Carbohydrates as part of a healthy diet
In times where cutting carbs has been a popular weight loss strategy, and health policies worldwide postulate to reduce the intake of small-sized carbohydrates, respective sugars, questions are raised whether carbohydrates should be part of a healthy diet? And if so, to what extent?
Seidelmann and colleagues (2018) had followed about 15,000 US adults over 25 years regarding their carbohydrate intake and life expectancy in a public health study. When combining their data with other multinational studies in a meta-analysis, they observed that the greatest lifespan can be seen with 50% to 55 % of the daily energy intake coming from carbohydrate, while low carbohydrate intake (less than 40%) or high carbohydrate intake (over 70% of the daily energy intake) were linked with shorter residual lifespan. Their findings underline dietary recommendations worldwide which postulate that more than half of the daily energy intake shall come from carbohydrates, up to 30% from fat and about 15% to 20 % from protein (WHO 2003, Figure 1).
It is for good reasons, that most common foods of the daily diet contain carbohydrates, be it in form of starches, maltodextrins, sugars or dietary fibers. Carbohydrates supply the body with energy or fuel. In fact, glucose is the main fuel for the body, used by all its living cells, while some parts like the brain and central nervous system even depend on glucose as sole source of energy. As the main building block of carbohydrates, glucose is obtained upon digestion and uptake by the body.
The physiological quality of carbohydrates matters
Those, who look beyond fueling the body with carbohydrate energy and thrive for a long and healthy life, will consider the type of carbohydrate as well. While dietary fibers have important colon functions, sugars and starches supply the body with carbohydrate energy in form of glucose. The glucose release after digestion and uptake into the body is reflected in the blood glucose response and determines metabolic regulation and energy supply. The hormone insulin plays a key role in this. Carbohydrates with low or reduced effect on blood sugar levels are considered as preferred choices.
While modern diets contain large proportion of carbohydrate foods with high blood sugar rising effect, scientific evidence is mounting that reducing blood sugar levels is relevant to health and the prevention of lifestyle-related diseases. Among others, leading scientists and carbohydrate quality experts from around the globe, who formed the International Carbohydrate Quality Consortium, reviewed the available science in 2015 and concluded in their consensus statement (Augustin et al 2015): There is convincing evidence that reducing glycaemia has health benefits in the management or prevention of diabetes mellitus (improving insulin sensitivity and beta-cell function), in the prevention of coronary heart disease (improving blood lipids and inflammatory markers) , and with probable evidence also in weight management (reducing fat mass).
With today’s knowledge that weight management and healthy ageing already starts in mummy’s tummy and early infancy and continue as a life-long process, keeping blood sugar levels low cannot start early enough: It matters to people of all age groups who thrive for a healthy diet and lifestyle.
Which carbohydrates to look for?
Whether a carbohydrate triggers a high or a low blood glucose response is not a question of a starch- or a sugar-type carbohydrate, as commonly believed. Jenkins and colleagues showed in the early 1980th with their Glycaemic Index concept that starch-type carbohydrates as in boiled potatoes or white bread can behave like traditional sugars in terms of a fast and high blood glucose response, whereas starch in pasta or cooked legumes likes beans, peas or lentils have lower blood glucose responses (Jenkins et al 1981). Similarly, also sugars can vary in their glycaemic properties, from very high (e.g. glucose) to low and slow (e.g. isomaltulose) blood glucose responses (Figure 2). The GI database of Sydney University provides one of the worldwide largest collection of carbohydrate-based foods and their Glycemic Index values, classified into those foods with a high GI (70 or more), medium GI (56 to 69) or low GI (55 or less).
Isomaltulose supplies carb energy with low effect on blood glucose levels and insulin
Among the range of fully digestible carbohydrates, isomaltulose stands out as a carbohydrate with slow release properties. Resulting from these, isomaltulose supplies glucose in a slower, more steady and sustained way, with low effect on blood glucose levels and insulin (Figure 3). Its low glycaemic properties have been verified scientifically for healthy individuals as well as for those with prediabetic conditions or with diabetes mellitus (low blood glucose response scientifically established).
The Glycaemic Index (GI) of isomaltulose was tested at Sydney University according to international standards and confirms its classification as “low GI” carbohydrate with a Glycaemic Index of 32, in comparison with a GI of 100 for glucose, and a GI of 68 for sucrose (Figure 2).
Isomaltulose can help to bring a low GI diet into practice
Where individuals look for suitable carbohydrate to reduce their blood sugar levels over the day, the slow release carbohydrate isomaltulose can serve as valuable option: Consuming foods with isomaltulose in place of higher glycaemic carbohydrates can reduce the blood glucose response. A corresponding health claim has been approved in the European Union (Regulation 2012/432).
Following blood sugar levels and substrate metabolism over a day with the simultaneous use of continuous glucose monitoring and whole body calorimetry, Henry and co-workers illustrated in 2017, how isomaltulose can help to bring a carbohydrate-based low glycemic diet into practice with triple improvements: A low-glycemic diet with isomaltulose-containing foods lowered the blood sugar profile throughout the day as a result of the lower meal responses. Moreover, blood sugar levels were more stable, with less amplitude in fluctuations, and the metabolism was steered towards higher fat burning, in comparison with a high glycaemic diet with sucrose-sweetened foods. Replacing high glycemic carbohydrates with lower glycemic options can have a lasting effect on blood sugar levels, respectively, making isomaltulose a good option for individuals looking to manage glycemic control.
Creating a healthy metabolic profile with isomaltulose
With its low effect on blood sugar levels and insulin release, isomaltulose creates a metabolic profile that favors fat burning and supports normal blood glucose control and body weight management. While most pronounced improvements in blood glucose control and insulin sensitivity can be seen for those with raised blood glucose levels. Kahlhöfer et al (2016) illustrate in their study with 14 healthy physically active man, that insulin sensitivity already reduced during one week of physical inactivity, yet remained significantly higher when the men consumed isomaltulose drinks instead of sucrose drinks during this time. Apart from lower blood glucose levels and less insulin secretion, the isomaltulose drink was associated with longer arterial relaxation after the meal in comparison with the sucrose drink.
Existing research further suggest that sugars replacement for isomaltulose can lower body fat storage, in this case liver fat, with resulting positive effects on insulin sensitivity. In comparison to sucrose, Keyhani-Nejad et al (2015) observed that isomaltulose feeding for 22 weeks prevented non-alcoholic fatty liver and improved glucose tolerance in rats. The researchers further demonstrated that the different incretin response, along with the low effect of isomaltulose on GIP release in the early parts of the small intestine, plays a key role in the underlying mechanism. This emphasizes the potential of isomaltulose as a nutritional strategy to prevent fatty liver and insulin resistance independent of obesity. The physiological relevance of GIP for metabolic health and disease and related benefits of a low GIP release with isomaltulose have been described by the same researchers in a review (Pfeiffer and Keyhani-Nejad 2018), clearly showing that the type of sugar consumed can make a difference.
Augustin LS, Kendall CW, Jenkins DJ et al (2015) Glycemic index, glycemic load and glycemic response: An International Scientific Consensus Summit from the International Carbohydrate Quality Consortium (ICQC). Nutr Metab Cardiovasc Dis 25(9):795-815. doi: 10.1016/j.numecd.2015.05.005.
Henry CJ, Kaur B, Quek RYC, Camps SG (2017) A Low Glycaemic Index Diet Incorporating Isomaltulose Is Associated with Lower Glycaemic Response and Variability, and Promotes Fat Oxidation in Asians. Nutrients 9(5). https://www.mdpi.com/2072-6643/9/5/473/html
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Kahlhöfer J, Karschin J, Silberhorn-Bühler H, Breusing N, Bosy-Westphal A, Kahlhofer J, Silberhorn-Buhler H (2016) Effect of low glycemic-sugar-sweetened beverages on glucose metabolism and macronutrient oxidation in healthy men. Int J Obes (Lond) 40(6):990–997. https://www.nature.com/ijo/journal/v40/n6/full/ijo201625a.html
Keyhani-Nejad F, Irmler M, Isken F, Wirth EK, Beckers J, Birkenfeld AL, Pfeiffer, Andreas F H (2015) Nutritional strategy to prevent fatty liver and insulin resistance independent of obesity by reducing glucose-dependent insulinotropic polypeptide responses in mice. Diabetologia 58(2):374–383.
Seidelmann SB, Claggett B, Cheng S, Henglin M, Shah A, Steffen LM, Folsom AR, Rimm EB, Willett WC, Solomon SD (2018) Dietary carbohydrate intake and mortality: a prospective cohort study and meta-analysis. Lancet Public Health 3(9):e419-e428. https://doi.org/10.1016/S2468-2667(18)30135-X
Sydney University’s Glycaemic Research Service (SUGiRS) (2002): See GI Database at www.glycemicindex.com
WHO/FAO (2003) Diet, nutrition and the prevention of chronic diseases. WHO Technical Report Series 916. WHO/FAO, Geneva