REUTERS/Rebecca Cook

ANAHEIM, Calif. -- If you are confused about what a “natural” food is, turns out you’re in good company.

So are the food-makers whose advertising depends on the description.

At the nation’s largest annual gathering of organic and “natural” food makers, doubts are rife because while U.S. food regulators have yet to offer a clear legal definition, a spate of class-action lawsuits from consumers has made clear the penalties for not knowing.

“Who’s here to not get sued?” Michele Simon, an attorney who specializes in the area, asked a ballroom audience of about 200 industry types at the Natural Products Expo West yesterday.

A few score hands shot up, and the enthusiasm - or maybe it was confusion - was evident. When Simon’s presented a list of food additives that could be targeted by class-action lawyers, many in the audience held aloft their smartphones  to snap pictures. A later program about “Defining Natural” was standing-room only.

“I operate on the premise that the system is broken,” said Kim E. Richman, another attorney who addressed attendees. “One piece of advice: be careful with that “all-natural” claim.”

As consumer interest in the origins of food has grown in recent years, food-makers have profited from describing their products as “all-natural.”

The word "natural" helps sell about  $41 billion worth of food each year, according to data from Nielsen. But exactly what that word means has been left, to a large degree, for the courts to decide.

The U.S. Food and Drug Administration offers little more than that natural is “difficult” to define.

“FDA has not developed a definition for use of the term natural or its derivatives,” according to a statement placed on their website. “However, the agency has not objected to the use of the term if the food does not contain added color, artificial flavors, or synthetic substances.”

The U.S. Department of Agriculture, meanwhile, has offered that natural foods: “must be minimally processed.”

Even trade groups have struggled to define the word. Neither the Natural Products Association nor the Organic and Natural Health Association have yet offered rules, according to Simon.

Into this uncertainty have arisen scores of lawsuits brought on behalf of consumers, whose attorneys argue that the label has been used in a misleading fashion.

The lawsuits have forced big brands into paying to settle lawsuits or forcing them to remove “natural” claims from the packaging. But for the smaller entrepreneurs here touting everything from chia strawberry fruit spread to thyme-lemongrass deodorant, the potential harm from a lawsuit may be much greater.

Shoppers, meanwhile, may be left to guess.

And here, for those inclined to scrutinize the fine print on food labels, is Simon’s list of ingredients that have been targeted as potentially unnatural by lawyers.

•Ascorbic acid

•Beta carotene

•Biotin

•Calcium pantothenate

•Calcium phosphate

•Calcium sulfate

•Caramel color

•Citric acid

•Cochineal extract (color)

•Cyanocobalamin

•d-alpha-tocopherol

•D-calcium pantothenate

•Disodium phosphate

•Fibersol-2

•Fructooligosaccharides

•Glycerin or vegetable glycerin

•Hexane

•Inulin

•Magnesium phosphate

•Monocalcium phosphate

•Niacinamide

•Potassium cirate

•Potassium carbonate

•Potassium iodide

•Phytonadione

•Pyridoxine hydrochloride

•Sodium acid pyrophosphate

•Sodium benzoate

•Sodium citrate

•Sodium dioxide

•Sodium molybdate

•Sodium selenite

•Soy lecithin

•Soy protein concentrate

•Soy protein isolate

•Steviol glycosides

•Sucralose

•Soy ingredients (textured soy protein, soy grits, soy flour)

•Synthetic fiber such as Fibersol-2

•Thiamin hydrochloride

•Vitamin A palmitate

•Vitamin D2

•Xanthan gum

•Zinc methionine sulfate

•Zinc oxide