We all know that too much sugar is bad for us – it can lead to heart disease, type 2 diabetes, tooth decay, and elevated insulin levels which can contribute to cancer – but often it’s not clear what the difference is between ‘good’ and ‘bad’ sugars, what foods we find them in, and how much is too much.

‘Good’ and ‘Bad’ sugars

Essentially, there’s a difference between natural and added sugars and although we should always be aware of our sugar intake no matter where it comes from, natural sugars in small amounts such as fructose found in fruit and vegetables and lactose found in milk, also provide added benefits such as vitamins, fibre and calcium, and we can therefore worry about them less. In fact, we need some sugar in our diet to supply energy to our muscles and to keep our brains active.

Added sugars, however, are the real problem, and in the UK are mainly consumed in the form of sucrose (everyday white sugar). This added sugar is most commonly found in sweets, fizzy drinks, cakes, puddings etc, but can also be found ‘hidden’ in low fat diet foods to improve taste, as well as in ketchup, bread, breakfast cereals and baked beans. As well as being called sucrose, sugar has many different names to keep an eye out for in your foods, including glucose, dextrose, fructose, maltose and corn syrup. It’s also important to be aware that ingredients on packets are listed in amount order, so if one of these sugars is near the top of the list, the product is likely to be high in added sugars.

All sugars can be broken down further into two simple sugars – glucose and fructose. Glucose is vital for the function of our digestion and cell growth, and is the primary source of energy for the brain. Fructose is also important as a source of energy and is fine in small amounts such as in fruit, vegetables and lactose, however it can only be metabolised by the liver in certain amounts. Added sugars are high in fructose, some of which is burnt up through exercise, but most of which will be immediately processed into glycogen and then stored in the liver until it is needed for energy. However, if the liver already has too much stored glycogen, it will not be able to process even more fructose and will turn it into fat instead, which leads to serious health issues as mentioned above.

How much is ok?

New advice from the World Health Organisation (WHO) comes with strong recommendations to reduce added sugar intake to less than 10% of your total energy intake (less than 5% is ideal) – this works out to be about six teaspoons of sugar daily (25g for women, 35g for men). The WHO does not, however, refer to the sugars found in fresh fruits and vegetables or milk as there is no reported evidence of adverse effects of consuming these sugars. When your intake is 10-20% (or more) of your diet, not only are you in danger of developing serious health problems from too much added sugar, you are also creating a nutrient deficiency in your body. This is because added sugars supply calories but very little else (hence why they are often referred to as ‘empty calories’) which means our body has to draw on the nutrients from the rest of our diet to process the sugar, often resulting in our immune system being less supported leaving us more prone to colds and illness.

Fruit vs fruit juice

As stated by the WHO, it is basically impossible to overdose on fruit and vegetables. They are a great source of vitamins and nutrients, and when eaten whole, they contain fibrous structures that make us chew and swallow slowly. The fructose from the fruit and vegetables is then sent to the liver in small amounts and the liver has time to metabolise and process it. Drinking a glass of fruit juice however, is equivalent to consuming several pieces of fruit in one go, which means you are ingesting lots of sugar but with the fibre etc squeezed out, it makes it harder for your liver to process. This is unlikely to cause issues for healthy, lean people, who exercise regularly and are therefore able to easily use up their stored glycogen reserves. But for those already overweight or struggling with metabolic problems, it can lead to obesity, cardiovascular disease, and particularly type 2 diabetes.

Ways to cut back on your sugar intake

1. Watch out for hidden sugars – always check the label, especially for diet foods that may be low in fat but which overcompensate in taste by adding sugars.
2. Plan your meals – this will make you less likely to end up hungry and grabbing a sugary meal last minute to get your energy levels up. It will also mean you are more aware of how much sugar you are consuming throughout the day.
3. Keep healthy snacks to hand – fruit and nuts are the best option and if they’re readily available and you are consuming them when needed, it will help you turn down that extra slice of cake more easily.
4. Cook from scratch – you will be more aware of what it is you are eating and less likely to be consuming processed and sweetened foods.
5. Watch the juice – as explained above, a glass of juice contains much more sugar than a whole piece of fruit and is digested differently. It is suggested that 150ml as part of a varied diet is acceptable.

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