Are you shying away from foods that are actually good for you? With all the hoopla about healthful eating, it's hard to separate fact from fiction. As a nutrition consultant, I've come to realize that surprises and superstitions abound in the world of nutrition. Here are reasons to enjoy some of your favorites.
Gluten and wheat
They are "the most demonized ingredients beyond high fructose corn syrup and hydrogenated oil," said Melissa Abbott, culinary director at the Hartman Group, a company specializing in consumer research.
Yet decades of studies have found that gluten-containing foods, such as whole wheat, rye and barley, are vital for good health, and are associated with a reduced risk of diabetes, heart disease, cancer and excess weight.
"Wheat is a good source of fiber, vitamins and minerals," said Joanne Slavin, nutrition professor at the University of Minnesota. She added that the confusion about gluten, a protein, has caused some people to avoid eating wheat and other grains.
Only about 1 percent of the population, or less, cannot tolerate gluten and must eradicate it from their diet to ease abdominal pain and other symptoms, including the ability to fully absorb vitamins.
One reason wheat-free or gluten-free diets are popular is that people who don't eat wheat often end up bypassing excess calories in sweets and snack foods. Then they start feeling better, lose weight, and mistakenly attribute their success to gluten or wheat avoidance.
Eggs also don't deserve their bad reputation. In recent decades, their high cholesterol content has been thought to play a role in increasing LDL ("bad") cholesterol and heart disease risk.
But cholesterol in food is a minor factor contributing to high blood cholesterol for most people, and studies have not confirmed a correlation between eggs and increased heart disease risk. The major determinant of LDL cholesterol is saturated fat, and while eggs are high in cholesterol — 184 milligrams in the yolk — they're low in saturated fat — about 1.6 grams in the yolk.
Interestingly, some of the biggest egg eaters in the world, the Japanese, have low cholesterol and heart disease rates, in part because they eat a diet low in saturated fat. In contrast, Americans eat eggs alongside sausage, bacon and buttered toast.
"The amount that one egg a day raises cholesterol in the blood is extremely small," says Walter Willett, professor of epidemiology and nutrition at Harvard's School of Public Health. "Elevations in LDL (bad) cholesterol of this small magnitude could easily be countered by other healthy aspects of eggs."
Potatoes have been blamed for increasing blood glucose levels, insulin resistance, excess weight and Type 2 diabetes. A recent Harvard study that followed large populations and their disease rates linked potato eating with being overweight, blaming it on the rise in blood glucose.
But many foods, including whole-wheat bread and whole-grain cereals, cause similar spikes in blood glucose, and are correlated with superior health and lower body weights. How could the higher body weight in the Harvard study be explained?
The study lumped all potato products together, including potato chips and french fries, very fattening versions of potatoes usually eaten in large portions alongside hamburgers, hot dogs and sodas.
"It's an easy food to attack, but the meal pattern may be the culprit," said David Baer, a research leader at the Agricultural Research Service of the Department of Agriculture. "Other epidemiological studies have not verified a connection between potatoes and weight gain or any diseases, and no clinical studies have shown a connection."
Potatoes are a great source of potassium, Vitamin C and fiber that many cultures — Scandinavians, Russians, Irish and Peruvians — relied on as a nutritious staple for centuries. And they were not fat.
People often ask me if fruit is too high in sugar, especially for diabetics. This fear of fruit, I believe, is left over
from the Atkins craze, which discouraged eating some fruits on the grounds that they are high in carbohydrates.
Avoiding fruit could actually damage your health. Study after study over many decades shows that eating fruit can reduce the risk of some cancers, heart disease, high blood pressure and diabetes.
Fruit is high in water and fiber, which help you feel full with fewer calories, one reason why eating it is correlated with lower body weight. Even though they contain simple sugars, most fruits have a relatively low glycemic index. That is, when you eat fruit, your blood sugar rises only moderately, especially when compared with refined sugar or flour products.
Several health organizations, including the U.S. Dietary Guidelines, the National Cancer Institute and the American Heart Association, recommend Americans eat at least five cups of fruits and vegetables a day because of their superior health benefits.
Though popular for centuries in many Asian cuisines, soy is sometimes seen as dangerous after studies found elevated rates of breast cancer among rats when they were fed a concentrated soy derivative.
But studies looking at whole soy foods in humans have not found a connection. In fact, the reverse may be true.
Soy, "when consumed in childhood or adolescence, may make breast tissue less vulnerable to cancer development later in life and probably has no effect on breast cancer risk when consumption begins in adulthood," said Karen Collins, registered dietitian and nutrition adviser with the American Institute for Cancer Research.
Actually, Collins said, the evidence is so strong for protection against heart disease that the FDA allowed a health claim for labels on soy food products.
Alcohol is feared because of the potential for abuse and complications such as liver disease, which are valid concerns.
But decades' worth of research shows that moderate alcohol consumption "can reduce deaths from most causes, particularly heart disease, and it raises HDL (good) cholesterol," the USDA's David Baer said.
Wine may have additional benefits because grapes are filled with nutrients called polyphenols, which reduce blood-clotting, inflammation and oxidation.
The key is to drink alcohol moderately and with meals. What's moderation? One serving daily for women and two servings for men, with a serving being 5 ounces of wine, 12 ounces of beer or 1.5 ounces of spirits.
While it's true that frying food usually increases its caloric content, that doesn't necessarily make it unhealthful.
As long as food is fried in healthful oil instead of butter, shortening or trans fat, and it's eaten in moderation, it isn't less healthy. In fact, fat-soluble vitamins A, D, E and K and heart-healthy, cancer-preventive carotenoids such as beta-carotene (e.g., carrots, sweet potatoes), lycopene (e.g., tomatoes) and lutein/zeaxanthin (deep-green leafy vegetables such as spinach and kale) need fat in order to be absorbed by the body.
"The consumption of certain fats, such as saturated fatty acids and trans fatty acids (fats that are solid at room temperature) is associated with an … increased risk of cardiovascular disease. On the other hand, the unsaturated fats, monounsaturated fatty acids and polyunsaturated fatty acids (canola, safflower and olive oils) have significant metabolic benefits and are health promoting," said the 2010 U.S. Dietary Guidelines Advisory Committee.
Katherine Tallmadge is a registered dietitian and author of "Diet Simple: 195 Mental Tricks, Substitutions, Habits & Inspirations" (LifeLine Press, 2011).