5 food myths busted

Nutrition misinformation fools men into being confused and frustrated in their quest to eat healthily, even if they're already achieving great results. Thankfully, you're about to be enlightened by science. Here are 5 food fallacies you can forget about for good.

Food 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 1.27g per pound (about 500g) of body weight a day - damages healthy kidneys.

The bottom line: As a rule of thumb, shoot to eat your target body weight in grams of protein daily. For example, if you're a chubby 180 pounds (81kg) and want to be a lean 150 (68kg), then have 180g of protein a day. Likewise if you're a skinny 120 pounds (54.5kg) but want to be a muscular 150.

Food Myth #2
"Sweet potatoes are better for you than white potatoes."

The origin: Because it's more common to eat the highly processed version of the white potato - for instance, french fries and potato chips - consumption of this root vegetable has been linked to obesity and an increased diabetes risk. Meanwhile, sweet potatoes, which are typically eaten unprocessed (soups, desserts etc), have been celebrated for being rich in nutrients and also having a lower glycaemic 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 fibre and vitamin A, but white potatoes are higher in essential minerals, such as iron, magnesium, and potassium. As for the glycaemic 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 glycaemic index of a meal.

The bottom line: The form in which you consume a potato - for instance, a whole baked potato versus a processed potato that's used to make chips - is more important than the type of spud.

Food 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.

The bottom line: Don't stop grilling. Meat lovers who are worried about the supposed risks of grilled meat don't need to avoid burgers and steak; rather, they should just trim off the burned or overcooked sections of the meat before eating.

Food Myth #4
"High-fructose corn syrup (HFCS) is more fattening than regular sugar is."

The origin: In a 1968 study, rats that were fed large amounts of fructose developed high levels of fat in their bloodstreams. Then in 2002, University of California at Davis researchers published a well-publicised paper noting that Americans' increasing consumption of fructose, including that in HFCS, paralleled their skyrocketing rates of obesity.

What science really shows: Both HFCS and sucrose - also known as regular sugar - contain similar amounts of fructose. For instance, the two most commonly used types of HFCS are HFCS-42 and HFCS-55, which are 42 and 55 per cent fructose, respectively. Sucrose is almost chemically identical, containing 50 per cent fructose. This is why the University of California at Davis scientists determined fructose intakes from both HFCS and sucrose. The truth is, there's no evidence to show any differences in these two types of sugar. Both will cause weight gain when consumed in excess.

The bottom line: HFCS and regular sugar are empty-calorie carbohydrates that should be consumed in limited amounts. How? By keeping soft drinks, sweetened fruit juices, and prepackaged desserts to a minimum.

Food Myth #5
"Salt causes high blood pressure and should be avoided."

The origin: In the 1940s, a Duke University researcher named Walter Kempner, MD, became famous for using salt restriction to treat people with high blood pressure. Later, studies confirmed that reducing salt could help reduce hypertension.

What science really shows: Large-scale scientific reviews have determined there's no reason for people with normal blood pressure to restrict their sodium intake. Now, if you already have high blood pressure, you may be "salt sensitive". As a result, reducing the amount of salt you eat could be helpful. However, it's been known for the past 20 years that people with high blood pressure who don't want to lower their salt intake can simply consume more potassium-containing foods. Why? Because it's really the balance of the two minerals that matters. In fact, Dutch researchers determined that a low potassium intake has the same impact on your blood pressure as high salt consumption does. And it turns out, the average guy consumes 3,100mg of potassium a day - 1,600mg less than recommended.

The bottom line: Strive for a potassium-rich diet by eating a wide variety of fruits, vegetables and legumes. For instance, spinach, broccoli, bananas, white potatoes and most types of beans each contain more than 400mg of potassium per serving.

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