Vegetarian diet and all its variations (f.e. vegan) provides you with plenty of health benefits, if done correctly. When on this diet, you need to pay extra attention to the following vitamins, minerals and microelements to avoid their deficiency: calcium, iron, zinc, iodine, vitamin B12, vitamin D, omega-3 fatty acids and sufficient amount of protein.
This post is about calcium.
The role of calcium in the body
The first association with the role of calcium on our health is the bone health. Vegan diets, which provide much less calcium through food compared to other types of vegetarian diets, significantly increase the risk of fractures. However, calcium does much more than that. It is required for blood clotting, muscle function, nerve transmission, hormone release, intracellular signaling, and regulating key enzymes. That is why it is so important to provide your body with adequate amounts of calcium.
How to get sufficient amount of calcium?
The body gets the calcium in 3 ways:
1. through foods, rich in calcium
2. through supplementation with calcium, and
3. by removing calcium from bones, if it doesn’t receive enough calcium from food or supplements for its needs. This is a dangerous situation as once it happens, it can’t always be corrected just by eating more calcium later on.
Foods, rich in calcium
Meeting your calcium needs through your diet is safe. Non-vegans get most of their calcium from yoghurt, cheese and other dairy products. As for vegans, the good sources of calcium are:
leafy, green vegetables such as kale, bok choy, broccoli, cabbage and okra
sesame seeds and tahini
pulses such as garbanzo, white and pinto beans
soybeans and its products
squash such as acorn or butternut
dried fruit, such as raisins, prunes, figs and apricots
While using plant-based food as a source of calcium, you need to be aware of anti-nutrients, such as phytic and oxalic acids, that inhibit calcium absorption from food by your body. To give you an example. Spinach stays always high in the list of plant-based products, rich in calcium, as it has the most calcium in this category (260mg/cup cooked). However, it’s not only about what products contain the highest amounts of calcium, but also about whether your body can use calcium from them. In the case of spinach, its high amounts of oxalates lower the bioavailability of calcium so that only 5% (about 13 mg) of calcium can be used by the body! To compare, calcium absorption from from dairy and soy products is about 32%. This means that you would need to eat 16 servings of spinach (85 gr) to obtain as much calcium as from a glass of milk! As you can see, it is not wise to rely on spinach as a significant source of calcium since most of it will not be absorbed by the body.
Regarding the bioavailability of calcium from other leavy green low-oxalate vegetables, it is pretty good. Here are few examples:
a serving of bok choy has 79 mg of calcium, with the calcium absorption of 79%
a serving of kale contains 61 mg of calcium, and about 50% of it is absorbed
a serving of broccoli has 35 mg of calcium, but the absorption is much higher – around 61%.
You can also get the sufficient amounts of calcium in your plant-based diet by selecting calcium-fortified foods, such as fortified breakfast cereals and plant-based beverages.
Another way to meet calcium needs of our body is to take calcium supplements. Here you need to be careful with the right amounts of calcium and its supplementation form. Too much calcium through supplementation might not only upset your stomach, but also can contribute to heart attacks and other unpleasant illnesses.
Our body can’t process more than 500 milligrams of calcium at a time. If you take a supplement with more than that, your body will need to get rid of it and can deposit its excess along artery walls, narrowing the blood vessels, or can form blood clots, creating obstacles for your blood stream to pass through the veins and reach organs.
The highest safe amount for calcium in form of supplementation (the tolerable upper intake levels, ULs) is for adults aged 19-50 – 2.500 mg/day; for adults over 51 years old – 2.000 mg/day.
It is advised to take calcium supplements with food. It is better to split the doses, larger than 500 mg, over the day. And don’t forget about the absorption. For your body to make use of calcium properly, you also need to get enough vitamin D and magnesium.