Common nutrition myths debunked by science

Naveed Saleh, MD, MS | June 04, 2021

As a physician, you likely have a good sense of what constitutes a healthy diet for maintaining optimal weight.

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Man shopping in dairy aisle

Many of our long-held beliefs about nutrition are actually myths, according to studies.

According to the CDC, a healthy eating plan emphasizes ample fruits and vegetables, low-fat or fat-free milk products, and whole grains. Proteins should include lean meats and poultry, seafood, eggs, legumes, nuts, and seeds. Saturated fats, trans fats, cholesterol, salt, and added sugars should be limited.

“An eating plan that helps manage your weight includes a variety of healthy foods. Add an array of colors to your plate and think of it as eating the rainbow,” writes the CDC. “Dark, leafy greens, oranges, and tomatoes—even fresh herbs—are loaded with vitamins, fiber, and minerals."

Much of this advice seems like common knowledge by now. But the field of nutrition is rapidly evolving. New research has disabused some of our previous perceptions, and these days, counterintuitive stances—such as the benefits of consuming whole compared with reduced dairy—are emerging.

The following are five common misconceptions that are debunked by the evidence.

Myth #1: Whole milk is bad for you

In recent years, saturated fats have gotten a bum rap. Epidemiologic research published in the BMJ, however, points to the health benefits of whole vs reduced-fat milks in terms of metabolic syndrome.

In the Prospective Urban Rural Epidemiology (PURE) study, researchers followed 147,812 adults for a median of 9.1 years to determine the link between dairy intake and metabolic syndrome, hypertension, and diabetes. Their results were eye-opening.

Previous studies have shown that the increased intake of dairy was linked to a lower chance of metabolic syndrome. In the current study, whole-fat dairy—and not reduced fat—was associated with lower prevalence of metabolic syndrome, as well as a lower incidence of hypertension and diabetes.  

“Possible pathways for metabolic benefits of dairy include angiotensin-converting enzyme, peroxisome proliferator activated receptors, hepatic de novo lipogenesis, hepatic and adipose fatty acid oxidation, and inflammation,” the authors wrote. “Further, bioactive peptides or amino acids produced through yogurt or cheese fermentation improve insulin sensitivity, while branched chain amino acids in whey [have] been shown to improve postprandial insulin response.”

The authors suggested that their findings on whole-fat dairy should be evaluated in large randomized trials. 

Myth #2: Eggs are unhealthy

Eggs are chock-full of essential nutrients. Many people believe, however, that because of their high cholesterol content, eggs are unhealthy.  Nevertheless, it remains to be elucidated the exact impact that the different components of eggs have on heart health, with recent research indicating that some components may increase the risk of heart disease while others protect against it.  

According to the authors of a review published in Cholesterol, current research has tended to show that the consumption of eggs is not a risk factor of cardiovascular disease (CVD) in healthy people. 

“However, people who are at high risk of CVD such as those with diabetes or hypertension need to have caution with dietary cholesterol intake, especially egg intake. Also, some people seem to be more sensitive to dietary cholesterol whose blood cholesterol level is highly correlated to dietary intake," the authors wrote. "Therefore, even though the recommendation of restricting cholesterol and egg consumption in AHA [American Heart Association] and DGAC [US Dietary Guidelines Advisory Committee] has been eliminated, we still need to have caution with them based on the physiological status of people.”

To learn more about eggs and cardiovascular disease, read 6 clinically proven reasons why eggs are great for heart health, on MDLinx.

Myth #3: Avoid midnight snacking

A common misconception is that nobody should eat after midnight for fear of weight gain and so forth. But it depends on what is driving you to snack and what you are eating. According to MIT Medical, if you find yourself wanting to snack after midnight, try evaluating your hunger using the acronym HALT.

  • Are you eating out of Habit?

  • Are you feeling Anxious, Angry, or overwhelmed?

  • Are you feeling depressed or Lonely?

  • Are you feeling Tired?

If you answer "yes" to any of these screening questions, you may want to lay off midnight snacking and find a way to address what's really driving you to eat in the wee hours.

Keep in mind that many late-night eating options are unhealthy, such as food from the vending machine, fast food, or gas-station fare. Instead, plan out your late-night eating and look at this option as a meal rather than snack. Foods high in protein are good choices, such as half a turkey or tuna sandwich on whole wheat. Other good options include whole-grain cereal, low-fat cottage cheese, and nuts.

Keep in mind, late-night snacking can affect the quality of your slumber. Read What to eat and what to avoid for better sleep on MDLinx.

Myth #4: Protein supplements are good for you

In recent years, protein supplements have become popular among athletes who wish to enhance muscle and fitness. Although the scientific community generally recommends moderate protein intake, these levels may be inadequate for athletes, the elderly, or in those who wish to maintain or reduce weight, according to the authors of a review published in Nutrients.

As for protein supplements, they may carry certain risks, according to the study authors. 

“[W]hen a high-protein diet is recommended, special attention should be paid to the origin of these proteins and the overall quality of the food,” the authors wrote. “The consumption of ultra processed foods has been associated with the higher prevalence of several diseases, possibly due to high content of processed vegetable fats, sugars, salt and artificial sweeteners among other components.”  

Ingredients present in protein and amino acid supplements may induce adverse effects over the long run, and casual or recreational exercisers might be more susceptible to these than athletes, they noted.

Rather than adding these supplements to high-protein diets, the authors suggest that “protein should be preferably received from whole foods, such as fish, eggs, dairy products, legumes, and cereals, along with fibers and other food components supporting the well-being of both the host and their gut microbiota.”

So how much protein do you really need? Click here to learn more at MDLinx

Myth #5: Avoid snacks

Many people think that snacks are no good for those trying to maintain or lose weight. Fortunately, this is not the case, according to the US National Library of Medicine.

“They can provide energy in the middle of the day or when you exercise. A healthy snack between meals can also decrease your hunger and keep you from overeating at meal time,” they wrote. “There are many snacks to choose from, and certainly not all snacks are healthy or will help you manage your weight. Try to limit the unhealthy snacks you bring into the house. If they are not available, you are more likely to make healthy choices.”

When snacking, watch out for serving size, and select options that are high in fiber, high in water, low in fat, and low in sugar. Good choices include fruits, vegetables, whole-grain options, and lower-fat dairy. Finally, one trick to remaining full involves pairing a protein with a carbohydrate, such as an apple with peanut butter, or celery with hummus. To learn more about staying satiated, read 5 healthy foods to keep you feeling fuller longer at MDLinx.

Want to learn more about nutrition myths? Click here

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