Our daily intake
may in fact be
lower when you consider that, depending on our particular genetic makeup
and the composition of a given meal, our bodies may in fact only absorb
30-35% of the total calcium advertised for a given serving
Strengthening bones
through bioavailability
by Jeff D Leach
Paleobiotics Lab
Osteoporosis.
Just saying the word makes my bones ache.
If you are a
woman and over the age of 50, you have about 40% chance of suffering from
an osteoporotic fracture. That’s higher than your risk to breast and
ovarian cancer. Even worse, 50% of the osteoporotic hip-fracture patients
never fully regain independence and more than 20% will die within 6
months. Not good odds.
If you are
someone who thinks osteoporosis is a “women’s disease,” think again. It
affects 25% of men over the age of 50 and an alarming number of young
people. If the current trends continue, the problem is expected to worsen
by 60% in the next 20 years – regardless of gender.
Most folks are
aware that osteoporosis is characterized by bone fragility and related to
dietary intake of calcium, or the lack of. Simply put – calcium is used to
build bones and to a lesser extent, teeth. From the time we are born until
our mid twenties, our bones are continually growing and require calcium to
do so. The goal during this critical growth period is to achieve peak bone
mass. Thick, mineral dense, bones.
Your peak bone
mass – which again, you can only control until your mid twenties – will
strongly influence your risk of osteoporosis later in life.
From our mid
twenties to about age 50, the density of our bones is relatively stable.
This means no matter how much calcium you consume, your bones are not
going to get any denser. The goal now is to maintain the bone mass you
developed in youth and minimize bone loss associated with aging. This is
especially important for women, who must contend with a number of bone
loss issues exaggerated during and after menopause – not to mention the
demands of pregnancy and lactation on bone health.
While you are
older and wiser, the efficiency at which your body absorbs calcium in
later years, like some many things associated with aging, isn’t what it
used to be.
Despite the fact
that we are confronted daily with the “eat more calcium” message for
“healthy bones” on TV, in newspapers and magazines, on annoying
billboards, and along the isles of our favorite grocery store, nearly 70%
of Americans consume less than the daily recommended allowance of 1,000
mg of calcium a day – give or take.
Our daily intake
may in fact be lower when you consider that, depending on our particular
genetic makeup and the composition of a given meal, our bodies may in fact
only absorb 30-35% of the total calcium advertised for a given serving.
Think about that little piece of critical information for a minute.
Calcium that is
not absorbed is mostly excreted in our urine and feces, which brings up an
important issue – and the point of why I am writing this column on
osteoporosis – bioavailability.
The terms
“bioavailability” and “absorption” are critical nutritional terms that are
often used incorrectly. Absorption describes the process of transport of a
mineral like calcium from your intestine across the intestinal mucosa (the
wall) into the circulatory system, so that it may be utilized or stored by
the body. On the other hand, the bioavailability of a mineral like calcium
means the “proportion” that is “actually” absorbed and thus utilized or
stored.
The key here is
solubility. A swallowed penny, for example, has zero bioavailability. It
will simply enter one end and come out the other, intact. Whereas a glass
of water is highly soluble and will be easily absorbed – nearly 100%
bioavailability.
Even though you
think you are getting 500 to 1,000 mg of calcium from a given food item,
meal, or “supplement,” you may not.
Given this piece
of information, it’s not only important that we increase our daily intake
of calcium to recommended levels, we should seek out means to increase the
bioavailability of the calcium that we do consume – so that it’s not
wasted, so to speak.
One way of doing
this is to lower the pH of your gastrointestinal system by delivering food
to the trillions of tiny bacteria that live in your colon.
Food items that
are not digested in the small intestine are therefore end up in the colon,
are known collectively as fiber. Once in the colon, fiber is broken down
by the bacteria through a process called fermentation, which produces,
among other things, short chain fatty acids and lactic acid. These acids
then in turn make the colon more acidic which increases the solubility of
the calcium, making it more absorbable. One of the short chain fatty acids
produced (butyrate) has been shown to induce cell growth in the colon,
which in turn increases the “absorptive surface” of the colon. This means
more calcium is absorbed and less is excreted in feces.
Among the 500
plus species of bacteria living in your colon, you want to increase the
number of the bifidobacteria and lactobacillus. These two particular
groups are known to be especially useful in increasing the acidity of your
colon – and they thrive well on special inulin and oligofructose-type
fibers that occur naturally in onions, garlic, artichokes, asparagus, and
in lesser amounts in wheat-based products. They are also commercially
extracted from chicory roots (think chicory coffee) and added as a food
ingredient in a growing number of foods. These special fibers are known as
prebiotics.
By increasing the
bioavailability of the calcium that we do consume by a more acidic colon,
we can add an additional dietary measure to the preventive strategies for
fighting this terrible disease.
