Calcium Bio-Availability

As with most science, the story is often much more complicated than is generally communicated. The story behind calcium is very much like this. Although figures are published on how much calcium is needed in the diet there are many other things to consider. The main concept is bio-availability of calcium. Many foods have calcium in them, but often this is simply not available to the body. This is even the case with calcium supplements.

Firstly let’s discuss oxalates and phytates, these are chemicals that exist in food, that actively bind to calcium and stop it being used in the body in an effective manner.

While the calcium rich plants in the kale family (broccoli, bok choy, cabbage, mustard, and turnip greens) contain calcium that is as bio available as that in milk, some food components have been found to inhibit the absorption of calcium. Oxalate is the most potent inhibitor of calcium absorption and is found at high concentrations in spinach and rhubarb and somewhat lower concentrations in sweet potatoes and dried beans. Phytic acid is a less potent inhibitor of calcium absorption than oxalate. Yeast possess an enzyme called phytase, which breaks down phytic acid in grains during fermentation, lowering the phytic acid content of breads and other fermented foods. Only concentrated sources of phytate, such as wheat bran or dried beans, substantially reduce calcium absorption.

While it is important to eat a balanced diet a diet consistently high in oxalates should be avoided. Oxalates will only bind to calcium when they are eaten, and at no stage are we saying not to eat food high in oxalates, simply keep them in moderation. Many foods high in oxalates have great nutritional value in other areas, and some oxalates in the diet are fine.

There are many foods high in oxalates, far too many to mention, some that are very high include rhubarb, spinach and beet. There is a comprehensive list in the articles section of our website.

Please be aware we are not saying don’t eat these foods, just keep them in moderation and don’t eat them all the time.

Foods with a high content of oxalates:

• Vegetables: Green beans, yellow and dry, beet, tooth of lion, eggplant, endive, cabbage, leek, green mustard, parsley, pepper, potato, turnip, spinach, pumpkin, roots and sharp leaves of betabel, carrots, chicory, peppers, green cabbages, bell peppers, olives (green), beet, tomatoes, zucchini, soup.

• Cereals: Plum white corn cake, semoline, cakes of soy bean, whole wheat and wheat based foods, amaranth, black wheat, corn semoline, pretzels, toasted bread, bread made of whole wheat, wheat flour.

• Fruits: Blackberry, currant, raspberry, mill, bilberry, cocktail of fruits, black grapes, skin of lemon, skin of Lima and skin of orange, rhubarb, mandarins and juice of these fruits.

• Fruit droughts and fats: Sesame butter, peanuts, almonds, hazelnuts, pecan nuts, pistachios, seeds, nuts of soybean.

• Drinks: Beer out of barrel, tea, black tea, milk with chocolate, instantaneous coffee, ovaltine, milk of soybean.

• Several: sauce of soybean, chocolate, jams, commercial tomato sauces, conserves made out of tomato sauce.

Foods that have significant amounts of oxalates (each 100 gr.)

• Rhubarb 600 mgs

• Spinach 600 mgs

• Beet 500 mgs

• Fruits droughts 187 mgs

• Chocolates and products with cacao 117 mgs

• Parsley 100 mgs

• Tea 55 to 78 mgs

When discussing bio-availability it is important to look at the biological response. This is the case when comparing conventional calcium supplements and supplements containing MCHC.

MCHC has been clinically proven to be superior at preventing osteoporotic bone fractures than conventional calcium supplements such as calcium carbonate, calcium citrate, calcium gluconate and calcium triphosphate. The superior preventative ability of MCHC over conventional calcium supplements is thought to be due to the higher calcium bio-availability as well as the supplement containing other building blocks of bone, including Phosphorus, Magnesium and Collagen.