Starches are COMPLEX carbs containing long chains of joined glucoses.
- Starchy vegetables – potato, sweet potato, yams, taro, squash, parsnips, beetroot, pumpkin
- Wholegrains / cereals – wheat, oats, rice, rye, barley, millet, quinoa and corn
- Legumes – beans, lentils, soybeans, peas, chickpeas
These are digested and broken down in the intestines into single glucose molecules + nutrients + fibre. This process of digestion leads to a slower release of the fuel into the body.
Glucose and Nutrients
A good way to look at this idea of glucose chains is to think back on when you were last chewing on a dry biscuit. It starts off being slightly sweet – but – the longer you keep it in your mouth, the sweeter it tastes. This is because the salivary enzymes are breaking down these glucose chains by constantly splitting off single glucoses. And the way you know that is happening, is that the biscuit becomes sweeter and sweeter the longer it stays in your mouth. Your taste buds are telling you the glucose content in your mouth is increasing.
In their natural form starches are very slow to digest compared to fruits and so produce a good form of slow burning fuel. When present as an unprocessed whole food, they also come packed with an enormous amount of important nutrients, and this is why they are considered to be an important part of a balanced diet. They act to provide both fuel and nutrients.
High GI and Low GI Starches
Starches are naturally slow-burning and therefore are generally LOW-GI carbs. The
Glycaemic Index refers to how fast or slow burning the carb is, where slower burning is preferred. High GI foods are quickly digested and burnt to produce a rapid rise in blood sugar levels. This contributes to weight-gain and the development of diabetes and needs to be restricted in a healthy diet.
Unprocessed and Processed Starches
Processed carbs, like white rice and white flour, to varying degrees have had the nutrients and fibre stripped out of the starch and so move towards the ‘empty calories’ area. They become both low-nutrient as well as faster burning high-GI carbs.
High Fibre and Low Fibre Starches
In their natural state the starches also contain varying amounts of fibre. Processed grains such as white flour and white rice have had their fibre content removed.
So why does this matter? Firstly, because low fibre starches then become high GI carbs which we need to restrict in a healthy diet. And secondly, because fibre is a critically important part of our diet in terms of maintaining gut health.
Stay tuned for Part 3 of Carbohydrates: FIBRE