What's complex about carbs?

I honestly wasn’t sure where to start with this article – there is so much to say about carbohydrates! I love a pun though, so I apologise for the title 😉

Carbohydrates periodically get a bashing from the diet industry just like fats. I don’t really think this is deserved – all carbs are not created equal! To say that we need to cut all carbs from our diet is a bit of a generalisation. Realistically we just need to show some discernment and only choose good quality carb sources.

I will cover the theory, pros, and cons of a low-carb diet in another article – for the moment, let’s just get to know them a bit better! Let’s kick off with…

The science bit!

So, as the name suggests carbohydrates are made up of carbon, hydrogen, and oxygen molecules (CHO). They’re basically all one or more sugar molecules that are bound together. It’s the combination of these sugars which dictate the form the carbohydrate takes.

There are three different types of carbohydrates:

• Monosaccharides – these are made up of one sugar molecule so are referred to as “simple”, and include glucose and fructose

• Disaccharides – these consist of two sugar molecules, are also referred to as “simple” and include sucrose and lactose

• Polysaccharides – several sugar molecules bound together, these are the “complex” variety and include starch, glycogen and cellulose

As you can imagine, mono- and disaccharides are the ones that are absorbed quite quickly into the blood (and which can cause blood sugar spikes). Polysaccharides take a bit more time to be digested and are therefore absorbed over a longer period. This is because all carbohydrates have to be broken down into monosaccharides by the body before they can be used.

The digestion mechanism

I don’t know why, but the name of the enzyme amylase has stuck with me right the way from GCSE biology! It’s not really helped much in my life and career choices until now…

As soon as we put food in our mouths this funky little enzyme (in its salivary form) gets to work on cooked starches, breaking them up into shorter polysaccharides. Not much happens to these polysaccharides in the stomach, the action all takes place for them in the small intestine.

Here, pancreatic amylase is secreted in the duodenum (how do you pronounce it? DuODDenum or DuoDEEnum?) to break the polysaccharides down into disaccharides. Then, in the ileum the enzymes maltase, lactase, and sucrase work to break these disaccharides into monosaccharides ready for absorption.

And what happens to these monosaccharides?!

These babies are the main source of energy for our bodies, mostly in the form of glucose. Once the monosaccharides have been broken down in the small intestine (into glucose, fructose, and galactose) they are absorbed through the walls of the small intestine into the bloodstream where they are first transported to the liver. These busy little molecules then get put to work:

• Fructose is converted into glucose, glycogen and lactate

• Galactose is converted into glucose and also stored as glycogen

• Glucose is transported via the bloodstream to cells in the body where it is needed as an energy source

Any glucose that is not needed for energy is converted to glycogen and stored in the liver and muscles. And when those storage lockers get filled up we see the excess glycogen laid down as fat in those sneaky little balloon-like fat cells that can be founded under the skin and around our internal organs.

The Glycaemic Index

As I mentioned earlier, the various saccharides are absorbed by the body at different rates. How can we quantify this and why is it important? Well, the glycaemic index is a good place to start! Although I want to point out before we get too far that the absorption rates used for the GI are based on fasted intake of an isolated food source.

This can be a little misleading as it’s unlikely, for example,that we would ever eat cornflakes on their own – we would most likely consume them with milk or yoghurt (which contain fats and protein) which will slow down digestion and therefore the rate of absorption.

While researching the glycaemic index I discovered that the University of Sydney and Glycaemic Index Foundation have been undertaking studies into the Glycaemic Load rating. Essentially, the GL takes into account both the quality and quantity of the carbohydrate in question, giving more of a “real world” picture of the metabolic effect a particular food will have.

Anyway. What does the glycaemic index look like in real terms and how can we use it to make educated food choices?

Foods and their ratings

The glycaemic index is a scale that runs from 1 – 100, with 1 being low and 100 high. In order to be given a score, the extent to which each food raises the blood sugar levels after being eaten is measured. The amount of each food tested potentially could vary (obviously some foods are higher in carbs than others!), but the amount of carbs present in each food will be the same.

The rate at which each food raises blood sugar levels is then compared with the rate of absorption of glucose (which of course has a GI value of 100), and a value is given. Foods with a score of over 70 are those which are digested rapidly and are therefore considered high GI. These include:

• White bread

• Bagels

• Cornflakes

• Instant oatmeal

• Rice cakes

• Popcorn

Any foods that have a score between 56 and 69 are recorded as being moderate GI. For example:

• Banana

• Basmati rice

• Wholemeal durum pasta

• Rolled oats

• Swiss style muesli

• Raisins

Foods that scored between 0 and 55 contain carbohydrates that break down more slowly, therefore having less of an immediate impact on blood sugar. These low GI foods include:

• Broccoli

• Sweetcorn

• Beans/peas/legumes

• Lentils

• Most fruits

• Non-starchy vegetables

Interestingly, sweet potato is low GI when boiled or steamed (GI of 44) but high GI when baked (94)! This, I think, is another reason why the glycaemic index should be used as a guideline when researching which foods to include in your meals.

Simple Carbohydrates

You’ve probably heard of “simple” carbs and “complex” carbs, but what does this actually mean? I mentioned earlier about mono- and disaccharides being “simple” and polysaccharides being “complex” – essentially these are your carbs!

We’ve already established that mono- and disaccharides are absorbed more quickly into the bloodstream and can therefore cause a spike in blood sugar. So on that basis, foods that are high in these are “simple carbs” and it would be sensible to limit these in your diet. Some examples of these are:

• Sports drinks

• Cakes and pastries

• Table sugar

• Alcohol

So all of the fun stuff then!

However, it’s worth remembering that simple sugars also occur naturally in dairy products such as milk and yoghurt, and of course in fruit and honey. These simple sugars are not in and of themselves bad for you as they are also, for the most part, nutrient dense. As a rule of thumb, if you’re eating processed food then it will most likely have sugar added to it. These types of foods should be limited or avoided as they will quite often not have the nutritional benefits that food with naturally occurring sugars will provide.

If we can agree that the majority of processed foods contain these simple carbs, what about the “complex” variety?

Complex Carbohydrates

The main difference with complex carbs is that they generally have more nutritional value than simple carbs. More often than not they are also higher in dietary fibre – this is a win for two reasons.

The first is that fibre, as we know, helps maintain bowel health and can improve digestion by looking after good gut bacteria. Secondly, including fibre in your diet will help you to feel full for longer. Obviously, fibre has a lot more benefits than this, but we will talk about those in another article!

I’m not going to bore you with a huge long list of “healthy” carbs, but here are a few that can easily be incorporated into the diet on a daily basis.

Sweet Potato

As I mentioned earlier, the way that these are prepared can have an effect on blood sugar levels so it’s worth keeping that in mind. And let’s be honest, if you’re eating a sweet potato then it’s quite likely that you will have some form of protein and/or fat with it which will slow down digestion.

But the humble sweet potato still has a pretty hefty 23.6g of carbs (medium-sized potato). They also contain both soluble and insoluble fibre so all of your gut health needs are covered!

We can guess from their orange colour that they are high in beta-carotene which is converted to vitamin A by our bodies. This is really beneficial for good eye health and for supporting our immune systems. Sweet potatoes are also rich in vitamin C, manganese, potassium, and copper.

Quinoa

These tiny seeds have become something of a food hero in the West over the last five years or so, although in South America they have been consumed for thousands of years.

A cup of these beauties will give you about 39g of carbohydrate as well as around 5g of dietary fibre. You’ll also be getting a substantial hit of magnesium and phosphorous and a not inconsiderable amount of folate. Great for mums-to-be!

Quinoa is also surprisingly high in protein (well, I was surprised anyway!), coming in at around 8g per cup. And it’s one of the only plant-based food sources to contain all of the essential amino acids.

As many of you will already know, it doesn’t really have much flavour by itself so is a perfect vehicle for sauces, etc. And it can be eaten as a sweet or savoury meal, as I discovered with a delicious toasted quinoa recipe recently.

Bananas

I think that bananas really are underrated. They’re easy to carry around, have their own compostable wrapper, and are great for an energy boost at any time of day. But the common or garden banana is actually packed full of all kinds of good things!

We know that they are pretty high in potassium, but did you know that they also contain about a third of your daily recommended amount of vitamin B6? They’ll provide 24g of carbs (from a medium-sized fruit), only about 110 calories, and practically no fat.

If we eat a banana that’s still a little green it can taste almost “dry” and doesn’t have much flavour. That’s because the carbohydrates have not yet turned from starch to sugar. As the banana ripens it gets sweeter as the starch is converted into fructose, glucose, and sucrose. And that’s why it’s so delicious in banana bread – no need to add any more sugar!!

Sweetcorn

Now, I’ve never really been a fan of sweetcorn – I think it’s the memory of waterlogged kernels in school dinners! However, since trying it chargrilled on a barbecue (admittedly with a fair amount of butter!) I’m a convert!

Obviously, they taste sweet so we know that there has to be a fair amount of carbohydrates here. In fact, 100g of sweet corn will provide about 19g of carbs and just over 3g of protein. Sweetcorn also contains useful amounts of vitamins B1 and B9, as well as vitamin C. You won’t be surprised to hear that water makes up approximately three-quarters of the weight of sweetcorn, so you’re also staying hydrated!

So what’s the bottom line here?

Well, I know that the idea of cutting carbs significantly or completely from the diet has been around for decades. And I get that, really, carbohydrate is considered a non-essential macronutrient – we can get our energy from protein and fats easily enough.

But protein is the source of the building blocks that keep our bodies healthy and strong (more on that in a future article 😉). I think I would rather that all of the protein I consume goes into repairing and building strong healthy tissue than fuelling my workouts.

I realise that this is massively oversimplifying the processes involved but the principle still holds, I think.

I’ve said it before and I’ll say it again…!

We don’t all have to be paragons of virtue here – I’m usually the first in line for pizza, doughnuts, and crisps when they’re on offer! But including these things now and again into an otherwise balanced diet is not, unless you have underlying health issues, a big deal.

Everything in moderation, right?

Where possible I will always choose organic wholegrain bread and pasta etc., and I make sure to include a good wodge of fibre-rich fruit every day in the form of a smoothie. I also limit cooked carbs (potatoes, bread, pasta, and so on) to one or maybe two portions a day depending on how big they are. I’m fortunate that I don’t have a gluten sensitivity so I do have a wide choice available to me.

Making your choices a “lifestyle” thing and not a “diet” thing means that you can eat more varied foods which will, of course, mean that you’re also getting a more balanced and varied range of nutrients. And that has to be a good thing, right?