Quick question: when you think of calcium, what's the first thing that comes to mind? Is it milk? Dairy? True, those are good sources of calcium, but are they the best?
What about people who are vegan, lactose-intolerant, or who have a milk-protein allergy? Well folks, I've got good news for you, it's totally possible to get all the calcium you need on a dairy-free diet. And to help you out, I've put together this handy guide to plant-based calcium.
What is calcium?
Calcium is the most abundant mineral in our bodies. Of course you’ve heard before that calcium is important for healthy bones, and in fact 99% of the body’s calcium supply is stored in our bones and teeth where it supports their structure and function.
But the other 1% is incredibly important as well! Calcium is necessary for muscle function (including our beating hearts!), proper blood flow throughout our bodies (vascular contraction and vasodilation), intracellular signalling and hormone secretion, and nerve transmission. It’s important stuff!
How much calcium do I need?
How much calcium you need in your diet really depends on who you are. We adult people tend to need about 1000mg per day, with an increase to 1200mg/day for women over 50.
Some groups of people need to pay extra attention to their calcium intake as they either don’t get enough calcium in their regular diets, or don’t absorb it well. This includes:
-Vegans and vegetarians
-Those with compromised gut function such as Celiac, Chrohn’s disease or IBS
-Women over 50
Calcium and bone health:
Our bodies very carefully regulate the amount of calcium present in our bloodstream, referred to as serum calcium, so it doesn’t fluctuate with dietary intake. Rather, the body uses bone tissue as a calcium reserve in order to maintain constant concentrations of calcium in our blood, muscle, and intracellular fluids.
Our bones are in an ongoing state of remodelling, with constant resorption of calcium into the bloodstream, and deposition of calcium from the bloodstream into new bone.
When we’re young and growing, bone formation exceeds resorption. In the stages of early and middle adulthood, the processes are more or less equal, but in ageing adults, especially among postmenopausal women, bone breakdown exceeds formation.
What are some sources of plant-based calcium?
The first thing that most people jump to when they think about dietary calcium is dairy. While it’s true that dairy is a good source of calcium, it’s not the only one out there! Vegans and lactose intolerants can breathe easy knowing there are lots of plant-based ways to get calcium into your diet.
- Tofu (depends on brand and how it's made, but roughly 350mg per 100g of firm tofu)
- Collard greens (268mg per 1 cup cooked)
- Kale (172mg per 1 cup cooked)
- Bok choy (158mg per 1 cup cooked)
- Spinach (136mg per 1 cup cooked)
- Tempeh (111mg per 100g)
- Pinto beans (109mg per half cup cooked)
- Chickpeas (105mg per half cup cooked)
- Sesame seeds (88mg per tablespoon)
- Almonds (75mg per ounce)
- Tahini (64mg per tablespoon)
- Chia seeds (65mg per tablespoon)
- Blackstrap molasses (41mg per tablespoon)
So a recipe like these Winter Veggie Meal Prep Bowls with greens, tofu, and tahini sauce is packed with plant-based calcium!
There are also many foods that are fortified with calcium, such as orange juice, non-dairy milks, and cereals, all of which can contribute to your daily calcium intake.
How do I enhance absorption of plant-based calcium?
Eating your calcium-rich foods together with vitamin D and magnesium-rich foods will help your body to absorb the calcium more easily.
On the contrary, iron and zinc both compete with calcium, so supplements or foods especially rich in these minerals should be avoided at the same time as calcium.
Phytates, oxalates, and tannins also inhibit calcium absorption. But there are simple ways to work around this!
Phytates are antioxidant compounds found in whole grains, beans and legumes, nuts, and seeds. You can reduce the phytates and make calcium more bioavailable by soaking your whole grains, nuts, and beans before you cook them.
Oxalates are found in leafy greens such as spinach, chard, and kale. Again, by cooking your greens you will reduce the amount of oxalic acid and improve calcium absorption. This is one of the reasons I prefer to use frozen greens in my smoothies - they've been blanched prior to freezing.
Tannins are found in black tea (and in wine) and are the compound responsible for the astringent (powdery) feeling in your mouth. If calcium absorption or bone density is a problem for you, avoid drinking black tea with your meals.
For a calcium-packed smoothie, try this Date Almond Smoothie. It's made with fortified almond milk, almond butter, and frozen, blanched spinach.
Does protein enhance calcium absorption?
The effect of protein, like that found in cow's milk, on calcium absorption remains uncertain. Some studies show that high-protein diets result in increased calcium loss, and may be associated with an increased risk of fractures.
Other studies show that high-protein diets are advantageous for calcium absorption, reducing the risk of bone fractures and increasing bone density.
There is very likely a genetic component to these differences, so if you enjoy and tolerate high-protein calcium-rich foods such as dairy products, then go ahead and eat them. If you prefer to get your calcium from plant sources, that's ok too.
Do I need a calcium supplement?
In general, it should be quite easy to get adequate calcium through your diet. If you’re in one of the at-risk groups mentioned above, however, you should speak to your health care professional about your calcium intake and whether supplementation is right for you.
Calcium supplements can be quite hard on the digestive system, causing constipation and bloating. Taking calcium supplements together with magnesium can help with this, as can taking it with food. It’s also worth noting that the body has a limited capacity to absorb calcium, so rather than taking 1000mg once a day it would be better to take 500mg twice a day.
If you know that you’re prone to kidney stones, it’s especially important to speak to your doctor before you begin supplementing with calcium, as excess or high doses of calcium can cause larger and more frequent stones.
The bottom line
You should be able to get all the calcium you need to meet your daily requirements from a plant-based diet. Include foods such as leafy greens (cooked to reduce the oxalic acid content), beans, and tahini in your diet to boost the calcium content naturally. If you're concerned about deficiency or are in an at-risk group, speak to your heath care professional about supplementation.
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This article was originally published April 7, 2015. It was most recently updated on January 31, 2019.