Calcium Intake for Women

Calcium plays an important role in our bone health and supports other basic functions in the body. A healthful plant-based diet can provide sufficient calcium for most women, but those who fall short in their dietary intake may benefit from a supplement.

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What is calcium and why do I need it?

Calcium is a mineral with an essential role in skeletal development and many other body functions. Most of our calcium, around 99%, is stored in bones and teeth, where it supports their structure and hardness. The remaining 1% circulates in our blood and is critical in supporting our muscular function, neural signaling, and hormonal secretion.

Because calcium is so critical to those functions, the exact amount in our blood does not fluctuate day to day (but it does change in different stages of life). That means that if there is not sufficient dietary intake, calcium will be drawn from our bones to support proper muscular and neural activity. When too much calcium is released from the bones, they become weaker, which could lead to osteoporosis.

Adequate intake of calcium is especially important during pregnancy to reduce the risk of hypertension and pre-eclampsia [1]. Studies have shown that for individuals with a diet low in calcium can significantly improve gestational outcomes with a supplement.

How much calcium do I need?

The National Academy of Medicine (NAM) has a Recommended Dietary Allowance (RDA) of 1,000 mg of calcium per day for women between the ages of 19 and 50 [2]. The Upper Intake Level for this group is 2,500 mg per day. This includes pregnant women and those who are breastfeeding.

Can I get enough calcium from a vegan diet?

Yes, calcium is abundant in plant foods and a varied diet provides sufficient amounts while decreasing the risk of osteoporosis later in life. Foods high in calcium include almonds, beans (kidney, great northern, lupini), and leafy greens (kale and turnip greens). Note that spinach, Swiss chard, and collard greens have binders that decrease calcium absorption called oxalates. Okra is another food that is high in oxalates and although it contains a lot of calcium, it should not be relied on for meeting your daily intake. Many other foods are fortified such as tofu, fruit juices, plant-based milks, and cereals [3].

Absorption of calcium varies depending on the type of food. While dairy is often touted as the best source of calcium, it is actually less bioavailable than from many plants. For example, our bodies are able to absorb about 30% of calcium from cow’s milk and nearly 60% from kale [4]. Fortified foods are also in the 30% range for absorption. The RDA of 1,000 mg daily takes into account the average absorption rates across different foods.

To give you an idea of how much calcium you’re getting, let’s take a look at some common meals. A cup of oats with soy milk, molasses, and a handful of almonds provides approximately 575 mg of calcium – that’s over half of your daily needs. A serving of tofu scramble with kale, broccoli, and kidney beans meets a quarter of the recommended intake.

Vegans should be aware of calcium-rich foods and plan their meals accordingly. Regardless of your food selection, adequate levels of vitamin D are important for calcium absorption.

Should I supplement with calcium during pregnancy?

Supplementing is not necessarily recommended for everyone because negative health outcomes such as kidney stones have been linked to high supplemental calcium intake [2]. Keep in mind that with calcium (as with many other nutrients), more is not necessarily better.

However, in populations with low calcium consumption, studies show that supplementation during pregnancy significantly reduces the chances of preeclampsia [1]. This appeared to apply only to individuals with low intake, meaning take women who consume enough dietary calcium do not benefit from an added supplement.

If you and your health provider believe that a supplement is needed, the World Health Organization (WHO) recommends taking 1.5-2 grams of elemental calcium daily starting at 20 weeks gestation [1]. The NAM and WHO have conflicting recommendations on whether it’s best to supplement calcium with meals or in between [1, 2], so I suggest to follow your healthcare provider’s advice. Note that iron can impede calcium absorption, so avoid taking them at the same time.

Vegan Supplements with Calcium

There are several forms of calcium in supplements, including calcium carbonate and calcium citrate, both of which are vegan. Their bioavailability is different, but luckily the labels of supplements and fortified foods list the elemental calcium equivalents.

I don’t have a particular recommendation for a vegan supplement with calcium, instead, I want to point out that the majority of prenatal supplements and multivitamins include calcium – and that may be unnecessary. In case you’re looking for one without calcium, I suggest Ritual’s Essential Prenatal or Essential for Women supplements.

Summary

1. If you consume calcium-rich foods daily, you do not need to supplement before, during, or after pregnancy.
2. Aim for 1,000 mg of calcium per day from food sources (for women ages 19-50).
3. Vitamin D helps with calcium absorption and iron can impede it.
4. Supplementation during pregnancy is not generally recommended but may be beneficial for those who have a low dietary intake.