June 2008 - Vol 3 Issue 6

Calcium Challenges
Factors that fight calcium absorption
by Michelle Gibeault Traub, R.D.

As you learned in last month’s "Get More from Your Calcium Supplement", some nutrients and conditions help with calcium absorption. You’ve been using what you learned to properly balance your calcium and vitamin D intake everyday, right? If so, congratulations, you are well on your way to strong bones. But, be warned, there are challenges lurking. Some nutrients can actually interfere with calcium absorption, or even strip it from the bones. Let’s review some of the worst offenders.

Calcium’s Enemies

• Iron – Although iron is essential for maintaining healthy red blood cells it competes for absorption with calcium. This means that foods or supplements containing iron should be taken separately from calcium supplements or calcium-rich foods. This is one reason why a standard multi-vitamin really can’t meet your calcium needs. Most also contain iron which means absorption of the mineral will potentially be inhibited.
  
  
• Soda containing phosphoric acid – Phosphorus in excess can upset the balance of calcium ultimately causing it to be released from the bones. Regular soda-drinkers (especially colas) have been found to have lower bone density (see also, “Drink to Your Health”)
  
  
• Sodium –Our food supply is overflowing with sodium. Other than promoting high blood pressure in salt-sensitive individuals, the mineral has not been considered a major concern. However, experts are now questioning sodium’s impact on overall health. Osteoporosis is one of their primary concerns since excess sodium tends to pull calcium from the bones. Limiting sodium intake to 2400 mg per day and being diligent about calcium intake can help remedy the situation.
  
  
• Protein – High protein diets tend to upset the calcium balance in the body. As a result, foods like cottage cheese and cheese, which contain calcium, are not considered to be ideal sources of the mineral because of their high protein and sodium content.
  
  
• Tobacco, Alcohol & Caffeine – They can be considered the toxic trio in terms of bone health. Smoking, drinking alcohol, or consuming excess caffeine all strip calcium from the bones.
  
  
• Phytate – A compound found in wheat bran and legumes such as pinto beans and peas, phytate can inhibit the absorption of calcium. Since phytate is found in very healthy foods, these foods should not be avoided, but rather calcium-rich foods or supplements should simply be taken separately from high phytate foods whenever possible.
  
  
• Oxalic acid (found in spinach, rhubarb, and chocolate) – While phytate can impair absorption of the calcium in foods eaten with it, oxalic acid only impacts the calcium in foods that contain it. For example, Adora Calcium is made with premium chocolate which naturally contains oxalic acid. Some of the calcium in this supplement is actually bound to that oxalic acid. As a result, the makers of Adora add additional calcium to insure that the product delivers a full 500 mg of elemental calcium per piece. In the case of spinach, it is a bit trickier to estimate how much oxalic acid is actually present. Therefore, even though spinach is considered to be fairly high in calcium (272 mg per cup), it is not really recommended as one of the more absorbable sources of the mineral.    
  
  
• Tannins – Tannins are acidic compounds primarily found in tea that can also bind to calcium. Their impact seems to be minimal, but adding a splash of milk to your tea will help offset their effects.
  
  
• Sweat – While sweat is a healthy way for the body to cool off, excessive sweating takes some calcium with it. If you are very active (working out for an hour or more), be mindful of replacing not only the fluids you lose through sweating, but also the vital minerals like potassium, sodium, and calcium.

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