being high in calcium. Such misinformation is routinely seen online in blogs and infographics, but it also to some extent makes its way into the official UK and US dietary guidelines (which I will expand on later).

In an effort to improve the plant-based community’s level of clarity on this micronutrient, below I have ranked foods commonly touted as good sources of calcium from best to worst. Foods were graded on the basis of their expected calcium absorbed per portion, which I approximated by multiplying a food’s fractional calcium absorption rate by its calcium load. For reference, the fractional calcium absorption of dairy milk is about 30%.

Wherever possible I have used the fractional calcium absorption rate(s) as measured in clinical trials. But where direct evidence is lacking, I estimated them using the algorithm created by Weaver et al1.


🥇 Calcium fortified white & brown breads/flours

Example: 2 slices of Kingsmill Mighty White = 244mg of calcium.

In the UK white & brown flour is fortified with calcium by law (note: brown flour is not wholemeal flour, but it does contain more fibre than white). Unfortunately, wholemeal flour bread is not usually fortified with calcium.

Be aware that not all countries have legally mandated flour fortification programs.

💬 White & brown breads may not be the healthiest food in the word, but it’s not terrible either. Guidelines recommending eating mostly higher fibre and whole grain starches.

Calcium load per portion: 🟩 High
Oxalates: 🟩 Low
Phytates: 🟩 Low
Fractional calcium absorption: 🟩 High (43%; measured2)
Absorbable calcium: 🟩 High

Verdict: ⭐️ Top-tier source of calcium.

🥈 Calcium fortified cereals

A 30g serving of Ready brek = 402mg of calcium.

Most other calcium fortified cereals don’t contain quite this much, but still can offer a jolly good amount of calcium (especially when combined with a fortified plant milk).

💬 Ready brek is fortified with lots of other goodies (e.g., B12, vitamin D, iron).

Calcium load per portion: 🟩 High
Oxalates: 🟩 Low8
Phytates: 🟩 Low9
Fractional calcium absorption: 🟩 High (~31%; estimated)
Absorbable calcium: 🟩 High

Verdict: ⭐️ Top-tier source of calcium.

🥉 Calcium-set Tofu


Example: 100g of Cauldron Authentic Tofu = 405mg of calcium

Tofu can be high in phytates (and inhibitor of calcium absorption), but this is offset by its high calcium load and low oxalate content (a more potent inhibitor).

💬 I am unsure what impact the phytate content may have on absorption when eaten in high amounts.

Calcium load per portion: 🟩 High
Oxalates: 🟩 Low
Phytates: 🟥 High
Fractional calcium absorption: 🟩 High (39%; measured7)
Absorbable calcium: 🟩 High

Verdict: ⭐️ Top-tier source of calcium.

Fortified juices

Example: 1 cup of Uncle Matt’s orange juice contains 325mg of calcium.

It seems that juices may be a better medium for calcium fortification compared to plant milks [because more of the fortificant is suspended in the supernate26].

💬 Unfortunately, most fortified juices on the market are not vegan (usually because they include animal-derived vitamin D3). Let’s hope that more vegan friendly products become available in the near future.

Calcium load per portion: 🟩 High
Oxalates: 🟩 Low
Phytates: 🟩 Low
Fractional calcium absorption: 🟩 High (38%, measured25)
Absorbable calcium: 🟩 High

Calcium fortified plant milks

Example: 1 cup of alpro no sugars soy milk = 288mg of calcium

Two studies found soy milk to display a similar level of calcium bioavailability to dairy milk3,4. Soy milk fortified with tricalcium phosphate (although still a good source) may be somewhat less bioavailable3,5.

💬 Although to the best of my knowledge the fractional calcium absorption of other plant milks has not been observed in clinical trials, I would expect these products to perform roughly as well due to high calcium content and low levels of anti-nutrients.

Calcium load per portion: 🟩 High
Oxalates: 🟩 Low
Phytates: 🟩 Low
Fractional calcium absorption: 🟧 Moderate (~23%, measured3,5)
Absorbable calcium: 🟧 Moderate

Verdict: Excellent source of calcium.

Calcium fortified plant-based yogurts

Example: 125g of alpro no sugar yogurt = 150mg of calcium

💬 As far as I know, no study has as yet measured calcium bioavailability in animal-free yogurts, but I assume it is similar to plant milks.

Calcium load per portion: 🟧 Moderate
Oxalates: 🟩 Low16
Phytates: 🟩 Low (assumed)
Fractional calcium absorption: 🟧 Moderate (~38%; estimated)
Absorbable calcium: 🟧 Moderate

Verdict: Good source of calcium.

Tahini

According to the USDA, 2 tablespoons of tahini contains 128mg (and ~200 Calories).

💬 But be aware that hulled sesame seeds are not a good source of calcium (I have addressed this food separately below).

Calcium load per portion: 🟧 Moderate
Oxalates: 🟩 Low10
Phytates: 🟩 Low10
Fractional calcium absorption: 🟩 High (~40%; estimated)
Absorbable calcium: 🟧 Moderate

Verdict: Moderate source of calcium.

Chia seeds

According to the USDA, 2 tablespoons of chia contains 126mg of calcium (and ~100 Calories).

💬 Bonus: chia is also a good source of ALA (omega-3).

Calcium load per portion: 🟧 Moderate
Oxalates: 🟩 Low11
Phytates: 🟩 Low12
Fractional calcium absorption: 🟩 High (~40%; estimated)
Absorbable calcium: 🟧 Moderate

Verdict: Moderate source of calcium.

Certain low-oxalate leafy greens

According to the USDA, ½ cup of cooked kale contains 89mg of calcium.

Other high calcium low-oxalate leafy greens include: boy choy, mustard greens, turnip greens, collard greens, watercress and broccoli (not technically a green leafy vegetable, I know).

Not all low-oxalate leafy greens are good sources of calcium (e.g. green cabbage, lettuce, rocket).

💬 The bioavailability of the calcium in these foods = hard to beat.

Calcium load per portion: 🟧 Moderate
Oxalates: 🟩 Low (the clue is in the name)
Phytates: 🟩 Low
Fractional calcium absorption: 🟩 High (~47%; observed13,14,15)
Absorbable calcium: 🟧 Moderate

Verdict: Moderate source of calcium.

Tempeh & soy beans

According to the USDA, ½ cup of tempeh contains 92mg of calcium & ½ cup of soy beans contains 88mg.

💬 Not everyone likes the taste of tempeh, but I love it.

Calcium load per portion: 🟧 Moderate
Oxalates: 🟩 Low17
Phytates: 🟩 Low17
Fractional calcium absorption: 🟩 High (~35%; estimated)
Absorbable calcium: 🟧 Moderate

Verdict: Moderate source of calcium.

Oranges

According to the USDA, 1 orange contains 52mg of calcium.

💬 Fortified orange juice is a good source of calcium; oranges are not.

Calcium load per portion: 🟧 Moderate
Oxalates: 🟩 Low (assumed)
Phytates: 🟩 Low (assumed)
Fractional calcium absorption: 🟩 High (~50%; estimated)
Absorbable calcium: 🟥 Low

Verdict: Poor source of calcium

Magnesium-set tofu

Example: Naked Tofoo contains 82mg per 100g.

💬 I sometimes include this form of tofu in my diet, but’s not a good source of calcium.

Calcium load per portion: 🟥 Low
Oxalates: 🟩 Low (assumed)
Phytates: 🟥 High (assumed)
Fractional calcium absorption: 🟩 High (~30%; estimated)
Absorbable calcium: 🟥 Low

Verdict: Poor source of calcium

Non-soy legumes

Example: According to the USDA, kidney beans contain 25mg of calcium per ½ cup.

💬 A first class foods from a health perspective; but they’re too low in calcium and too high in anti-nutrients to be considered a valuable source of calcium.

Calcium load per portion: 🟥 Low
Oxalates: 🟥 High18
Phytates: 🟥 High18
Fractional calcium absorption: 🟧 Moderate (~22%; observed19)
Absorbable calcium: 🟥 Low

Verdict: Negligible source of calcium.

Dried fruit

Example: According to the USDA, raisins contain 1 small box of raisins (43g) contains 26.7mg of calcium.

💬 The NHS recommends dried fruits as a source of calcium for those on a vegan diet20, I don’t know why.

Calcium load per portion: 🟥 Low
Oxalates: 🟩 Low (assumed)
Phytates: 🟩 Low (assumed)
Fractional calcium absorption: 🟩 High (~56%; estimated)
Absorbable calcium: 🟥 Low

Verdict: Negligible source of calcium.

Okra

According to the USDA, 8 pods contains 65mg of calcium.

💬 The Vegan Society23 & the NHS20 (among others) consider Okra to be a good source of calcium: I think they are mistaken.

Calcium load per portion: 🟥 Low
Oxalates: : 🟥 High24
Phytates: 🟩 Low (assumed)
Fractional calcium absorption: 🟧 Moderate (~24%; estimated)
Absorbable calcium: 🟥 Low

Verdict: Negligible source of calcium.

Nuts and seeds

Example: According to the USDA, 28g of nuts = 73mg of calcium.

Neither nuts nor seeds contain much calcium per portion/calorie.

💬 While tahini is a moderate source of calcium, hulled sesame seed contains very little calcium per portion.

Calcium load per portion: 🟥 Low
Oxalates: Variable.
Phytates: Variable.
Absorbable calcium: 🟥 Low

Verdict: Negligible source of calcium.

Spinach


According to the USDA, cooked spinach contains 200mg of calcium per ½ cup.

💬 I thought it was common knowledge that the calcium found in spinach is not accessible. However, it seems that the USDA has not gotten the memo21.

Calcium load per portion: 🟩 High
Oxalates: 🟥 High
Phytates: 🟩 Low (assumed)
Fractional calcium absorption: 🟥 Low (5%; observed22)
Absorbable calcium: 🟥 Low

Verdict: Negligible source of calcium.

Cauliflower

According to the USDA, cooked cauliflower contains 10mg of calcium per ½ cup.

💬 Eat cauliflower, it’s good for you. But it ain’t a source of calcium, my friends.

Calcium load per portion: 🟥 High
Oxalates: 🟩 Low (assumed)
Phytates: 🟩 Low (assumed)
Fractional calcium absorption: 🟩 High (64%; estimated)
Absorbable calcium: 🟥 Low

Verdict: Negligible source of calcium.

References: 
 
1. Weaver, C.M., Wastney, M., Fletcher, A. and Lividini, K., 2023. An Algorithm to Assess Calcium Bioavailability from Foods. The Journal of Nutrition.  
 
2. Martin, B.R., Weaver, C.M., Heaney, R.P., Packard, P.T. and Smith, D.L., 2002. Calcium absorption from three salts and CaSO4-fortified bread in premenopausal women. Journal of Agricultural and Food Chemistry, 50(13), pp.3874-3876. 
 
3. Zhao, Y., Martin, B.R. and Weaver, C.M., 2005. Calcium bioavailability of calcium carbonate fortified soymilk is equivalent to cow’s milk in young women. The Journal of nutrition, 135(10), pp.2379-2382. 

 
4. Tang, A.L., Walker, K.Z., Wilcox, G., Strauss, B.J., Ashton, J.F. and Stojanovska, L., 2010. Calcium Absorption in Australian Osteopenic Postmenopausal Women: an Acute Comparative Study of Fortified Soymilk to Cows’ Milk. Asia Pacific journal of clinical nutrition, 19(2), pp.243-249. 
 
5. Heaney, R.P., Dowell, M.S., Rafferty, K. and Bierman, J., 2000. Bioavailability of the calcium in fortified soy imitation milk, with some observations on method. The American Journal of Clinical Nutrition, 71(5), pp.1166-1169. 
 
6. Smith, K.T., Heaney, R.P., Flora, L. and Hinders, S.M., 1987. Calcium absorption from a new calcium delivery system (CCM). Calcified tissue international, 41, pp.351-352. 

7. Weaver, C.M., Heaney, R.P., Connor, L., Martin, B.R., Smith, D.L. and Nielsen, S., 2002. Bioavailability of calcium from tofu as compared with milk in premenopausal women. Journal of food science, 67(8), pp.3144-3147. 
 
8. Siener, R., Hönow, R., Voss, S., Seidler, A. and Hesse, A., 2006. Oxalate content of cereals and cereal products. Journal of agricultural and food chemistry, 54(8), pp.3008-3011. 
 
9. López-Moreno, M., Garcés-Rimón, M. and Miguel, M., 2022. Antinutrients: Lectins, goitrogens, phytates and oxalates, friends or foe?. Journal of Functional Foods, 89, p.104938. 
 
10. Jimoh, W.A., Fagbenro, O.A. and Adeparusi, E.O., 2011. Effect of processing on some minerals, anti-nutrients and nutritional composition of sesame (Sesamum indicum) seed meals. Electronic Journal of Environmental, Agricultural & Food Chemistry, 10(1) 
 
11. HP Avila-Nava, A., Medina-Vera, I., Rodríguez-Hernández, P., Guevara-Cruz, M., Canton, P.K.H.G., Tovar, A.R. and Torres, N., 2021. Oxalate content and antioxidant activity of different ethnic foods. Journal of renal nutrition, 31(1), pp.73-79. 
 
12. Turck, D., Castenmiller, J., deHenauw, S., Hirsch‐Ernst, K.I., Kearney, J., Maciuk, A., Mangelsdorf, I., McArdle, H.J., Naska, A., Pelaez, C. and Pentieva, K., 2019. Safety of chia seeds (Salvia hispanica L.) as a novel food for extended uses pursuant to Regulation (EU) 2015/2283. 
 
13. Heaney, R.P., Weaver, C.M., Hinders, S.M., Martin, B. and Packard, P.T., 1993. Absorbability of calcium from brassica vegetables: broccoli, bok choy, and kale. Journal of Food Science, 58(6), pp.1378-1380. 
 
14. Charoenkiatkul, S., Kriengsinyos, W., Tuntipopipat, S., Suthutvoravut, U. and Weaver, C.M., 2008. Calcium absorption from commonly consumed vegetables in healthy Thai women. Journal of food science73(9), pp.H218-H221. 
 
15. Heaney, R.P. and Weaver, C.M., 1990. Calcium absorption from kale. The American journal of clinical nutrition51(4), pp.656-657. 
 
16. Massey, L.K., Palmer, R.G. and Horner, H.T., 2001. Oxalate content of soybean seeds (Glycine max: Leguminosae), soyfoods, and other edible legumes. Journal of agricultural and food chemistry, 49(9), pp.4262-4266. 
 
17. Al-Wahsh, I.A., Horner, H.T., Palmer, R.G., Reddy, M.B. and Massey, L.K., 2005. Oxalate and Phytate of Soy Foods. J. Agric. Food Chem53, pp.5670-5674. 
 
18. Weaver, C.M., Wastney, M., Fletcher, A. and Lividini, K., 2023. An Algorithm to Assess Calcium Bioavailability from Foods. The Journal of Nutrition
 
19. Weaver, C.M., Heaney, R.P., Proulx, W.R., Hinders, S.M. and Packard, P.T., 1993. Absorbability of calcium from common beans. Journal of Food Science58(6), pp.1401-1403. 
 
20. https://www.nhs.uk/live-well/eat-well/how-to-eat-a-balanced-diet/the-vegan-diet/ [accessed 15/01/2024] 
 
21. https://www.myplate.gov/eat-healthy/dairy [accessed 15/01/2024] 
 
22. Heaney, R.P., Weaver, C.M. and Recker, R.R., 1988. Calcium absorbability from spinach. The American Journal of Clinical Nutrition, 47(4), pp.707-709 
 
23. https://www.vegansociety.com/resources/nutrition-and-health/nutrients/calcium [access 15/01/2024] 
 
24. SIENER, R., SEIDLER, A. and HÖNOW, R., 2020. Oxalate-rich foods. Food Science and Technology, 41, pp.169-173. 

25. 25. Smith, K.T., Heaney, R.P., Flora, L. and Hinders, S.M., 1987. Calcium absorption from a new calcium delivery system (CCM). Calcified tissue international41, pp.351-352. 

26. Heaney, R.P., Rafferty, K. and Bierman, J., 2005. Not all calcium-fortified beverages are equal. Nutrition Today40(1), pp.39-44.

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