Calcium: Gorilla in the Parlor

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What you need to know

Calcium is one of the two most abundant major minerals in the human body, along with phosphorus. It has been the focus of intense scientific research for a very long time, and certainly has caught the attention of the news media and public alike. Osteoporosis has made it so. Who isn’t concerned today about developing brittle bones in a distant tomorrow?

Let’s look at some of the facts about calcium to see if we really need to be as concerned about it as we have been led to believe.

The latest NHANES Population studies from the USDA examines dietary intake of the US population for many different nutrients. The results for calcium are not impressive.

Typical daily intake of calcium ranges from 494 to 2197 mg. The numbers tell us consumption among individuals is wildly variable. But you should think carefully about your own personal diet before you decide that your personal nutrition is adequate, and that it must be the “other guy” who isn’t getting enough calcium.

Calcium

Usual intakes from food and water in mg

Adequate

Percent

Age in yrs.

Intake (AI) in mg

Mean

in mg

above AI

Male/Female

 

 

 

1-3

500

947

95%

4-8

800

961

68%

Males

 

 

 

9-13

1300

1023

17%

14-18

1300

1256

42%

19-30

1000

1141

56%

31-50

1000

1145

58%

51-70

1200

991

26%

Females

 

 

 

9-13

1300

942

12%

14-18

1300

843

10%

19-30

1000

851

28%

31-50

1000

886

33%

51-70

1200

795

8%

 

The most interesting columns in the chart above are the two on the right: 1) the “mean” intake for various age groups and 2) the percentage of the population above the scientifically determined adequate intake. The mean number is the middle number, indicating that half of the population takes in less than the mean vlaue shown while the other half takes in more. As you can see, the mean intake of calcium for children ages 1 to 8 years is significantly higher than the adequate intake needed to maintain health. But even though the mean is higher than the adequate intake, there will be some children on the low side of the mean that will not receive enough calcium in their diets. The percentage of those underfed children in the general population is revealed in the next column to the right. That column tells us 95% of the children ages 1 to 3 receive an adequate intake, but 5% do not. In the next age group, 68% receive enough calcium but 32% do not.

As we examine the other age groups, we see that only males in the prime of life between ages 19 to 50 achieved a mean that exceeds the daily adequate intake. And yet, even in these two groups, the percentage of male population actually receiving enough calcium is barely above 50%.

All other age groups, both male and female, do not have means that rise above the adequate intake, and the numbers of individuals in the population whose diets meet or exceed the adequate intake are woefully small.

Epidemiological studies tell us that women, in general, begin to lose more calcium in their urine than they absorb from their gastrointestinal tracts by age 30. A woman must take in calcium at levels significantly above the adequate intake throughout childhood and young adulthood in order to build up sufficient calcium reserves to sustain a healthy skeleton throughout life. For men, the critical age at which calcium begins to drain out of the body is targeted a bit later at age 40.

We can see why osteoporosis has become a major concern for women when only 10%, 12% and 28% of women from childhood up to age 30 exceed the adequate intake of calcium. Men only do slightly better. But the factors influencing skeletal health are more complex than just a measure of calcium intake might imply. Diet and nutritional intake, age, and lifestyle all come into play.

CHECKING SOME NUMBERS

Healthy adults, under the best conditions, may absorb up to 30% of the calcium ingested. More common, however, is an absorption rate of 22% to 26%. Children fare better; they may absorb up to 75% of dietary calcium. Nevertheless, as we age, our ability to extract and absorb calcium diminishes, whether from the food we eat or supplements we take.

The human body loses some calcium each day. The quantity lost will vary depending upon age, environment, lifestyle and personal characteristics. For instance, a large man engaged in physical labor in a hot climate may lose up to 1,500 mg. per day in perspiration, feces and urine. For the rest of us though, daily losses will run about 350 mg. on a temperate day to 520 mg. on a hot summer day.

Based on an ideal absorption of 30%, daily calcium losses of 350 mg. to 1,500 mg. per day indicate that 1,167 mg. to 5,000 mg. of calcium must be ingested in order to compensate for daily losses.

Lifestyle factors including stress, high consumption of grains and/or dairy foods, high fat diets, increasing age, smoking, drinking more than 2 cups of coffee per day, excess alcohol consumption, and lack of exercise can reduce the amount of calcium absorbed. Low dietary intake of boron, zinc, vitamin K2, magnesium, vitamin C and vitamin D can also diminish the efficiency with which the body handles the calcium it does eventually absorb.

Clearly most of us do not include enough calcium in our diets. Few individuals take in quantities greater than the 1,100 to 1,300 mg. needed to compensate for even moderate daily losses. If daily losses exceed the amount of calcium absorbed, one is said to be in negative calcium balance. Persistent negative calcium balance has been identified as one of the major risk factors for osteoporosis, and may be a causative factor in hypertension and other degenerative diseases.

WHO NEEDS CALCIUM?

Everyone. It was once believed that only children needed large amounts of calcium in their diets. We now know that calcium is just as important to adults. And the amount required is somewhat controversial within the scientific community. Based on its conservative evaluations of the science, our federal government established the adequate intake amounts shown in the chart above.

The chart below was compiled from over 94 scientific research papers. It clearly shows that calcium is needed at all ages, and simultaneously reveals the dynamic nature of scientific research. Our understanding of what constitutes an adequate intake today may change tomorrow based on new research.

 

AGE

Requirement

per

day

Newborn

200

mg

from breast milk

1 month

235

mg

from breast milk

3 months

300

mg

from breast milk

8 months

350

mg

from breast milk

1 year

600

mg

 

1 – 10 years

800

mg

11 - 13 (preadolescent)

1,500 – 2,500

mg

 

14 – 19 (adolescent)

1,000 -1,500

mg

20 – 40 (young adult)

600 – 1,000

mg

 

40 and up (middle age to elderly)

1,000 – 2,500

mg

Pregnant and lactating women

1,200 – 2,000

mg

 

 

The older you are, the harder it is to absorb calcium. Age-related differences in the ability to absorb calcium were considered in establishing the above general requirements for each group. The daily intakes shown should help prevent most of us from slipping into negative calcium balance.

WHERE CAN WE GET CALCIUM?

Next to dietary supplements, dairy products are commonly considered the most economical and readily available source of dietary calcium. Skim milk can provide over 300 mg. of calcium in each 8 oz. glass. Full fat milk usually provides 250 mg. or more. Yet recent research indicates that calcium from dairy products may essentially do no good. How can that be?

Digestion, absorption and metabolism of dairy foods and grains (e.g. wheat, rye, oats, barley, corn, etc.) contribute large amounts of hydrogen ions to body fluids. Since the measure of acidity is a measure of the concentration of hydrogen ions in solution, then dairy foods and grains are the most acidifying categories of foods that one can ingest. As a result, the metabolic acid load from dairy products leads to the leaching of calcium and some other minerals from the body as it battles to neutralize the acidic load. If not balanced with an overwhelming amount of alkalinizing foods in the form of whole, non-starchy vegetables, consumption of dairy products can actually lead to a net loss of calcium from bones. The situation is exacerbated when grains are also a significant portion of an individual’s diet.

Some high calcium foods are listed below.

Selected Food Sources of Calcium [NIH]

Milligrams

Food Description

(mg) serving

% DV*

Yogurt, plain, low fat, 8 ounces

415

42%

Mozzarella, part skim, 1.5 ounces

333

33%

Sardines, canned in oil, with bones, 3 ounces

325

33%

Yogurt, fruit, low fat, 8 ounces

313–384

31–38%

Cheddar cheese, 1.5 ounces

307

31%

Milk, nonfat, 8 ounces**

299

30%

Soymilk, calcium-fortified, 8 ounces

299

30%

Milk, reduced-fat (2% milk fat), 8 ounces

293

29%

Milk, buttermilk, lowfat, 8 ounces

284

28%

Milk, whole (3.25% milk fat), 8 ounces

276

28%

Orange juice, calcium-fortified, 6 ounces

261

26%

Tofu, firm, made with calcium sulfate, ½ cup***

253

25%

Salmon, pink, canned, solids with bone, 3 ounces

181

18%

Cottage cheese, 1% milk fat, 1 cup

138

14%

Tofu, soft, made with calcium sulfate, ½ cup***

138

14%

Ready-to-eat cereal, calcium-fortified, 1 cup

100–1,000

10–100%

Frozen yogurt, vanilla, soft serve, ½ cup

103

10%

Turnip greens, fresh, boiled, ½ cup

99

10%

Kale, raw, chopped, 1 cup

100

10%

Kale, fresh, cooked, 1 cup

94

9%

Ice cream, vanilla, ½ cup

84

8%

Chinese cabbage, bok choi, raw, shredded, 1 cup

74

7%

Bread, white, 1 slice

73

7%

Pudding, chocolate, ready to eat, refrigerated, 4 ounces

55

6%

Tortilla, corn, ready-to-bake/fry, one 6″ diameter

46

5%

Tortilla, flour, ready-to-bake/fry, one 6″ diameter

32

3%

Sour cream, reduced fat, cultured, 2 tablespoons

31

3%

Bread, whole-wheat, 1 slice

30

3%

Broccoli, raw, ½ cup

21

2%

Cheese, cream, regular, 1 tablespoon

14

1%

* DV = Daily Value. DVs were developed by the U.S. Food and Drug Administration to help

consumers compare the nutrient contents among products within the context of a total

daily diet. The DV for calcium is 1,000 mg for adults and children aged 4 years and older.

Foods providing 20% of more of the DV are considered to be high sources of a nutrient,

but foods providing lower percentages of the DV also contribute to a healthful diet. The

U.S. Department of Agriculture’s (USDA’s) Nutrient Database Web site lists the nutrient

content of many foods and provides comprehensive list of foods containing calcium

arranged by nutrient content and by food name.

** Calcium content varies slightly by fat content; the more fat, the less calcium in the food

*** Calcium content is for tofu processed with a calcium salt. Tofu processed with other

More alkalinizing vegetable sources of calcium include:

Food Description

Serving

Ca (mg)

Acorn squash, cooked

1 cup  

90

Garbanzo Beans, cooked

1 cup

80

Figs, dried, uncooked

1 cup  

300

Tofu, firm, calcium set

4 oz    

250 to 750

Tofu, soft regular

4 oz

120 to 390

Orange juice, calcium fortified

8 oz

300

Sesame seeds, whole roasted    

1 oz.

280

Spinach, cooked

1 cup

240

Broccoli, cooked

1 cup

180

Molasses, blackstrap    

1 Tbsp    

135

Sesame tahini

1 oz (2Tbsp)

130

Arugula, raw

1 cup

125

Chard or Okra, cooked

1 cup

100

Soybeans, boiled

0.5 cup    

100

Dandelion greens, raw

1 cup

80

Turnip greens, raw

1 cup

80

Almonds, toasted unblanched

1 oz.

80

Pinto Beans, cooked

1 cup

75

Tempeh

0.5 cup

75

White Beans, cooked

0.5 cup

70

Kelp or Kombe

1 cup

60

Kale, raw

1 cup

55

Collard greens

1 cup

50

Kiwi, raw

1 cup

50

Sunflower seeds, dried

1 oz.

50

Bok Choy, raw

1 cup

40

Chicory (curly endive), raw    

1 cup

40

Mustard greens

1 cup

40

Orange juice, from concentrate    

1 cup

20

Legumes, general, cooked    

0.5 cup

15 to 50

Corn, brine packed

1 cup

10

 

WHAT CALCIUM DOES FOR YOU

Calcium does more than keep your bones rigid and strong. And, although it is certainly critical to have a sound skeleton upon which to hang the rest of you, calcium does perform a number of other equally critical functions. For instance:

·        Calcium helps regulate the acid/base balance of body fluids.

·        Calcium causes muscles to contract.

·        Calcium is required for energy production within each cell.

·        Calcium plays a role in the transmission of nerve impulses.

·        Calcium is essential to blood coagulation following injury.

·        Calcium is needed for tissue repair.

·        Calcium helps regulate blood pressure.

·        Calcium is active in numerous enzymes that help regulate body functions.

WHAT YOU CAN DO TO GET THE MOST FROM YOUR CALCIUM

Calcium has become a media star. Almost every day we are reminded of calcium’s importance to health through news stories and advertisements. Often we are told that we need only take extra calcium as dietary supplements in order to avoid osteoporosis and provide adequate calcium nutrition. But the answer to the calcium dilemma is more complex. Some of the valuable things you can do to get the most from your calcium are:

1. EXERCISE

Exercise may be the single most important thing you can do to preserve your skeleton. When bones are physically stressed through exercise, more calcium is deposited in them. Bones are strengthened by use just as muscles become stronger when they are used. In addition, absorption of calcium from the intestines improves too. So walk, run, bicycle, play tennis, lift weights, ice skate, hike. Choose a favorite pastime that will put some stress on your skeleton and do it. It will help your overall calcium metabolism.

2. TAKE IN MORE CALCIUM

There is no getting around the need to increase calcium intake. If you take in more calcium, you will absorb more calcium. That extra calcium improves your chances of keeping bones strong and of fulfilling all the other roles played by calcium. Reinforce dietary calcium with supplements of recognized bioavailability. These include calcium citrate, calcium citrate malate, calcium aspartate, calcium glycinate, calcium orotate and calcium lactate. The least bioavailable form of calcium is calcium carbonate, the one most commonly used in dietary supplements. Read labels carefully and avoid calcium carbonate if at all possible.

3. REDUCE DIETARY FAT

Aside from known cancer and heart disease risks, a high fat diet also impedes calcium absorption. Diets typical of industrialized western societies supply 40% or more of their calories from fats and oils. Your doctor or nutritionist can help you determine if your diet is over-rich in fats. If it is, reduce the use of sauces, fried foods, snack foods, and fatty meats in order to reach a more prudent fat intake of 20 to 25 of total dietary calories. Calcium absorption and utilization will be improved.

4. AVOID ACID FORMING FOODS

Your blood and tissues must not become too acidic. Special systems (called buffer systems) in your body control acidity, keeping it within a narrow range. The most acid forming foods are #1, grains and #2 dairy products. Grains and starchy vegetables were never part of the human diet as our ancestors adapted to their food supply over the last 256 million years. Human biochemistry is ill-equipped to handle them even today, and the acid load (hydrogen ions) contributed by their metabolism too easily creates a net acid balance that drains calcium and other minerals from the body. Dairy products eaten in excess can do the same.

Protein is commonly maligned as a strong contributor to metabolic acidity. A high protein diet can create an acid load which may test the capacity of buffer systems, but protein in the form of meat ranks distinctly third behind grains and dairy products in the hierarchy of acid forming foods. Most amino acids, the building blocks of protein, are neutral or alkaline when metabolized. It is only a few abundant amino acids that pour in the hydrogen ions when metabolized.

Excess acid in the form of hydrogen ions must then be eliminated through the urine. Before they can be sent on their way, the “acids” or hydrogen ions must compound themselves with sodium, potassium, phosphorus, magnesium and/or calcium in order to be neutralized and rendered suitable for excretion.

Too much pasta, dinner rolls, pastries, breakfast cereal and other foods made from grain and/or too much milk and cheese can drain calcium and other minerals employed in buffering right out of the body. When you add a hefty amount of protein to the dietary mix, the problem is only made worse.

But please don’t fear protein. It is essential to life. In fact, bone itself is over 50% protein (some texts claim 80%) in the form of type I collagen. But too much of a good thing can work against you. 50 to 75 grams of protein per day is usually adequate. Your needs will be based on your physical stature and lifestyle. It would be far more accurate to develop a healthy sense of caution against the consumption of grains and dairy products as a way of preserving bone health and body stores of calcium.

5. AVOID PROCESSED FOODS

Boxed, canned and frozen foods often deliver synthetic additives that combine with calcium in the intestine and prevent absorption. Processed meats and breaded, fried foods are usually the greatest offenders, containing sodium phosphates, diphosphates and triphosphates. These are three of the strongest binders of calcium. Also, some canned and frozen vegetables have been treated with agents that pull out minerals from the food in order to preserve or enhance the natural color of the canned food. The result is a denatured food, lacking full nutritional value due to its loss of minerals. Often one of the lost minerals is calcium.

6. DON’T WORRY, STAY CALM

Easier said than done. But if you can control your reactions to stress, you will be far better off. The human body spills calcium under the influence of hormones released during stress. Negative calcium balance in periods of stress can often exceed 500 mg. per day even if calcium intake from food and supplements is high. So be sure to get your rest, meditate, organize your life, and do whatever you can to minimize stress – for the sake of calcium and health.

7. GET ENOUGH MAGNESIUM, VITAMINS A, C, K & D, Boron and Zinc

The list of major nutrients that help you use calcium is probably larger than you think. Magnesium is needed to activate vitamin D. Active forms of vitamin D then tell cells in the body to reach out and take in calcium. Of course, when this message is delivered to cells lining the intestine, absorption of calcium occurs. Vitamins A and C along with zinc and calcium are required to build body tissues, i.e. muscles, tendons and bones. Vitamin K, and especially vitamin K2, is required to carboxylate a curious little transporter protein that moves calcium efficiently through the body, placing the mineral where it is needed.

But boron could very well be the most critical factor for bone health and the retention of calcium. Animal studies from mice through dogs to horses and humans has demonstrated that just a little bit of boron in the diet will obliterate negative calcium balance, ultimately resulting in stronger bone tissue. Boron, especially as calcium fructo borate, has the unique ability to restore normal hormonal balance among estradiol, testosterone, dehydroepiandrosterone (DHEA) and calcitriol, the hormonal form of vitamin D (also called 1-25 dihydroxy cholecalciferol). When these hormones are at their optimal level under the influence of boron, calcium ceases to be spilled in the urine, and is instead correctly deposited into bone. Skeletons become stronger.

Deficiencies of any of these key nutrients can compromise your ability to get the most from your calcium. The following amounts should assure efficient utilization of the calcium you take in each day from food and supplements:

Magnesium         600 – 1000 mg.

Vitamin D            2,000 – 10,000 i.u.

Vitamin A             5,000 – 10,000 i.u.

Vitamin C             500 – 5,000 mg.

Zinc                       15 – 30 mg.

Boron                   3 – 6 mg.

The decreasing level of trace nutrients per calorie in even our freshest foods indicates that it is difficult to reach an optimum level of nutrition for the support of bone health. Appropriate supplementation is the best way to assure skeletal health in modern times.

©Mark Timon, April 2014

 

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