Nutrient Sinks: Scenarios Leading to Reduced Nutrient Absorption

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10/22/2005| 0 comments
by Kathy Zawadzki

Nutrient Sinks: Scenarios Leading to Reduced Nutrient Absorption


People tend to look at nutrients independently when they consider their nutrition needs. We?re concerned about our bones, so we look at how much calcium we?re consuming. We?re worried about anemia, so we find sources of iron. What we rarely consider, however, is how different minerals and other micronutrients interact with each other when they?re present in the same meal, and how that can impact what compounds make it into our bodies.


Many different minerals and other nutrients interact in ways that affect their availability or absorption in the body.   Some minerals even compete with each other. Calcium and iron are two minerals that are very important to the active individual.   Since the absorption of these minerals is affected by the other foods we eat and drink on a regular basis, it is important to take a look at some of these complex interrelationships.



We have been hearing for years how ingesting more calcium may help to prevent osteoporosis or fragile bones as we age.   Active individuals need to be aware of their calcium intake since we lose more in sweat and use more for muscle contractions than the average adult.   There is new evidence that suggests the key it is not only the availability of calcium in our bodies, but also the interaction between calcium and phosphorus.   The amount of calcium in our bones is very carefully regulated by hormones and increasing calcium intake does not fool these hormones into building more bone any more than delivering an extra load of bricks will make a construction crew build a larger building.  


The high intake of phosphorus found in protein-rich foods such as meat, poultry, fish, eggs, nuts, and legumes as well as carbonated beverages, may be contributing to much of our bone loss . Although its exact role is far from clear, scientists believe that diets in which phosphorus and calcium intake are roughly equal (1:1 ratio) help keep calcium in the body, while diets in which the two are unbalanced are thought to harm calcium balance.   Unfortunately, the typical Western diet is imbalanced in these two minerals. Most people consume roughly two to four times more phosphorus than calcium. For example, meat and poultry contain 10 to 20 times as much phosphorus as calcium, and carbonated sodas have as much as 500 mg of phosphorus, and no calcium, per serving.


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When there is more phosphorus than calcium in the system, the body draws on calcium stored in bones to balance out the ratio. This can lead to reduced bone mass (namely, osteopenia or osteoporosis) that makes bones brittle and fragile. For the vast majority of people, the answer is not only in boosting calcium intake but, rather, limiting calcium loss by reducing the amount of phosphorus they ingest.   


Sodas do contain phosphorus, but there's no need to be concerned about drinking the occasional can. However, drinking too much soda (approximately five cans/day according to a USDA research study) has been shown to upset the


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