It was a tough workout. Anyone who can handle three days of eating Turkey Jerky, Tofu Scrambler, Loveburgers and barley juice deserves those free samples of natural spring powders for his or her hot tub. Nonetheless, they came, they saw and they networked last weekend at the Natural Foods Expo East, held on this coast for the first time, at the Washington Convention Center.

They are the retailers and suppliers who do an annual $3.3 billion worth of business selling food, vitamins and other assorted devices in the nation's health-food stores, natural-food chain stores and supermarket nutrition centers. And they represent as many mini-religions as there are definitions for the term "natural."

Sikhs in white turbans wandered the exhibition floor amidst vitamin salesmen in three-piece suits. Women in thick makeup and aerobic leotards promoted a high-energy drink near a macrobiotic merchandiser. An exhibitor dressed as a belly dancer clicked her way down an aisle with castanets as she headed for her halvah table. Organic prune juice and fresh, sweet persimmons could be sampled at booths, mixed in with displays for such processed foods as tofu weiners or "delicious, nutritious" candy made with brown sugar and saturated palm oil.

This is a schizophrenic industry with a broad range of professionalism and purpose. There are the companies that promote, according to one exhibitor, "dead food" -- the weight loss aids, the vitamins, the edible plant health products, some of which have been studied and questioned by government agencies and national coalitions. It is an industry with a credibility problem -- and it knows it.

In fact, some of the harshest critics of the natural foods industry are the members themselves. In what Bill Aufricht, marketing coordinator of Arrowhead Mills, growers of organic grains, calls the "immaculate deception," some companies try to sell the facts before they can substantiate the information.

Yet other segments of the industry -- progressive and forward-thinking -- have been preaching for years that foods such as whole grains and fresh produce may be an important element in prevention of disease, findings that have only recently been promoted in the conventional medical and corporate food worlds.

Ironically, this development has caused steadily declining sales in the natural-foods industry, according to Morris Shriftman of Shriftman Associates, a marketing and management consulting firm. Supermarkets and large food companies are taking away many of the industry's bestselling products, Shriftman said. Consumers now have lots of choices of where to buy "natural" foods.

Consumers "no longer believe that 'natural' food from the traditional supermarket is any different than what we're selling," said Tony Harnett, president of Bread & Circus Wholefood Supermarkets in Boston, at a seminar on industry trends, a comment rebuked by at least a few retail shop owners who pointed out that some of the "natural" foods being displayed on the exhibition floor were hardly more nutritious than what traditional supermarkets sell.

Here then, is a quick trip through the expo and exhibition floor, a demonstration that the interpretation of natural foods is as different as whole-wheat and white breads. Eating Their Words

It's not enough to preach natural foods; you have to show people you really eat them. Thus, seminar speakers cleared their throats not with Coke or Pepsi but with natural spring mineral water. And the Cafe Expo, the makeshift snack bar set up for the convention, served up recipes as seen in Delicious! magazine (published by New Hope Communications, the sponsor and promoter of the conference). Among the entrees: goat cheese nachos with tomato-orange salsa, perfect-protein tabouli and mixed-grain supper salad with mustard dressing. And at a luncheon for the Organic Foods Production Association of North America (OFPANA), the menu consisted of vegetable and millet casserole, broccoli, potatoes, roasted chicken and fruit salad -- all organically grown. From Hippie to Yuppie

Not surprisingly, natural food shops are mirroring national trends, where upscale, fast and frozen are the buzzwords of the day.

Upscale: natural foods packages are looking more Madison Avenue. Take the case of International Protein's sesame flour. According to the company's William Robertson, the packaging went from a simple design in earth tones to the present higher-tech package in bright blue and green.

Fast: Arrowhead Mills' quick brown rice, which cooks in 12 minutes.

Frozen: Croissants, natural foods-style, come in whole wheat (although still loaded with butter). And similar to mass marketers, who seem not to be able to leave well enough alone, the variations are endless. Witness Croissant Cuisine, made by a Los Angeles company, which has a new line of whole-wheat croissants with such fillings as tofu mexicana or vegetarian barbecue ("tasty beef-like strips in a tangy western BBQ sauce. The hottest new meal on the range," says the promotional material).

More fast, more frozen, more whole wheat: fish sticks and pizza.

And for the "perfect food to serve for short notice meals": Lala's Natural Brown Rice Knishes. Natural Versus Organic

If there's one contingent that doesn't want to go the way of undefined natural, it's the organic farmers. They don't want just anybody slapping an "organic" label on a food and they're determined to do something about it.

Situated in what became dubbed in convention lingo as "Organic Alley," a collection of producers brought goods such as fruits, vegetables, flours, produce, coffee and cereals, making their first concentrated appearance at the natural foods show.

"To be natural is not to be organic," said Tom Harding, president of the newly formed OFPANA, an international association dedicated to creating a common image for organic growers by endorsing already-established certification programs. Organic foods, as defined by OFPANA, are "produced under a system of ecological soil management which relies on building humus levels through crop rotations, recycling organic wastes and applying balanced mineral amendments." No pesticides or herbicides are used.

According to Harding, more and more conventional farmers ("not 1960s hippie farmers") are making the move to organic, seeing it not only as a way to produce chemical-free goods and prevent further soil erosion, but as an alternative to failing farms.

And some organic growers, such as David Miskell of Miskell's Primeur Organic Vegetables in Shelburne, Vt., who supplies vegetables such as mache to fancy restaurants, are going upscale. Here in Washington, Nora's, Trader Vic's, Le Souperb, Tony Linn's and the Washington Hilton are among the restaurants that have bought organic produce from Organic Farms in Beltsville. Aloe Vera Everywhere

What are the benefits of aloe vera juice? It has an "electrical effect," said one of the many aloe vera exhibitors. Placed on the head, it will make a headache disappear, said one. And it will make muscle cramps go away in six minutes, he said. When asked how these medical miracles worked, he replied that his company spends 25 percent of its yearly profits just trying to figure that out. The Oriental Influence

Ginseng, the Oriental root that got its claim to fame for its rumored aphrodisiac abilities ("It is true that Oriental men have been known to sire children at an age when most of us would have given up," says the literature from the Ginseng-Up Corporation), was cropping up everywhere. Now there's Ginseng-Up in ginger, cola and orange flavors. There's even a Ginseng Association and a toll-free ginseng number (1-800-GINSENG) to place orders for -- you guessed it -- ginseng. Attention K-Mart Shoppers

What's "nutritious" about yogurt peanut clusters made with brown sugar and saturated palm oil? "The package," laughed Scott Sher, owner of Maramor, the company that makes the candies bearing that logo.

The company doesn't think it's misleading to the public, Sher said. People are "only confused if they want to be confused." And whole milk, peanuts and eggs make candy nutritious, he said. Anyway, Sher said, the company sells the yogurt clusters to K-Marts. Shoppers there won't buy candy made without sugar, he said. The Substitute Artists

As if there weren't enough tofu ice creams, there are more coming. Tofait, Tofreezi, Tofrozen. What distinguishes them from each other? Less sugar, says Tofrozen. Honey, says Tofreezi. Real tofu, says Tofait.

And if soy ice cream is becoming such a big hit, then soy milkshakes can't be far behind. Westbrae Natural Foods in Emeryville, Calif., had a veritable shake shop set up, offering its soy-based Malted's in various flavors such as vanilla, carob and cocoa-mint.

Going down the soy food chain, there's now soybean mayonnaise, called Nasoyannaise, made with tofu, sunflower oil and spices, and weighing in at 40 calories per tablespoon (compared with egg-based mayonnaises of 100 calories per tablespoon).

And Tofu Scrambler, made by Fantastic Foods, is a boxed tofu product meant to simulate scrambled eggs (but can be prepared in "so many different ways," such as in stuffed peppers, tostadas and potato boats, says the company). Better Babies

Ron and Arnie Koss of Shelburne, Vt., are in the financing stages now, but by July they hope to have their new product, organic baby food, out on the natural foods shelves. The Koss brothers have done a lot of research in processing and taste panels (with babies and their parents) and have found that the same people who won't spend the money on organic food for themselves will spend it on their babies. From the Peanut Gallery

*The West Coast is "years ahead of us," in terms of product variety, says Hugo Van Seenus, owner of Hugo's Natural Foods Market here in Washington. In all, the industry should reach for a higher level, Van Seenus said, to ensure that the products sold taste good, and are truly natural or organic.

*The biggest trends nowadays in natural foods, according to Norman Cloutier, president of Cornucopia Natural Foods in Coventry, R.I.: soyfoods, specialty juices, nonalcoholic beers, alternatives to honey-sweetened products and athletic vitamin enhancers. Also, adds Morris Shriftman: macrobiotics.

*There aren't that many hippies left in the natural foods business, says Mike Hornfeld, sales manager of Oak Feed, a Coconut Grove, Fla., macrobiotic wholesale company. Many have gotten swallowed up by bigger companies, Hornfeld said, referring to the current trend of small natural-foods companies being bought by large corporations (i.e. Quaker Oats bought Arden, a rice cracker company). And if hair style is any indication, there were only about three ponytails spotted, but their owners were in pinstripe suits.