Carbohydrates

Like protein and fat, carbohydrates are a macronutrient. In a similar way to protein being made up of amino acids, carbohydrates are made of building blocks called ‘saccharides or ‘sugars’. Glucose, a common example of the simplest type of sugar, is a monosaccharide, together with fructose, found in fruit. Two monosaccharides joined together are called disaccharides, the most common being sucrose or ‘white cane sugar’ as we know it. Another example is lactose, found in milk. When large numbers of saccharides are joined together, they form polysaccharides and are found in the foods we commonly think of as ‘carbohydrates’, e.g. bread, potatoes and pasta.

Dietary fibre belongs to the carbohydrate group but is not digestible and doesn’t provide you with energy. Fibre has important roles in helping you feel full after a meal, adding bulk to stools, preventing constipation, and generally for good gut health. Note, fibre is only found in plant-based foods.

Why are carbohydrates so important?

During digestion, carbohydrates are broken down into glucose which is then absorbed into your bloodstream. Glucose, also known as blood sugar is the main source of energy for your body’s cells, including your brain. Glucose can be used immediately or can be stored in the liver or muscle as glycogen.

Which foods contain carbohydrates?

Most foods contain some carbohydrates, but foods containing the most include fruit, starchy vegetables (e.g. potato and kūmara), bread, cereals (e.g. oats), rice, pasta, legumes (chickpeas, lentils), milk, yoghurt, sugar.

Which types of carbohydrates should I eat?

Carbohydrate quality is very important for overall health. A good rule of thumb is to eat mainly whole, minimally processed carbohydrates and minimize refined carbohydrates and sugars.

• Choose mostly whole grains over refined grains. Whole grains are foods like whole-wheat bread, brown rice, corn kernels, and oatmeal. They offer lots of nutrients that your body needs, like vitamins, minerals, and fibre. To figure out whether a product has a lot of whole grain, check the ingredients list on the package and see if a whole grain is one of the first few items listed. Refined grains (white flour, white bread and white rice) are foods that have had some parts of the grains removed. This also removes some of the nutrients that are good for your health.
• Choose fibre-rich carbohydrates. In addition to whole grains, fibre-rich carbohydrates include fruit and starchy vegetables (with the skin on), and legumes and lentils (which also provide some protein).
• Reduce added sugars: the usual suspects are fizzy drinks, baked goods, cholate and lollies. Watch out for hidden added sugars in packaged foods such as cereals and muesli. Foods with a lot of added sugars can have many calories but not much nutrition and don’t fill you up as well.

How much carbohydrate do we need?

The amount of carbohydrate you need will depend from person to person, taking into account your age, sex, activity levels and preferences. The Nutrient Reference Values (2015) recommends that 45%-65% of an adult’s energy intake comes from carbohydrates. Eating the recommended number of servings from each food group, particularly from the grain foods and vegetables and fruit food group, will help you meet this range.

Carbohydrates and Glycaemic Index (GI)

A food’s glycaemic index indicates the rate at which the carbohydrate in that food is digested by the body. In high GI foods, carbohydrate is digested and absorbed into the blood quickly, causing your blood glucose (sugar) level to rise rapidly. In low GI foods, carbohydrate is digested slowly resulting in a more gradual rise in blood glucose levels.

Pairing carbohydrates with non-starchy vegetables (e.g. tomato, salad greens), protein and healthy fats, slows down the digestion of the carbohydrates, lowering the overall glycemic load of the meal.

Can carbohydrates help with weight loss?

For those wanting to lose weight, low GI carbohydrates as part of a balanced diet may be helpful. The carbohydrate in low GI foods is digested slowly, making you feel fuller for longer.

Tips

• Include carbohydrate-containing foods, such as bread, pasta, or rice, at every meal, to provide a constant source of energy.
• Choose mainly wholegrain and wholemeal types of bread and breakfast cereals for extra fibre.
• Keep the skin on of fruits and starchy vegetables for the most part.
• Legumes and lentils are cheap and versatile source of carbs, fibre and protein

References

National Health and Medical Research Council (Australia) and Ministry of Health (New Zealand) (Date) Nutrient Reference Values for Australia and New Zealand: Carbohydrates.

Last reviewed: 05/05/2022