chicken soup but also of heart-healthy sulfur compounds in garlic and onions, anticholesterol dietary fiber in grains and beans, bone-building calcium in milk and greens, and mood elevators in coffee, tea, and chocolate.
Of course, foods pose some risks as well: food allergies, food intolerances, food and drug interactions, and the occasional harmful substances, such as the dreaded saturated fats and trans fats (see Chapter 7). In other words, constructing a healthful diet can mean tailoring food choices to your own special body, which is the subject of Part 5.
Finding Nutrition Facts
Getting reliable information about nutrition can be a challenge. For the most part, you’re likely to get your nutrition information from TV and radio talk shows or news, your daily newspaper, your favorite magazine, a variety of nutrition-oriented books, and the Internet.
If you’re not a nutrition expert, how can you tell whether what you hear or read is really right? By looking for the validation from people who are, of course, and by knowing what questions to ask.
Nutrition people
Not every piece of nutrition news is nutritious. The person who makes the news may simply have wandered in with a new theory — “Artichokes cure cancer!” “Never eat cherries and cheese at the same meal!” “Women who take vitamin C are more likely to give birth to twins!” The more bizarre, the better.
Those most likely to give you news you can use with confidence are
Nutrition scientists and researchers: These are people with undergraduate or graduate degrees in science subjects, such as chemistry, biology, biochemistry, or physics, and are engaged in research dealing primarily with the biological effects of food on animals and human beings. Some nutrition investigators come from other fields entirely, such as a historian or sociologist, whose research concentrates on food history and habits.
Dietitians and nutritionists: These people have undergraduate degrees in food and nutrition science or the management of food programs. A person with the letters RD (registered dietitian) after his name has completed a dietetic internship and passed an American Dietetic Association licensing exam. In some states, a person who claims the title “nutritionist” must have a graduate degree in basic science courses related to nutrition.
Nutrition reporters and writers: These are people who specialize in giving you information about the medical and/or scientific aspects of food. 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; others gain their expertise through years of covering their beat.
Questions to ask about any study
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. 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.
Consider the saga of dietary fiber and colon cancer. In the early 1990s, based on a respectably large number of studies including a 1992 meta-analysis of 13 case-control efforts in nine different nations, all kinds of health experts urged everyone to increase his or her consumption of high-fiber foods to reduce the risk of colon cancer. Then in 1999, data from the long-running Nurses’ Health Study at the Harvard School of Public Health showed absolutely no difference in the risk of colon and rectal cancer between women who ate lots of high-fiber foods and those who didn’t.
Imagine the confusion. Imagine the number of boxes of high-fiber cereal tossed in favor of scrambled eggs, once considered a cholesterol risk, now regarded as perfectly healthful, for breakfast. Imagine the reaction to a report in the Journal of the National Cancer Institute two years later saying that while cereal high in dietary fiber may not be protective, people whose diets are low in fruit and vegetables have the greatest risk of colorectal cancer. What to do? Toss the cereal? Keep the banana?
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 ask five common-sense questions about any study to arrive at a sensible conclusion that says, “Yes, this may be true,” or “No, this may not be.”
Does this study include human beings?
True, animal studies can alert researchers to potential problems, but working with animals alone can’t give you conclusive proof of the effect in human beings because different species react differently to various foods and chemicals and diseases. Cows and horses can digest grass and hay; humans can’t. 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.
Are there enough people in this study?
No, a researcher’s saying, “Well, I did give this to a couple of people,” is not enough. To provide a reliable conclusion, a study must include sufficient numbers of people to establish a pattern. Otherwise, there’s always the possibility that an effect occurred by chance.
Equally important, the study needs people of different ages, races, ethnicity, and, yes, gender. Without them, the results may not apply across the board. One good example can be found in the original studies linking high blood cholesterol levels to an increased risk of heart disease and linking small doses of aspirin to a reduced risk of a second heart attack involved only men. It wasn’t until follow-up studies were conducted with women that researchers were able to say with any certainty that high cholesterol may be hazardous for men and women and that aspirin is protective for women as well as men — but not in quite the same way. As cardiovascular researchers eventually learned, men taking low-dose aspirin tend to lower their risk of heart attack. For women, the aspirin reduces the risk of stroke. Vive la difference!
Is there anything in the design or method of this study that may affect the accuracy of its conclusions?
Some testing methods are more likely than others to lead to biased or inaccurate conclusions. A retrospective study (which asks people to tell what they did in the past) is always considered less accurate than a prospective study (one that follows people while they’re actually doing what the researchers are studying), because memory isn’t always reliable. People tend to forget details or, without meaning to, alter them to fit the researchers’ questions.
Was this study reviewed by the author’s peers?
Serious researchers
