Do Calcium Vitamin Supplements Cause Kidney Stones and Constipation?
First, the important fact is that 90% of the composition in kidney stone is calcium oxalate. Oxalate is a type of organic compound found in certain foods (such as spinach and beets), and can have chemical reactions with calcium to form the insoluble calcium oxalate. So to a certain degree, kidney stones are the result of abnormal metabolism of calcium, not because of its high intake. A broad studies have shown that sufficient daily intake of calcium may significantly reduce the risk of kidney stones. The calcium sold on market contains pretty much 100% calcium carbonate which is not a natural form of calcium, it alone is very difficult to be absorbed by human body. Without assistance of the vitamin D, taking this form of calcium basically is useless. Calcium left out without being absorbed during metabolic process is what may cause constipation and formation of stones. Although calcium utilization and absorption are equal in calcium carbonate and calcium citrate with the presence of vitamin D, calcium carbonate may cause constipation in some individuals. So put it bluntly, kidney stones and constipation are caused by taking "bad" calcium, not because of high calcium consumption!
As a nutritional supplement, there are several forms of calcium:
- Calcium Carbonate - Most easily synthesized, lowest cost, yet not easily absorbed
- Calcium Lactate - Calcium in milk exists mostly in this form. It is still controversial as of how well calcium can be absorbed by human body when existed in the form of calcium lactate. Some believe it has similar absorption as calcium carbonate, but is more expensive. Calcium lactate and calcium gluconate are less concentrated forms of calcium and are not practical oral supplements
- Calcium Phosphate - Exists in milk in the form of colloidal calcium phosphate. It costs in between calcium carbonate and calcium citrate. It is easily absorbed and is less likely to cause constipation and gas than either.
- Coral Calcium - This calcium was once bragged as being capable of treating all sorts of diseases, including cancer. But it really is just a salt of calcium derived from fossilized coral reefs and is composed of calcium carbonate and trace minerals. Living coral reefs are endangered species. People are only allowed to collect coral reefs on the exposed surfaces, it would be unlawful otherwise. But study shows it no better than other forms of calcium, so be careful not to be fooled by those marketing schemes.
Then what calcium vitamins should we choose?
Below are some basic guidelines when pick and choose your calcium:
- Calcium must first dissolve in the stomach before it can be absorbed in the small intestine. Please refer to consumerlab.com's advise on testing vitamins for proper disintegration: http://www.consumerlab.com/results/hometest.asp
- Calcium citrate is more easily digested and absorbed than calcium carbonate if taken on an empty stomach and less likely to cause constipation and gas than calcium carbonate. it also has a lower risk of contributing to the formation of kidney stones. Calcium citrate is about 21% elemental calcium. 1000 mg will provide 210 mg of calcium. It is more expensive than calcium carbonate and more of it must be taken to get the same amount of calcium. It would be more appropriate to take calcium citrate if you are currently taking anti-acid medicine, but you may want to consider getting a calcium product with both calcium citrate and calcium carbonate combined. With the help of proper amount of vitamin D, plus taking with meal, the absorption of calcium carbonate will not be affected. The coexistence of calcium citrate helps disintegration of calcium carbonate, but it cannot completely offset the impact on its disintegration caused by decrease in gastric acid, the absorption may still be affected as the result. Therefore, calcium citrate is still your first choice.
- Check out amount of the elemental calcium. More often, the amount on the label refers to the amount of calcium compounds, not elemental calcium. This should be clear at the first place. Daily optimized intake should be 800mg.
- Make sure vitamin D is added. First, calcium can only be digested and absorbed by human body when accompanied by other trace elements. Calcium is digested in the small intestine, and vitamin D helps in this process, it also contributes to calcium's utilization during the formation of our bones. Vitamin D also affects the use of phosphorus in our body. Phosphorus is another very important mineral for the bone health
- High quality calcium vitamins should also contain magnesium and several other minerals. Magnesium is an important element in making strong healthy bones. Magnesium and calcium work together can generate new bone mass. The ideal ratio of calcium and magnesium is 2:1. Calcium products containing magnesium, vitamin D, vitamin K, and small amount of boron and silicon are excellent active calcium specifically designed to supplement calcium needed for healthy bone growth and development. The conjunction of these elements is excellent combination for healthy bones.
The calcium metal is hazardous due to its high reaction with water and acids, but toxicity of calcium ion and other calcium compounds is very low. So it is usually safe to take calcium vitamins on the regular bases as long as consumption is not excessive. For more details, check out calcium on Wikipedia.
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