Calcium
I think most of us believe there is an abundance of calcium in our diets
considering many of us consume a great deal of dairy products. Interestingly,
however, this is not the case! It turns out that calcium deficiency is
extremely common. The average dietary intake of calcium in the U.S. is well
below the recommended levels. You may ask yourself how can this be so after all
of that Ben & Jerry's? Well, it just so happens that consumption of dairy
products such as milk, cheese, ice cream and yogurt are only a small piece of
the puzzle when it comes to calcium. Many factors affect the absorption of the
calcium in our diets, and even more surprising is that calcium is actually more
absorbable in foods such as dark green leafy vegetables—something many of us
are sorely lacking in our diets!
Role in the body
When I hear the word calcium—a vision of strong teeth and bones comes to
mind—however, calcium has many other important roles in the body. Besides
acting as a structural component of bones and teeth, calcium plays a large role
in muscle contraction, nerve impulse transmission, and the maintenance of a
regular heart beat. It also acts as an intracellular messenger—mediating the
constriction and relaxation of blood vessels. When levels of calcium are low,
the body will use calcium stores in the bones—this is a precarious situation as
it can eventually lead to osteoporosis and many other physiological problems
such as arthritis, muscle cramps, muscle pain, high blood pressure,
irritability, and parasthesias (numbness and tingling in the hands and feet).
Deficiency
Unfortunately, absorption of calcium from our food is not a straightforward
matter. Many factors affect its absorption in both positive and negative ways.
Calcium needs other nutrients such as vitamin D for proper absorption. There
are also some obstacles: foods containing oxalates decrease absorption of
calcium. Oxalates are found in high concentrations in spinach, rhubarb, Swiss
chard, beetroot, peanuts, tea, and cocoa. Other problematic substances include:
- caffeine – approximately 2-3 cups a day of coffee can promote excessive urinary loss of calcium
- sodium - increased sodium intake results in increased loss of calcium
- phosphorus - diets high in phosphorus and low in calcium promote calcium loss
Unfortunately, this is not a difficult feat to accomplish as Americans consume
approximately double the RDA of phosphorus daily. This is a result of drinking
soda and eating processed foods containing polyphosphate food additives.
Include it in Your Diet
Excellent food sources of calcium are dark green leafy veggies such as Brussels
sprouts, kale, broccoli, bok choy, cabbage, mustard, collard and turnip greens.
Other good sources include milk, cheese, yogurt and fortified tofu.
For adults under 50 years of age, an adequate intake level is 1,000mg a day.
For adults over 50, 1,200 mg is considered to be adequate. Here are a few
estimated absorbable calcium values to guide you in choosing how many servings
you need a day to meet your requirement:
Milk 8oz: 96mg; Yogurt 8 oz: 96mg; Chinese Cabbage 1 cup: 190mg; Mustard Greens
1 cup: 88mg; Bok Choy 1 cup: 86mg; Kale 1 cup: 60mg; Broccoli 1 cup: 44mg;
Tofu, fortified 1 cup: 160mg.
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