Black Friday Weekend Sale : Save 30% or more on all our guides and exclusive bundle offers. Learn more

The Nutrition Examination Research Digest (NERD) aims to provide rigorous, unbiased analysis of the latest and most important nutrition and supplementation studies. Click here to subscribe or login if already a subscriber .

In this article

Gucci vs. Gap carbs

Quality matters when it comes to carbs. This series of meta-analyses explored what measures of carb quality are most useful for predicting health outcomes.

Tags:
Study under review: Carbohydrate quality and human health: a series of systematic reviews and meta-analyses.

Introduction

Generally made up of sugars, starches, and dietary fiber[1], carbohydrate-containing foods are a prominent source of dietary energy worldwide. However, there have been reports as early as 1969PMID: 0 warning about associations between refined carbohydrate and chronic disease. Now, recommendations embrace a 45%-65% range[2] of total energy from carbohydrate, with sugar making up less than 10% of total energy[3] in the overall diet.

Indeed, studies[4] have demonstrated that an excessive consumption of calorically dense and micronutrient-poor foods, or “empty calories,” that are generally found at a convenience store[5], are associated with various cardiometabolic complications such as coronary heart disease[6], stroke[7], and type 2 diabetes[8]. However, researchers have also started to understand how carbohydrate-containing foods may not be all that bad when whole. As you can see in Figure 1, the processing[9] to achieve a refined grain removes several healthful components (especially dietary fiber), turning this staple into a demon—transforming the whole grain into an “empty” grain.

This has become even more relevant as the benefits of different components of carbohydrates are revealed, raising the question of whether different carbohydrate components might serve as markers of carbohydrate quality in the overall context of a diet. Dietary fiber is one component in particular that has demonstrated modest beneficial influence on satiety[10], appetite, and blood lipids[11]. While dietary fiber is a kind of carbohydrate that can’t be digested by our body’s enzymes, the ‘good’ microbiota in our guts feed on them and appear to be driving some of the potential benefits[12] attributed to dietary fiber. Beside that indigestible part of our diet, whole grains[13] also carry phytochemicals, such as carotenoids and polyphenols, and vitamin E that exhibit antioxidant potential and have been associated with reductions in inflammation[14] and chronic disease[15].

Previous studies[16][17] have demonstrated positive associations between health and diets characterized by higher markers of carbohydrate quality. However, these studies only explored a single aspect of carbohydrate quality (e.g., whole grain intake) and a limited number of clinical outcomes. This makes it difficult to determine how useful markers of carbohydrate quality are for predicting their potential for chronic disease prevention. The authors of the study under review aimed to quantify the predictive potential of several markers for carbohydrate quality and determine which might be most useful to predict chronic disease mortality and risk. A particular focus was placed on dietary fiber and deriving a quantitative recommendation for its intake. For this purpose, the researchers used data from both prospective studies and randomized controlled trials (RCTs) to quantify and ideally bridge the gap between experimental and observational data.

Carbohydrates are a staple of the human diet. Types of dietary carbohydrates include sugars, starches, and dietary fiber. Excessive processing of whole sources of carbohydrates might be stripping the foods of components that might improve their quality by making them healthier. Whole grains and dietary fiber have been associated with various benefits, including associations with reduced chronic disease, but previous studies have only investigated single markers of carbohydrate quality and a limited number of clinical outcomes. The authors of the study under review aimed to quantify and compare the predictive potential of several markers of carbohydrate quality for chronic disease mortality and risk based on data from both observational and experimental data.

Who and what was studied?

Become a subscriber to the Nutrition Examination Research Digest to read the full article.

Becoming a member will keep you updated on the most important nutrition studies every month, and give you access to our back catalog of over 500 other articles.

NERD also includes access to Examine Personalized, which includes 150+ monthly summaries on the most important recent studies and access to our database of 10,000+ studies across 600+ health topics.

Stop wasting time and energy — we make it easy for you to stay on top of nutrition research

Try free for a week

Already a member? Please login to read this article.

What were the findings?

Subscribe to the Nutrition Examination Research Digest to unlock this article.

Free 7-day trial!

Already a member? Please login to read this article.

What does the study really tell us?

Subscribe to the Nutrition Examination Research Digest to unlock this article.

Already a member? Please login to read this article.

The big picture

Subscribe to the Nutrition Examination Research Digest to unlock this article.

Already a member? Please login to read this article.

Frequently asked questions

Subscribe to the Nutrition Examination Research Digest to unlock this article.

Already a member? Please login to read this article.

What should I know?

Subscribe to the Nutrition Examination Research Digest to unlock this article.

Already a member? Please login to read this article.

A Black Friday Weekend Sale for Science Lovers!

Looking to improve your health using the latest evidence? Examine.com offers a membership and guides based on personalized, comprehensive research analysis.


Click here to save 30% »

Other Articles in Issue #55 (May 2019)