Are the nutrition study’s conclusions reasonable?

When a study comes up with a conclusion that seems illogical to you, chances are the researchers feel the same way. For example, in 1990, the long-running Nurses’ Study at the Harvard School of Public Health reported that a high-fat diet raised the risk of colon cancer. But the data showed a link only to diets high in beef. No link was found to diets high in dairy fat. In short, this study was begging for a second study to confirm (or deny) its results. And while we wait for that second and, naturally, third study, you can bet we’re keeping an open mind. The nature of life is that things do change, sometimes in surprising ways. Consider dioxin, a toxic contaminant found in some fish. Consider Olestra, the calorie-free fat substitute that makes some tummies rumble. As you read this page, dioxin’s still a bad actor, but in 2005 researchers at the University of Cincinnati and the University of Western Australia announced that eating foods containing Olestra may speed your body’s elimination of — you guessed it — dioxin. A-maz-ing.

Does nutrition study always involve human subject?

Not always, animal studies can alert researchers to potential problems, but working with animals alone cannot give you conclusive proof. Different species react differently to various chemicals and diseases. For example, although cows and horses can digest grass and hay, human being can’t. And while outright poisons such as cyanide clearly traumatize any living body, many foods or drugs that harm a laboratory rat won’t harm you. And vice versa. For example, mouse and rat embryos suffer no ill effects when their mothers are given thalidomide, the sedative that’s known to cause deformed fetal limbs when given to pregnant monkeys — and human beings — at the point in pregnancy when limbs are developing. (And here’s an astounding turn:

Modern research shows that thalidomide is beneficial for treating or preventing human skin problems related to Hansen’s disease [leprosy], cancer, and/or autoimmune conditions, such as rheumatoid arthritis, in which the body mistakenly attacks its own tissues.)

Can you trust recent studies related to nutrition?

You open your morning newspaper or turn on the evening news and read or hear that a group of researchers at an impeccably prestigious scientific organization has published a study showing that yet another thing you’ve always taken for granted is hazardous to your health. For example, the study says drinking coffee stresses your heart, adding salt to food raises blood pressure, or fatty foods increase your risk of cancer or heart disease. So you throw out the offending food or drink or rearrange your daily routine to avoid the once-acceptable, now-dangerous food, beverage, or additive. And then what happens? Two weeks, two months, or two years down the road, a second, equally prestigious group of scientists publishes a study conclusively proving that the first group got it wrong: In fact, this study shows coffee has no effect on the risk of heart disease — and may even improve athletic performance; salt does not cause hypertension except in certain sensitive individuals; only some fatty foods are risky.

Who’s right? Nobody seems to know. That leaves you, a layperson, on your own to come up with the answer. Never fear — you may not be a nutritionist, but that doesn’t mean you can’t apply a few common-sense rules to any study you read about, rules that say: “Yes, this may be true,” or “No, this may not be.”

Nutritional people

The people who make nutrition news may be scientists, reporters, or simply someone who wandered in with a new theory (Artichokes prevent cancer! Never eat cherries and cheese at the same meal! Vitamin C gives you hives!), the more bizarre the better. But several groups of people are most likely to give you news you can use with confidence. For example:

• Nutrition scientists: These are people with graduate degrees (usually in chemistry, biology, biochemistry, or physics) engaged in research dealing primarily with the effects of food on animals and human beings.
• Nutrition researchers: Researchers may be either nutrition scientists or professionals in another field, such as medicine or sociology, whose research (study or studies) concentrates on the effects of food.
• Nutritionists: These are people who concentrate on the study of nutrition. In some states, a person who uses the title “nutritionist” must have a graduate degree in basic science courses related to nutrition.
• Dietitians: These people have undergraduate degrees in food and nutrition science or the management of food programs. A person with the letters R.D. after his or her name has completed a dietetic internship and passed an American Dietetic Association licensing exam.
• Nutrition reporters and writers: These are people who specialize in giving you information about the medical and/or scientific aspects of food. Like reporters who concentrate on politics or sports, nutrition reporters gain their expertise through years of covering their beat.

Most have the science background required to translate technical information into language nonscientists can understand; some have been trained as dietitians, nutritionists, or nutrition scientists. Consumer alert: Regardless of the source, nutrition news should always pass what you may call The Reasonableness Test. In other words, if a story or report or study sounds ridiculous, it probably is.