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Good Carbs vs. Bad Carbs? Researchers Suggest a Different Approach

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Key Takeaway

  • Some dietary choices, like grains and dairy products, are getting skipped due to their carb amounts, a recent commentary suggests.
  • Considering that only one in 10 Americans is getting enough fruits and vegetables, these researchers believe that carb-counting alone is a faulty approach.
  • Instead of labeling only low-carb choices as “good” they suggest considering carb quality instead.

One of the three main macronutrients along with protein and fat, carbohydrates are one of the largest sources of energy for the body, yet they’ve been disparaged to some degree within the past few years. As low-carb eating continues to be popular, the viewpoint of “good carb” sources and “bad carb” choices has become pervasive, and researcher commentary in Advances in Nutrition suggests that perspective lacks much-needed nuance.

Labels like “good” and “bad” assigned to carb-heavy foods are based on overly simplistic measures, like glycemic index or fiber content, according to commentary co-author Rebekah Schulz, a graduate student in food science at the University of Minnesota.

“While these aspects can be individual pieces of the puzzle, they don’t reflect the full picture of carbohydrate quality,” she says. “For example, the glycemic index isn’t representative of real-life dietary intake when carbohydrates are consumed with other foods.”

Rebekah Schulz, graduate student

A different approach would be to assess carb quality, not just quantity.

— Rebekah Schulz, graduate student

That can lead to consumer confusion when it comes to nutritional recommendations, such as fruits and vegetables, she adds. For example, if some fruits or vegetables are considered “high-carb”, they may not make it into a shopping cart at the supermarket.

Around nine in 10 Americans are falling short of fruit and vegetable intake recommendations. Schulz says, “A different approach would be to assess carb quality, not just quantity.”

Proposed Carbohydrate Strategy

Rather than rely on carb-counting to drive eating decisions, the researchers propose looking at these aspects instead:

  • Whole-grain content
  • Amount of added sugars
  • Fiber amount
  • Ratio of total carbohydrate to fiber and added sugar
  • Protein quality
  • Degree of processing
  • Environmental impact of food

“Of all the macronutrients, carbohydrates have been stigmatized when it comes to health impacts,” says Schulz. “However, they make the highest percentage of intake worldwide, so defining quality is paramount.”

The Grain Question

Although fruits and vegetables seem like an easy choice to add into a fresh approach to carb consumption, what about grains? Schulz says any food or nutrient can have a place as part of a healthy lifestyle, but when it comes to highly refined grains, previous research still supports the recommendation to choose whole grains instead.

For example, a study in The BMJ looked at consumption of both types of grains in 21 countries, with over 137,000 total participants, and compared dietary patterns over a 16-year period with the incidence of cardiovascular disease, blood lipids, blood pressure, and total mortality.

Refined grain products included:

  • White bread
  • Pasta
  • Breakfast cereals
  • Crackers
  • Bakery products

Whole grain items were made with wheat, rye, oats, barley, and other flours where all the components of the grains were left intact.

Angie Asche, RD, CSSD

In general, reducing refined grains is a great strategy, unless there are specific reasons why you would want that effect ... for example, the classic ‘carb loading’ before any race longer than two hours...

— Angie Asche, RD, CSSD

They found that having more than seven servings of refined grains per day was associated with a 27% greater risk for early death, 33% higher risk for heart disease, and 47% higher risk for stroke.

In terms of why refined grains might have this effect, the study noted that these products have lower fiber content and are lacking in vitamins and minerals, essential fatty acids, and phytochemicals.

As a result, they’re absorbed quickly in the small intestine, which can increase blood glucose concentrations—a situation that’s been connected to poorer cardiovascular health.

Using the lens of the recent commentary, whole grains would qualify for the focus on a lower degree of processing and a higher amount of fiber.

“In general, reducing refined grains is a great strategy, unless there are specific reasons why you would want that effect,” says Angie Asche, RD, CSSD, owner of Eleat Sports Nutrition and author of Fuel Your Body. “For example, the classic ‘carb loading’ before any race longer than two hours is done for a reason, and that’s because you want to saturate the glycogen stores in your muscles.”

For everyday consumption, though, whole grains are a better choice for fiber as well as minerals like magnesium, potassium, calcium, and sodium, she says.

Just like refined grains, ultra-processed foods should also be eaten only very occasionally, says Schulz, who suggests focusing instead on high-quality carb sources, rather than basing your diet on carb amounts alone.

What This Means For You

When selecting carbohydrates, it's important to consider whole-grain and fiber content, the amount of added sugars, the ratio of total carbohydrate to fiber and added sugar, protein quality, degree of processing, and the environmental impact of food. Looking solely at the carbohydrate count of certain foods, such as dairy products and whole grains, may mean that you're missing the bigger nutrition picture.

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Article Sources
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  1. Schulz R, Slavin J. Perspective: Defining carbohydrate quality for human health and environmental sustainability. Adv Nutr. 2021:12(4): 1108-1121. doi:10.1093/advances/nmab023

  2. U.S. Department of Agriculture. Dietary Guidelines for Americans, 2020-2025. Published December 2020.

  3. Swaminathan S, Dehghan M, Raj JM, et al. Associations of cereal grains intake with cardiovascular disease and mortality across 21 countries in Prospective Urban and Rural Epidemiology study: prospective cohort studyBMJ. 2021:m4948. doi:10.1136/bmj.m4948