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Supplement Guide: ZMA

This all-natural product could significantly increase muscle strength

Where it comes from: ZMA is a combination of zinc and magnesium asparate—plus a bit of vitamin B6. "It's an all-natural product that has been clinically proven to significantly increase muscle strength in trained athletes," adds Barbie Broschart, RD and a nutritional counselor.

What it'll do for you: Zinc is involved in many metabolic reactions. "Athletes have been reported to have lower levels of zinc and magnesium possibly due to increased sweating or inadequate intake in diet," explains Broschart. "But zinc deficiencies may impair immune function and decrease performance." Zinc also plays a crucial role in protein synthesis and cell growth. Testosterone levels fall without adequate zinc and has a correlation with liver function.

Similarly, magnesium is involved in more than 300 metabolic reactions. It is essential for bone strength, a strong immune system, muscle contractions and a healthy nervous system. Magnesium deficiency is a key cause of poor sleep and can also lead to insulin insensitivity.

Vitamin B6 helps the body convert protein into energy. Some research has shown that it works with folic acid and B12 to reduce levels of certain amino acids in the blood, which helps to reduce the risk of heart attack.

All three minerals are powerful on their own, but packaged together, they can pack a powerful punch. Here, a closer look at the possible benefits of ZMA:

  • May enhance hormonal profiles
    The study most often used to support the hormone effects of ZMA is one done at Western Washington University. Dr. Lorrie Brilla (and a ZMA supplement manufacturer) studied 12 NCAA division II football players who took ZMA nightly during an eight-week spring training program and a separate group assigned a placebo pill. The athletes taking the ZMA had 2.5 times greater muscle strength gains than the placebo group; the ZMA group increased by 11.6 percent compared to only 4.6 percent in the placebo group. The ZMA group also had 30 percent increases in testosterone levels (compared to 10 percent in the placebo group). Worth noting: There were no changes in body weight in either group, suggesting that ZMA has no effect on muscle mass.

    However, recent research suggests that the use of ZMA has no significant effects regarding serum testosterone levels and the metabolism of testosterone in subjects who consumed a zinc-sufficient diet.

  • May reduce catabolism
    During a workout, the body and its muscles get broken down in a process called catabolism in order to release energy. It's a necessary evil but, obviously, the shorter the catabolism phase the faster anabolism sets in (the phase when your muscles repair themselves) and the stronger you can become. Although several companies market ZMA supplements for their ability to reduce catabolism during training—and even increase anabolic hormone levels—there's no strong evidence to prove the case. In fact, a recent study at Baylor University in Waco, Texas, found that ZMA has no effect whatsoever. Researchers observed 42 resistance-trained males who kept diet and training logs. For eight weeks, they were tested, put through a series of exercises and tested again. The results did not support contentions that ZMA supplementation effects anabolic or catabolic responses to resistance training.
  • Can boost the immune system
    It's a well-proven fact that zinc can strengthen the immune system and that a deficiency can lengthen the time of colds, cause muscle wasting and lower appetite. Experts believe the same holds true for ZMA.

Suggested intake: Zinc, magnesium and vitamin B6 are found naturally in many foods. Broschart names a few foods high in zinc: beef and other red meats, shellfish (like oysters and shrimp), nuts and legumes. "Bioavailability is highest in meat, eggs and seafood because of the presence of amino acids, cysteine and methionine, which improve zinc absorption in the body," she explains. On the opposite side of the spectrum, the zinc in whole grain products and plant proteins has a lesser bioavailability due to their relatively high content of phytic acid, a compound that inhibits zinc absorption.

Broschart goes on to name foods high in magnesium (bananas, nuts, shredded wheat, brown rice, milk, spinach and swiss chard) and vitamin B6 (fortified cereal, bananas, salmon, potatoes, chicken and turkey).

"While, ZMA supplements are considered safe, they may not be necessary if you have balanced diet," says Broschart. Most successful ZMA products have 11 mg of vitamin B6, 450 mg of magnesium and 30 mg of zinc.

Associated risks/scrutiny: ZMA supplements are usually all-natural and there are no known negative side effects. "However, more than 350 mg of magnesium through supplementation can result in diarrhea," Broschart warns. If you are taking medication for your heart or to treat osteoporosis, you should consult your physician before supplementing with magnesium as there may be a drug/nutrient interaction. Vitamin B6 toxicity, can cause neurological effects, but this only occurs when amounts exceed 100 mg per day. Studies have found that zinc ingestion of about 60 mg per day through diet and supplementation can cause copper deficiency.

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