There are three macronutrients in the diet that provides us with energy; protein, fat and carbohydrates! And today I will go more into detail about carbohydrates.
What are carbohydrates?
Carbohydrates refers to different sugars, starches and fibres in our diet. These are all based on single sugar molecules, called monosaccharides. This is the most basic unit of a carbohydrate and they consist of carbon, hydrogen and oxygen.
To simplify things you can see monosaccharides like lego pieces; and when you put them together you get different forms and sizes, depending on how many there are and how you put them together. And depending on structure, they will have different effects on the body.
When you put them together you’ll get a different kind of saccharide, as you can read below
MONOSACCHARIDES: The basic unit of a carbohydrate molecule. All carbohydrates are built with these. The ones present in our diet are
DISACCHARIDES: Two units of monosaccharides.
- Sucrose (glucose + fructose) found in table sugar, brown sugar, coconut sugar)
- Lactose (glucose + galactose) is a milk sugar
- Maltose (glucose + glucose) found in beer and grains
OLIGOSACCHARIDES: Three to nine monosaccharides
- Inulin – a form on fibre
POLYSACCHARIDES: Ten and more sugar molecules
- Starch ( 10 and more glucose molecules), complex carb, found in seeds, rice, corn, grains, vegetables.
Function of carbohydrates
Carbohydrates are important for us as they provide us with energy that the body can easily and quickly utilise.
Many foods rich in carbohydrates are also a good sources of various micronutrients, antioxidants and other phytonutrients that we need for good health.
Also, fibre is a kind of a carbohydrate and fibre is important for general health. Eating fibre can lower LDL cholesterol (the “bad” cholesterol) and raise HDL cholesterol (the “good” one), it’s important for a healthy gut biota and it helps you to stay full for longer as it will prevent the food from being broken down to quickly!
Carbohydrates are also important for the brain, as the brain alone uses around 120-140 g of glucose a day! Red blood cells also rely on glucose for energy.
Digestion of Carbohydrates
Now I’ve covered the basics about carbohydrates, lets get into how carbohydrates are digested.
Digestion of carbohydrates start in your mouth as you start chewing your food.
Enzymes in your salvia, such as amylase, start to break down polysaccharides into smaller fragments.
When the carbohydrates enter the stomach it gets mixed with stomach acids. Here the activity of amylase will slow down the digestion of carbohydrates. When the carbohydrates from the stomach reach the duodenum (the first section of the small intestine), amylase is released from the pancreas and the digestion of carbohydrates into smaller polysaccharides, oligosaccarides and disaccharides will start at a fast rate.
All carbohydrates need to be broken down into monosaccharides for the body to be able to absorb it. So in the small intestine, enzymes such as sucrase, fructase, lactase and maltaste are released to break down the carbohydrate fragments to monosaccharides.
Carbohydrates that are not broken down to monosaccharides, such as dietary fibre and resistant starch, continue to move down to the colon where some of them will be fermented by microflora. Carbohydrates not broken down by your microflora, such as insoluble fibres, add bulk to your stool and help you to stay regular.
Once the carbohydrates are broken down to monosaccharides glucose, galactose and fructose, they are absorbed by the intestine and transported to the liver.
And as glucose levels rise, insulin will be secreted from the pancreas as a response to the increased glucose levels in the blood.
Insulin is a hormone that regulates blood sugar levels and facilitates the absorption of glucose to the cells to be used for energy. Any excess glucose will be stored as the polysaccharide glycogen in liver and muscle, which is the body’s storage of glucose.
If the glycogen stores are full, glucose will go to the adipocytes (fat cells), where they will be converted to fat and be stored. Galactose is metabolised to glucose in the liver.
Fructose is absorbed differently than glucose and galactose in the intestine. Fructose is transported to the liver where it’s converted to glycogen, glucose or fructose be converted to triglycerides (fat). Fructose does not affect blood sugar levels or insulin release in the way glucose does.
How much carbohydrates do you need?
Basically none, as the body can produce glucose via gluconeogenesis from glycerol (a part of triglycerides) and proteins.
However, how much we need for optimal health is not established, but many recommendations span around 45-60% of the energy intake from carbohydrates.
Your activity levels, general health, medical conditions, weight etc. can affect how much is ideal for you.
But as mentioned before, the brain uses around 120 g of glucose each day, so that’s one thing to bare in mind!
What kinds of carbs?
One of the reasons why carbs have gotten a bad reputation is that unfortunately, many foods that are widely consumed and eaten in excess are refined carbohydrates (think biscuits, sugary drinks, cookies, cakes etc) that are devoid of the nutrients you need. Eating these can give you a big dose of carbohydrates in one go and can spike your blood sugar levels. These foods are often also eaten in excess, meaning you may consume more energy than you need which can lead to weight gain.
When eating food rich in carbohydrates it’s good to choose a whole grain and one with lower GI such as brown/black rice, oats, quinoa or whole grain products. As these are all more fibrous, the body will have to work harder to break it down to release the energy and this will portion out the energy more evenly and keep your blood sugar levels in check.
If you eat food in its natural form, they usually don’t only consist of carbohydrates, but are often also a source of protein and sometimes smaller amounts of fat! Therefore it can be tricky to categorise a food as a strict carbohydrate (unless talking about sugar)
Here is a list of good food source that are rich in carbohydrates!
- Whole grains: Oats, Quinoa, brown rice, black rice and wholewheat pasta, rye, barley if you can tolerate gluten . Many grains are also a good source of protein too, with oats containing 13 g / 100 g and Quinoa with 14 g / 100g!
- Sweet Potato and Potato: Source of complex carbs and fibre as well as vitamins and minerals. Also, cold potatoes contain resistant starch which are not digested, instead it goes to the colon were it can feed the gut biota!
- Legumes/ Beans /Pulses:These little powerhouses are a good source of carbohydrates, protein and fibre, also they’re usually rich in minerals such as iron, zinc and copper and B-vitamins!
- Vegetables: All vegetables contain carbohydrates in various amounts! Root vegetables generally contain more carbohydrates than leafy greens and veg grown over ground! Vegetables contain important fibre, antioxidants and vitamins and minerals that are essential for us!
- Fruit and Berries: Natures own sweets! These have varying degrees of carbohydrates in them. Generally berries have less sugar than fruits. Both fruit and berries are a good source of antioxidants, vitamin and minerals! Banana is one of my favourite fruits to eat when I need a filling snack which I usually pair with a small handful of nuts and seeds!
If you eat the more refined carbohydrates, such as white pasta, rice and bread, make sure to pair it with protein, some fat and a good portion of vegetables, as this will prevent the food being broken down too quickly and will slow down the release of glucose in the body! Also, don’t go too crazy on the portion size!
So whether you strive on carbs, or feel better eating less, when you eat them, make sure you focus on eating the ones such as root vegetables, fruits and whole grains that will truly give your body nutrients, fibre and complex carbs that your body needs, instead of eating ones with empty calories such as sugary drinks, cakes and biscuits!
I hope this post was helpful! If you have any further questions, just leave a comment and I’ll answer as soon as possible!