Calcium Chart Updated – Calcium Absorption Modified

For the last many weeks, I have been in an undisclosed location working on an article on oxalates. I think it has been my 3rd biggest project to date, the other two being the epic adventure Vitamin B12: A Love Story followed by Soy: What’s the Harm?

But before I release the article on oxalates, I am writing to let you know that upon getting a bit more information about the oxalate content of foods and re-analyzing the data, I have expanded and moved the table Calcium & Oxalate Content of Foods to a new page and also slightly modified the absorption category for some greens:

– Studies have shown that calcium in fortified soymilk, bok choy, kale, and mustard greens is absorbed well.
– Based on oxalate levels, the calcium in turnip greens, watercress, and broccoli should also be absorbed well.
– Based on oxalate levels, the calcium in collards should be absorbed moderately well.
– Studies have shown that the calcium in spinach and rhubarb is not absorbed well.
– Based on oxalate levels, the calcium in beet greens and swiss chard should not be absorbed well.

I know a lot of people have oxalate stories, but please do not send me any links to oxalate info before I publish my piece! Once it comes out, I’ll be happy to receive any info you think I have missed. Thanks!

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24 Responses to “Calcium Chart Updated – Calcium Absorption Modified”

  1. James Thompson Says:

    Hi Jack,

    I’m looking forward to your oxalates article.
    One question which I hope you address in the article is the extent to which high oxalate foods impact the absorption of calcium from other foods consumed at the same time. I’ve seen some references that suggest if the oxalate/calcium ratio in a food is > 2, then it will decrease the calcium absorption from other foods consumed at the same time.

    Jim

  2. Sarah Says:

    I am really looking forward to this piece! Thanks so much for all your hard work on it. In the meantime, can you clarify why there are differences in the oxalate levels among some of the same vegetables – for example the 1/2c of raw Broccoli shows there are 173mg of oxalate, where as 1/2 cup of chopped raw broccoli shows there are only 13mg of oxalate. There are a number of double entries that have quite substantial differences. Is this just due to multiple testings coming up different? Any clarification would be much appreciated!!!

  3. Dan Says:

    Hi Jack,
    I don’t want you to divulge too much, too early in advance of your forthcoming article, but I did want to ask you if the following practice was safe. I’ve started consuming a fair amount of raw cruciferous vegetables at each meal – specifically, sprigs of broccoli, cauliflower, red cabbage – as well as carrots. I did this for a couple reasons, mostly because I felt I was not getting enough veggies, and the cruciferous vegetables are supposed to help prevent cancer; they also have alot of fiber which helps with gastric stretch and satiety. But in light of the oxalate content, do you think I should back off?

    (Personally, having not really reviewed the oxalate issue, I was not too worried about it. Even though these vegetables are being consumed with each of my three daily meals, I figured the health benefits outweighed any risks of calcium malabsorption).

    Any thoughts?

    Thanks!

    Dan
    (PS really looking forward to your article).

  4. Jack Norris RD Says:

    Dan,

    I doubt it’s a huge problem, but what is “a fair amount”?

  5. Dan Says:

    Hi Jack

    By “fair amount” I mean:
    - large sprig of broccoli (florets and stem)
    - large sprig of cauliflower (florets and stem)
    - 2-3 “sheaves” of red cabbage
    - 1 large carrot

    Multiply by three meals per day, taken raw, before the main course. Except that I take out the carrot with dinner.

    Thanks again for your help and all the sharing of insights you do on this site!

  6. Jack Norris RD Says:

    Hi Dan,

    Why do you eat them raw? I’m as concerned about the goitrogens as the oxalate. If you were to boil the broccoli, cauliflower, and cabbage and discard the boiling water, you’d reduce the goitrogens and the oxalate. That would be one way to minimize any potential problems.

  7. Dan Says:

    Hi Jack,

    “Why do you eat them raw?”

    Partly laziness and time-efficiency, partly because I thought raw was best and steaming them would destroy healthy phytochemicals. I realize this is not the case for things like lycopenes and beta-carotene.

    I think I’ll cut back on amounts and frequencies. Eating anything in excess is probably bad for you. I do have several regular iodine sources (in terms of offsetting goitrogens).

  8. Jack Norris RD Says:

    My vote is to eat them, but cook them for a couple minutes and discard the water. :)

  9. Dan Says:

    Great idea – I’ll steam them in a pot first and chuck out the drainage water. Thanks very much, Jack. :-)

  10. Melissa Says:

    I’m really looking forward to your article on oxalates!

  11. Sarah Says:

    Just a note Dan: If you either chop them an then wait 10mins before cooking or else eat a small portion of them raw along with the cooked that will help activate the enzymes in the crufiverous vegetables for more cancer protection. Otherwise the heat destroyes the enzyme activity and you loose that benefit.

  12. Doris (Cobie's Mom) Says:

    Hi, Jack -

    I have a big question about oxalates that I would love to have answered in your piece. Does the oxalate in a food carry through to the oil? I see olives listed as high; olive oil as low – but I wonder. It would also be nice to know about sesame oil.

    Far less important – but I’ve wondered about carob, and have not found an answer.

    I’m eagerly looking forward to seeing the article.

  13. Dan Says:

    Just steamed a bunch of cruciferous vegetables and interestingly (at least to me) the color of the drainage water was the same as Windex cleaner – i.e. a florescent neon blue. Makes sense as red cabbage contains a pH indicator. Hopefully all the goitrogens and oxalate is in the water.

  14. Jack Norris RD Says:

    Dan,

    I don’t think the goitrogens would be in the water, but they should be denatured. A large percentage of the soluble oxalate should end up in the water, and the soluble oxalate is what you especially don’t want. But more on that in my article…

  15. Dan Says:

    Dr. Greger quotes an interesting case report from the New England Journal of Medicine regarding an 88 year old woman who ate herself into a hypothyroid coma by consuming 1 – 1.5 kg of raw bok choy for a period of several months ( http://www.nejm.org/doi/full/10.1056/NEJMc0911005 ). Apparently (I did not know this), the myrosinase enzyme in brassica is what activates the goitrogens (compounds called glucosinolates). I had heard about goitrogens in soyfoods (e.g. tofu) but never in cruciferous vegetables; I’m surprised this is not more widely known. Especially because there are so many people on raw kale smoothie diets and the like. Over on Dr. Greger’s site, there is another report of a couple eating their way into significant hypothyroidism over a period of 5 weeks by consuming kale from their garden. So perhaps all cruciferous veggies should be boiled or steamed unless they are being consumed in relatively small amounts. The amounts I have been eating are not relatively small.

  16. Dan Says:

    Response to Sarah:

    Thanks for that great advice! I will eat some raw to ensure I get that enzyme — think I read some of that over on Dr. G’s site, but can’t recall which video.

    Dan

  17. Jack Norris RD Says:

    Doris,

    I’ve heard carob is high, but didn’t come across any measurements by sources I trust in my research.

    > Does the oxalate in a food carry through to the oil?

    I was just about to say that since oxalate salts tend to be water-soluble they probably aren’t so fat-soluble, but thought I’d look it up to make sure and according to UW-Madison School of Medicine and Public Health, oxalate is fat-soluble: http://www.uwhealth.org/urology/oxalate/11252 But it is probably still likely that a lot would be lost in the oil production process. Sigh, I’ve read about 40 papers and that’s the first I’ve seen that oxalate is fat-soluble. In fact, people with fat malabsorption can have higher oxalate absorption (e.g., http://www.ncbi.nlm.nih.gov/pubmed/21295813 ), so this makes little sense to me.

  18. Jack Norris RD Says:

    Doris,

    Oh, I see, the fat malabsorption leads to calcium loss and thus prevents calcium from binding with oxalate, leading to oxalate absorption:

    http://www.ncbi.nlm.nih.gov/pubmed/15253722 (Please excuse the rat portion of that study. I wasn’t citing it for the study, but rather just the intro line.)

    I now remember hearing Susan Owens say that in a podcast. My article isn’t focused much on fat malabsorption, obviously, but I guess I should add this info. Yet more delay in the article being published!

    2 months ago, I had no idea what a huge issue oxalate is. It makes me wonder if there are also phytate support groups out there I need to look into.

  19. Jack Norris RD Says:

    Sarah,

    > for example the 1/2c of raw Broccoli shows there are 173mg of oxalate, where as 1/2 cup of chopped raw broccoli shows there are only 13mg of oxalate.

    I don’t know the specific details of each testing case, but boiling and draining broccoli can get rid of much of the oxalate. It also depends on the parts of a plant you’re measuring (leaves vs. stalk) as well as the different cultivars and growing methods. It’s a huge mess, I’m afraid! I am also rather frustrated about it.

  20. Sarah Says:

    Thanks Jack. It is quite a mess! Have you been to the Trying Low Oxlates yahoo group run by Susan Owens? It’s primarily looking at oxalates for kidney problems and autism, however, she has a big spreadsheet of foods that have been tested. They are constantlytesting and updating it. (Ans it lists Carob as having 462g of total oxalae per 100g – 29.20 of it being soluable). Here’s the link to the group if you are interested: http://groups.yahoo.com/neo/groups/Trying_Low_Oxalates/info

    Sorry, I know you said you didn’t want people sending you this stuff, but it is a great resource for the oxalate content of foods if you are looking for more.

  21. Sarah Says:

    No problem Dan. And here’s a link to one of Dr. Gregor’s video on it: http://nutritionfacts.org/video/sometimes-the-enzyme-myth-is-true/ He says you need to wait 40mins afer chopping, but Dr. Fuhrman and others have said that 10 should be sufficient and also that if you eat some raw there will be enough to activate the enzymes in the cooked. This food chemistry stuff is complicated!

  22. Jack Norris RD Says:

    Thanks, Sarah. Yes, I know about the Yahoo Group. 100 g seems like a lot of carob, btw. But even at 20 g, it’s still fairly high.

  23. Sarah Says:

    I’m glad you have found the group, Jack. And 100g is definitley a lot more carob than I think anyone would ordanirly consume. 1TBSP is suppossed to be abot 7.5g so that takes the oxalate to 34.65 and 2.19 for the soluable. So then it’s really not so bad.

    I can’t wait for this article!!! Thanks again for all your work on it! I’ve been hoping someone like you would take a deeper look into the issue since I’m having a hard time sifting through it all myself!

  24. Dan Says:

    I too am very interested in the oxalate article. I was never aware it was a problem except in a few special groups – people who have oxalate kidney stones, people with intestinal malabsorption syndromes, and people with compromised kidney function who do a lot of juicing. Beyond that, I wonder what contribution it makes to vegan (un)health.

    Sarah, does Dr Greger say how much broccoli or cruciferae you have to eat raw to activate the enzymes in the cooked version? I guess I’ll head on over to that video link to see what he says. I love this stuff …. vegans helping vegans. Just today I was seeing a bunch of non-vegetarian people and trying to convince them to go vegan – there is so much resistance out there in the general population, it’s really incredible. I have to be very careful how I broach the subject as each person’s attitudes and beliefs are slightly different, but everyone has been brainwashed into thinking meat/dairy/eggs/fish should be the center of one’s diet.

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