the scoop on ZMA? Does it work?
is a popular new supplement that claims to increase anabolic hormones
and strength in athletes. What is the evidence for these claims
of improving athletic performance and overall fitness?
does ZMA work?
is a combination of two essential dietary minerals (zinc and
maganesium) and vitamin B6. Zinc and magnesium are sometimes
not adequately supplied in the diet, while vitamin B6 generally
is. The zinc is in the chemical forms zinc methionine and
aspartate; the magnesium is in the aspartate form.
is no scientific evidence for any claim that ZMA has any effects
beyond those of taking equivalent amounts of zinc, magnesium
and vitamin B6 in any other form.
of these substances are healthy and thus the combination will
also be healthy so long as it is not overdosed.
Are there any side effects?
side effects can arise from taking too much (overdosage).
More than 50 mg daily often increases the need for dietary
copper; more than 100 mg daily might cause toxic symptoms.
More than 1000 mg daily might cause diarrhea.
B6: More than 200 mg per day may lead to peripheral neuropathy
(nerve pain in the extremities).
What else do I need to know about ZMA?
study claiming that ZMA increases anabolic hormones and strength
in athletes was conducted by L. R. Brilla, Western Washington
University, Bellingham, WA, and V. Conte, BALCO Laboratories,
their results show statistically significant differences between
the ZMA and placebo groups following 8 weeks of intensive
training (higher testosterone levels and greater increases
in strength) -- the study was significantly flawed.
beginning levels of zinc and magnesium in these athletes'
blood were already low. (Average serum zinc was 0.82 mcg/ml;
deficiency threshold is 0.7 mcg/ml. Average serum magnesium
was 19.6 mcg/dl; deficiency threshold is 16 mcg/dl.)
exercise raises the body's need for zinc in a variety of ways.
The fact that levels of zinc and magnesium dropped in the
control groups' blood (to 0.8 mcg/ml of zinc and 18.0 mcg/dl
of magnesium) shows that the increased exercise had this expected
both groups needed more of these essential minerals, probably
even before the intensive training, but only one group got
happened here can be understood if one thinks about the normal
diet eaten by "members of the University football team" (the
study's subjects). Their diet is probably low in zinc, magnesium
and B6, if not actually deficient -- which is probably true
for most unsupplemented people in the US. High protein intake
(undoubtedly consumed by these football players) increases
the need for B6, and zinc is particularly important for protein
details of Tom's critique of this study, together with abstracts
of his own sources of information, can be found on the LEF
Paul Wakfer (was Tom Matthews)