Calculating Your Intake of Calcium

Calcium is a very important mineral that makes up about 1-2% of an adult human’s body weight. Calcium provides bone support, helps maintain the pH balance of your blood, and supports muscle and nerve health. Calcium also helps protect colon cells from cancer-causing chemicals, prevents bone loss that can occur as a result of menopause or certain conditions such as rheumatoid arthritis, prevents migraine headaches, and reduces premenstrual symptoms.

Getting too little calcium can result in bone loss, but excess calcium can end up in places where it doesn’t belong, including your blood vessels (causing hardening of the arteries) and your kidneys (in the form of kidney stones). The good news is that it’s pretty much impossible to get too much calcium from plants.

About 99% of your total body calcium is in your bones and teeth. This calcium plays a critical role in maintaining the structural integrity of your skeleton. While calcium is the most critical nutrient to skeletal health, other nutrients help you absorb and use calcium. These nutrients include vitamin Dvitamin K, and magnesium.

Your body is constantly building and breaking down your bones. When your calcium intake is too low, your body pulls calcium from your bones to keep your blood levels close to constant. As long as you eat enough calcium on most days, this borrowing and returning process works very well. But if you do more borrowing from than replenishing to your calcium stores, your bones can become dangerously weak. You do not have to get the exact same amount of calcium each day, as long as you get an adequate amount on most days. As long as your diet contains a wide variety of whole plant foods, your calcium intake should be sufficient to maintain strong bones.

Low bone mineral density, or osteoporosis, is a problem for the elderly, but the damage that leads to it can start early with a poor diet during childhood and adolescence. Between the ages of 10 and 15 years, nearly 40% of your adult bone mass is established, so it’s a critical time to be eating plenty of leafy green vegetables.

The acid/alkaline balance (also called pH) of your blood is essential to sustain your life, and it controls many processes from your breathing rate to your ability to transport oxygen in blood cells. A complex set of tightly regulated hormonal interactions in your body works very hard to keep your blood pH at 7.4 (slightly alkaline), and calcium is essential in this process. When your blood pH starts getting a tiny bit low (down to 7.35), your bones start releasing calcium to bring your pH back into balance.

Most of us have been brainwashed by the dairy industry into thinking that the only way to get enough calcium in our diets is to drink milk and eat yogurt and cheese. But in 1992, a researcher from Yale University studying animal protein intake and hip fracture rates in 16 countries around the world found that those with the highest meat, fish, egg, and dairy product consumption had the most fractures. In a 12-year Harvard study of 78,000 women, those who drank milk three times a day actually broke more bones than women who rarely drank milk. Similarly, a 1994 study of elderly men and women in Sydney, Australia, showed that higher dairy product consumption, particularly at age 20, was associated with increased fracture risk in old age. The latest figures, from 2012, show that in the countries where the consumption of dairy and meat is relatively low, the rates of osteoporosis and/or hip fractures are also low and vice versa.

Protein molecules are composed of amino acids, which contain nitrogen and sometimes sulphur. One very important distinction between animal and plant-derived protein is that animal proteins contain very large amounts of the basic element sulfur. This sulfur is found in two of the amino acids, methionine and cysteine. Your body makes other sulfur-containing amino acids from these two primary sulfur-containing amino acids, including keto-methionine, cystine, homocysteine, cystathionine, taurine, and cysteic acid.

Amino acids, as the name implies, are acids. The sulfur-containing amino acids, which are abundant in meat, dairy, and eggs, are the strongest acids of all, because they break down into powerful sulfuric acid.  Animal protein causes the acidity of your blood to rise. Your body must neutralize this acid by releasing calcium and other alkaline materials from your bones. Fruits and vegetables, on the other hand, are alkaline, and eating these plant foods helps you easily neutralize acid and preserve your bones. The acidic condition caused by eating meat and dairy also raises cortisol levels. Cortisol is a steroid, and elevated cortisol causes severe chronic bone loss. Hard cheeses, including cheddar and Parmesan, are the most acidifying foods, while spinach is one of the most alkalinizing foods.

After calcium is released from your bones, it moves through your blood stream to your kidneys, where it is eliminated in your urine. Eating animal protein results in a large amount of waste products in your blood. In an effort to remove this overabundance of waste protein, the flow of blood through your kidneys increases, and calcium is filtered out of your body. While your kidneys attempt to return much of this filtered calcium back to your bones, the acid and sulfur-containing amino acids from the animal foods thwart your body’s attempts to conserve calcium. In fact, the calcium in your kidneys can form into solid kidney stones. Every 10 grams of animal protein in excess of 30 grams daily increases urinary calcium loss by 16 mg.  Doubling animal protein intake increases the loss of calcium in your urine by 50%. Plant protein does not have a detrimental effect on calcium, bone loss, or kidney stones.

Diets high in sodium also increase the loss of calcium in your urine. The standard American diet contains between 4000 and 5000 mg per day. Reducing dietary sodium to 2400 mg or less per day may increase calcium retention by an extra 20 or so mg each day. Meat and dairy are high in sodium, while plants are low in sodium.

When a muscle cell receives a signal from a nerve telling it to fire, that muscle cell responds by allowing a flood of calcium in, leading to a cascade of activity that causes the muscle cell to contract. If calcium levels are either too high or too low, this process can be interrupted, which leads to muscle spasm. The balance of calcium inside and outside of your nerve cells helps to control the flow of sodium in and out. This sodium flow is how your nerves conduct signals to and from your brain. As with your muscles, abnormal calcium concentrations in the blood stream may adversely affect the ability of your nerves to transmit signals. Because your body has such extensive calcium stores to draw upon to keep blood levels constant, it is very unlikely that simple dietary deficiencies would contribute to problems in your nerves or muscles. However, imbalances caused by disease (especially kidney disease) or hormonal problems (such vitamin D or parathyroid abnormalities) plus poor or excessive calcium intake may be enough to cause nervous or muscular symptoms.

With most other nutrients, deficiency is defined as an amount below which you develop a deficiency disease. Calcium deficiency is defined as an intake amount below what is required to prevent net daily calcium loss. For most adults, this amount is 1 gram of calcium per day. Because children and adolescents are actively depositing new bone, up to an extra 400 mg per day of calcium may be necessary to keep up with bone growth. Likewise, absorption of dietary calcium becomes progressively less efficient with age, and we absorb about 0.2% less per year after age 40.

You can get your calcium from a wide variety of foods, especially green leafy vegetables like spinach, collard greens, mustard greens, turnip greens, kale, and bok choy. Another food that contains calcium is tofu. The amount of calcium in tofu depends on the coagulating agent used. Calcium sulfate and nigari (magnesium chloride) are two commonly used agents. Check the label for ingredients. Choosing tofu made with calcium sulfate comes close to doubling the amount of available calcium per serving.

Americans, especially women, very frequently fail to get the daily recommended intake of calcium. Moving from a standard American processed food diet toward a whole-foods, vegan diet that contains plenty of leafy green vegetables and calcium-set tofu will diversify your calcium intake among a wide variety of foods.

The calcium content of foods is stable. Calcium does not degrade or leech out of foods as they are stored, and there does not appear to be any major change in bioavailability of calcium over the shelf life of the best food sources.

Calcium can be a relatively difficult mineral to absorb from foods. Depending on the type of calcium, and more importantly other nutrients present in the meal, calcium absorption can vary greater than ten-fold from food to food. The most important contributors to this variability are the two nutrients (sometimes referred to as anti-nutrients) oxalic acid and phytic acid (also be referred to as “oxalates” and “phytates”). Both oxalates and phytates can bind together with calcium and other minerals, and some studies show that this binding process may lower the amount of calcium that gets absorbed from your digestive tract into your body. Cooking a high-oxalate food like spinach can reduce its oxalate content. Even though the phytate found in plant foods may impair calcium absorption, diets high in phytates are not associated with loss of bone density. In fact, the opposite is true—diets high in phytate have been associated with improvements in bone mineral density. This is good news since plant-based diets are rich in phytic acid. Phytates, found in seeds, beans, nuts, legumes, and grains, can be reduced by soaking or sprouting. Fermenting can also lower a food’s phytate content, so you may get some increased calcium benefits from eating calcium-containing, traditionally fermented foods including tofu, tempeh, and sauerkraut. Eat several servings of calcium-rich vegetables throughout the day to maximize its availability of this.

Bok choy is uniquely beneficial for its calcium availability – bok choy is lower in oxalate, a substance that binds up calcium and prevents it from being absorbed, than most other leafy greens. About 54% of the calcium in bok choy can be absorbed by your body – compare this to 5% in spinach, a high oxalate vegetable, and 32% in milk. You can much more readily absorb calcium from bok choy than from dairy products.

One of the biggest contributors to calcium nutrition is vitamin D. Calcium and vitamin D work together in metabolism. Low levels of vitamin D can impair absorption of calcium from your intestines. Also, low levels of vitamin D can impair the ability of your kidneys and bones to maintain normal circulating calcium levels. Very high dose supplementation with calcium, vitamin D, or both may result in an imbalance for these two nutrients. If you are taking daily vitamin D supplements well above the Tolerable Upper Limit for vitamin D as set by the National Academy of Sciences at 4,000 IU for adults, and/or calcium supplements well above the Tolerable Upper Limit for adults ranging from 2,000-3,000 mg, talk with your healthcare provider about the best supplementation plan to follow, so that you can be sure to get an optimal and safe ratio of these two nutrients.

Calcium can compete with many other minerals for absorption, most importantly magnesiumzinc, and iron. If you routinely eat more than 1500 mg of calcium per day, you may need to increase your daily iron and zinc supply accordingly.

The following chart lists the best foods in terms of calcium content.

Food

Serving Size

Calories

Amount (mg)

DV

Tofu

4 ounces

86.2

396.89

39.7%

Sesame Seeds

0.25 cup

206.3

351.00

35.1%

Collards

1 cup cooked

49.4

266.00

26.6%

Spinach

1 cup cooked

41.4

244.80

24.5%

Turnip Greens

1 cup cooked

28.8

197.28

19.7%

Bok Choy

1 cup shredded raw

20.4

158

16%

Mustard Greens

1 cup cooked

21.0

103.60

10.4%

Blackstrap Molasses

2 tsp

32.1

117.56

11.8%

Chard

1 cup cooked

35.0

101.50

10.2%

Kale

1 cup cooked

36.4

93.60

9.4%

Dill

2 tsp

12.8

63.67

6.4%

Basil

2 tsp

7.0

59.16

5.9%

Oregano

2 tsp

9.5

57.49

5.7%

Thyme

2 tsp

7.7

52.92

5.3%

Cinnamon

2 tsp

12.8

52.10

5.2%

Leeks

1 cup raw

54.3

52.51

5.3%

Oranges

1 medium

61.6

52.40

5.2%

Broccoli

1 cup raw

30.9

42.77

4.3%

Fennel

1 cup raw

27.0

42.63

4.3%

Celery

1 cup

16.2

40.40

4%

Cumin

1 teaspoon

15.8

39.10

3.9%

Green Beans

1 cup raw

31.0

37.00

3.7%

Brussels Sprouts

1 cup raw

37.8

36.96

3.7%

Sea Vegetables

0.25 cup

8.6

33.60

3.4%

Garlic

1 ounce

26.8

32.58

3.3%

Asparagus

1 cup raw

26.8

32.16

3.2%

Romaine Lettuce

2 cups

16.0

31.02

3.1%

Rosemary

2 tsp

7.9

30.72

3.1%

Coriander

2 tsp

17.8

29.20

2.9%

Cabbage

1 cup raw

17.5

28.00

2.8%

Cloves

2 tsp

13.6

27.13

2.7%

If you look at nutrition data, cooked food may appear to have more calcium than raw food, but that’s just because the cooked food has become more concentrated in a smaller volume.

Another way to look at calcium is by density (milligrams per calorie). The following chart shows 200 calories worth of whole foods and their calcium content. All of these foods have more calcium than a 200-calorie serving of whole milk.

Food (200-calorie serving)

Calcium

DV

Watercress

2181 mg

218.1%

Bok Choy

1615 mg

161.5%

Arugula

1280 mg

128.0%

Turnip Greens

1187mg

118.7%

Beet greens

1064 mg

106.4%

Rapini

982 mg

98.2%

Kale, Scotch

976 mg

97.6%

Collards

966 mg

96.6%

Cabbage, chinese (pe-tsai)

962 mg

96.2%

Chicory greens

870 mg

87.0%

Spinach

861 mg

86.1%

Mustard Greens

792 mg

79.2%

Kelp

781 mg

78.1%

Parsley

767 mg

76.7%

Wakame

667 mg

66.7%

Endive

612 mg

61.2%

Kale

540 mg

54.0%

Chard

537 mg

53.7%

Celery

500 mg

50.0%

Lettuce, green leaf

480 mg

48.0%

Lettuce, red leaf

413 mg

41.3%

Nori

400 mg

40.0%

Cabbage, common

392 mg

39.2%

Romaine Lettuce

388 mg

38.8%

Radishes, white icicle

386 mg

38.6%

Many processed foods add calcium in the manufacturing process, including non-dairy milks, juices, and breakfast cereals. While these fortified foods might be able to provide you with more calcium than they would otherwise contain, they cannot provide you with calcium in a naturally balanced ratio with other nutrients or in a form that evolved along with the food. It’s best to stick with whole, natural, minimally processed foods to meet your calcium needs.


This blog uses the latest nutritional data available from the USDA (United States Department of Agriculture), and the FDA (United States Food and Drug Administration), as well as nutritional data provided by food growers and manufacturers about their products. We believe the information on this website to be accurate. However, we are not responsible for typographical or other errors. Nutrition information for recipes is calculated by Living Cookbook based on the ingredients in each recipe based on statistical averages. Nutrition may vary based on methods of preparation, origin and freshness of ingredients, and other factors.

This blog is not a substitute for the services of a trained health professional. Although we provide nutritional information, the information on this blog is for informational purposes only. No information offered by or through this blog shall be construed as or understood to be medical advice or care. None of the information on this blog should be used to diagnose or treat any health problem or disease. Consult with a health care provider before taking any product or using any information on this blog. Please discuss any concerns with your health care provider.

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