An All-Natural Carob Hi-Proteen Energy Bar was perched next to the cash register in the health food store. What the manufacturer presumably wanted me to think was: Buy it for your kids and give them candy with a clear conscience. It's good for them. It's all natural. It won't rot their teeth.

Aside from the price of the All-Natural Carob Hi-Proteen Energy Bar -- 60 all-natural cents, plus a high energy 5 percent sales tax -- something instinctual told me not to buy it. The buzz-words were phony. Laboratory scientist for food companies routinely argue, with straight faces, that everything we eat is natural: Addditives and chemicals come from nature's bounty as much as the vitamin C in a fresh orange. Fake food is real food.

The "hi-poteen" was maningless because most Americans are already overloaded with protein.And what does "energy" mean? There is caloric energy in a meal of banana skins and boiled peanut shells.

What saved me from buying the carob bar -- instinct -- is about all any of us have when trying to make sense of food and nutrition. Of late, a banquet table of studies, reports and guidelines has been made available to the public, all of it designed to get information into our heads about what we put into our mouths.

In April, the General Accounting Office issued a report titled "What Foods Should Americans Eat?" And Other Question Kids Ask About Food and Nutrition Board of the National Research Council came forward with its report, "Toward Healthful Diets."

Whatever else this glut of commentary may do, it surely replaces the thinking in Ecclesiastes that we should eat, drink and be merry. That was fine for ancient Israelites, but modern Americans know better: Our task is to eat, drink and read a report about the aftereffects.

If that doesn't make us merry, we can read a counter-report.That is what the Food and Nutrition Board offered last week when it went against prevailing opinons and said, among other startling things, that fatty foods aren't so bad after all.

The meat and diary industries, champions of foods laden with fats, are sure delighted with this news. Now it has a battering ram with which to strike back at the 1977 dietary guidelines from a Senate committee that advised citizens to cut down on fatty foods.

But instead of battering the politicians, the industires are likely to smash into the sensibilities of citizens who are more confused then ever. the old belief that if the consumer doesn't want a product, seller will stop making it, no longer works because even before the consumer gets to the supposedly free and open marketplace to buy his food he must travel through the marketplace of food industry propaganda about food. It is anything but free and open.

In its current ad program,for example General Foods comes on as a benign and friendly counselor. It is repring material from the Federal goverment's dietary guidelines -- which are little more than the traditional advice about eating a variety of foods in moderation -- and then offering its own bland comments. The sell is as soft as of Cool Whip, a General Foods product, and withabout as much substance. The benefit to General Foods is that of enhancement: It can associate its name with right-thinking nutritional policy while continuing to seek profits from its evergrowing line of nutritionally inferior products. It gets it both ways.

General Foods is able to reach the public this way because of a total ad budget that is over $400 million a year. Unlike the marketplace of products and services, in which there is still shelf space for real whipping cream and a choice for consumers, the marketplace of ideas usually keeps out the independents. Small consumer groups alarmed about junk food have no funds to place full-page ads to counter the unrelenting views of General Foods.

With debate on food and health dominated by food companies, their paid experts, and public officials of ordinary vision, consumers have little choice but to trust their own instincts when pronouncements are served up by this board or that council -- or today's study and tomorrow's report.