The amino acid that can knock out depression

You don't need meds to win a fight against the blues -- just a little muscle, because a key amino acid used to build strength can actually knock depression down for the count.

It's called creatine, and while it's found in meats and fish it's also sold by the bucket to weightlifters and bodybuilders because it can help build and maintain muscle.

But a number of studies show it can also put some muscle into your mental health, including new research on 52 women in South Korea who were given either 5 grams of creatine or a placebo to take each day with the SSRI drug Lexapro.

These were women battling major depression -- but eight weeks later, half of the women given creatine were cured. Only a quarter of women on the placebo saw similar results.

Even many of the women who weren't cured saw big improvements, and it didn't take eight weeks for those results to kick in. At two weeks, the women on creatine improved by an average of 32 percent on a widely used test that measures depression symptoms. And by week four, those improvements shot up to 68 percent.

In those given the placebo, the numbers were 3.7 percent at two weeks and 29 percent at the four-week mark.

The only problem with creatine in the levels used in this and other studies is getting it -- because you'd need to open a butcher shop to get enough from meat alone.

You'd have to eat a pound of beef a day to get the 5 grams used in the new study. So for most people, a supplement is a much easier and far more practical solution.

Bear in mind that creatine can occasionally come with some unpleasant side effects. The women in the study didn't report any, but creatine use can sometimes cause diarrhea and muscle cramping.

And if you've had liver or kidney problems, check with your doctor before trying it out.