HOW DO WE DEFINE ‘QUALITY’ CARBOHYDRATES?

You may have heard that the retired United States FDA Commissioner Dr David Kessler has sought to define some carbohydrate ingredients as unsafe unless proven otherwise. On his hit list are the following: processed starches, starch conversion products and refined flour and starches that are utilized in food extrusion technology. Examples include maltodextrins, chemically and physically modified starches, corn syrups, corn solids, and high fructose corn syrups, dextrose, glucose syrups, maltose, and syrups, wheat, corn, tapioca, oat, and potato flour and starches that are processed by extraction or similar technology.

Note: ordinary table sugar (sucrose) is not on the list. Nor any flours that you can buy in the supermarket. If you can make it at home, it’s benign. If it’s made in a factory using technology or ingredients not found at home, it’s ultraprocessed. The implication is that it’s beyond the pale.

David Kessler wrote to me a while back, asking if I had a name for ‘problem carbs’. Ideally, it would combine both a glycemic index approach and a processing approach. This is because the US has a different system of defining food additives compared to the rest of the world. They have a list called the GRAS list that is Generally Recognised As Safe. It includes substances like salt, sugar, refined fats and oils, anything that’s been used in home kitchens for donkey’s years. You can use these substances in any amount for any purpose. You could call it the ‘free for all’ list.

If it’s not on the GRAS list, it’s automatically defined as a food additive and therefore required to have appropriate safety data to back up its use in specified quantities in specific foods. The food industry is responsible for producing that data and it must pass FDA muster. This is the reason why Kessler needed a dual approach.

I think it will be simpler for the rest of the world to define a high-quality or poor-quality carbohydrate food. To their credit, Spanish scientists have already endeavoured to come up with a scientific way of defining carbohydrate quality [1]. They summed the scores for 4 attributes of a food: its glycemic index, fibre content, proportion of whole grains and whether it’s liquid or solid. They called it the Carbohydrate Quality Index and it’s since been shown to predict cardiometabolic health [2] and risk of developing breast cancer [3].

There’s no doubt that sugar-sweetened beverages (aka soft drinks, soda, etc…) are ‘empty glycemic bombs’ and public enemy #1 in the food supply (unless you count alcoholic beverages). They are usually consumed quickly in large amounts and typically, there’s not an antioxidant in sight. There are oodles of observational studies that shows they are linked to ill-health, while other sources of sugar (e.g., solid foods) are generally not [4]. Indeed, a recent dose-response meta-analysis showed no association between increasing sugar intake and risk of type 2 diabetes [5]. Surprised? I’m not. We consume just as much starch as we do sugar, and both raise glycemia (blood glucose).

Some studies have associated other carbohydrate-containing foods such as bread, rice and potatoes with type 2 diabetes, but the findings are not as consistent as with soft drinks, possibly because it depends on the ‘company they keep’. In other words, the rest of the meal may or may not include the micronutrients that can quench oxidative stress.

In my own mind, I’ve come to the conclusion that the problem carbs (for want of a better word) are those that produce a substantial glucose spike without being accompanied by the antioxidants like Vitamin C that would normally be closely associated (empty calories in other words). In plants, highly reactive molecules like glucose are always packed with the appropriate quantity of protective molecules. These include many phytonutrients such as the flavonoids as well as vitamins.

So, back to where we started. How do we define what we mean by high quality carbs and what name can we give them? Perhaps those that come with other essential nutrients like vitamins and minerals? Personally, I think we should prohibit the sale of empty calories in any form. We add Vitamin B1 to cheap alcohol to protect the vulnerable from a disease called Wernicke-Korsakoff Syndrome. We don’t make a song and dance about it. We add iodine to salt to make up for deficiencies in soil and protect against thyroid disease. We have refined oils that fortunately still include fat soluble vitamins like Vitamin E that are powerful antioxidants. They would go rancid quickly without them. Why not regulate the composition of sugary soft drinks so that they must contain Vitamin C? Like alcohol, they are not going to go away anytime soon. So why not reduce their harm? We could even regulate empty starches the same way.

Above all, we must not demonise yet another food group or nutrient. Carbohydrates have been an important component of our diet since the beginning of human evolution over 5 million years ago. Our ancestors were frugivores, ripe-fruit specialists whose habitat was a tropical forest [6]. Only recently, perhaps 1 million years ago, we learned to master fire and to cook and process the starch in seeds, roots and tubers [7]. Cooked starch became another source of glucose for our increasingly greedy big brain. Let’s hope we are intelligent enough to consume carbs – both sugars and starches – in the way that nature intended i.e., both enjoyable and optimised for good health. There should be no such thing as empty calories.

Read more:

1. Zazpe and colleagues. Association between dietary carbohydrate intake quality and micronutrient intake adequacy in a Mediterranean cohort: the SUN (Seguimiento Universidad de Navarra) Project. Br J Nutr, 2014.
2. Nikrad and colleagues. Dietary carbohydrate quality index (CQI), cardio-metabolic risk factors and insulin resistance among adults with obesity. BMC Endocr Disord, 2023.
3. Romanos-Nanclares and colleagues. Carbohydrate quality index and breast cancer risk in a Mediterranean cohort: The SUN project. Clinical Nutrition, 2021.
4. Li and colleagues. Consumption of sugar sweetened beverages, artificially sweetened beverages and fruit juices and risk of type 2 diabetes, hypertension, cardiovascular disease, and mortality: A meta-analysis. Front Nutr 2023.
5. Della Corte and colleagues. Dietary Sugar Intake and Incident Type 2 Diabetes Risk: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies. Advances in Nutrition, 2025.
6. Cerling and colleagues. Stable isotope-based diet reconstructions of Turkana Basin hominins. Proceedings of the National Academy of Sciences, 2013.
7. Gowlett and Wrangham. Earliest fire in Africa: towards the convergence of archaeological evidence and the cooking hypothesis. Azania: Archaeological Research in Africa, 2013.

Emeritus professor Jennie Brand-Miller held a Personal Chair in Human Nutrition in the Charles Perkins Centre and the School of Life and Environmental Sciences, at the University of Sydney until she retired in December 2022. She is recognised around the world for her work on carbohydrates and the glycemic index (or GI) of foods, with over 300 scientific publications. Her books about the glycemic index have been bestsellers and made the GI a household word.