Did you know that the Recommended Dietary Allowance (RDA) varies by country? For example, in America, the RDA for adults is 1200mg of elemental calcium per day while it is only 800mg per day in Europe and several Asian countries. If, as we claimed Canada’s Food Guide, this contribution is made according to the most rigorous science, then how is it that varies from one country to another? Scientific data, however, cross the borders! The most curious in all this is that osteoporosis is more common where the RDA for calcium is lower … Moreover, researchers have shown in young women, a higher intake to 800mg of calcium daily did not provide any additional benefit on bone development.
Several authors argue that in America, the RDA for calcium was increased due to significant political pressure lobbies milk (such as the Dairy Farmers of Canada). Thus, it is now, for all practical purposes, impossible to achieve the recommended intake without consuming milk and its derivatives.
A maximum absorption
The concept of maximum absorption, yet very important, is too often overlooked when it comes to calcium. The maximum absorption is the maximum that can be absorbed by the intestine. When the intake is too high, the intestine can not absorb the surplus beyond this limit. This concept is well accepted when it comes to vitamin C, magnesium or glucosamine. Indeed, Health Canada issued a dose limit for vitamin C 2000mg per day. This limit is based on the maximum absorption is 1000mg per dose (2 doses per day = 2000mg). In fact, if you take more than 1000mg of vitamin C per dose, you run the risk of having loose stools. When the dose exceeds the absorptive capacity of the intestine, the amount of vitamin C remains unabsorbed in the intestine and can cause loose stools. However, establishing a dose limit by Health Canada seems to imply that to exceed this dose of 2000mg per day is dangerous, what is wrong.
The magnesium case is similar. Health Canada has established a maximum dose of 350mg per day. Again, this dose is based on the maximum absorption and the only risk, beyond this dose, is having loose stools with one exception, people with kidney failure should consult before take some extra magnesium whatsoever. In addition, this dose is arbitrary because the amount of unabsorbed magnesium can vary depending on the magnesium salt selected (for example, the absorption of magnesium oxide is very low while that of citrate and aspartate is very good).
The maximum absorption of calcium is documented since the 70s, and yet we never hear about. This limit is 500mg per dose. Beyond this dose, absorption is reduced and the excess calcium remains in the intestine. In the case of calcium, an overdose has the side effect of constipation rather than loose stools. As for other nutrients, the bioavailability of calcium is increased by splitting the dose during the day. Indeed, a single dose of 1000mg is less well absorbed (by a factor of 60%) than the same dose divided into 3 or 4 times a day.
We still see frequently prescribed calcium supplements of 1000mg to 1500mg per day. The utility of such high doses is being questioned. It is true that some research on osteoporosis have studied the effect of large doses of calcium. By cons, when evaluating the results of many studies, we realize that the dose of calcium is not a very significant factor. Indeed, studies using only calcium showed little evidence of effects on decision-bone mass and reducing fractures. Only studies with a protocol containing vitamin D, regardless of the dose calcium, showed positive effects of interest.
Undesired effect of calcium overdose
Constipation is unfortunately not the only side effect of an overdose of calcium. The cells that make bone, osteoblasts, are also affected. Contrary to what is taught by those who sell calcium overdose of calcium, rather than to stimulate these cells prevents their normal function, making them even senile and inhibits their ability to reproduce. This was demonstrated KLOMPMAKER. has revealed a mechanism of aging of osteoblasts when they are “too well fed.” This new understanding of the effect of calcium may explain why osteoporosis is more prevalent in countries where people eat lots of dairy products compared to those where it consumes very little.
credit to: jydionne
Tags: absorption, calcium, Osteoporosis
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