Article: Carbs: The Good, the Bad and the Sometimes ‘Farty’!

By Katey Watson, November 2019

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Image: Joshuemd from Pixabay

Introduction

I chose to debut with carbohydrates (carbs), because they are often perceived as the ‘bad guy’, with many diet-trends advocating minimal carbs (e.g. ‘Keto diet’). The thing is, not all carbs are equal. Yes, some are best avoided, but importantly, the remainder protect our long-term health.

Image: Momental from Pixabay

50% of our Diet should be Carbs – Yep, 50%!

Carbs are classified as a macronutrient, because they are a large essential component of our diet, along with protein and fat. Around 50% of our diet should be carb-based[1], making it the largest macronutrient group.

Carbs are our primary source of energy – we need carbs to function properly – physically (e.g. fuelling muscles)[2] and mentally (the brain needs a constant glucose supply – about 20% of the total carbs we consume!)[3].

Types of carbs: The 3 types of dietary carbs are sugar, starch and fibre.

Types of carbohydrates

Carbs are built-up from molecules (or monomers) of sugar. The main dietary carb structures are monosaccharides (1 ring sugars), disaccharides (2 ring sugars), oligosaccharides (3-9 ring sugars) and polysaccharides (10+ ring sugars).

Carbohydrate structure types

Rings of Sugar? Huh?…

…Glucose, fructose and galactose are ‘simple sugars’, each made up of 1 ring sugar. When these sugars are joined in different quantities and formations, they become a larger structure. For example, when 1 glucose and 1 fructose sugar are joined, they become sucrose (table sugar), a 2-ring sugar (disaccharide).

Sugar ring structures: 1 glucose sugar + 1 fructose sugar = sucrose (2 ring sugar)

Okay, enough of that!…

…So, which Carbs are the ‘Baddies’?

It’s the ‘simple sugars’, now known as ‘free sugars’ that we need to be careful about. These are sugars added into our foods (e.g. cakes, biscuits, sugar-coated breakfast cereals), honey and fruit juice. I know – those things many of us love!

Image: Christian Dorn from Pixabay

What’s the Issue with Free Sugars?

These free sugars enter the bloodstream quickly, rapidly raising blood sugar level and soon drop dramatically after equivalent insulin release. Short-term, rapid sugar-drops cause tiredness and brain fog, whilst long-term can lead to type 2 diabetes. Any surplus sugar is converted to fat![1].

How much free sugar can we have? – Less than 5%![1] – that’s about 7 sugar cubes for an adult[4]

Carbs: Monosaccharides and disaccharides (includes the harmful free sugars)

So, which Carbs are the ‘Heroes’? …Fibre and some Starches

Image: Erika Wittlieb from Pixabay

What is Starch?

Starch is made from glucose ring sugars and originates from plant products, including potato, pasta, rice and bread.

Why Eat Starch?

Starch is our main source of energy, providing slow-releasing fuel to power our brain and muscles. Starchy foods can contain calcium, iron, B vitamins and folate[5, 6].

How Much Starch? – A Third of our Diet[6].

Image: Gundula Vogel from Pixabay

What is Fibre?

Fibre is an indigestible carbohydrate found in plant cell walls. Fibre is unique – it travels through the small intestine (where most nutrients are absorbed) and into the large intestine.

Why Eat Fibre?

Fibre promotes bowel health by reducing the time food takes to move through our system and bulks up stools, making it easier to poop. It also feeds our friendly gut microbes (gut microbiota) residing in our large intestine that protect against inflammation, heart disease and colorectal cancers (more on gut microbiota in the future).

How much Fibre? – Adults should consume 30 grams of fibre daily from a variety of sources[1].

Which Carbs contain Fibre? Mostly plant-based wholefoods[5, 7]:
– Wholegrains (e.g. brown rice, whole wheat pasta)
– Cereals and cereal products
– Legumes (e.g. beans, peas & lentils)
– Vegetables (especially with skin on)
– Fruit (especially with skin on).

Carbs: Oligosaccharides & polysaccharides (including health-promoting fibres)

Farty’ Fibres!

Okay, so for some people there can be a bit of an unfortunate side-effect with suddenly introducing fibre into the diet. Fibre feeds our gut microbiota that release their own gases and enlarge the colon, which can cause uncomfortable bloating and wind. It’s best to gradually increase fibre intake so that the body can adjust.

Important: If you experience ongoing IBS-like symptoms[8] consider seeking medical advice/referral to a Dietician[9] to ensure you obtain sufficient fibre whilst minimising symptoms.

Image: Darko Djurin from Pixabay

So, time to ‘carb-up’ on the good stuff and use that energy to get out there and burn any excess calories!…

Intographics from Pixabay
Carbohydrates overview

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References

1. Scientific Advisory Committee on Nutrition, 2015. Carbohydrates and Health [online]. Available from: www.gov.uk/government/publications/sacn-carbohydrates-and-health-report.
2. British Nutrition Foundation, 2017. Starchy foods (carbs) – page 3 [online]. Available from: www.nutrition.org.uk/nutritionscience/nutrients-food-and-ingredients/carbohydrate.html?start=2.
3. Mergenthaler, P., Lindauer, U., Dienel, G. A. and Meisel, A., 2013. Sugar for the brain: the role of glucose in physiological and pathological brain function. Trends in Neurosciences [online], 36 (10), 587–597. Available from: www.ncbi.nlm.nih.gov/pmc/articles/PMC3900881/.
4. NHS Eatwell, 2017. How does sugar in our diet affect our health? [online]. Available from: www.nhs.uk/live-well/eat-well/how-does-sugar-in-our-diet-affect-our-health/.
5. British Nutrition Foundation, 2017. Starchy foods (carbs) – page 1 [online]. Available from: www.nutrition.org.uk/healthyliving/basics/carbs.html?limit=1&limitstart=0.
6. NHS Eatwell, 2017. Starchy foods and carbohydrates [online]. Available from: www.nhs.uk/live-well/eat-well/starchy-foods-and-carbohydrates/.
7. NHS Eatwell, 2018. How to get more fibre into your diet [online]. Available from: www.nhs.uk/live-well/eat-well/how-to-get-more-fibre-into-your-diet/.
8. British Dietetic Association, 2019. Irritable bowel syndrome and diet: Food fact sheet [online]. Available from: www.bda.uk.com/foodfacts/IBSfoodfacts.pdf.
9. British Dietetic Association, 2017. What is a Dietician? [online]. Available from: www.bda.uk.com/foodfacts/what_is_a_dietitian.

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