Carbohydrates

Refined and unrefined grains

The foods listed above (apart from potatoes) are all produced from grains, such as wheat, corn or rice. They should be a part of all meals, filling about a third of your plate. They can come in two forms – refined or unrefined (often known as whole grains).

Refined grains have been stripped of their outer bran coating and inner germ during the milling process, leaving only the endosperm. They include white rice, white bread and white pasta.

In a whole grain the bran, germ and endosperm are all still present. The bran is an excellent source of fibre; the germ is a source of protein, vitamins and minerals; and the endosperm supplies most of the carbohydrates, mainly in the form of starch. Unrefined or whole grain forms provide far more nutrients than their refined counterparts.

Whole grains are rich in phytochemicals and antioxidants, which help to protect against coronary heart disease, certain cancers, and diabetes. Studies have shown people who eat three or more servings of whole grains a day are less likely to suffer from heart disease.

Most people get their whole grain from wholemeal bread or whole grain breakfast cereals such as porridge, muesli or whole wheat cereals. Choose a whole grain variety over processed or refined grains, and look out for added sugar or salt.

Other whole grain foods include:

• Brown rice
• Whole barley
• Rye bread
• Rye crackers
• Oatcakes
• Popcorn

Fibre

Dietary fibre is found in plant foods (fruit, vegetables and whole grains) and is essential for maintaining a healthy digestive system. Fibre cannot be fully digested and is often called bulk or roughage. The two types of fibre found in food are soluble and insoluble.

Soluble fibre, which can dissolve in water, is found in beans, fruit and oat products, and can help to lower blood fats and maintain blood sugar.

Insoluble fibre cannot dissolve in water, so passes directly through the digestive system. It’s found in whole grain products and vegetables and it increases the rate at which food passes through the gut.

Evidence for health benefits of fibre

• High-fibre foods take longer to digest, so keep you feeling fuller for longer. The slow and steady digestion of food through the gut helps control blood sugar and assists with weight maintenance
• Fibre helps in the digestive process and can help lower blood cholesterol
• Fibre promotes bowel regularity and keeping the gastrointestinal tract clean to help reduce the risk of developing diverticular disease and constipation
• A high-fibre diet may reduce the risk of developing Type 2 diabetes and colorectal cancer

How much is enough?

It's recommended that adults need to eat about 18g of fibre a day, chldren need less. Try some healthy recipes from the BBC Food website

What about GI?

The glycaemic index (GI) is a way of ranking carbohydrate foods based on how quickly they increase blood sugar levels. Low GI foods are especially helpful for people with diabetes, who need to have more control over their blood sugar levels than the general population.

Ideally foods with a low GI, such as those rich in soluble fibre like oats, beans and pulses should be eaten more frequently than those with a high GI. But the texture, type of cooking or processing used, and the amount and type of sugars present can all affect the GI. Since foods are often consumed as part of a meal or snack, it can be difficult to calculate the GI. Focusing on unrefined, high-fibre, whole grain cereals and minimising rapidly absorbed, refined cereals and sugary foods will all help to lower the GI of your diet.