Power Up On Plant-Based Calcium – Sharon Palmer, The Plant Powered Dietitian

Learn how to include plant-based calcium sources in your healthful, bone-protective vegan, vegetarian, or flexitarian eating style.

How do you get enough calcium on a plant-based diet? Well, when you think about calcium sources in your diet, most people go straight to dairy products, like milk and cheese. And while those sources do, indeed, provide calcium, this important mineral can be found in many other food items. But before we talk about plant-based calcium food sources for your diet, let’s set the record straight on calcium and health first.

Calcium and Your Health

What is calcium? It’s the most abundant mineral in the body. Most of the body’s calcium is in bones, including teeth, where it plays an integral part of bone structure and contributes to a calcium bank. Bones are gaining and losing this abundant mineral continuously as part of a remodeling process. When calcium intake is adequate, bones benefit; when intake is low, the bones suffer.

It is important to remember that whether you are living a plant-based lifestyle or an omnivorous one, you need to incorporate calcium into your eating regimen. In addition to bone health, calcium is important for other body functions, such as muscle contractions, releasing hormones, and transmitting messages through the nerves. The body takes calcium from the bones when it is not getting enough in the diet, which can lead to weakened bones. Vitamin D, along with regular exercise, helps the body absorb and process calcium, too. Additionally, nutrients such as protein, magnesium, and antioxidants play critical roles in maintaining bone health. So, you need to make sure all of these nutrients are part of your daily lifestyle. Learn more about maintaining healthful bones on a vegan diet here.

Calcium in a Plant-Based Diet

Getting enough calcium in a plant-based diet isn’t impossible, but it does require some planning. Calcium is an essential nutrient, because the human body doesn’t produce enough calcium on its own so you need to get it in your diet. In a plant-based eating style, calcium can be found in dark leafy vegetables like broccoli and kale, beans, soy products, and calcium-fortified foods and drinks, to name a few. Some plant foods like spinach, sweet potatoes, and legumes contain oxalic acid and phytates. Oxalates and phytates, sometimes referred to as antinutrients, can bind to calcium and inhibit their absorption. These compounds can be removed during the process of cooking, fermenting, sprouting, or soaking, in the case of nuts and legumes. However, keep in mind that high-oxolate sources of calcium, like spinach and chard, may not be as available to the body as cruciferous, low-oxalate sources, such as kale, broccoli, and mustard greens.

If possible, the best way to receive your calcium is from food sources. However, low-dose calcium supplements can be a helpful addition to your day if you are struggling to meet your needs (see below). Make sure to talk to your health care provider before starting any dietary supplement regimen.

How Much Calcium Do You Need?

So, the Recommended Dietary Allowances (RDAs) for Calcium set by the NIH below.

Courtesy of the National Institutes of Health

*AI = Adequate Intake

How to Increase Calcium Absorption

There are many health benefits associated with eating a well-balanced, plant-based diet. One of these benefits includes increased calcium absorption. The absorption of calcium can be aided by increased vitamin D and vitamin C intake. Calcium, vitamin D, and vitamin C play different roles in maintaining bone health. Vitamin D can be received from sun exposure, but absorption is dependent on several factors such as: geographical location, pigment, and duration in the sun. Most people do not get enough vitamin D from the sun and need to consume vitamin D in their diet to meet their RDA. Plant-based food sources of vitamin D include mushrooms exposed to light, fortified orange juice, and fortified plant milks. Vitamin C synthesizes collagen and maintains cartilage found in bones and teeth. Vitamin C can be found in many fruits and vegetables, including cruciferous vegetables, peppers, and citrus fruits.

Calcium Bioavailability

Calcium absorption is dependent on calcium bioavailability. Bioavailability describes how well your body absorbs and uses nutrients. The bioavailability of a calcium food source determines the amount of calcium your body can readily absorb. It is important to eat with intention when trying to increase calcium in a plant-based diet. Where you get your calcium, how you cook food containing calcium, the quantity of food you consume, and what you consume with your calcium sources all affect how well your body will absorb calcium.

Dairy sources of calcium contain more calcium, but have a lower bioavailability (about 30%) than some plant sources of calcium, like bok choy, kale, and broccoli, (about 50%). When deciding which calcium- rich foods to include in your diet, choosing more bioavailable food sources allows you to meet your suggested RDA for calcium and maintain a well-balanced diet.

Sources of Highly Bioavailable Calcium (>50%):

• Kohlrabi, 13.4 mg of 20 mg absorbed (67%)
• Cauliflower, 11.7 mg of 17 mg absorbed (68.6%)
• Green Cabbage, 16.2 mg of 25 mg absorbed (64.9%)
• Brussel Sprouts, 12.1 mg of 19 mg absorbed (63.8%)
• Broccoli, 21.5 mg of 35 mg absorbed (61.3%)
• Bok Choy, 42.5 mg of 79 mg absorbed (53.8%)
• Watercress, 13.4 mg of 20 mg absorbed (67%)
• Radish, 10.4 mg of 14 mg absorbed (74.4%)

Plant-Based Calcium in the Diet

Calcium can come from many tasty, plant-based food sources. The amount of calcium our bodies receive from plant foods is dependent on oxalate content.

Oxalates (oxalic acid) are naturally occurring plant compounds that bind to minerals. Plant foods high in oxalates bind to calcium which results in decreased calcium absorption. Avoiding foods with oxalates isn’t necessary as they still provide nutritional benefits. Instead, we should be aware of which foods contain oxalates and add additional sources of calcium to our diet to make up for decreased absorption. See the chart below to see how you can incorporate more calcium-rich, low-moderate oxalate plant-based foods into your diet.

Low-Moderate Oxalate Plant-Based Sources of Calcium

5 Tips for Getting Calcium in Your Plant-Based Diet

1. Include a few calcium-rich foods each day.
Instead of eating one calcium-rich food per day, try adding a few to increase your dietary calcium intake. Tofu, broccoli, and spinach work well together to make a savory stir-fry packed with calcium and protein. Remember to look for fortified plant-based milks as a great source of calcium, too.

2. Increase vitamin D intake.
Vitamin D helps the body utilize calcium. Along with regular exposure to sunlight, a diet including regular plant-based sources of vitamin D, like mushrooms, and fortified plant milk and orange juice are great ways to ensure good calcium utilization in your body.

3. Try some new foods.
Take a step out of your comfort zone and add some interesting plant-based calcium sources like molasses, seaweed, and chia seeds to your cart on your next shopping trip. Molasses can be used in baking or on cereals, seaweed is great for homemade sushi, and chia seeds can be sprinkled on top of oatmeal or soaked into chia pudding.

4. Be balanced, move more.
Well-balanced meals and exercise are important parts of any healthy lifestyle. You can avoid deficiencies in multiple nutrients by eating well-balanced meals. Additionally, regular exercise encourages good bone health and helps maintain calcium homeostasis.

5. Make it portable.
It’s easy to get plant-based calcium in your busy lifestyle with a few tips. Almonds, oranges, kiwi, and sunflower seeds are wonderful sources of plant-based calcium that also travel well.

Image: Easy Vegetable Tofu Bibimbap Skillet, Sharon Palmer, MSFS, RDN

Written by Sharon Palmer, MSFS, RDN with Cara Joseph, Dietetic Intern

For more information on meeting your nutrient needs on a plant-based diet, check out the following:

How Do I Get Vitamin D on a Plant-Based Diet?
How to Get Vitamin B12 on a Vegan Diet
Meeting Your Nutrient Needs on a Vegan Diet

References:

1. Harvard School of Public Health. (n.d.). The nutrition source: Calcium. Retrieved from: https://www.hsph.harvard.edu/nutritionsource/calcium/
2. Lindshield, B. (n.d). Kansas State University Human Nutrition Flexbook. Kansas State University. https://courses.lumenlearning.com/suny-nutrition/chapter/12-22-calcium-bioavailability/
3. NIH Osteoporosis and Related Bone Diseases National Resource Center. (n.d.). Exercise for your bone health. Retrieved from: https://www.bones.nih.gov/health-info/bone/bone-health/exercise/exercise-your-bone-health
4. Norris, J. (n.d). Calcium: research. Vegan Health. Retrieved from: https://veganhealth.org/calcium-part-2
5. USDA Food Database. USDA website. https://ndb.nal.usda.gov/ndb/search/list. Assessed September 27, 2016.
6. Whitney E, Rolfes S. Water and the Major Minerals. In Whitney E, Rolfes S. Understanding Nutrition. 13^th ed. Belmont, CA: Wadsworth Cengage Learning; 2013.