Research: Better quality of carbohydrates leads to better outcomes


Clinical outcomes improve with the quality of your carbohydrate intake.  



Clinicians and researchers have long suspected that not all carbohydrates are created equal.  It makes perfect sense that an unprocessed starchy food with 100 calories would not result in similar clinical outcomes as the same number of calories of table sugar.  The whole foods that are less processed should be more abundant in fiber and thus take longer to process by our bodies and result in less of an insulin and blood sugar spike.  The big problem is that there is a limited appetite to research such differences and thus there is little proof to back up such beliefs.  

The quality of carbohydrates is tied to the amount of processing.  Foods that are made of low-quality carbohydrates tend to be higher in sugar or readily digestible starches and lower in fiber.  Fiber slows digestions and helps to keep you full longer.  Foods with lower levels of fiber tend to faster digested and can lead to higher insulin blood glucose levels.  

The good news is that researchers publish in The Lancet appears to back up this hypothesis[1].  The World Health Organization recommends that dietary sugar be restricted to less than 10% of total energy intake because of this hypothesis.  Sugar remains fairly well studies, but other less processed carbs are not.  In the study, researchers performed systematic reviews and meta-analyses of a group of 185 prospective cohort studies and 58 randomized clinical trials in which markers of dietary carbohydrate quality and critical clinical outcomes were examined. 

In studies of total dietary fiber consumption, participants who consumed more fiber had significantly lower relative risks for all-cause mortality and nearly all coronary artery disease equivalents.  Higher fiber intake resulted in significantly greater decreases in body weight and lower blood pressure.  

Analysis of diets with high versus low glycemic indices did not yield significant differences.  This result may be contrary to what is expected.  Low fiber diets can be higher in red meat and fat and still have a low glycemic index.  Both of these have been tied to a higher risk of heart disease, so I suspect that is the cause or link.  

Researchers found a strong dose-response effect with dietary-fiber and whole-grain intake.  This finding is consistent with results of prior studies and analysis I have reviewed.   This finding supports a causal relation between measures of carbohydrate quality and better clinical outcomes. The researchers suggest minimum daily dietary fiber intakes of 25 to 29 g.  I would go one step further and recommend 35-40 grams daily.  

The bottom line: This analysis of prior research suggests that increasing the quality of the carbohydrates you eat might improve your clinical outcomes for neal all causes of mortality.   I recommend an increase in dietary fiber to 35 grams or more per day.  This study not only showed that outcomes improve, but also that weights were lower in those that ate more fiber and higher quality carbohydrates.  


A. Reynolds, J. Mann, J. Cummings, N. Winter, E. Mete, and L. Te Morenga, “Carbohydrate quality and human health: a series of systematic reviews and meta-analyses,” The Lancet, vol. 393, no. 10170, pp. 434–445, Feb. 2019 [Online]. Available: 10.1016/S0140-6736(18)31809-9″ target=”_blank” rel=”noopener noreferrer”>
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About the Author

I am a family physician who has served in the US Army. In 2016, I found myself overweight, out of shape, and unhealthy, so I made a change to improve my health. This blog is the chronology of my path to better health and what I have learned along the way.

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