What affects Calcium absorption?

Updated on 11. Jan 2009

Before I write anything here, it is important to note that a healthy and balanced diet as we know it from our parents and grand parents is normally good enough to take care of any problems and parents of healthy and happy children growing properly need not worry.
Sometimes, if some doubts appear about the child's growth then it is surely good to consult the doctor and clarify things and ask for some good tips on increasing the calcium intake, if required.

I am required to remove some important calcium sources from my son's diet temporarily. Here are some facts I collected subsequently to ensure a good calcium intake despite that:

Calcium Absorption is affected by:

1. Vitamin D: Vitamin D is very important for good calcium absorption. It is the signal for the body to absorb calcium , if absent causes calcium malabsorption. Among children known as Rickets among children and osteomalacia in adults. Apart from being produced by the body from sunlight, some common and good sources of Vitamin D are saltwater fishes (sea fishes) ; milk and milk products; eggs (egg yolk); liver; fortified products - cereals, margarine, vegan milk sources etc.
   
2. Phytates (phytic acid) : reduce calcium absorption by binding to the calcium ions. These are found naturally in plant sources like grains, whole grain breads, (wheat) bran, soy beans (although the calcium is still partially available for absorption by the body - source), soy isolates, nuts and seeds. Phytates can be reduced by cooking, sprouting and fermentation (lactic acid - through naturally occurring yeasts). Some examples of such fermented products are yoghurt, sour /leavened breads, sour dough starters, yeast breads, rice preparations like idlis, dosas uttapams made with fermented/leavened rice. Sprouting is another wonderful way of reducing these toxins.
   
3. Oxalic acid: It reduces calcium absorption by binding to the calcium ions. Found highly in vegetables like spinach, collard greens, sweet potatoes, rhubarb and beans. (check the link to jugalbandi for more infomation that)
   
4. Age: The amount of calcium absorbed by the body decreases with age. This is one of the reasons why increasing the calcium intake after the age 50+ is so important to prevent calcium malnutrition and prevent osteoporosis, a not so uncommon problem among women and men at this age.
   

Calcium excretion (loss) is affected by (source):

1. Sodium (Na⁺ ; the mineral, a constituent of table salt) and proteins in the food increase the loss of calcium. However, if the food high in sodium and proteins also contains calcium, then it could counteract the effect of calcium loss, as this calcium will get used up to prevent further loss.
2. Potassium (Ka⁺ ; the mineral): High potassium diet, like eating more than 7-8 servings of fruits per day, in the presence of high sodium diet can help decrease the calcium loss .
3. Caffeine intake can temporarily increase calcium loss, but it can be easily counteracted by increasing the amount of calcium intake. Do not drink it together with meals.
   

Sources:
Office of Dietary Supplements
AboutCalcium.net
Wikipedia

As a response to a comment, a clarification:
Please note that building of stones to our present scientific knowledge in whichever part of the body is not less frequent among those who eat meat than those who don't. Vegetarians do not have more stones than those who eat meat. It is, however, advised to those who have kidney stones, for example, to avoid eating plant products high in oxalic acid, or also those who have gaut or rheumatoid arthritis. It is usually a genetic predisposition for some.
If you do not agree with the facts given here or believe them not to be true, then you are most welcome to disagree, but then please include a reliable source of your information, or mention it accordingly and please don't claim it to be a fact just because you have been hearing it from a "neighbour", or have some vague information in your mind, it is irresponsible. use this as a chance to check the information you have before you put it here, please.

Another important aspect of calcium uptake is its interference with the intake of other important dietary minerals like Iron, Magnesium, Zinc and Phosphorus (a separate post on this topic will follow).

Other related posts at H&T:
How much calcium does a child need?

Update on 11. Jan 2009:
Just found this very informative page on calcium at Bee and Jai's Jugalbandi:
Calcium Q&A