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Vegans and Calcium Intake
The RDA for calcium for adults is 1,000 to 1,200 mg per day depending on sex and age. It’s practically impossible to meet these recommendations without large amounts of dairy, calcium-fortified foods, or supplements. Because vegans don’t eat dairy products, without fortified foods or supplements their calcium intakes tend to be low (about 400–600 mg per day).
During the 1990s, the vegan community responded to these lower calcium intakes by saying that osteoporosis is a disease of calcium loss from the bones rather than a lack of calcium in the diet. This view was based on research showing that there are more hip fractures in countries with higher dairy product intake and research showing that animal protein causes an increase in calcium loss through the urine. Therefore, the thinking went, calcium intake isn’t important for preventing osteoporosis and vegans are protected due to the lack of animal protein in their diets.
But both of these ideas have turned out to be misleading.
Subsequent research showed that between countries, hip fractures are more indicative of the risk of falling than of osteoporosis. A study from Hong Kong found that while men and women in Hong Kong had lower rates of hip fractures, they had higher rates of vertebral fractures, and the women had higher rates of osteoporosis than Caucasian women. And research in the 2000s showed that the calcium that’s excreted after a large protein intake comes from the diet by way of increased absorption.
So where does it leave vegans?
Vegans and Bone Health
A 2009 meta-analysis on the bone mineral density of vegetarians concluded that vegans have statistically significant, moderately lower bone mineral density than meat-eaters, but that it’s unlikely to result in a clinically important increase in fracture risk. A long-term cohort study following a large number of meat-eaters, vegetarians, and vegans found vegans to have higher rates of bone fracture. We conducted a thorough analysis of this report, Bone Fractures among U.K. Vegans: Implications and Recommendations, and concluded that low calcium intakes were probably not responsible for the increased fracture rates. However, it’s important for vegans to aim for the United Kingdom’s Dietary Reference Intake of 700 mg of calcium per day for adults.
Plant Sources of Calcium
High-calcium, lower-oxalate, dark leafy greens are the best sources of calcium for vegans: turnip greens, mustard greens, kale, bok choy, and collard greens. Choy sum and gai choy are two high-calcium greens common in Asian cuisine. Although less common in the United States, some specialty Asian markets may carry them. In addition to calcium, greens also contain vitamin K, potassium, and magnesium, which contribute to better bone health.
While spinach, Swiss chard, and beet greens are high in calcium, the calcium isn’t well absorbed due to their high content of oxalate, which binds calcium and prevents absorption from the digestive tract.
Other sources of calcium are fortified drinks, calcium-set tofu, figs, and supplements.
It’s safe for vegans to supplement with 300 mg of calcium per day or less if they aren’t getting large amounts of calcium from other sources. Research is mixed about whether calcium intakes above 1,400 mg per day can put people at risk for chronic disease.
Please see Daily Needs for our most up-to-date calcium recommendations.
4 thoughts on “Calcium: Basics”
when I calculate my calcium intake should i also consider the drinking water?
what other types of foods, beside spinach, Swiss chard, and beet greens prevent absorption of calcium from the digestive tract?
> when I calculate my calcium intake should i also consider the drinking water?
No.
> what other types of foods, beside spinach, Swiss chard, and beet greens prevent absorption of calcium from the digestive tract?
High-oxalate foods can’t be relied upon as good sources of calcium even if they contain significant amounts of calcium, but you don’t need to worry about them impacting the calcium absorption from other foods in your diet. It’s best to avoid large amounts of spinach, swiss chard, beet greens, and rhubarb, but not to worry about other foods unless instructed to do so by a bona fide health professional.
“Low-oxalate, dark leafy greens are the best sources of calcium for vegans—collard greens”
My sources indicate that collard greens are not a low oxalate food…..that they contain almost half as much oxalate as spinach, which is an extremely high oxalate food.
My source is the USDA: https://www.ars.usda.gov/northeast-area/beltsville-md-bhnrc/beltsville-human-nutrition-research-center/nutrient-data-laboratory/docs/oxalic-acid-content-of-selected-vegetables/
Oxalic Acid Content of Selected Vegetables
Appreciate your comments on this
Robert,
> “Low-oxalate, dark leafy greens are the best sources of calcium for vegans—collard greens”
In the article Calcium–Part 2: Research, I separate collards from those other greens, and I shouldn’t have listed it first on this page. I’ve changed the statement to:
High-calcium, lower-oxalate, dark leafy greens are the best sources of calcium for vegans—turnip greens, mustard greens, kale, bok choy, and collard greens.
> My sources indicate that collard greens are not a low oxalate food
I agree that as foods go, collards are not a low-oxalate food and if you’re following a low-oxalate diet, they might not be a good choice. I got my oxalate number for raw collards from a table Harvard published in 2007 as distinct from the USDA’s table which was published in 1984. I was also checking my numbers against another table of oxalate content that I couldn’t completely verify the source for (and thus didn’t cite) and it listed numbers on the lower end for collards. That said, I don’t know for sure which table is more accurate and the USDA’s info is, I agree, significantly higher.
In reviewing the number just now, I saw that I listed boiled, drained collards as having 5 mg of oxalate per 1/2 cup and cited the Harvard table although that table doesn’t list boiled, drained collards. I’m not sure where I got that number so I’ve removed it. I’m sorry for that mistake.
To sum up my view, I think collards are a decent source of calcium for vegans, but I wouldn’t promote them as a food for people trying to minimize their oxalate intake.