Boning up on Calcium

[Guest guest]

" JoAnn Guest " <angelprincessjo

Thu Nov 7, 2002 1:10 pm

Boning Up On Calcium

 

 

 

 

 

Boning Up

On Calcium

 

Are you getting enough? Too much?

The solution isn't as easy as gulping milk by the gallon or popping

supplements by the handful.

 

 

To call calcium the most hyped mineral in history would be an

understatement. There are dozens of heavily advertised supplements on

the market. On grocery store shelves, everything from orange juice to

bread is fortified with it. Packages of antacids, such as Tums and

Rolaids, brag about their calcium content. And no one hypes the

health benefits of calcium more than the dairy industry.

All these products purport to help prevent osteoporosis, the

deterioration of bone mass due to calcium depletion, which afflicts

10 million Americans and causes 1.5 million fractures annually. The

specter of spending our senior years stooped over like a question

mark, slowly, carefully and painfully crossing the street with the

aid of a cane or a walker, afraid of sustaining a serious or even

fatal injury from a simple fall, is frightening indeed.

It would seem, therefore, that we should all eat as many calcium-rich

foods as possible and take calcium supplements to guard against this

debilitating condition, right?

Wrong. At least, not without knowing what we are doing. Studies have

shown that those who ingest large quantities of calcium can also be

among the most at risk to develop osteoporosis. The reason for this

is that the amount of calcium we ingest does not necessarily

translate into the amount of calcium we absorb. At least as important

as the amount of calcium in our diet is the type of calcium we eat,

and what we eat with it. Certain cofactors in proper proportion are

absolutely necessary for the body to absorb calcium, while other

substances inhibit the body's ability to do so. The amount of gastric

hydrochloric acid and the acidity (pH level) of our bodies is also of

fundamental importance. Even our hormonal balance plays a key role in

calcium metabolism. Without taking all these factors into account,

blithely loading up on calcium can actually result in a net

deficiency of the mineral.

The bones: our blood's calcium bank

Bone cells are the body's savings account of calcium. When blood

levels of calcium rise above normal, the excess is stored in the

bones. Conversely, when calcium levels in the bloodstream dip, the

body turns to its bone bank to balance the deficit.

 

Our serum calcium level is affected by many factors, many of which

are not directly related to the amount of calcium in our diets. For

example, stress can reduce free calcium by disrupting hormone

balance. Stress stimulates the production of the hormone cortisol,

which in turn increases levels of the steroid hormone aldosterone, a

key regulator of mineral balance in the body. Chronic stress can

reduce blood calcium levels, requiring the body to continually make

withdrawals from the bone bank.

The dairy myth

There is no question that we need an adequate dietary intake of

calcium. But how much is adequate? What are the best sources? And

what factors are necessary to absorb and utilize this calcium and to

maintain proper levels of calcium in both our bones and our

bloodstreams?

People equate calcium with dairy, and dairy products contribute 75%

of the calcium in American diets. Milk is a $19 billion industry in

the United States, and the Dairy Council spends hundreds of millions

of dollars in advertising and marketing every year. The Got Milk ad

campaign is among the most successful in advertising history.

However, scientists long have challenged the assumption that dairy

consumption equals strong bones. Now, thanks to new studies, their

argument is gaining momentum.

It's easy to understand why the dairy industry touts milk as the

perfect calcium conveyor. An eight-ounce glass packs 300 mg of

calcium along with significant amounts of vitamins A and D, magnesium

and phosphorus all cofactors for bone health. Cheese and yogurt are

similarly endowed. But not everyone swallows the idea that a diet

chock-full of dairy is the best way to bank calcium.

The dairy industry's armor was badly pierced five years ago by a

Harvard Nurses' Health study published in the American Journal of

Public Health. Researchers examined the diets of 77,761 women during

a 12-year period. What they found was that drinking milk did not

protect the participants against bone breaks. In fact, those who

drank the most milk (three or more glasses a day) had more fractures

than those who barely touched the stuff (less than one glass per

week). I'm not surprised that people who consume a lot of dairy don't

necessarily have better bones, says Diane Feskanich, lead author of

the study and an epidemiologist at Brigham and Women's Hospital in

Boston. Feskanich is still monitoring the nurses to see how they're

faring, and she hopes to publish more data sometime this year. We

updated the analysis and found the same results: We don't see fewer

hip fractures with higher milk consumption, she says. There is

definitely a link between protein consumption and osteoporosis.

 

What the Nurses' Health study showed is that, as a preventative

strategy against osteoporosis, eating dairy products is no better

than a placebo, says Neal Barnard, M.D., president of the Physicians

Committee for Responsible Medicine, a nonprofit organization that

promotes vegetarianism and opposes milk consumption. The dairy

industry is built on convincing people that it works.

A more recent strike against the dairy industry came in the form of a

scientific review published last September in the American Journal of

Clinical Nutrition. Researchers at the University of Alabama gathered

all of the credible clinical evidence they could find on bone health

and dairy-rich diets. After an exhaustive review of nearly five dozen

studies, they concluded that there is no solid body of evidence to

support eating dairy foods.

If dairy foods are so loaded with calcium, why are they not

protective of bones? One reason is dairy products' relatively high

protein and salt content. The body utilizes calcium to metabolize

both protein and salt. Approximately 1 mg of calcium is needed to

process 1 g of protein, and Americans routinely eat 65 to 100 g or

more of protein each day. The authors of the study found that some

dairy foods, such as cottage and processed cheeses, are so high in

protein and sodium, which also acidifies the blood, that the

combination could actually negate the food's calcium benefits.

That discovery doesn't surprise Loren Cordain, Ph.D., an evolutionary

biologist at Colorado State University in Fort Collins. [see

Cordain's story, A Diet Solution Based on Evolution, March 2002.]

Cordain is one of a growing number of theorists who believe that the

crux of Americans' high rate of osteoporosis is not a lack of calcium

but our Western diet: heavy on acid-inducing proteins and light on

alkaline-enhancing fruits and vegetables. What we're seeing is a

calcium imbalance, says Cordain. It's not about how much comes in,

it's about how much is going out. Americans have the highest rates of

osteoporosis-related fractures in the world, yet we eat more dairy

products than almost any other country. The data sticks out like a

sore thumb.

Indeed, the facts are confounding. People in North America and

northern European nations consume two to three times as much calcium

as their Asian counterparts, yet break two to three times as many

bones. Milk advocates chalk that up to anatomical differences.

Caucasians have a longer hipbone than Asians; therefore, they are

more susceptible to fracture, says Connie Weaver, P.h.D., head of the

Foods and Nutrition Department at Purdue University in Indiana.

Cordain doesn't buy it. Take that same theory and go to Africa, where

the population has longer bones than Caucasians, and it doesn't hold

up, he says. They eat 500 milligrams of calcium a day, yet the

fracture rate is half what it is in the West.

The United States has one of the world's highest recommended daily

allowances for calcium, and it keeps creeping higher. According to

the National Academy of Sciences, which sets the RDA, daily calcium

recommendations start at 1,300 mg for adolescents ages 9 to 18, then

lower to 1,000 mg for adults ages 19 to 50, and, finally, rise again

to 1,200 mg for people 51 and older. Reaching the RDA for calcium is

virtually impossible unless you're eating tons of dairy products,

which is precisely the point, says Cordain.

Cordain likes to refer back to the diets of hunter-gatherers for

dietary guidance. He points out that milk is a recent phenomena and

that if what dairy advocates say is true, then everyone living before

the age of milk should have had osteoporosis. We don't find that at

all, he says. What we do find are robust, fracture-resistant bones.

Holistic nutritionists also point out the unnatural aspect of what

was touted by the dairy industry as nature's most perfect food: No

other mammal drinks milk from its mother after it is weaned, and no

other species drinks the milk of another species.

Feskanich is also skeptical of the RDA for calcium. Upping the

calcium requirements doesn't seem to be helping prevent hip fractures

in America, she says. It's almost as though we keep raising it in

hopes that it will have some effect, and it just doesn't work.

So what does all this mean to someone who wants to eat a bone-healthy

diet? The science may be complicated, but the dietary advice is not.

Eat plenty of fruits and vegetables

If you find it hard to believe that eating green vegetables is a

superior way to get adequate calcium, consider the diet of dairy

cows. These animals maintain their own huge bone structures and

produce calcium-rich milk from a diet of grass. While it's true that,

cup for cup, most vegetables have less calcium than milk, the body is

able to absorb more of the mineral when it comes from a veggie

source, explains Barnard, because it doesn't come packaged with

protein and salt. In fact, the body absorbs more calcium from kale

and broccoli than from milk.

A 1997 study published in the New England Journal of Medicine found

that as participants upped their fruit and vegetable intake from 3.6

to 9.5 servings a day, their calcium loss declined 30%. A minimum of

five servings of fruits and vegetables a day is important for bone

health because it creates a more alkaline environment, and less

calcium is lost in the urine, Weaver says.

 

Among the richest sources of plant-based calcium are dark, leafy

greens, such as brussels sprouts, mustard greens, broccoli, turnip

greens and kale. But be aware: Not all calcium-rich veggies translate

that calcium into bone. For example, spinach and sweet potatoes are

loaded with calcium but are reluctant to deposit it as they travel

through the body; both are high in oxalate and phytate, two compounds

that inhibit calcium absorption. (Cooking eliminates the oxalate

problem.)

Don't depend on fortified foods

When deciding where your calcium should come from, fortified foods

belong at the bottom of your list. The vitamins and minerals added to

processed foods are necessarily the cheapest available, and their

sources and forms are uncertain. Foods that are artificially pumped

full of calcium shouldn't replace natural sources. There are so many

beneficial factors in food that haven't even been identified; you

really need to go to foods first, says dietician Lola O'Rourke, a

spokesperson for the American Dietetic Association.

Watch your salt

A high-sodium diet drags calcium from bones to aid digestion. Every

day, the typical American eats 3 to 4 g of sodium, equaling a daily

calcium loss of up to 80 mg. By reducing your daily sodium intake by

1 g, you'll save 1% of your skeletal mass each year. Be sure to use

natural sea salt containing at least 2% trace minerals. And do your

best to avoid sinfully salty snacks, such as potato chips and

microwave popcorn. Give high-sodium, processed foods, such as frozen

dinners, the boot, too.

 

Trim animal protein

Eating just one meat-free meal a day can reduce your protein intake

by 40 g, meaning that 40 mg of calcium will stay in your bones, where

it belongs. Plant-based proteins have the added advantage of

containing fiber, an adequate supply of which is essential for proper

digestive functioning. Calcium is absorbed from the small intestine

into the bloodstream, and the health of the small intestine directly

affects the amount of calcium we absorb from our food.

Don't smoke

As if you needed another reason not to smoke, consider this: Smoking

increases your risk of osteoporosis. In one study of smoking and bone

health, researchers followed sets of identical twins in which one

twin smoked and the other abstained. In the end, the smoker had a 40%

higher risk of suffering an osteoporosis-related fracture. One more

reason to quit: Women smokers often enter menopause up to a year and

a half before nonsmokers. Early menopause means that the body can be

deprived of bone-building estrogen even longer than necessary.

Shun soda

Last year, scientists at Harvard found that teens quaffing soft

drinks were three times more likely to break a bone than those who

didn't partake. The risk of injury jumped to five times more likely

for girl athletes. Some researchers point to phosphoric acid as the

culprit since it's thought to hamper calcium absorption. Many milk

advocates argue that soda replacing milk as the beverage of choice

among adolescents is the real problem.

Get plenty of vitamin D

Vitamin D must be present in sufficient quantity for your body to

absorb calcium from the intestines into the bloodstream. Be sure to

get outside and get adequate sunlight our bodies synthesize vitamin D

through the action of ultraviolet radiation on sterols (fat-like

substances) in the skin. You can also add vitamin D-rich egg yolks

and fish oil to your diet. For adults, the recommended daily

allowance for vitamin D is 400 to 600 IU. Many seniors, especially

those who are housebound, suffer from a vitamin D deficiency. The

National Osteoporosis Foundation recommends up to 800 IU per day for

the elderly. Make sure you get your fill, but don't get carried away.

More than 1,000 IU of vitamin D a day can actually inhibit calcium

absorption.

Exercise

Bone density rises and falls according to the demands placed upon it,

so physical activity has lifelong implications for skeletal health.

Adults who were physically active during childhood have better bone

density than those who were couch potatoes. A recent study by

scientists at Pennsylvania State University found that exercise

during the crucial bone-building years is the best predictor of a

woman's adult bone health. Researchers tracked the diets and exercise

habits of 81 girls from age 12 to 18. Those girls who saw the

greatest bone gains as adults were those who exercised the most

during their teens, not those who consumed the most calcium.

So, boost your bone density by hitting the pavement or the gym.

Experts agree that 30 minutes of weight-bearing exercise, such as

walking or jogging, three times a week is all it takes to see

results. Strength training is also an excellent way to keep bones

strong. Either way, it is never too late to start. In studies that

examined physical activity among the elderly, exercise reduced the

risk of bone-breaking falls by 25%. Exercise gives your bones a

reason to live, says Barnard.

Check your stomach acidity

Calcium cannot be digested without sufficient stomach acid. It is

estimated that by age 50, most Americans have lost 50% of their acid-

producing stomach cells to protein overload, parasites, poisonous

substances in food and other factors. Under the best of

circumstances, only about 30% of the calcium we ingest is absorbed;

without sufficient hydrochloric acid in our stomachs, this figure can

drop as low as 4%. This is also why antacids, which claim to be a

calcium source, actually work against calcium absorption. Ironically,

many people take these products because they suffer from heartburn,

which they attribute to excess stomach acid. Yet, according to

gastroenterologist William Stuppy, M.D., the vast majority of his

mature patients suffer from too little stomach acid, which can

produce the same symptoms as excess acid. Dr. Stuppy warns especially

against taking acid blockers such as Pepcid AC. For patients with

chronic digestive problems, stomach pH can be easily measured during

routine tests. One more way to help your stomach is to chew your food

well: Food that is thoroughly masticated generally requires less

stomach acid to digest.

Supplement only with professional advice

When it comes to obtaining calcium from food, the options are

plentiful. However, long-term calcium supplementation, particularly

without the other factors necessary for bone health, is not likely to

stave off osteoporosis. And without the advice of a qualified

holistic nutritionist or naturopathic doctor, it is possible to do

more harm than good.

The amount of bone-density increase you get from supplementation is

dubious, says Feskanich. One theory is that it works initially and

then plateaus. And there's the issue of consuming too much. Regularly

ingesting calcium in excess of 2,000 mg a day may cause constipation,

kidney stones or other problems.

Michael Borkin, N.M.D., often puts his patients on a calcium

supplement or, more accurately, supplements. He recommends rotating

the form of calcium, however, between calcium citrate (one of the

easiest forms to absorb), calcium ascorbate and calcium gluconate. He

also makes sure his patients supplement the necessary cofactors in

proper proportion, including vitamin D and phosphorus.

The relationship between calcium and magnesium is a good example of

the complexities of calcium supplementation. Magnesium has an inverse

relationship with calcium. While calcium relaxes muscles, magnesium

stimulates contraction. Both compete for the same receptor sites in

cells, but a proper balance of both is necessary for health.

Borkin generally recommends that his patients supplement with about

half as much magnesium as calcium although that ratio can vary

considerably from patient to patient. He also recommends patients

take magnesium in the morning and calcium during the day and in the

evening; the body can't absorb more than 500 mg of calcium at a time,

so supplements are best taken in small doses throughout the day.

Calcium can interfere with some medications, including antibiotics.

So if you're taking a prescription drug, consult your health-care

practitioner before adding a calcium supplement.

Contaminants, such as aluminum and lead, are also a concern with some

calcium supplements. To find out if a supplement has aluminum, check

the list of ingredients on the label. Avoid supplements made with

bone meal, dolomite or oyster shells, as they often contain lead.

Remember, ingesting more calcium is not necessarily the key to

preventing osteoporosis. But getting the right calcium may be just

what your body needs.

Catherine Guthrie's health and medical writing has appeared in Self,

Yoga Journal, Health and on WebMD.

Sidebar

Men and calcium: A cautionary note

Calcium is usually talked about in connection with women and

osteoporosis (80% of osteoporosis sufferers are women), but more than

a dozen studies show a link between a high-calcium diet and prostate

cancer. In one of the largest, scientists at the Harvard School of

Public Health studied the diets of 20,885 male physicians to tease

out the relationship between dairy products and prostate cancer risk.

Their results, published in the October 2001 issue of the American

Journal of Clinical Nutrition, found that men who consumed more than

600 mg of calcium per day had a 32% increased risk of prostate cancer

compared with those who took in less than 150 mg per day. The authors

concluded high calcium intake, mainly from dairy products, may

increase prostate cancer risk by lowering concentrations of 1,25-

dihydroxyvitamin D3, a hormone thought to protect against prostate

cancer. For each additional 500 mg of calcium from dairy products per

day, researchers saw a 16% jump in the men's prostate cancer risk.

There's a general message that the more calcium the better, says June

Chan, the study's lead author. That's not necessarily the case,

especially for men.

 

Even more surprising were results from a 1998 study that traced the

health of 50,000 men. The researchers found that those men who were

avid calcium consumers (more than 2,000 mg per day) had a nearly

fourfold increase in the incidence of prostate cancer over their

calcium-shirking counterparts (500 mg or less a day).

Should men swear off calcium-rich foods? Chan says no. She suggests

that men are safe to stay within their RDA of 1,200 mg and can avoid

going overboard by taking a hard look at how much calcium they take

in daily, adding up the calcium they consume from dairy products,

fortified foods and multivitamins. Don't forget to tally the calcium

in antacids; Chan suspects that an overdependence on the stomach-

soothers may be to blame for men's megadoses.

Other experts aren't so willing to rely on the RDA. Chan's advice is

flat out wrong, says Neal Barnard, M.D. He feels that medical

researchers, like Chan, are simply afraid to take a stand against the

dairy industry. I understand that people hate to make a

recommendation against a product that we've known and loved, but

enough is enough, says Barnard. We can't cut the risk of prostate

cancer to zero, but there are things that help. I think men would be

well-advised not to drink cow's milk.

Sidebar

Why We Need Calcium

There's no doubt that calcium is crucial to good health. It is the

most abundant mineral in our bodies, making up 1.5% to 2% of our

weight. Ninety-nine percent of this is stored in our bones and teeth;

our bones consist of about 70% calcium salts by weight. Calcium makes

our bones strong and rigid by forming part of the substance that

cements together the walls of adjacent cells.

But calcium does more than maintain our skeletal structure. It is

essential for the normal functioning of all body cells, acting as a

mediator for many vital cell functions. While our bones contain 99%

of our calcium, the remaining 1% of free calcium circulating in our

soft tissues, bloodstream and extracellular fluid also performs some

crucial functions. For example, without calcium, blood will not clot.

Calcium also regulates muscles' contractility their ability to relax

and the beating of our heart. It regulates neurotransmitters at

synaptic junctions, where nerve impulses are passed from one neuron

to another, and calcium disregulation can cause mental and emotional

problems.

The body carefully regulates these calcium levels, keeping them

within the range of 50 to 65 mg per liter of extracellular fluid.

More or less than this can quickly lead to serious and even life-

threatening conditions.