Wednesday, September 8, 2010

Zinc - blood levels not a good indicator

Metals are stored up in the body for release when needed. This is because you would die without the minerals. Zinc has over 200 functions in the body. If these were to remove all zinc from your body you would be dead very quickly. Now metals don't get "used up" like vitamins. Therefore turnover is lower. One of the way minerals get lost is though urine. Because we pee out urea - from excess protein / protein break down and sulfuric acid. Both are nasty and acidic. Therefore the body balances these out with metals, typical calcium, hence peeing doesn't acid etch out our body.

When you go for an iron test they take your blood and analyze it for its current iron content. They also measure your iron stores (or infer it from blood levels? I actually don't know). This clearly works.  Is a blood test a valid way to measure your zinc levels?

As mentioned above zinc is really important to the body. Hence measuring your bodies zinc levels would be an important step to determine if you are low on zinc. However the following methods don't work:
  • Urine analysis 
  • Blood analysis. This is the most common way of determining zinc status. However this is not a accurate method. 
  • Zinc levels in red blood cells, again it doesn't correlate.
So basically we have no idea about how to measure your zinc levels.

The RDI for Zinc is 15 mg a day. A study looked at supplementing zinc at 0 (control), 15 mg and 30 mg per day. After 6 months they did some fancy measurements to determine the total zinc in the body (zinc being "used" and zinc being stored). They found that the control group at total of 2.15 mg, the 15 mg group had 12.7 mg and the 30 mg group had 100.5 mg.

These results tell me that supplementation of zinc is a good idea. Having only 2.15 mg in total body when you are supposedly on a healthy diet (of 15 mg a day) seems rather low. Hence people in Europe were the study was undertaken are not getting enough zinc in their diets. The large jump between 0 mg supplementing and 15 mg supplementing is large. I would prefer to have the large total level of zinc so that all my enzymes and processes run well, not just at minimal levels.   

There is also a massive increase, by factor of approx ten, in body stores between the 15 mg and 30 mg group. This tells me that 15 mg was actually too low and 30 mg to high. Therefore the optimal level of supplementation is somewhere between these two numbers. Hence make sure your multi tablets have about 15 mg in them.

Reference: Christine Feillet-Coudray, Nathalie Meunier, Mathieu Rambeau, Marion Brandolini-Bunlon, Jean-Claude Tressol, Maud Andriollo, Andrzej Mazur, Kevin D Cashman and Charles Coudray Long-term moderate zinc supplementation increases exchangeable zinc pool masses in late-middle-aged men: the Zenith Study American Journal of Clinical Nutrition, Vol. 82, No. 1, 103-110, July 2005

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