Vegan Calcium – Food Sources, Requirements, Absorption
March 4, 2022
Calcium is an essential dietary mineral necessary for many biological functions.
It is well known for building strong teeth and bones but also plays roles in the development and maintenance of the skeleton, nerve signalling, contraction of muscles and healthy regulation of the heart (2)(4).
In this article, we take a look at how much you need each day, vegan calcium food sources and how to meet your needs on a plant-based or vegan diet.
Calcium requirements for vegans
Calcium requirements for vegans change throughout their lifecycle.
Requirements are highest during adolescence to allow for the rapid growth of bone mass and density.
Below are the daily calcium requirements for the population as stated by the Nutrient Reference Values for Australians and New Zealanders (4):
While some minerals require a higher intake during pregnancy, calcium RDI’s remain the same based on the corresponding age group.
Best sources of calcium on a vegan diet
Within Australia, there are a wide variety of vegan calcium sources, both fortified and naturally occurring.
Traditionally, calcium intake was associated with consuming dairy such as milk, cheese and yoghurt. In recent years, with the rising popularity of veganism and increased availability of dairy alternatives, there has been a strong movement for calcium fortification in several dairy-free milks and other products.
Calcium fortification is not mandatory within Australia. It is essential to read the nutrition panels found on the back of the package when choosing tofu or plant milks.
A good rule of thumb is to aim for at least 120mg of calcium per 100ml or 300mg per cup.
Some of these products may also be fortified with vitamin b12, another crucial nutrient for vegans.
The amount of calcium in plant-based milks can vary significantly between brands. For example, Vitasoy Soy Milky Lite contains 300mg of calcium per 250mL whereas Bonsoy soy milk only has 53mg per 250mL. For our full list on calcium-fortified plant milks, read our article on this topic here.
Comparably, tofu can be set with either magnesium or calcium. When trying to choose a calcium-rich tofu, look out for the following on the ingredients list:
- E516 – Calcium Sulphate
- E170 – Calcium Carbonate
- E509 – Calcium Chloride
The following picture contains brands of calcium-set tofu you can find at Woolworths and Coles.
You can find our full list of calcium-fortified vegan products such as milks, yoghurts, cheese and tofu in our Ultimate Vegan Shopping Guide.
In addition to consuming fortified products, there is a wide range of vegan foods that naturally contain this mineral.
Vegan calcium-rich day on a plate
Porridge with ½ cup Vitasoy Calci-plus soy milk served with 1 banana and handful blueberries (approx. 200mg)
Mango and berry smoothie made with 1 cup So Good oat milk served with 6 dried figs and a handful of brazil nuts (approx. 513mg)
Roast chickpea and veggie salad with 1 tbsp tahini dressing (with ½ cup chickpeas, ½ cup cucumber, 1/3 medium avocado and ½ medium tomato), approx. 145mg
Vanilla Cocobella yoghurt pouch and 1 cup of fortified orange juice (approx. 324mg)
Sesame tofu poké bowl (with Nutrisoy calcium-fortified tofu, broccoli, bok choy & shredded nori), approx. 155mg
Total: 1337mg calcium
Maximising calcium absorption on a vegan diet
Although there is a diverse range of calcium sources, there are many factors that can inhibit absorption.
High intake of oxalates and phytates
Typically, those following a vegan diet may consume higher levels of oxalates and phytates. Oxalates are a natural substance found in many plants that bind to calcium molecules, making them unavailable to the body for digestion. Foods high in oxalates include:
- Soy, almonds, cashews
- Spinach, potatoes, rhubarb, beetroot
- Dates, berries, kiwi fruits
While oxalates reduce absorption, one tip to minimise oxalate levels in vegetables is to boil or steam them.
Phytates can also inhibit the absorption of many dietary minerals including calcium, iron and zinc. Phytates are most commonly found in nuts, seeds, legumes and wholegrains.
To minimise the effects of phytates, try soaking nuts and sprouting seeds and wholegrains.
Low vitamin D intake
The human body needs vitamin D to facilitate calcium absorption within the intestine and regulate levels in the blood.
Vitamin D is found within our skin, in an inactive state. Getting outside with exposure to the sun will convert this form of vitamin D to the body’s preferred form for metabolism.
Combining this with adequate dietary sources of vitamin D can help to make sure that you get enough and help to combat calcium inhibitors. Some calcium-fortified products are also fortified with Vitamin D to assist with absorption. Examples of this include Vitasoy Calci-Plus soy milk.
High protein diets
Protein intake can also affect dietary calcium requirements. Diets high in protein can slightly increase the amount of calcium excreted from the urine.
It is important to note that a low protein diet can also be a concern for bone health, so protein shouldn’t be avoided for this reason.
For each gram of protein, 1 mg of calcium is excreted. By simply consuming a little more dietary calcium, these losses can be mitigated.
Is being vegan a risk factor for calcium deficiency?
While there are some studies to indicate that vegans and vegetarians may not meet calcium requirements, around 50% of Australians do not meet their daily needs, regardless of whether they are following a vegan or plant-based diet (2).
With more and more brands introducing vegan calcium-fortified foods, reaching daily requirements is now more attainable than ever.
However, for vegans who may not consume fortified products, it is more likely that a calcium deficiency may develop.
99 percent of calcium is stored within our bones and teeth. This means when we do not replenish stores through our diet, the body takes deposits from our bones to assist with necessary biochemical functions. Over time this affects bone density. Ultimately, severe deficiencies can result in osteoporosis and osteopenia. (2)
Symptoms that people may experience from severe calcium deficiency include:
- Muscle spasms
- Memory loss
- Easy fracturing of bones
- Weak and brittle nails
Sadia, a plant-based dietitian from Canada has a short video that sums up why it’s important to prioritise bone health as a vegan and talks about how to prevent calcium deficiency.
While it is always recommended and completely attainable to meet calcium requirements from a vegan diet, sometimes additional support may be needed.
When looking at calcium supplements, it is important to check dosage levels. Supplements should not exceed 500-600mg as our body cannot digest large quantities of calcium at a time. Additionally, too much calcium can have negative effects on heart and gut health (7).
Calcium supplementation generally comes in two forms – calcium carbonate and calcium citrate. Supplementation should be closely monitored, and it is always recommended to speak to a GP or dietitian before commencing any supplements.
1. Calcium carbonate
Calcium carbonate-based supplements are usually cheaper in price and are recommended to be taken with food. Calcium carbonate-based supplements are not recommended for vegans currently taking antacids as it requires stomach acid for absorption (9).
2. Calcium citrate
Calcium citrate does not use stomach acids for absorption and can be taken on an empty stomach for those who cannot take calcium carbonate. However, these types of supplements will come at a higher cost (9).
Getting enough calcium on a vegan diet is important to maintain bone health and other important bodily functions. Dietary requirements change across the life cycle and increase during adolescence and for older adults. Following a vegan diet does not necessarily increase your risk of deficiency.
The best vegan calcium sources are calcium-set tofu and fortified plant-based milks, cheese and yoghurt products.
Getting adequate vitamin D is essential for calcium absorption. Certain plant compounds including oxalates and phytates can reduce calcium absorption, and it can be beneficial to cook, soak and or/sprout foods that are rich in these anti-nutrients.
Supplementation may be beneficial for some people, however this should be undertaken with guidance from your GP or dietitian.
Wondering whether you are meeting your calcium requirements on a vegan diet? Our dietitians at Plant Nutrition and Wellness are experts in all things vegan, vegetarian and plant-based nutrition. You can book an online appointment here.
This article was co-written by PNW Clinic dietitian Kiah Paetz and student volunteer Leanna Fyffe.