Every other week, new research claims one food is better than another, or that some ingredient yields incredible new health benefits. Couple that with a few old wives’ tales passed down from your parents, and each time you fire up your stove or sit down to eat a healthy meal, it can be difficult separating food fact from fiction. We talked to a group of nutritionists and asked them to share the food myths they find most irritating and explain why people cling to them.
Myth #1: “High protein intake is harmful to your kidneys.”
The origin: Back in 1983, researchers first discovered that eating more protein increases your “glomerular filtration rate,” or GFR. Think of GFR as the amount of blood your kidneys are filtering per minute. From this finding, many scientists made the leap that a higher GFR places your kidneys under greater stress. What science really shows: Nearly two decades ago, Dutch researchers found that while a protein-rich meal did boost GFR, it didn’t have an adverse effect on overall kidney function. In fact, there’s zero published research showing that downing hefty amounts of protein—specifically, up to 1.27 grams per pound of body weight a day—damages healthy kidneys.
Myth #2: Sweet potatoes are better for you than white potatoes.”
The origin: Because many Brits eat the highly processed version of the white potato—for instance, chips —consumption of this root vegetable has been linked to obesity and increased diabetes risk. Meanwhile, sweet potatoes, which are typically eaten whole, have been celebrated for being rich in nutrients and also having a lower glycemic index than their white brethren. What science really shows: White potatoes and sweet potatoes have complementary nutritional differences; one isn’t necessarily better than the other. For instance, sweet potatoes have more fiber and vitamin A, but white potatoes are higher in essential minerals, such as iron, magnesium, and potassium. As for the glycemic index, sweet potatoes are lower on the scale, but baked white potatoes typically aren’t eaten without cheese, sour cream, or butter. These toppings all contain fat, which lowers the glycemic index of a meal.
Myth #3: “Red meat causes cancer.”
The origin: In a 1986 study, Japanese researchers discovered cancer developing in rats that were fed “heterocyclic amines,” compounds that are generated from overcooking meat under high heat. And since then, some studies of large populations have suggested a potential link between meat and cancer. What science really shows: No study has ever found a direct cause-and-effect relationship between red-meat consumption and cancer. As for the population studies, they’re far from conclusive. That’s because they rely on broad surveys of people’s eating habits and health afflictions, and those numbers are simply crunched to find trends, not causes.
Myth 4: Microwaving food destroys the nutritional content
The term “radiation” frightens people, and it’s a common misconception that cooking food in the microwave can be damaging to our health. While the waves of energy used to heat food in the microwave are similar to other, more dangerous types, the point is that they are much, much shorter, and only target certain molecules, such as water. The energy from the waves causes the molecules to vibrate, therefore generating heat and cooking the food. Harvard Medical School points out that using a microwave to cook food can actually be beneficial, as cooking times are shorter and less water is needed, allowing foods such as broccoli to maintain more of their nutritional value than if they’d been boiled.
Myth 5: You shouldn’t eat too many eggs
In the past, we were told not to eat too many eggs due to fears about high levels of cholesterol. However, the British Heart Foundation dropped its advice to limit consumption to three eggs a week in 2007, and scientists argue that the impact on cholesterol is “insignificant”. In fact, eggs have multiple health benefits: the yolks are a good source of protein and fat, while the whites contain selenium, vitamin D, B6, B12, and minerals such as zinc, iron, and copper.
Myth 6: Detox is good for you
Every January we are besieged by new diets (usually involving juice, soup, or nothing at all) that claim to “detoxify” the body by removing dangerous substances building up the body. Unless you happen to have mislaid your liver, you’ll be relieved to hear that your body is already doing this, and doing it rather well. Your internal organs use chemical reactions to convert dangerous substances into safe ones that are naturally excreted. Restricting yourself to a liquid diet could actually do more harm than good: juices lack the essential fiber of whole fruits and vegetables, and you could be denying yourself essential proteins and minerals.
Myth 7: Fresh is better than frozen
Frozen produce can be as nutritious as fresh, Heller says, because it’s flash-frozen shortly after picking, which means it retains more nutrients than if it has to travel, unfrozen, for days before being sold. Plus, frozen often costs less. If you prefer fresh, try to buy local.
Myth 8: Coffee is dehydrating
Yes, coffee is a diuretic (aka, promotes urine production), but it’s an extremely mild one. It also has a lot of water in it and therefore actually counts toward your daily fluid intake. The amount it would take to dehydrate you is more than anyone should be consuming in a day—if you have two or three cups daily, your fluid levels will be completely fine.
Myth 9: Low-fat options are better than the originals
When fat is removed from foods, it’s usually replaced by sugar or salt, so it’s important to read the ingredients list before choosing the adulterated version. Usually, you’re better off eating a small serving of the full-fat kind so you actually enjoy it and feel satiated, Kaufman says.
Myth 10: Nuts are fattening so eat them sparingly
To be sure, nuts contain a lot of fat, but it’s mostly the good kind. Dry-roasted peanuts, for example, have three to four times more heart-healthy monounsaturated fat than saturated fat. Recent research suggests that eating nuts as part of a healthy diet may even help you lose weight.
Researchers believe that the fat in nuts helps people feel full, and the protein may use up calories as it digests. What’s more, a study by British researchers shows that high-protein foods help trigger the release of a hormone known to reduce hunger.