What's driving the explosion? In 1804, Yankee sailors leaving China loaded their clipper ship with bags of soybeans. But they weren't sustenance - they were a cheap form of ballast.

Nearly 200 years later, Americans are again loading up on soybeans. But this time, consumers are using soybeans to lose a little ballast around their middles, or for a myriad of other health benefits and dietary uses.

"The whole market is driven by consumer demand," says Mark Messina, president of Nutrition Matters, a nutrition consulting service in Port Townsend, WA. "You need a specific reason to eat soy, and the health effects are those reasons."

Consumers are snapping up popular soyfood items such as veggie burgers, soymilk and soy protein for a healthy total of $2.1 billion in sales in 1999. Of that total, soymilk is projected to account for $300 million, up 38% from 1998. And it's not just in health-food stores any more. Soymilk sales in mainstream supermarkets reached $126 million for the year that ended in February - a 60% increase, according to data tracking firms SPINS and A.C. Nielsen. In fact, soymilk's increasing popularity is prompting the dairy industry to ask for the elimination of the term "milk" in soymilk.

That's a dramatic turnaround from two decades ago, when soymilk sales were just $2 million and only liver outranked soy as Americans' least-liked food.

Since then, sales of soy-based foods have been growing at an average pace of 10-15% every year. And since the FDA's October 1999 approval of a health claim on soy protein for prevention of heart disease, the number of consumers eating soy products once a week or more rose to 27% in 2000, according to the United Soybean Board (USB).

That's no small bag of beans. Last year, USB calculated that U.S. consumers ate 37 million bushels of soybeans via soyfoods. It expects that figure to rise to 66 million bushels by 2005 and 100 million bushels by 2010.

Shoppers are eagerly reaching for new soy products, such as White Wave's strawberry soymilk, Twinlab's chocolate fondue soy bar, Lightlife's Smart Bacon and EssenSmart's Almond Delight soy cookies.

"It's sort of like an acorn from an oak tree," says Richard Borgsmiller, Illinois soybean farmer and USB secretary. "It's still small, but growing exponentially. In the last year, it's grown from a two-foot sprout to a four-foot sprout."

What's changed U.S. consumers' minds about this versatile bean?

Over the past 20 years, physicians and dietitians have increasingly recommended soy because of positive research on soy's low saturated fat and high protein and isoflavone content. The reputed health benefits include reduction of colon disorders and menopausal symptoms, as well as prevention of coronary heart disease. More recently, soy isoflavones have been credited with reducing the risk of osteoporosis and some cancers.

Surveys on U.S. consumers' perceptions of soy have been positive, as well. A recent checkoff-funded study showed that 76% of Americans consider soy to be healthy, up from 71% in 1999. For many of those consumers, soy is enhancing favorite foods.

"I like it when the soy food is actually replacing something else in the diet that is perhaps not as healthy," says Messina.

Two of the largest categories of soy consumers include women 35-plus and men 40-plus, who tend to notice changes later in life, says Julie Tockman, director of health benefit communications at Protein Technologies International. "We're in the midst of a paradigm shift," she says. "People are seeing food as their friend now."

This recent "self-care" movement, as Tockman calls it, creates a ripe opportunity for soyfood manufacturers.

"The soyfood industry was waiting for a reason to jump on board. When the demand got large enough, they came out with all of these products," says Messina. The FDA ruling also "was a great boom to the industry," he adds. "That put a lot of companies over the fence. Not only could they put it on their labels, but it was a kind of official recognition of the health benefits of soy."

The FDA claim provided companies with a marketing tool, agrees Nancy Chapman, Executive Director of the Soyfoods Association of North America. "It ratified the research results, which are based on 20-25 years of study," she says.

Will the interest in soy fade? "That's unlikely to happen to soy just because the products are really good, so versatile and there's so much of a momentum in interest right now," says Messina. "To some extent, the ball is now in the court of industry."

So far, industry has responded successfully. For example, soymilk comes in a rainbow of flavors, as do soy-based frozen desserts. Soy hot dogs, cereals, noodles and even coffees are vying for customer attention, too. In 1999 alone there were 1,000 new soyfood products, according to Chapman.

Several offerings are now from big players: Pepsico's Tropicana, Kellogg, Dean, Bestfoods and Kraft are also moving in to carve their chunk out of the soyfoods market.

"Obviously, industry has played a big role here - not just in terms of products but in their promotion," says Messina. "I think soybean farmers need to be credited for starting all this."