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Fact Check - Carbs: friend or foe?

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.

In a minute we will list a number of tips & tricks, but first we want to talk briefly about a term that may not be unfamiliar to you: the glycemic index (GI). This term is used to indicate how quickly the carbohydrates in a food are converted into glucose and then absorbed into the blood. After eating a carbohydrate-rich meal (especially the simple or fast carbohydrates), your blood sugar levels will rise. Our bodies then produce insulin to bring it back down. Too many and too rapid blood sugar spikes are thought to increase the risk of insulin resistance and diabetes, which is why some nutrition experts recommend eating mainly products with a low glycemic index. You can find extensive lists online where foods are ranked from a low to a high GI. There is some nuance to this. First of all, only 10 (!) test persons were used for the classical calculation of the glycemic index of foods. Moreover, the GI of a given product can vary greatly depending on how the product is prepared, the time of day you eat it, and its effect even varies from person to person. Moreover, and again: we usually eat combinations of foods. Fats, proteins and fiber, for example, lower the GI, since they stay in the stomach longer. So it doesn't make much sense to be blinded by these kinds of lists, it's much more efficient to try to limit your consumption of added sugars and increase your intake of high-fiber products.

So much for the theory! But how do you put this into practice? We are happy to give you a few tips & tricks:

- The more processed the product is, the more added sugars it contains. This also applies to the quantities of salt, saturated fats and preservatives. So you better opt for unprocessed products as much as possible.

- Choose whole grain products as much as possible.

- In doubt? Check the label! Unfortunately, dietary fiber is not usually mentioned, but it is compulsory to indicate how much sugar the product contains. Note: the sugars listed include the intrinsic sugars (i.e. the sugars that are naturally present), so for some products this can give a distorted picture. This may be the case for example with yoghurt, jams, apple sauce or other fruit preserves. In that case, choose products with the statement no added sugars.

- Checking the list of ingredients can also be helpful, if you know what to look for. Added sugars operate under various aliases: glucose, fructose, maltodextrin, maltose, dextrose, sucrose, malt syrup, etc. Another thing many people don't know: the earlier an ingredient is listed, the greater its share in the product. Bunch of rascals, those manufacturers.

- The healthiest sources of carbohydrates are whole grain products, potatoes, vegetables, fruit and legumes. All food sources that are also rich in vitamins and minerals. Easy!

- Feel free to eat the occasional cupcake, a giant plate of white pasta or a tasty baguette. Just make sure that these things are not the primary share of your diet. Balance, right?

- If you exercise intensively, it is extra important to take in plenty of carbohydrates. If your supply is not sufficiently filled, your body will switch to proteins as an energy source. You will therefore start to break down your muscles, and not burn fat as some people wrongly assume. Not that efficient.

Hopefully we've been able to convince you that most carbs are our friends. For those of you still in doubt, next week we will go into a little more detail about the different types of low-carb diets. They are very popular and consequently big business. Unfortunately, they usually lack scientific evidence and can even be dangerous, which is why we believe they deserve a separate blog post.

Do you have any questions or suggestions after reading this blog post? Feel free to leave a comment!


· Vlaams Instituut Gezond Leven, Suiker, onverbloemd,

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