Issue date:
April 3-5, 1998

Low-fat isn't always best

A low-fat diet might even worsen cholesterol. Confused? Here's help.

This week's recipe: Quick Nutty Salmon Jean Carper's current best-selling book is Stop Aging Now! Comments? Write: Eat Smart, 1000 Wilson Blvd., Arlington, Va. 22229-0012 (fax: 703-276-5518; e-mail: eatsmart @usaweekend.com). Please include your age and daytime phone number. Because of the volume of mail, not all will be answered.

ill a low-fat diet always reduce cholesterol and the risk of heart attack? No. In fact, startling new evidence shows very low-fat diets are hazardous to some people.

"It's myth that one low-fat diet fits all," says Wayne Callaway, M.D., of George Washington University.

Whether a low-fat diet is good or bad often depends on your genetic makeup, says Ronald Krauss, M.D., at the University of California in Berkeley. "As much as one-third of the population may react adversely to a very-low-fat diet," increasing their risk of heart disease, says Krauss.

At a recent Harvard-sponsored conference, 50 worldwide experts concluded it doesn't matter how much fat you eat, as long as you restrict animal fat and partially hydrogenated oils (such as solid shortening) and eat an otherwise healthful diet of fruits, vegetables, legumes, whole grains, fish, nuts and low-fat dairy products.

THE SCIENCE THAT'S SHAKING THE LOW-FAT DOGMA

1. ODD NEW HAZARD FOR THE HEALTHY
If you have normal cholesterol and no heart disease, severely restricting fatty foods could be hazardous, according to new research by Krauss.

		What to do in your daily diet
		Regardless of age or health, it's a good idea to pay attention to the type of fat you eat, not just total fat. ADD Eat a diet rich in plant foods: fruits, vegetables, nuts, beans, grains. Eat more omega-3 fat (mackerel, salmon, sardines, herring, walnuts). Get carbohydrates in vegetables and fruits, not in sugar or in fat-free, sugary foods like cookies. Maintain normal weight by exercising, watching total calories. AVOID Restrict saturated animal fat (fatty meat, cheese, butter) as much as possible; everyone agrees it's very dangerous. Avoid trans-fatty acids, or partially hydrogenated fat (common in margarine, crackers, doughnuts, processed foods). They appear worse than animal fat. SWITCH Substitute monounsaturated fat (olive oil, avocados, almonds) for other fats. Mono fat has been found to be beneficial against stroke, heart disease, diabetes and other chronic diseases. Use canola oil instead of corn, regular safflower or soybean oils.

In his study of healthy men who cut fat calories from 46 percent to 24 percent, about one-third had a bad reaction (an increase in the number of vicious "small" LDL particles in blood cholesterol, and therefore an increased heart disease risk). When fat was cut to 20 percent and below, about two-thirds of the study group had the bad reaction. "Clearly, because of genetic differences a very low-fat diet doesn't benefit everyone and can be harmful," Krauss says. Thus, encouraging a whole population to drastically restrict fat could backfire.

What if you already have heart disease, high cholesterol, high blood pressure or diabetes, or you are overweight? Then you are probably genetically predisposed to high amounts of hazardous small LDL particles, and slashing animal fat can dramatically reduce them and be lifesaving, Krauss says. Other ways to reduce the menacing particles: exercise, weight loss and large doses of niacin (1,500mg a day), under a doctor's supervision.

How do you know if you have high levels of small LDL particles? One clue: If your triglycerides are over 200, you probably do, says Krauss. If triglycerides are below 100, it's unlikely. Exact tests for small LDL particles currently are available only in research labs.

2. NEW STROKE DANGER
Restricting fat may save you from a heart attack but boost your chances of stroke, according to new Harvard research using data from the famed Framingham Heart Study.

The 20-year study of 832 men, ages 45-65, concludes that those who ate more fat, including animal fat and olive oil-type fat, had fewer strokes caused by a blood vessel blockage in the brain or neck. Indeed, for every 3 percent increase of calories in fat, the risk of blockage-type strokes dropped 15 percent. Such blockages account for 80 percent of strokes among Americans. Fat did not influence the risk of strokes caused by ruptured blood vessels.

The only logical conclusion, argues lead researcher Matthew W. Gilman, M.D.: "Fat intake does not increase the risk of stroke," even in those with coronary heart disease. In short, what's good for big heart arteries may not be good for the brain's small blood vessels. Why is a mystery.

3. LOW-FAT DIETS HARM OLDER WOMEN
As women enter menopause, their risk of heart disease skyrockets. One common recommendation -- to drastically cut fat and eat more carbohydrates -- is a bad idea, says Stanford's Gerald Reaven, M.D.

In recent tests, he put healthy postmenopausal women on two diets. On a low-fat (25 percent of calories) and high-carbohydrate (60 percent of calories) diet, bad triglycerides rose and good HDL dropped, dramatically boosting the chances of developing heart disease. The high-carbo diet also drove up blood sugar and insulin levels, adding to the risk of heart disease.

Reaven insists that a diet high in fat (45 percent of calories, mostly olive oil-type fat, not animal fat) and low in carbohydrates (40 percent of calories) reduces heart disease risk better than an overall low-fat diet.

4. LEAST FAT, WORST CHOLESTEROL
Even if you have high cholesterol, drastically cutting fat may be counterproductive, says Robert H. Knopp, M.D., of the University of Washington. Knopp put 444 men with high cholesterol and/or high triglycerides on one-year diets. The most beneficial: 30 percent fat for those with both high cholesterol and triglycerides, and 26 percent fat for only high cholesterol.

Cutting fat to 22 or 18 percent lowered good HDL cholesterol and raised hazardous triglycerides, worsening the chances of heart disease.

5. HIGH-FAT ALONE IS NOT THE CULPRIT
Harvard researchers recently concluded that total fat intake does not determine heart disease risk; in fact, women who ate 5 percent more olive oil-type fat had 20 percent lower risk of heart disease than women eating less. But increasing intake of saturated animal fat boosted heart disease risk 17 percent. The worst villain: Adding a mere 2 percent of trans-fatty acids nearly doubled the odds of heart disease. What counts is the type of fat, concluded researchers.

Though high in total fat, this recipe has the right fats.

Quick Nutty Salmon 3/4 pound salmon fillet or steak 1 Tb. Dijon mustard 1 Tb. nonfat yogurt (for more monounsaturated fat, substitute olive oil) 1/4 cup ground pecans Freshly ground black pepper, to taste Combine mustard and yogurt. Spread mustard mixture on top of salmon, then cover with pecans and pepper. Place on a baking pan sprayed with olive oil or canola oil. Bake 12-15 minutes in a preheated 450-degree oven until fish flakes easily. Serves 2. Per serving: 404 calories, 35g protein, 2.1g carbohydrates, 1g fiber, 26.2g fat (4.2g saturated, 11.8 monounsaturated), 368mg sodium.

-- Increase in small LDL particles
Personal interview with Ronald Krauss, M.D., at the University of California in Berkeley. Also, Krauss, R.M. Editorial Am J Clinical Nutr. 65:885-6, 1997.

-- 30 percent fat diet for high cholesterol and triglycerides
Knopp, RH. JAMA 1997; 278:1509-1515

-- Risks of low-fat, high-carbo diet
Jergen, J, et al, Am J Clin Nutr 1997;65:1027-33

-- Stroke risk
Gillman, Matthew W JAMA, 1997:278:2145-50

-- More olive oil type fat reduced heart disease
Hu, FB, N Engl J Med 1997 Nov 20; 337(21): 1491-9

The main things to know

Old vs. new ideas