This is a really good deal. $16 for 3 months of ZMA (I take 2 caps/night).
The mojor benefit that I got from supplementing with ZMA was having awesome sleep, from the instance my head hit the pillow to when my alarm clock whent off. Not sure about testosterone boosting proporties, the main reason why I took it was because I wanted more quality sound sleep, and it sure as hell worked.
As said above.... It gives me awesome sleep. Not sure of much else. All the info about increased test has been in Z or M deficient subjects . You wake up without any grogginess, unlike benadryl or the like. Worth a shot if cheap enough.
It may have the ability to increase testosterone if deficiencies in other areas are causing decreased testosterone. For example, if it gives you a better nights sleep, that in itself can increase testosterone. Another example, intense exercise depletes zinc, which can deplete testosterone, so if its not replenished elsewhere, then it is well worth the money.
Would you say there's a qualitative difference between these two products?
As far as I can see the last one has more zinc in it - but then you could just buy some extra zinc separately for the first one - it would still be cheaper than the the ZMA from met-rx!
With ZMA also, there is a huge debate about Calcium, and absorption of the ZM in the presence of Calcium. I have seen very different opinions on this, with some saying that any calcium will ruin the ZMA, and others saying the aspartate form has a higher affinity than the calcium. The debate rages, with most favoring no calcium. As a sleep aid, I have found no difference with either the total absence of calcium or sprinkled on my cottage cheese. I still sleep like a rock with it.
Agreed with Eli... combining calcium and ZMA is controversial, but imo, highly blown out of proportion.
Dietary Factors Influencing Zinc Absorption.
"It appears unlikely that calcium per se has a negative effect on zinc absorption. We added calcium to cow’s milk formula to a level of ~1300 mg/L and found no significant difference in zinc absorption from the formula with the regular level of calcium (500 mg/L) through the use of radioisotopes in human adults and paired observations (Lönnerdal et al. 1984 ). Similarly, Spencer et al. (1984) and Dawson-Hughes et al. (1986) added large amounts of calcium to a meal and found no effect on zinc absorption in human adults. It also appears that the long-term use of calcium supplements has no effect on zinc status; Gambian women who were given 1000 mg calcium/d had plasma zinc concentrations similar to those of unsupplemented women (Yan et al. 1996 )."
I don't take a ZMA supplement per se, as you can get Zinc supplements that have the same ingredients. ZMA is Zinc monomethionine aspartate and Magnesium Aspartate, and is just zinc magnesium and Vit B6 (pyridoxine). It was developed by Victor Conte (founder of BALCO Labs) and the formula is "patent pending" and the name "ZMA" trademarked.
So if it is ZMA it just means you have one of the bioavailable forms of zinc and magnesium. There are others and they can't be called ZMA. As long as it has those 3 in a bioavailable form it is very good to take. I actually take it instead of a multi. And yes the sleep is much better.