That is true up to a certain extend.Novidez wrote:The way you say that, it makes me think that supplements aren't that bad. After all, our bodies will absorb only the necessary.RRM wrote:it may be that both take up exactly the same amounts of calcium and phosphorus
(Unless, of course, supplements forces our body to absorb them involuntarily. I don't know how they work.)
If your intake of nutrients from both supplements and food is about the same magnitude of what your diet alone may provide you, there is no problem at all.
If that intake is way too high, you may have a problem.
Something similar is true for when you suddenly change your diet drastically towards the intake of foods that are extremely high in specific nutrients. Oysters, for example, may be extremely high in zinc, which may result in a too high uptake of zinc if you are not used to eating oysters regularly for a very long time.
And what defines excessive intake depends on the nutrient, of course.
Another issue is is that our body is naturally, designed for digesting foods.
Foods that may contain a lot of water and/or fiber, plus nutrients.
The nutrients are surrounded by lots of other stuff. This allowes the body to take up us much as it wants. (Naturally, the uptake mechanism differs per nutrient)
Supplements, on the other hand, are extremely concentrated.
Because of this extreme nutrient density, it is much harder to keep them out.
You may compare it (in warfare) to a position that the enemy tries to take; if the enemy attacks with a steady trickle of a couple of soldiers at the time, they may stand little chance, but if they overrun it with a large number of soldiers all attacking at the same time, its much harder to resist them.