calcium absorption

Question
My question is about calcium absorption.  I抳e read that calcium absorption is reduced due to  Oxalates, which are found in spinach, chocolate, rhubarb, walnuts and tannins (tea), which bind calcium into insoluble complexes and reduces its ability to be absorbed and Phytates, which are found in bran, cereals, seeds and beans, also bind calcium into an insoluble complex. Soy is high in phytates but also contains soy isoflavones. The isoflavones have been shown to increase calcium absorption, balancing out the phytates. Calcium-fortified soy is still absorbed only about 70% of milk calcium.  I try to get my vitamins and minerals the natural way instead of from supplements.  How can I help the absorption of natural calcium when I eat things like spinach, walnuts and such?

Answer
Hello Christina!

  Thank you for your nutrition question.  Calcium from many foods such as milk, cheese, yogurt, kale and tofu is well absorbed. Some substances in other foods bind calcium and make it unavailable for absorption. This is not a problem in a balanced and varied diet. Two common calcium-binding substances are oxalates (found in many green vegetables and chocolate) and phytates (found in unleavened grain products).

My suggestions are:

1.If green vegetables, legumes, nuts and seeds are your main calcium sources, it is especially important to depend on those that contain well-absorbed calcium.


2.If greens are significant calcium sources for you, be sure to rely on low oxalate sources such as broccoli, kale and bok choy or other mustard greens.


3.Don't worry about the oxalates in chocolate milk. There aren't enough oxalates to interfere with the much larger quantity of calcium.


Calcium absorption is dependent on many factors. The total amount of calcium in your diet and your calcium needs are probably most important in determining how much calcium you absorb from a food.


Most researchers agree that the effect of calcium binding substances is not a problem if you eat a variety of well-absorbed calcium-rich foods. However, the calcium in high oxalate foods, such as those listed below, is unavailable for absorption.  

High oxalate foods
beet greens
chard
rhubarb
spinach

Low oxalate, calcium-rich vegetables
broccoli
collards
kale
mustard greens
turnip greens


Phytate seems to be a problem only when whole grain cereals are a major part of the diet (i.e. not just for breakfast) and calcium intake is low. Leavened bread does not present the same problem since yeast fermentation breaks down phytate.

For more answers to your nutrition questions check out www.planetyorgos.com

-George Rapitis, MS
www.juiceblend.com

1. Prev:Passing on my obsession
2. Next:Carbs and Sugars and Fibre