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Calcium: Vegetarian Nutrient of Concern #3

Jennifer Hanes MS, RDN, LD

Hey there, fellow plant-based foodies!

Since we were kids, calcium and its link to bone health were driven into our brains. We were told to drink our milk, so we have strong bones.

But does calcium have any other function in our bodies? 

And what if we’re vegan? Or lactose-intolerant?

This mineral is a nutrient of concern for vegetarians, particularly for vegans. But how can we ensure that we get enough?

Today, we’re diving into one of the essential nutrients for vegetarians: calcium. It’s part of my series on nutritional habits that lead to unhealthy vegetarians, but fear not!

We’re here to debunk myths, explore calcium-rich foods, and ensure you’re getting your daily dose of this bone-saving mineral. And hey, we’re doing it with a weight-neutral approach because health is about nourishment, not numbers on a scale.

This post is part of a series on the habits that can lead to an unhealthy vegetarian.

Understanding Calcium Needs

Calcium is the primary building block of our bones, including our teeth, but that isn’t really all it is responsible for.

It also plays a role in the messaging system between our cells; it tells your nerves to transmit signals and your muscles (including your heart) to contract.

Finally, calcium plays a role in regulating certain proteins, even optimizing some enzymes and helping your blood to clot when you have an injury. 

The thyroid, parathyroid, bones, small intestine, and kidneys all play a role in maintaining a steady level of calcium in the blood, making deficiency very difficult to detect.  If you’re not eating enough, your body will actually remove it from your bones in order to maintain the steady blood level it wants.

Menopause, excessive caffeine intake, and low vitamin D intake can all reduce your absorption of calcium from your food and vegetarian calcium supplements, such as vegan calcium carbonate.

On the flip side, calcium supplementation can reduce the activity of certain medications, such as thyroid meds, lithium, some antibiotics, and HIV prophylactic medications.

Vegetarian bowl with from tofu and beans
Photo by Anh Nguyen on Unsplash

Recommended Intake

The RDA (recommended daily allowance) for calcium is 1,000 mg per day for all people between the ages of 19 and 50. This does not change during pregnancy or lactation.

Women over 50 and men over 70 should increase to 1,200 mg per day.

Note that these dietary reference intakes are meant for healthy individuals.

Vegetarian Calcium Sources

Dairy products are the most accessible places to find calcium in food. A serving of yogurt has ~40% of your daily needs.

Examples of Vegetarian Calcium Sources:

  • 8 oz Plain yogurt – 415 mg
  • Fortified orange juice – 349 mg
  • 1.5 oz part-skim mozzarella – 333 mg
  • 1 cup milk – 299 mg
  • 1/2 cup Firm tofu, made with calcium sulfate – 253 mg
  • Fortified breakfast cereal – 130 mg
  • 1/2 cup Turnip greens – 99 mg
  • 1 cup Kale – 94 mg
  • 1/4 cup Almonds – 94 mg
  • 1/2 cup Canned pinto beans –  54 mg

Because vegans do not consume dairy products, their intake may be inadequate. These people should take special care to eat tofu that is set with calcium (read the label), drink fortified orange juice, and get plenty of beans and greens in their diet.

The calcium in plant milk varies depending on each company’s individual fortification processes.

Those with lactose intolerance or a dairy allergy may also have difficulty getting enough.

Challenges for Vegetarians and Vegans

There are plant-based sources of calcium, but it is relatively difficult to get enough in from just plants (mostly green leafy vegetables).  You’d have to have ~10 servings of kale a day to get enough calcium!

In comparison, a vegetarian could get enough calcium in with a cup of yogurt, 1.5 oz of cheese, and 2 servings of leafy, green vegetables.  

Additionally, calcium absorption is much lower in many plant-based food sources (~5% for spinach) than in dairy sources (~27%).  

Because of this, I strongly recommend that vegans use calcium-fortified foods and/or a calcium supplement.

Symptoms of deficiency

Deficiency is difficult to diagnose since the body tightly regulates calcium in the bloodstream.  If your blood work reveals low calcium, this may be an indication that something is wrong with your parathyroid or your kidneys. 

Alternately, magnesium in certain antacids and alcoholism can make your serum calcium levels low. A bone density test can tell you if your bone mass is normal for your age. 

Bone density increases until your early 30s.  Getting adequate amounts of calcium (and vitamin D) is imperative during this part of your life. After this age, inadequate intake accelerates the bone loss that can occur later in life.

Because your body will leach calcium out of your bones if you don’t eat enough, there are rarely symptoms related to a deficient diet.

You won’t necessarily have overt symptoms of a calcium-deficient diet until you experience an unexpected fracture or a bone scan reveals weak or brittle bones.

Causes of secondary Calcium deficiency

Remember that a secondary deficiency occurs when the diet contains enough of a nutrient, but you have poor absorption or abnormally high needs for that nutrient.

Vegetarians and vegans typically consume more vegetables and thus more compounds called oxalic and phytic acids. While these are not bad for you, they can make it more difficult for you to absorb calcium in your foods.  So take extra measures to ensure you are getting enough.

One study showed that omnivores, pescatarians, and vegetarians had the same bone fracture risk. However, the risk of fractures rose significantly in vegans

Renal failure, use of diuretics (“water pills”), and poor parathyroid function can lead to low blood calcium levels. If this occurs, symptoms can include numbness and tingling in the fingers, muscle cramps, convulsions, lethargy, poor appetite, abnormal heart rhythm, and death.

High caffeine intake can increase calcium loss through the urine in anyone, so make sure to moderate your coffee intake.

Heavy alcohol can decrease the absorption of calcium as well.

Conditions that increase Calcium needs

Menopause leads to decreased absorption and then increased bone resorption causing approximately 1% bone loss every year after 65.

As a result, women after the age of 51 (and men after the age of 71) should increase their intake to slow the bone loss process as much as possible.

Treatments for deficiency

Osteoporosis requires an increase of calcium than the recommended intake, adequate vitamin D intake, gentle weight-bearing activity, and medical management.

Low blood levels require correction or management of the condition that caused the poor calcium regulation, likely your kidneys or parathyroid.

Fortified cereal is a good source of calcium. Combined with milk you've got a good breakfast that includes protein, fiber, and calcium! Shown here on a yellow background
Photo by Nyana Stoica on Unsplash

Symptoms of toxicity

Just like low blood levels, high levels are typically related to another health problem. 

Too much calcium in your blood can weaken your bones, create kidney stones, and disrupt your brain and heart function. Overactive parathyroid glands are the most common cause.  

Other causes include cancer, tuberculosis infection, sarcoidosis, long-term immobility, severe dehydration, the medication lithium, some genetic disorders, and some supplements.

Signs and symptoms can range from none to excess thirst and frequent urination, upset stomach (nausea, vomiting, constipation), confusion, lethargy, fatigue, depression, heart palpitations, and fainting.

Treatments for toxicity

You have to treat the underlying cause of elevated calcium levels.

Once the underlying problem is addressed, your levels should return to normal, and any symptoms you may be experiencing will resolve.

yogurt with berries and sliced almonds on a white marbled background.
Photo by Joanna Kosinska on Unsplash

Strategies for Meeting Calcium Needs on a Vegetarian Diet

Vegetarians should make sure that they are getting 1-2 servings of dairy per day, whichever source they prefer.  Additionally, include calcium-set tofu, leafy greens, and beans consistently as well.

If you are vegan, lactose intolerant, or allergic to dairy, it becomes very important to use fortified foods such as orange juice and cereal (check the label) and to take a supplement.

To make sure you are absorbing as much calcium as possible from your food, make sure you are also getting enough vitamin D.  This is why you’ll often see calcium supplements that already contain vitamin D.

Here is an example of 1 day of adequate calcium intake for a vegetarian:

  • Breakfast: 2 pancakes with 1 cup of calcium-fortified soy milk (~500 mg)
  • Lunch: 1 serving hummus on 1 serving pita, 1/4 cup almonds, 5 dried dates (~355 mg)
  • Dinner: scrambled tofu and bok choy over brown rice, green salad with sesame seeds, 1 serving chocolate pudding (~315 mg)
  • Total: ~1150 mg calcium

Importance of Balance and Variety

When discussing one particular nutrient, it is important not to become hyperfocused on only the food sources that contain that nutrient.

This can lead to an imbalance of nutrient intake as other foods are limited.  Variety is still an important aspect of any healthy dietary pattern.

Should I take a supplement?

In the past, we were told yes, absolutely. But further studies have muddied the water.

Supplemental calcium intake dramatically increases your risk of developing a kidney stone. 

More scary is a group of studies that were released linking calcium supplementation to cardiac disease, including myocardial infarction (fancy word for heart attack).

One study showed a 20% increased risk of a heart attack in men supplemented with calcium compared to men who did not. Interestingly, women did not appear to have any change in risk.

There are some concerns about the data collection methods for this study, so more testing is needed.

The current stance of the National Osteoporosis Foundation and the American Society for Preventative Cardiology is that as long as the combined amount of dietary and supplementary intake does not reach the Tolerable Upper Limit, there isn’t any increased risk of heart disease.

However, this can be difficult for the average person to monitor. 

People who take osteoporosis medications, certain antibiotics, levothyroxine, phenytoin, and tiludronate disodium should not take a calcium supplement (or eat a high-calcium meal) at the same time as they take their medications.

Personally, I take a multivitamin (which typically contains 15-20% of the RDA) and try to get my dietary calcium from food sources.

Luckily, many vegetarian sources of calcium are also sources of B12, another nutrient vegetarians should watch. 

Also, I take my multivitamin at night because I take my thyroid medication in the morning.

What supplementation won’t do

Supplementation won’t reverse bone loss once you have osteoporosis.

While you still need to consume adequate amounts of calcium, medication and special safety precautions will need to be followed.

Addressing A Common Misconception About Calcium for Vegans

There is a common misconception that vegans don’t need as much calcium as omnivores because they don’t lose as much through protein-related urine loss.

This going theory hinges on the idea that a high-protein diet causes your kidneys to excrete more calcium.  However, there is no evidence to back the idea that a vegan needs less calcium than a person who eats meat.  

However, there is evidence to suggest that vegans are more prone to low bone density and bone fractures than vegetarians and omnivores. Additionally, higher protein intakes are also associated with greater bone density and a lower risk of bone fractures.

Any Concern for the Omnivores?

Lactose-intolerant omnivores will need to ensure that they get their calcium in with lactose-free milk, or they may tolerate cheese and yogurt better. Whole fish, such as sardines, mackerel, and anchovies, will also help.

Regular dairy consumption will cover them. As will any beans or leafy greens, which they should be eating anyway!

References

Oregon State University

Better Health Channel

National Institutes of Health

Mayo Clinic

So there you have it, folks! Calcium isn’t just a concern; it’s a plant-powered powerhouse waiting to fuel your body.

Whether you’re sipping on fortified almond milk or munching on kale chips, remember that balance and variety are key. Let’s keep rocking those vegetarian vibes, staying mindful of our nutrient needs, and enjoying the delicious journey of plant-based eating.

My Tempeh Shepherd Pie includes tempeh and cheese, making it a good source of protein and calcium!

Also, consider my Mediterranean Quesadillas.

Here’s to strong bones and a vibrant life—cheers to you and your health journey!

How can I get 1200 mg of calcium per day without dairy?

It would be difficult to do, at least with some consistency, but a day with 1200 mg of calcium from food could look something like this:

1 cup of calcium-fortified orange juice, 1 cup of calcium-fortified cereal with 1 cup of calcium-fortified almond milk, 1/2 cup of firm tofu, and 1 cup of kale. This comes to 1294 mg of calcium, but it would depend on the amount of calcium in the fortified foods.

Why might a vegetarian be deficient in calcium?

The answer depends on how you are identifying deficient. If lab work shows low calcium, the individual needs to consult a doctor to see what underlying condition is causing the low levels. This is because your body will take calcium out of your bones to make sure your blood levels stay level.

If deficiency is thought to be due to diet, this could be due to inadequate intake of dairy products, fortified foods, or supplementation. Secondary deficiency could be due to intestinal damage, alcohol abuse, complications with the kidneys, thyroid, or parathyroid.

Can vegetarians eat calcium phosphate?

Calcium phosphate is vegan-friendly.

Is coral calcium vegetarian?

This is kind of an interesting question. Coral calcium is derived from the fossilized remains of coral that is above sea level.
So, while technically it is an animal product, animals are not harmed in the production process.
HOWEVER…
This could easily become quite an ethical dilemma. Coral calcium has become a fringe, dangerous, and unsubstantiated “alternative treatment” for a variety of conditions. If this becomes more popular, I could definitely see unscrupulous companies choosing to harvest live coral once they run out of this fossilized material.
This would be catastrophic for the environment.
I would steer clear for this reason alone.

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