High-Fiber, Low-Fat: Maintaining a Diet Fit for the Primitive Man : Books: People think of “natural” as meaning that which our grandparents or great-grandparents ate, argues “The Paleolithic Prescription” co-author Dr. S. Boyd Eaton. But it really should go back to what our genes are designed for.

There are reasons you don’t see many fat people in cave-wall paintings:

--Primitive man’s diet was better than ours. It was also the opposite of the Miller Lite beer slogan: It didn’t taste so great, but it was more filling.

--The next time someone talks to you about eating the old-fashioned way--the way it was done back in the old country--think of farmers so sick and undernourished that they were, on average, half a foot shorter than we are.

--If you want to fit into your jeans, eat a diet and maintain a life style that fit your genes.

Those are some conclusions of “The Paleolithic Prescription” (Harper and Row; $8.95), a “program of diet and exercise” recently out in paperback.

The book aims to vacuum away the blinding dust advertising has kicked up around the words “natural foods,” in order to make them meaningful again.

“This word ‘natural’ is grossly abused,” says Dr. S. Boyd Eaton, an Atlanta-based radiologist who co-authored “Prescription” with Melvin Konner and Marjorie Shostak, professors of anthropology at Emory University in Atlanta.

“People think of it in terms of what was appropriate for our grandparents or great-grandparents . . . but it really should go back to what our genes are designed for, and our genes are designed for the life style (and diet) that people living 20,000 years ago had.”

Unlike the car companies that come out with new models every year, evolution only changes us over tens of thousands of years.

Pantyhose and neckties aside, we are identical to the humans that emerged from the evolutionary assembly line 40,000 years ago, during the Paleolithic era, or “old Stone Age,” Eaton says.

And yet it is as if we decided to take what his book calls “a 40,000-year-old model body” and pour radically different fuels into the gas tank from what our genetic owner’s manual calls for.

“Prescription” argues that most of the “diseases of civilization”-- the metabolic breakdowns of diabetes, heart disease, osteoporosis, certain cancers, etc.--are the result of life styles and eating habits that have strayed far from what the human body was built for.

It was built for a time, before agriculture, when men and women roamed, hunting wild game and gathering wild fruits and vegetables. Unlike “The Flintstones,” both men and women worked, but men tended to be hunters and women gatherers.

The idea of a “noble savage” living better in some ways than modern man dates back to 18th-Century philosopher Jean Jacques Rousseau. But “Prescription” attempts to scientifically examine what those ways were--what we ate in the thousands of genetically formative generations before McDonald’s.

By analyzing ancient human skeletons, by checking out the type and quantity of animal bones in the equivalent of prehistoric restaurant dumpsters and by looking at the nutritional content of the wild fruits and vegetables that Stone Age humans ate--and that still grow today--Eaton and company assembled a picture of what people ate when they lived in a truly natural state.

(Other sources were studies of the diets of surviving primitive tribes, from the Kung San of the Botswana desert to the Agta of the tropical Philippine forests.)

It is reassuring that, with a few key exceptions, the nutritional content of the Paleolithic diet--wild game, vegetables and fruit--matches pretty closely what is now being recommended by various advisory boards based on clinical studies.

Essentially, primitive people ate a high-fiber, low-fat diet with very little sugar and salt (i.e., sodium). But they did this living on only two of the four food groups that we now are taught are essential.

Cows had not been domesticated yet. For tens of thousands of years, the end of weaning marked the end of lifetime milk consumption (This may explain why many humans are still lactose-sensitive and have trouble digesting certain milk products.)

Likewise, breads and cereal grains are a product of agriculture that came later. Wild wheat took too much trouble to work into edible form.

“Give us this day our daily bread,” is an ancient prayer. “But in relation to our long human existence, dependence on bread is a very late phenomenon,” write the “Prescription” authors.

(Indeed, with lower-grade farm animals and limited crops subject to the whims of weather, man’s agricultural era is far from the romantic ideal it’s sometimes made out to be.

(In fact, malnutrition and illness put so much biological pressure on our agricultural ancestors that men actually shrank 4 to 6 inches in height during that era, which began 10,000 years ago, Eaton says.)

So how did Stone Age humans get such good nutrition? They ate their vegetables, lots of vegetables--and fruits. And the fruits and vegetables they ate were richer in vitamins, minerals and fiber than modern varieties. They were often eaten raw, so none of those benefits were cooked away, either.

Today’s fruits and vegetables have been cultivated for thousands of years for durability and disease resistance, as well as for appealing looks, taste and even chewability. They don’t pack the nutritional wallop of their predecessors. They also carry more calories, Eaton says.

This conclusion is based on comparing a variety of wild vegetables still available today against a variety of cultivated vegetables, he says.

(Organic fruits and vegetables, which are grown without pesticides and other chemicals, don’t necessarily yield greater nutrition, he says.)

The other staple of the Paleolithic diet was wild game brought down by hunters’ spears--mammoths, bison, reindeer, wild cattle and horses.

In fact, the extremely meat-laden primitive diet--a third or more of our ancestors’ diets was animal protein--represents a departure from modern norms. And with that meat they were getting more cholesterol than we eat today.

Again, Eaton stresses qualitative differences between modern and ancient foods. Compared with domesticated, farm-bred animals, wild game has, and had, a lot less fat and a lower proportion of ultra-bad saturated fats.

Also, although primitive man ate more cholesterol, the authors argue that the cholesterol you get in your diet is only one factor affecting the level of cholesterol in your blood.

More important, Eaton says, is how much fat you consume overall, the ratio of polyunsaturated to saturated fats, and the amount of fiber you eat, especially soluble food fiber, which reduces blood serum cholesterol.

On each of those counts, primitive diets are better than our modern one. Tribes of modern hunter-gatherers typically eat a diet that is 20% fat compared with the 40% fat portion in the current American diet.

(But the view that other factors outweigh dietary cholesterol is still in the minority, at least in this country’s medical community, Eaton concedes.)

Ultimately, the “Prescription” authors decline to recommend so much meat for modern man. That’s partly because too much protein can endanger people with kidney problems. Also, buying low-fat animal protein these days--fish, for example--can get pretty expensive, Eaton says.

Otherwise, following a Paleolithic diet--a diet for “the world our genes ‘think’ we live in still”--is easy given the cornucopia of the modern supermarket, “Prescription” notes.

Mammoth steaks and uncultivated vegetables aren’t on supermarket shelves, but foods with the same nutritional value are.

For example, primitive man ate five to 10 times more fiber than we do. (This is known from studying both surviving hunter-gatherers’ diets as well as the content of ancient human fecal matter).

There’s far less fiber in our cultivated fruits and vegetables. But we can easily get more fiber from cereals and breads. In particular, cholesterol-mopping soluble fiber can be gained from oat and corn products.

And low- or non-fat dairy products offer both inexpensive protein and vital calcium, Eaton says (When milk has more than 1.5% fat, it begins yielding more calories from fat than from protein).

Recommending 1,500 milligrams of calcium per day--twice the calcium levels of our current diet and more than the latest Recommended Dietary Allowances--”Prescription” again departs from the modern mainstream.

Because the wild vegetables that hunter-gatherers ate contained a lot more calcium, our genetic forebears easily consumed that much, Eaton says.

“We have their bones,” he says. “They’re much stronger than the bones of today. They were like what you’d see in superior athletes.”

The Paleolithic prescriber also says calcium helps prevent high blood pressure and colon cancer.

If your daily calcium intake slips or is low, Eaton recommends a calcium supplement to make up the difference. Those made of calcium carbonate are best absorbed. With his latest book tour sponsored by Tums, he cites that antacid as an inexpensive and readily available source. Other supplements, such as Os-Cal, also contain calcium carbonate.

“Prescription” recommends vitamin and mineral supplements to help us match the nutrient-rich foods of our genetic past.

The toughest part of keeping a modern diet attuned to our ancient genetic roots is not what’s lacking in today’s food but what’s added to it.

Laden with sugar and salt, modern processed foods also tend to have more calories per volume. The unprocessed, primitive-style foods that shoppers should seek out are less “calorie-dense,” Eaton says.

Primitive people had to eat 5 pounds of food a day to get enough calories. “We get the same number of calories from only 3 pounds of food--less bulky and thus less satisfying,” write the “Prescription” authors.

A crucial point is that hunter-gatherers also burned more calories. Truly natural athletes, they expended at least 3,000 calories a day bringing home a diet in which bacon, or anything resembling fried fat, played no part. A typical non-athletic American male burns only 2,500 calories a day.