Choosing carbohydrates

Choosing some food for your ride can seem complicated even if you are just looking to meet a target amount of carbohydrates. Slow carbs, fast carbs, modified carbs, maltodextrin, amylose, amylopectin… the more you read the crazier it becomes. The thing is that these carbohydrates are actually different, they have been shown to produce different results in athletes as well as effects on your health. This article will give an overview of what a keen amateur cyclist should look out for when choosing a carbohydrate rich food rather than panicking and grabbing a bag of Haribo.

A carb is just a carb right, they are all the same? Unfortunately not, there are many different types of carbohydrates with different properties. Some are natural, some are created in labs and food often contain mixes of different types. To help cyclists make better choices we are going to look at three aspects of carbohydrates: the basic chemical structures, the two ways that your body absorbs different carbohydrates and some of the differences between natural and refined sources of carbohydrate.

From an athlete’s perspective the first place to start is to see carbohydrates as falling into three categories: starches (called polysaccharides), sugars (called mono and disaccharides) and fibre. Foods containing lots of starch are pasta, rice, potatoes, bread and grains. Foods containing sugars are fruit, sweets, soft drinks and dairy products. Fibre is contained in less processed whole foods. This is more useful from a nutrition perspective than the looser terms “simple” and “complex” carbohydrates that you may have seen. 

Solid food containing starches are generally slower to digest than sugars so most useful for eating before and after exercise to gradually top up glycogen reserves without raising blood glucose too quickly. Sugars can be eaten during longer or harder rides to provide extra carbohydrates that your body uses. Sugars are usually quickly digested which means that they will help you within a few minutes of eating them. The flip side of this rapid digestion is that they need careful dosing to prevent spikes and dips in blood sugar and the “roller coaster” effect. Fibre is not directly digested in the human gut but can be fermented by bacteria and has other effects on our digestion. Fibre is useful to delay food absorption and add bulk to food, among other things, and this is generally not useful in large quantities for food taken on the bike.

The second consideration for us cyclists is how different types of sugars use different routes to find their way into the bloodstream for use. These different routes are separately limited, they can both be used simultaneously. Glucose is absorbed directly in your intestine, which is an efficient and quick process but has been found to be limited to a rate of about 1g per minute. Fructose is mostly absorbed via the liver, which is an extra process so a little slower and can be absorbed at about 0.5g per minute. Eating either glucose or fructose more quickly than they can be absorbed will lead to them building up in your intestine and potentially to an upset stomach. This is the reason that you will see that high dose carbohydrate foods will include a mix of glucose and fructose, often in the ratio of two units of glucose to one of fructose (Jentjens et al). A mix of glucose and fructose enables you to absorb more carbohydrate during your ride, 1.5g per minute instead of the 1g or 0.5g of the individual sugars, without suffering stomach complaints. Being able to digest more carbohydrates will however not necessarily lead to you being able to burn more, experiments have shown that even if an athlete can successfully eat larger amounts they will only burn about 1g per minute of these carbohydrates. The rest is stored for later use.

It is also worth understanding that sucrose is a mix of glucose, fructose and sucrose. The table below shows the wide variation in the mix of glucose, fructose and sucrose found in some common carbohydrate rich foods. If you are trying to maximise your eating on the bike you will therefore need to take care when choosing the types of food, or choose products that have done this for you.

Natural carbohydrate rich foods contain a mix of carbohydrates and other nutrients. Some of these nutrients, such as B vitamins, potassium and phosphorus, are helpful to the digestion and metabolism processes (Huskisson et al). Natural, less refined carbohydrates are also sweet tasting. Recent research (Dalenberg et al) has discovered that artificial sweetening of foods containing carbohydrates creates problems with the way your body reacts to the carbohydrates leading to changes in your appetite. Most maltodextrin based sports foods are artificially sweetened so carry the risk of upsetting your response to the carbohydrates. Natural foods also often contain more fibre which can helps slow the digestion of the carbohydrates and reduce the risk of raising blood sugar too quickly. This is beneficial as long as you are looking to support your glucose availability and not  looking for a quick “hit” to try and recover from a serious dip in blood sugar.

By carefully choosing natural foods that are high in a mix of carbohydrates and contain appropriate other nutrients we can make eating during your ride healthier as well as more enjoyable without losing the performance benefits. This is a core part of the philosophy that guides Kalkman’s product development.

References

Jentjens, R. L., et al. 2004. Oxidation of combined ingestion of glucose and fructose during exercise. Journal Applied Physiology

Huskisson, E. et al 2007 The Role of Vitamins and Minerals in Energy Metabolism and Well-Being Journal of International Medical Research

Dalenberg,  et al 2020 Short-Term Consumption of Sucralose with, but Not without, Carbohydrate Impairs Neural and Metabolic Sensitivity to Sugar in Humans