Ask Amelia Nutrition

What are the Best Sources of Calcium?

couscous salad

Question: Is it true that some dark leafy greens, such as collard greens, have as much calcium as milk?  I’ve heard that the calcium in dark leafy greens is not as “bioavailable.”  I understand that to mean that your body cannot use it as easily or readily as the calcium in milk products.  What’s the whole story?

Answer: Yes, calcium from some foods is more easily absorbed by the body, because other components of the food may increase or inhibit absorption.  The calcium in both dairy products and some leafy greens is considered the most bioavailable, because the body is able to absorb and utilize most of this naturally-occurring nutrient.  Here are some examples of calcium-rich foods and how well the body can use them:

1 cup milk or yogurt 300 mg Yes
1 oz cheese 200 mg Yes
1 cup soy milk 300 mg Somewhat
1 cup fortified orange juice 300 mg Somewhat
1 cup cooked kale, mustard or collard greens 180 mg Yes
1 cup broccoli 50 mg Yes
4 oz canned salmon (with bones) 240 mg Yes
4 oz cooked salmon filet 20 mg Yes
1 cup lentils or beans 50 mg Not really, because fiber will limit calcium absorption
1 cup cooked Spinach or Swiss Chard 120 mg No, because oxalic acid in these greens prevents calcium absorption

Things that Increase Calcium Absorption

Vitamin D (15 minutes in the sun or a 400 IU daily supplement will help)

Lactose (why dairy is such a good source)

Protein (why fish with bones, some beans are good sources)

Things that Inhibit Calcium Absorption

Oxalic Acid, found in spinach, Swiss Chard, berries, nuts, tea, and cocoa (these foods will not only not provide calcium, they’ll also prevent the absorption of calcium from other foods if they’re present in the GI tract at the same time)

Fiber and Phytic Acid found in fiber and legumes

What About Fortified Foods?

Fortified soy milk, almond milk, orange juice, energy bars, etc can be good sources of calcium, but they’re not as well-used by the body as naturally-occurring sources like dairy.

Moral of the Story

Best to get most of your calcium from dairy products, broccoli, and leafy greens like kale, mustard greens, collards, turnip greens, and beet greens.

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  • Bridget
    December 26, 2011 at 6:16 am

    Just read this article again, needed some help with my calcium intake. I also need to learn more about beans. I want to make a black bean soup, any recommendations? Do you prefer soaking overnight or the fast method? Dried beans taste better and have a great texture. Besides less sodium, what are some of the other major nutritional benefits to using dried beans versus canned?

  • Amelia
    December 26, 2011 at 9:55 am

    I would say that dried beans are better because they’re 1) much cheaper and less wasteful packaging-wise, 2) lower in sodium, 3) you can make a big batch and use them for many different things throughout a given week! I love using black beans in a “burrito bowl” like this and in veggie chili

  • aj
    May 24, 2015 at 10:32 pm

    Dried beans are better in terms of health. I’ve read internet articles saying using canned beans are less healthy because they’re more processed with additives, can be older giving less nutrients, picked earlier giving less nutrients, and the can itself (the plastic coating in the can/ aluminium leaks) can give it nasty additives. I value my health too much to use cans despite their convenience and yummy sugar.

  • Amelia Winslow
    May 26, 2015 at 10:18 am

    You can also look for canned beans that are organic, low-sodium, and just have “beans, water and salt” as the ingredients — if you buy organic these are usually the only ingredients.

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