When it comes to making body odor worse, synthetic fabrics tend to trap odors at a greater rate than natural fabrics. Although many of these man-made fabrics, like polyester, are quick to wick moisture away from the skin and equally quick to dry, their construction can up the "stink" quotient.
Within the weave of synthetic, moisture-wicking fabrics are notches designed to pool minute amounts of sweat as it transfers from the inner layer to the outer layer of the fabric. The concept is a good one, as the moisture will generally evaporate once it reaches the fabric's outer layer. The problem is that as sweat collects in the nooks and crannies of the fabric on its way to freedom, it is devoured by bacteria that have made themselves at home in the same recesses. This traps body odor within the fabric.
To reduce rowdy odors, look for synthetic fabrics that have an added antimicrobial ingredient. For example, the addition of silver to polyester or spandex fibers can help prevent body odor from accumulating. Silver nanoparticles (particles so small that 80,000 of them could fit within the diameter of a human hair) are integrated into synthetic fabric. When they get wet, the silver nanoparticles release silver ions that initially slow the growth of odor-causing bacteria and, eventually, kill them off altogether [source: Siauw].
Some fabrics are infused with a different type of odor-inhibiting agent: molecules of volcanic ash. The ash molecules, known by the brand name Minerale, have a pore size that is similar to that of an odor molecule. When the two meet, the odor molecule is absorbed and trapped within the ash molecule. This prevents the odor molecule from releasing its characteristic smell -- until the fabric is washed in warm water [source: Beresini].
To prevent body odor, look for clothing made from fabrics that will help keep you dry and have the added might of antimicrobial helpers. And don't forget the antiperspirant.