By Pure Matters

Whether you're a serious bodybuilder or simply enjoy strength training as a way to stay fit, you've no doubt heard about supplements that claim to offer nutritional support for stronger, healthier muscles. Here's what you need to know about six of them.

Muscle up with creatine. This amino acid helps muscles generate energy for high-intensity, short-burst activities such as weight lifting. A number of studies have found that creatine supplements may improve endurance and strength in repetitive sets of an exercise, so performance in later sets is 5 to 20 percent better. Creatine may also increase muscle strength and mass.

Recover faster with MSM (methylsulfonylmethane). The S in MSM represents sulfur, which is linked with easing joint pain and aiding in muscle repair. In one study of 24 people recovering from athletic injuries, those who took MSM needed fewer visits to a chiropractor and reported a 58-percent reduction in pain and other symptoms, compared to a 33-percent improvement in those who took a placebo pill. The researchers suspect MSM may increase blood flow to damaged tissue.

Feed your muscles vitamin C. Your body uses vitamin C to help build collagen, an important component of blood vessels, tendons, ligaments, and bone. Vitamin C also plays a role in keeping muscles energized. Plus, research shows that vitamin C aids the production of carnitine, which is used to move fat into mitochondria, the tiny power plants in every cell of your body that convert fat and sugar into energy. Adults need a minimum of 75 to 90 milligrams of vitamin C daily; the safe upper limit is 2,000 milligrams per day.

Build strength with melatonin. Don't let its fame as a sleep helper fool you. Several studies suggest melatonin also helps support the production of growth hormone after a round of resistance exercise, especially in men. Other research shows that growth hormone can increase muscle mass and strength. A typical dose is between 1 and 10 milligrams per day.

Power your workout with zinc. During exercise, zinc moves out of muscle cells and is lost in sweat. Replacement is important because your body has no specialized zinc storage system. And a steady supply of zinc is needed for everything from a healthy immune system to cell division. One in five men and two in five women may be low in zinc; numbers may be higher among people who exercise regularly. This can reduce strength and power and make you feel tired sooner, say researchers. Adults need 8 to 11 milligrams daily; the safe upper limit is 40 milligrams per day.

Get the iron your workout needs. Intense activity like running, cycling, and competitive swimming may reduce iron levels by wearing out iron-containing red blood cells (which carry oxygen to every cell in your body) faster. If you think you have symptoms of low iron -- such as feeling tired, weak, or cold, see your doctor for iron tests.

Even if you take advantage of supplement help, don't forget the power of a healthy diet in your muscle-building plan. Aim for good sources of carbohydrates and lean protein.