Move over functional foods. Their liquid counterpart -- the functional beverage -- is here.

What's a functional beverage? Nope, it's not coffee -- even though some of us couldn't really function without it. It is a drink that is spiked with herbs, phytonutrients ,and other additives that profess to have medicinal or disease-fighting values.

These include juices, teas, soft drinks, flavored waters. You might not have realized it, but popular brands fit the bill, such as SmartWater, VitaminWater, SoBe, Propel Fitness Water, and even Gatorade, the grand-daddy of enhanced water. Last month, I bought some Pomegranate White Tea, partly because the box tells me that it's an "anti-oxidant powerhouse."

Even though functional beverages have been around for years now, their popularity continues to surge. More varieties are coming to a grocery aisle near you.

Earlier this week, Pepsi rolled out Aquafina Alive, a new, low-calorie, vitamin-laden drink. Along with a hint of fruit juice, it packs in Vitamins B6, B12, E, and Niacin. It hits stores this month, and comes in three yummy-sounding flavors, Berry Pomegranate, Peach Mango, and Orange Lime.

And Nutritional Iced Tea for Women from the Republic of Tea/Luna "wellness collection" grabbed attention at the 2007 Winter Fancy Foods Show, which highlights food and drink trends.

For years, Gatorade was pretty much the only "enhanced" water in the market. But in the past five or so years, it's easy to find bottled drinks that claim to boost intelligence, increase energy, fight diseases, assist with balance, and maybe even grant eternal youth. (Well, the last claim may not actually appear on any bottles.)

Still, are these health benefits valid?

According to the American Dietic Association, most functional beverages haven't been shown to have special health benefits for the average consumer. They note that most of these claims aren’t proven; the amount of the added ingredient is neither standardized nor identified on the label; and their safety isn’t known.

So, a functional drink may not make good on its promises. But if nothing else, these drinks are great alternative to soda.