In the previous blogpost you learned all about proteins, this week the spotlight is on carbohydrates. Carbs have a bad reputation, which appears to have grown exponentially in recent years. Advocates for low-carb-, keto-, paleo- or combination diets like to portray them as being pure sugars (and therefore fattening), or as a food group that has adverse effects on your digestion. Is this true? Or is this a bit short-sighted, in many cases unhealthy and sometimes even dangerous (SPOILER ALERT: yes)? Because while all sugars are indeed carbohydrates, not all carbohydrates are sugars. In this blog post we will give you the most important information, as well as some tips & tricks to be able to distinguish friend from foe.
Carbohydrates can be divided into simple and multiple (or complex) carbohydrates. The simple carbohydrates - referred to as sugars - occur naturally in fruit (fructose) and in milk (lactose). For this reason they are also known as ' intrinsic sugars '. But they can as well be added to foods by means of pure sugar, extracted from sugar beet or sugar cane. In the latter case they are called 'free sugars'. The chemical name of the 'pure' sugar is sucrose. Sucrose consists of two molecules: glucose and fructose. Honey, agave syrup and coconut sugar are some of the alternatives that are often portrayed as healthier options. This is not entirely true, as they are chemically the same molecules, and therefore behave in exactly the same way in your body as pure sugar. The 'raw' products do contain vitamins and minerals that you won't find in regular sugar, but due to the heating process they undergo to transform them into syrup, almost all of these are lost.
The complex carbohydrates are chains of simple carbohydrates and can be divided into starch (digestible) or dietary fiber (indigestible). Starch (just like the simple carbohydrates) must be broken down or converted into glucose by our bodies before it can be used as an energy source. This is perhaps why they are sometimes wrongly considered to be the same as simple carbohydrates. Dietary fiber, on the other hand, is not digested in the digestive system and reaches the colon intact.
Carbohydrates are first and foremost energy suppliers, they contain 4 kcal per gram. You can safely consider them as the fuel for our body. Especially for our brain and our red blood cells, they play an important role. As we read in the post about proteins, all macronutrients are best ingested in a certain percentage of the daily energy requirement (En%). In the case of carbohydrates, this is 55 En%, in other words more than half of what you eat in a day. Given the complex chemical classification of carbohydrates, it is not easy to simply translate them into physical properties or health effects. That is why it is much more useful to look at the foods in which they are found.
The WHO recommends limiting free (or added) sugars to 5 En%. For an adult, this amounts to no more than 25 grams per day. In comparison, a glass of coke (25cl) contains 21.2 grams of sugar, the same amount as a glass of fruit juice. Previously, the upper limit was set at 10 En%, but this was adjusted after new scientific research showed that the link between sugar and obesity, type 2 diabetes, cardiovascular disease and even certain cancers is even more significant than previously suspected. The most recent food consumption survey (2014) showed that Belgians currently consume almost half of their carbohydrate budget on simple carbohydrates, which is far too much. This is partly because a lot of sugars are added to products from which you would not expect it at first glance, such as canned or jarred vegetables, sauces, cold cuts, ready meals (even the 'healthy' frozen meals often contain added sugars!) and baby food.
Starch sources can be divided into unprocessed and processed - or refined sources. The unprocessed starch sources are found in whole grain products (whole grain rice, - pasta, - bread) and in oatmeal, potatoes and legumes. They are a good choice, as they are often also a source of vitamins (all B vitamins except B12) and minerals (including iron, zinc, magnesium) and because they are high in fiber.
Sources with refined starch are less interesting, as most of the fiber, vitamins and minerals disappear when the flour is processed into white flour. You will find them in white bread, white pasta, cookies, cakes and sweet and salty snacks. Since many of the products on this list also contain large amounts of free sugars and saturated fats, they add little value to our daily diet.
Dietary fiber is important for the health of our intestinal system and even protects us against certain diseases such as constipation and colon cancer. Furthermore, they prevent the absorption of cholesterol and therefore help prevent cardiovascular diseases. Foods rich in fiber are digested more slowly, thus preventing strong peaks and dips in blood sugar. Finally, they provide a high level of satiety, thus reducing the risk of overeating and obesity. An adult needs about 30 grams of fiber per day. The Belgian adult currently barely touches 18 grams per day, and the total proportion of carbohydrates is only 44 En% (instead of the recommended 55 En%). Combined with the high consumption of sugars and the fact that 30% of the Belgian population is overweight, we can only suspect that the wrong types of carbohydrates are being focused on.