Best dietary sources of calcium

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Every time I tell someone I’m in nutrition, I get a question or comment about food, the latest diet craze, or my favorite nutrition habits. I realized that for every person that does ask me a question, there are a lot more who are wanting to know the same thing, but were too afraid to ask.

In this new series (as of yet unnamed), I’ll be answering the most frequently-asked questions I receive about nutrition as well as your questions! Have something you’d like to see me write about? Email me at samantha.attard[at]!

Today’s Question: What are the best dietary sources of calcium?

If I was to ask a group of people what the best dietary source of calcium is, undoubtably most people would answer – Milk! This unanimous uproar of support is a product of the truly amazing marketing campaigns from the Dairy Council over the last few decades. However, as Michele Simon and Andy Bellatti point out in their report, dairy products like milk are not the only dietary sources of calcium.

But is dairy the best source of calcium?

Calcium is found in a variety of plant- and animal-based foods including milk, cheese, kale, broccoli, almonds, black beans, sardines, and bok choy. Per serving, milk and dairy products have some of the highest levels of calcium, but the plant-based sources are not far behind, and particularly with a varied diet, it is possible to match the calcium levels of dairy foods while still eating a dairy-free.

There are a few important points we have to consider if we’re trying to find the best dietary sources of calcium:

1. Calcium absorption is more efficient and lower calcium intake levels.
2. Calcium absorption in the intestinal lumen requires adequate Vitamin D; Magnesium is required to adequately store calcium in bones rather than soft tissues.
3. Some calcium in plant-based sources is less bioavailable because the calcium is bound to oxalate and phytate.

Let’s investigate these points further to figure out the best ways to meet the recommended daily allowance (RDA) for calcium.

1. Calcium absorption decreases as the amount of calcium you consume increases.

This means that a smaller percentage of calcium is absorbed if you take a single 1000mg supplement compared to taking a 500mg supplement at two different times of day.

Thus, choosing a food with the highest amount of calcium on the label (like milk or dairy products), may not be the most efficient way of getting your calcium fix. Instead, multiple lower-calcium foods consumed throughout the day can allow for more efficient absorption of the calcium you are ingesting.

2. You can’t have adequate calcium without magnesium and vitamin D.

If there is one thing for sure in nutrition, it’s that the chemicals swirling through our bodies are highly regulated and are interrelated. Vitamin D is necessary for proper absorption of calcium into your blood stream. Magnesium, on the other hand, is responsible for getting the calcium you ingest into hard tissues like bone, instead of staying in your blood stream or in soft tissues like your arteries (where too much calcification is a bad thing). In fact, supplementing with magnesium versus calcium may be the best way to improve your calcium status.

It’s also important to note that vitamin D is a fat-soluble vitamin, so eating fat at the same time as you ingest your vitamin D and calcium is needed for good absorption. Thus, drinking skim milk or no-fat yogurt for their calcium content might not result in the highest absorption levels. Conversely, beans, nuts, and grains all have fat naturally, and we often consume these foods in mixed dishes that do have olive oil or other fat-containing foods.

And where do we get the most magnesium? Plant-based foods like almonds, cashews, soymilk/edamame, black beans, and seaweeds. More info on magnesium-rich foods can be found here.

Thus, eating foods high in calcium AND magnesium (which, you may recall, are the plant-based sources of calcium) may be the best way to improve your calcium status.

Which brings us to an important point…

3. To get the most out of your plant-based sources of calcium and magnesium, they need to be properly prepared.

I’ve mentioned the importance of soaking grains to reduce their phytate content before, but to recap – while there are lots of great nutrients in grains and beans, many of these nutrients are bound to phytate, and can’t be absorbed by the body. Soaking these foods, however, activates the enzyme phytase, which breaks down the phytate and allows your body to absorb the vitamins and minerals. So to get the full benefit of the calcium, magnesium, and the other vitamins, soak your oats, rice, lentils, chickpeas, and almonds!

Like phytate, oxalate is a chemical found in spinach, collard greens, and sweet potatoes that binds to the magnesium and calcium, reducing their bioavailability in your stomach. For best absorption, cook your leafy greens to break down these chemical compounds. It will make digesting the greens easier, too!

Even with cooking, oxalate can remain a huge barrier to calcium/magnesium absorption from spinach, so it would be best to think of some of the other greens, like kale and bok choy as your vitamin source, and not count on spinach to do the job. Regarding your grains and beans….soaking them is great so you have optimal vitamin and mineral absorption, not just for calcium and magnesium.

The takeaway:

Dairy can be a great source of calcium, but it’s definitely not the only one. It is possible to reach your nutritional needs for calcium while sticking to a dairy-free diet! However, varied plant sources and adequate food preparation are critical to getting the best absorption from these sources. If you feel that your nutritional intake is not sufficient in calcium or magnesium, I suggest taking more frequent, smaller doses of calcium throughout the day to increase your absorption.

I know, there’s a lot of info. If it makes you feel better, even nutrition professionals who have been studying calcium for years are still fighting about the best dietary sources of calcium. As always, I say do what feels best for your body and works best for your schedule and budget. We are all meant to shine!

Thanks for reading! Have a nutrition question you’d like to see demystified? Email me at samantha.attard[at]

Have a wonderful day,
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