Nutrient Focus

Calcium without dairy: fortified plant milks, calcium-set tofu, and the leafy-green caveat

The calcium-set vs nigari-set tofu distinction matters by a factor of three. The leafy-green oxalate question matters too.

Calcium on plant-based diets is a manageable nutrient with one specific failure mode that the literature documents clearly. The EPIC-Oxford cohort found that vegans had a higher fracture risk than meat-eaters and fish-eaters, and the elevated risk was concentrated in the lower tail of calcium intake (vegans consuming below approximately 525 mg/day calcium had substantially elevated risk; vegans above that threshold did not). The clinical implication is straightforward: plant-based eaters need to consume at the upper end of the recommended calcium range, and the apps and food choices that get them there matter.

This piece covers the food sources, the bioavailability nuances (especially the leafy-green oxalate question and the calcium-set vs nigari-set tofu distinction), and the practical recommendations.

The EPIC-Oxford finding

The EPIC-Oxford cohort followed approximately 55,000 men and women in the United Kingdom for an average of 17.6 years and reported on bone fracture risk by diet pattern. Vegans had a 43 percent higher fracture risk than meat-eaters in the overall analysis. Stratification by calcium intake showed that the elevated risk was concentrated in vegans with calcium intake below approximately 525 mg/day. Vegans hitting the higher calcium-intake quintiles did not show elevated fracture risk.

This finding is the strongest single piece of evidence shaping current plant-based clinical recommendations on calcium. The recommendation is not “vegans have higher fracture risk” (true on average but misleading without context); it is “vegans need to hit calcium intake targets, and at-target vegans are fine.”

Calcium intake targets

The standard RDA is 1000 mg/day for adults under 50 and 1200 mg/day for adults over 50. For plant-based eaters specifically, the practical target is to hit at least 1000 mg/day reliably and ideally to land in the upper quintile of plant-based calcium intake (which in EPIC-Oxford was above approximately 800 mg/day for the quintile that did not show elevated fracture risk).

This target is achievable from food alone for plant-based eaters who pay attention. It is not achievable for plant-based eaters who consume primarily unfortified plant milks and rely on leafy greens with high oxalate (spinach, chard) for calcium.

Plant-based calcium sources

Fortified plant milks

Most branded plant milks are fortified with calcium carbonate or tricalcium phosphate to roughly 300-450 mg per cup, which matches or exceeds dairy milk’s calcium content. Bioavailability of fortified calcium in plant milks has been measured at roughly 80-90 percent of dairy calcium bioavailability, which is acceptable.

The caveat: not all plant milks are fortified, and some artisan plant-milk brands explicitly market themselves as unfortified. A user who switches from a fortified mainstream brand to an unfortified artisan brand can drop hundreds of milligrams of calcium per day without realizing it. Database freshness matters here; reformulations occur and tracking-app entries can lag.

Calcium-set tofu vs nigari-set tofu

This is the single most-important database distinction in plant-based calcium tracking. Tofu set with calcium sulfate (calcium-set) has roughly 350 mg of calcium per 100g serving. Tofu set with magnesium chloride (nigari-set) has roughly 110 mg of calcium per 100g serving. The same volume of tofu can contain three times as much calcium depending on the coagulant.

US-market tofu is mostly calcium-set; Asian-market and artisan tofu is more frequently nigari-set. The label often specifies the coagulant, but tracker databases that lump tofu into one entry mislead by a factor of three on a clinically-meaningful nutrient.

The audit results: PlateLens distinguishes calcium-set from nigari-set in the database. Cronometer distinguishes them on the firm and silken entries. MyFitnessPal user-submitted entries frequently do not specify, which means a plant-based eater logging “tofu, firm” may be using a calcium value that is wrong by a factor of three for their actual purchase.

Leafy greens: the oxalate question

Leafy greens contain calcium, but oxalates in some greens bind calcium and reduce bioavailability dramatically. Spinach is the canonical example: spinach contains roughly 99 mg calcium per 100g but the oxalate content reduces bioavailable calcium to roughly 5 percent absorption. Chard is similar.

Low-oxalate greens (kale, collards, bok choy, mustard greens, broccoli) have calcium absorption fractions in the 40-60 percent range, comparable to dairy. Plant-based eaters should think of “leafy-green calcium” as low-oxalate-leafy-green calcium. Spinach is excellent for many other purposes (folate, magnesium, potassium) and not a meaningful calcium source.

Other plant calcium sources

• Almonds, 1 oz: ~75 mg
• Sesame seeds, 1 tbsp: ~88 mg
• Tahini, 2 tbsp: ~130 mg
• White beans, 1 cup cooked: ~160 mg
• Calcium-fortified orange juice, 1 cup: ~350 mg
• Calcium-set tofu, 100g: ~350 mg
• Fortified plant milk, 1 cup: ~300-450 mg
• Kale, 1 cup cooked: ~95 mg with high bioavailability
• Collards, 1 cup cooked: ~270 mg with high bioavailability

A plant-based eater consuming 1 cup fortified plant milk + 100g calcium-set tofu + 1 cup cooked collards + a serving of tahini reaches roughly 1100 mg of calcium with high bioavailability. The target is achievable; it is just specific.

Vitamin D and calcium

Vitamin D is required for calcium absorption. A plant-based eater hitting calcium targets but with vitamin D deficiency will not absorb the calcium efficiently. See our piece on vitamin D for the supplementation case.

How tracking apps handle calcium

The audit results from our March 2026 plant-food database audit:

• Cronometer: Distinguishes calcium-set vs nigari-set tofu on firm and silken entries. Plant milk fortification values are USDA-aligned and accurate. Best clinical tool for hand-tracked calcium.
• PlateLens: Distinguishes calcium-set vs nigari-set tofu in both database and photo recognition. Branded plant milk fortification values are within 5 percent of package values for 11 of 12 audited brands. Best when photo workflow is the primary use case.
• FoodNoms: Calcium tracking is straightforward; canonical USDA entries are accurate.
• MyFitnessPal: Calcium-set vs nigari-set distinction unreliable on user-submitted entries. Branded plant milk calcium values vary across entries. Not recommended for clinical calcium tracking on plant-based diets.

Special populations

Pregnancy and lactation. Calcium demand increases. Plant-based pregnant clients should hit the upper end of the recommended range and follow obstetric guidelines.

Older adults. Higher calcium target (1200 mg/day after age 50). Bone-density monitoring is reasonable for plant-based older adults at family-history risk.

Athletes. No specific increase in calcium demand for athletic training, but stress fracture risk is reduced by adequate calcium and vitamin D.

Summary

Plant-based calcium is achievable and the EPIC-Oxford evidence is reassuring for plant-based eaters who hit calcium targets. The critical attention points are: choose calcium-set tofu when the calcium contribution matters, recognize that spinach and chard are not calcium sources due to oxalates, prefer low-oxalate greens (kale, collards, bok choy), use fortified plant milks reliably, and track with an app that distinguishes calcium-set from nigari-set tofu (Cronometer, PlateLens).

Citations: EPIC-Oxford cohort findings on bone fracture risk; American Journal of Clinical Nutrition (multiple on calcium bioavailability and oxalate); Public Health Nutrition; Plant Foods for Human Nutrition.

Topics: plant-based calcium · vegan calcium · calcium-set tofu · fortified plant milk calcium · vegan bone health