Water soluble vitamins

juanitacarlos

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Dec 31, 2012
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Hoping someone could clarify this for me please...

I understand that the body can't store water soluble vitamins like it can with fat soluble vitamins, so does that mean if I eat a food high in a particular nutrient that is water soluble- say the zinc or selenium in oysters - will my body only use what it needs at that moment, and the excess just passes through the urine? It seems like a colossal waste. Is there no storage mechanism at all?

I just ask because I wonder if eating a dozen oysters at a sitting is a waste, or should I split it up into two meals over the course of a couple of days. I think the same of liver - is it better to have a smaller amount, 2-3 times a week?
 

Atalanta

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The body stores water soluble nutrients, but not much in the fat cells.

If the body did not store water soluble nutrients, then animals would not be good sources of these nutrients. Animal flesh, organs and bones are good sources of many water-soluble nutrients. We are animals, so our bodies must store these nutrients as well. Many water soluble nutrients are bound to proteins in the body after they are digested so they are not washed away; they are released when tissue is broken down, like when we cook or eat the animal.

But there is a limit to how much the body can store and use, so water-soluble nutrients can be wasted if too much is consumed at once. Some water soluble nutrients can reach toxic levels if the amounts consumed are too much for the body to excrete in a reasonable amount of time.

Some people can digest and absorb nutrients from large quantities of food. Some cannot. I personally prefer to eat my liver two or three times per week as opposed to once because I cannot eat large quantities of food (except milk and fruit) without getting digestive problems. So if you are a larger person with a very efficient digestive system, then eating 12 oysters or several ounces of liver at one time may be fine.
 

Mittir

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Feb 20, 2013
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What you are saying about water soluble vitamins are true, they have short term storage
compared to fat soluble vitamins. But your concerns about minerals are different than water
soluble vitamins. Selenium and zinc stays inside our body for long time, more than several months,
once it is absorbed.There many other factors that control the rate of retention and elimination for minerals.
You do not need to worry about wasting minerals. But it is possible that rate of absorption decreases with
increased amount. They found that that calcium has the best absorption rate when its is below 500 mg in a single dose.
 

Atalanta

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Mittir said:
You do not need to worry about wasting minerals. But it is possible that rate of absorption decreases with
increased amount. They found that that calcium has the best absorption rate when its is below 500 mg in a single dose.

I don't understand that statement. I think we do have to worry about wasting minerals. There is a limit to how much of any nutrient the body can absorb. If a person ingests more minerals than can be absorbed after digestion, the excess will be excreted if the body is functioning properly. In my opinion, whatever is excreted is wasted. For example calcium, which you mentioned. If a person ingests 1000 mg and can absorb only 500mg, the rest will be wasted because it will be excreted. So if the goal is to absorb as much calcium as possible, it is better to drink 8 ounces of milk on separate occasions than to drink 16 ounces of milk all at once. Sixteen ounces of milk contains about 600mg of calcium, so about 100mg of calcium will be excreted and therefore wasted. That is not really a problem since milk is relatively inexpensive, we can drink a lot of it and waste some calcium but still absorb enough of it in the course of a day.

I interpreted the question as asking whether there is a limit to how much water soluble nutrients the body can extract and absorb from a given quantity of food, not how long the body stores minerals vs water soluble vitamins after digestion. A person with good digestion will break down and extract more nutrients from a given quantity of food. The body is constantly excreting minerals. We also lose minerals through perspiration. After digestion, the body holds on more tightly to many minerals (like copper and iron) because they are covalently bonded to proteins and are not in ionic form.
 
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juanitacarlos

juanitacarlos

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Atalanta said:
I interpreted the question as asking whether there is a limit to how much water soluble nutrients the body can extract and absorb from a given quantity of food, not how long the body stores minerals vs water soluble vitamins after digestion. A person with good digestion will break down and extract more nutrients from a given quantity of food. The body is constantly excreting minerals. We also lose minerals through perspiration. After digestion, the body holds on more tightly to many minerals (like copper and iron) because they are covalently bonded to proteins and are not in ionic form.

I was actually asking how much the body can store at any given time, and how long it's stored, but my question was phrased poorly so I apologise for the confusion. You have both been very helpful.

Why I was asking is that it seems that when you hear of a vitamin being water soluble, the next thing you hear is that the body can't store water soluble vitamins so they must be replaced every day. This did not seem plausible for me. Surely there is some sort of storage mechanism in play, as there is with minerals? And yes I would like to know how long particular nutrients are stored in the body.

Thanks for your help guys!
 

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