Calcium and Vitamin D for Vegans: Summarized!

This is an abridged version of Calcium and Vitamin D, which includes references and more details on just about every paragraph below. This should conclude my calcium-vitamin D barrage of the past few weeks!

Calcium

Americans are regularly being urged to consume more calcium in order to prevent osteoporosis. It is practically impossible to meet the recommendations without large amounts of cows’ milk, calcium-fortified foods, or supplements.

Because vegans do not eat dairy products, without fortified foods or supplements their calcium intakes tend to be low (about 400-600 mg per day compared to the U.S. recommended intake of 1,000 mg per day).

Traditionally, the vegan community has responded to this by saying osteoporosis is a disease of calcium loss from the bones, not a lack of calcium in the diet. This was based on two ideas.

The first idea is that ecological studies have shown that the countries with the highest intake of dairy products (northern Europe and the USA) have higher rates of hip fractures than do Asian and African countries where much less milk is consumed. This in turn, can be explained by the second idea, which is that studies show that after ingesting animal protein, people urinate large amounts of calcium.

Therefore, the thinking goes, calcium intake isn’t important for preventing osteoporosis and vegans are protected due to the lack of animal protein in their diets.

Unfortunately, there is a lot of evidence to suggest that this is not correct. It turns out that hip fractures are more indicative of the risk of falling than of osteoporosis in some countries, with a recent study from Hong Kong showing that while men and women in Hong Kong had lower rates of hip fractures, they had higher rates of vertebral factures, and the women had higher rates of osteoporosis than Caucasian women.

As for protein leaching calcium from bones into the urine – it’s a lot more complicated than that. The studies that showed calcium to be urinated out were done using protein isolates whereas eating protein from whole foods does not result in a calcium imbalance. Population studies and clinical trials show that protein, including animal protein, does not have a negative effect on bones (more details here).

So where does that leave vegans?

Vegans’ bone mineral density, a measure of osteoporosis, has been shown in many studies to be slightly lower than non-vegans. More importantly, the one study on Western vegans measuring fracture rates over time found that vegans in the group who got less than 525 mg of calcium per day had a higher fracture rate than vegans in the group getting more than 525 mg. The vegans in the lower calcium group also had higher fracture rates than the meat-eaters and lacto-ovo vegetarians.

Although it is possible to meet the calcium recommendations by eating greens alone, the average vegan probably will not meet recommendations without drinking a glass of fortified drink each day, eating calcium-set tofu, or taking a 250 – 300 mg supplement (in addition to eating an otherwise balanced diet).

The greens highest in absorbable calcium are kale, mustard greens, bok choy, turnip greens, collards, and watercress (more info). In addition to calcium, greens also contain vitamin K, potassium, and magnesium, which also contribute to better bone health.

While spinach, Swiss chard, and beet greens are high in calcium, it is not well absorbed due to their also high content of oxalates, which bind calcium and prevent absorption from the digestive tract.

Research is mixed about whether calcium intakes above 1,400 mg per day can put people at risk for chronic disease. If you take a calcium supplement, it’s best not to go overboard. Most vegans taking 250-300 mg per day would not come close to 1,400 mg.

Vitamin D

Vitamin D is also important for bones, as it can increase calcium absorption when the body signals that it needs calcium. Research has shown that in populations with calcium intakes similar to omnivores in the United States, vitamin D is more important than calcium for preventing osteoporosis.

In recent years, vitamin D has also been linked to many other diseases and some researchers have suggested that the recommended vitamin D levels are too low. However, the Institute of Medicine has reviewed the research and concluded that is not the case. The controversy has resulted in many people thinking they are deficient in vitamin D when they are not.

The only significant, natural, dietary sources of vitamin D are fatty fish, eggs (if chickens have been fed vitamin D), and mushrooms (if treated with UV rays). Most Americans get their dietary vitamin D through fortified milk and fortified margarine. The vegan diet contains little, if any, vitamin D without fortified foods or supplements. On average, vegans’ vitamin D levels are adequate, but somewhat lower than non-vegans.

Most people get a significant amount of their vitamin D from the action of UV rays on their skin. While the body can store vitamin D made in the sunnier months for use during less sunny times, this does not work for everyone. In fact, some people, even those living in sunny climates, develop extremely low levels of vitamin D. This can manifest itself through fatigue and bone pain.

If your arms and face (or the equivalent amount of skin or more) is exposed to the following amounts of midday sun (10 am to 2 pm), without sunscreen, on a day when sunburn is possible (i.e., not winter or cloudy), then you should not need any dietary vitamin D that day:

• Light-skinned: 10 to 15 minutes
• Dark-skinned: 20 minutes
• Elderly: 30 minutes

On all other days, people older than one year should get 600 to 1,000 IU of vitamin D.

Due to skin cancer concerns, some dermatologists recommend getting all your vitamin D from supplements rather than the sun. The amounts of sun above for light and dark-skinned people should be safe, but I have not seen research on how much sun is safe for elderly people and recommend talking to your doctor about how to get vitamin D if you believe you are at risk for skin cancer.

600 to 1,000 IU of vitamin D is only available in supplemental form or specially treated mushrooms.

There are two forms of supplemental vitamin D: D2 and D3. Vitamin D2 is always vegan, made from exposing fungi to UV rays. Vitamin D3 normally comes from fish oil or sheep’s wool, but there is a vegan version made by Vitashine.

A great deal of research has been conducted on vitamin D2 and D3. Vitamin D2 is effective at increasing bone mineral density (when given to people who are deficient). Vitamin D2 can also increase vitamin D levels temporarily, but is not as effective as vitamin D3 at keeping vitamin D levels raised when taken only weekly. If you take vitamin D on a regular basis, D2 should be fine, whereas if you are only going to take it sporadically, without getting sun in the interim, or find that your vitamin D levels will not increase on D2, then you should opt for D3.

If you are trying to raise your vitamin D levels with D2, make sure the laboratory can detect vitamin D2, and not just vitamin D3. Also make sure that you are not trying to raise your levels beyond what the Institute of Medicine says is adequate (50 nmol/l or 20 ng/ml) as there’s no sense in worrying if you cannot seem to get your vitamin D levels twice as high as necessary!

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23 Responses to “Calcium and Vitamin D for Vegans: Summarized!”

  1. SM Says:

    thanks for the summary! What is your opinion about using calcium fortified vegan non-dairy milks such as soy or almond milk instead of calcium supplements?

  2. Jack Norris RD Says:

    SM,

    I don’t think there’s any difference except that you need to make sure you shake the carton because the calcium tends to settle to the bottom.

  3. tobias Says:

    Great job, thanks!

  4. dimqua Says:

    > The greens highest in absorbable calcium are collards, turnip greens, mustard greens, and kale (see chart).

    Is there any reasons why dandelion greens, watercress, bok choy and arugula are not included in this list?

    http://ndb.nal.usda.gov/ndb/foods/show/2946
    http://ndb.nal.usda.gov/ndb/foods/show/3242
    http://ndb.nal.usda.gov/ndb/foods/show/2880
    http://ndb.nal.usda.gov/ndb/foods/show/3551

  5. Michael Says:

    Hi!

    I think dermatologists are wrong. I think sun light has more positive effects on our body than just helping it to produce Vitamin D. I think with sun light it is the same as with everything….balance is the key. Even water is deadly when too much is drunk too fast.
    Here in Germany they give the same times as you give Jack, but the say two to three times a week is enough, because the body will produce up to 10 thousand units in that time (being in the sun for 10 to 20 minutes).

    thanks for your work!
    Michael

  6. Jack Norris RD Says:

    dimqua,

    dandelion greens, watercress, arugula – I don’t know the oxalate content.

    I added bok choy to the article (and the calcium chart here: http://veganhealth.org/articles/bones#catips).

  7. dimqua Says:

    There is information [1], that watercress contains 310 mg of oxalic acid per 100 grams. I don’t know whether it’s a lot or not. In two studies [2, 3], the calcium in it is well absorbed. But another article [3] says that: “The calcium in milk and dairy products is much better absorbed than the calcium in spinach or watercress, as these plants have high oxalate contents [64,84,92–96]“.

    I have not seen studies on calcium and dandelion greens, but it probably contains 492 mg of oxalate per cup (55 grams) [4]. So it seems like a bad source of calcium.

    1. http://www.ars.usda.gov/Services/docs.htm?docid=9444
    2. http://www.ncbi.nlm.nih.gov/pubmed/2819021
    3. http://ajcn.nutrition.org/content/59/5/1238S.full.pdf
    4. Resnick, Martin I.; Pak, Charles Y. C. (1990). Urolithiasis, A Medical and Surgical Reference. W.B. Saunders Company. p. 158. ISBN 0-7216-2439-1. | link: http://en.wikipedia.org/wiki/Oxalate#Occurrence_in_nature

  8. dimqua Says:

    Here is the correct link – http://www.jacn.org/content/19/suppl_2/119S.full

  9. Jack Norris RD Says:

    dimqua,

    1. Great find.
    2. Based on how the soup was prepared (with a significant amount of other ingredients) and other technical details I could not follow, I decided not to use that study.
    3. That study (Weaver 1994) simply extrapolated calcium absorption, they didn’t actually measure it.
    4. I followed the research there to another study, but it started to become a wild goose chase (sorry for the non-vegan pun, I only want to feed the geese healthy food if I find them) so I gave up on that line of reasoning.

    After putting in considerable time, I have changed the calcium absorption section of my article on VeganHealth.org to reflect what you and I found.

  10. Joe Says:

    Jack,

    Do you have any view on whether calcium and Vitamin D supplements should be taken at the same time to ensure they are absorbed properly? This seems to be the reason that calcium and Vitamin D are often sold in the same pill. Alternatively, if you aim to get Vitamin D from sunshine, should you wait to take the calcium supplement at that point of the day?

    Thanks for any guidance.

  11. Jack Norris RD Says:

    Joe,

    http://jacknorrisrd.com/do-calcium-and-vitamin-d-need-to-be-taken-together/

  12. Dan Says:

    Jack, I have been reading about calcium in UpToDate and seen some references to suggest that calcium is not as well absorbed from greens as from cow milk. For instance, UpToDate states:

    “While it is possible to estimate the amount of calcium in other sources of dietary calcium such as green vegetables and nuts, calcium absorption from these sources is more variable. In addition, vegetables and nuts have much lower calcium content than dairy products so that much more would need to be consumed to meet daily requirements.”

    In their monograph on Vegetarian Diets in Children, UpToDate also states:

    “Most of the calcium needs of children who consume lactovegetarian or lactoovovegetarian diets can be met by low-fat milk and dairy products that provide approximately 75 percent of the calcium in the average American diet [96,100,101]. Vegan children have more difficulty meeting calcium needs because they avoid dairy products, which contain more calcium than vegetables, fruit, and cereal grains [46]. Therefore, the calcium intake of children who consume vegan diets is generally lower than that of lacto-ovovegetarians and omnivores [102-104]. Vegan children can obtain calcium from foods naturally rich in calcium, calcium-fortified foods and beverages, calcium supplements, or a combination of these.

    The following foods are naturally rich in calcium and low in oxalate: kale, mustard greens, turnip greens, broccoli, bok choy, dried figs, blackstrap molasses, and lime-processed tortillas (table 3) [96]. However, to meet calcium requirements from these foods alone would be difficult, even with large portions.

    Calcium-fortified foods include soy milk, soy yogurt, and soy cheese, as well as calcium precipitated tofu and calcium-fortified cereals, breakfast bars, pastas, waffles, and juices [57,105]. Calcium bioavailability in most of these sources is equivalent to milk. As an example, one eight-ounce glass of calcium-fortified orange juice provides 300 mg of calcium, equivalent to an eight-ounce glass of milk. In contrast, the bioavailability of calcium in soy milk is only 75 percent of that in cow’s milk [106].”

    Comment:

    Thus if bioavailability of calcium is generally lower in a plant-based diet, and if quantity consumed in a typical plant-based diet is also lower, it would seem that calcium supplementation (and/or fortified food) would be necessary for most vegans to meet the RDI of 1000 mg of elemental calcium. Do you agree with that reasoning? Or did I miss something?

  13. Jack Norris RD Says:

    Dan,

    I agree with it and have for many years now.

  14. Dan Says:

    Jack,

    Thanks for replying. What if your peacounter profile tells you that you are already getting enough calcium without dairy OR fortified foods? Mine is. And that is without almond milk, which the pea counter USDA database does not list (and contains 300 mg of calcium). In that case, it does not seem necessary to add other fortified foods or a supplement, or am I missing something?

  15. Joe Says:

    Jack,

    What do you think of amaranth as a source of calcium?

  16. Jack Norris RD Says:

    Dan,

    Then you are one of the people who do not need further supplementation or fortified foods.

  17. Jack Norris RD Says:

    Joe,

    One cup cooked has 115 mg: http://peacounter.com/foods_pub.php?ndb=20002

    I don’t know what the absorption rate would be. I’d guess around 20-25%.

  18. Pim Says:

    Nutritional yeast. This seems to be a source of Vitamin D which I can’t see mentioned in your article, do you think adding this to food could over ride the need for a supplement?

    Thanks for a great research paper and an interesting summary.

  19. Jack Norris RD Says:

    Pim,

    I’m not aware of nutritional yeast being a source of vitamin D.

  20. Sathya Says:

    Dear Jack! Great article. I live in India and this is the only vegan calcium + vit D supplement that’s locally available at a reasonable cost -> http://unived.in/Products/CalDveg/21
    What do you think of this product? especially the bio availability of the product!

    Regards.

  21. Jack Norris RD Says:

    Sathya,

    The Unived website makes many claims that I would consider unsubstantiated. That said, the formulation looks decent to me. I wouldn’t take more than two capsules per day.

  22. Derek Says:

    Hi Jack,

    This video

    https://www.youtube.com/watch?v=hmqguIFMC-Y

    explains the way sunlight is turned into vitamin D, which in turn interacts with calcium to build bones. But their explanation implies that people who don’t consume cholesterol won’t have this happen. Do you know anything about the subject? See starting at 0:25

  23. Jack Norris RD Says:

    Derek,

    Your body makes cholesterol, so you shouldn’t need it from your diet. When I hear of vegan who are having trouble raising their vitamin D levels, especially those who get plenty of sun, I do sometimes wonder if low cholesterol is an issue, but I’m not aware of any evidence that it is.

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