sugar free diet

Sugar Science: Should I go on a Sugar Free Diet?

Sugar free diets are on the rise, but what is sugar and why is it harmful?

The rise in obesity over the last 70 years or so can be attributed to a number of probable factors including a sedentary lifestyle and a change in our diet that sees it increasingly made up of refined sugar, flour and processed vegetable oils. Sugar has been recently highlighted as being one of the worst offenders for promoting obesity.

Graph Source: Johnson RJ, et al. Potential role of sugar (fructose) in the epidemic of hypertension, obesity and the metabolic syndrome, diabetes, kidney disease, and cardiovascular disease. The American Journal of Clinical Nutrition, 2007.
Graph Source: Johnson RJ, et al. Potential role of sugar (fructose) in the epidemic of hypertension, obesity and the metabolic syndrome, diabetes, kidney disease, and cardiovascular disease. The American Journal of Clinical Nutrition, 2007.

There are certain foods that you expect to contain large amounts of sugar, for example jam donuts, sweets and bars of chocolate. However there have been numerous reports in the press over the last few years highlighting the amount of sugar that is also present in foods that you think would be sugar free, such as fresh fruit, fruit juices, smoothies, cereal bars as well as processed food like bread, pasta sauces and ready meals. In fact, when you start reading the labels on your food, you may well be amazed at how much sugar you actually eat on a daily basis.

Sugar in our diet, coming from both obvious and ‘hidden’ sources, means that the average person in the UK consumes approximately 30kg of sugar a year.

So what is sugar and is it really responsible for the rise in obesity and ill health that has been observed over the last decade?

What is sugar?

Sugar is the name given to sweet-tasting, short-chain, soluble carbohydrates that the body uses for energy. Sugars occur naturally and can be found it whole, unprocessed foods. As an example, most fruits contain a combination of fructose, glucose and sucrose. Fructose is also found in some root vegetables and honey.

Fruit and vegetables contain naturally occurring, intrinsic sugars

The sugars found in unprocessed food are often referred to as intrinsic sugars.

Sugar is also available to purchase in its refined, processed form. Refined, white sugar is produced by extracting natural sucrose (glucose and fructose) from sugar beet or sugar cane and processing it to remove the plant material and molasses. This pure white sucrose is then used as an additive to sweeten foods and drinks. White sugar is an example of an extrinsic sugar; other examples include honey, maple syrup and milk sugars (lactose). While the sugars found in fruit are considered to be intrinsic, fruit juices are classified as an extrinsic source of sugar.

Sugar has no nutritional value; it contains no vitamins, minerals or fibre and as such it is a source of ‘empty’ calories.

Context matters

Once sucrose, a disaccharide, has been consumed, it is broken down in the body into its two structural components, glucose and fructose (monosaccharides). Before the sugar industry exploded, fructose was not thought to be plentiful in our diets. Fructose is found in naturally high levels in dates, molasses, raisins and honey and in lesser amounts (<10%) in grapes, apples and blueberries. Fructose is not required by the body for energy, unlike glucose which is essential for our metabolism. We are however able to process limited amounts of fructose in the liver without harm.

It would be extremely difficult to eat harmful amounts of fructose in its intrinsic form, contained inside fruits and vegetables. The amount of fibre and cellular structure encasing the sugars means that we are naturally limited in how much we can eat in a sitting. The fibre also helps to slow down the digestive process, releasing sugar into the bloodstream more slowly.

In its extrinsic form however, for example in a glass of orange juice, a can of cola or a bar of chocolate, we are able to consume far higher amounts of biologically irrelevant fructose. This sugar is not encased in fibre and cellular structure and is rapidly released into the bloodstream causing our insulin levels to spike.

Sweets and candies contain rapidly accessible, extrinsic sugars
Sweets and candies contain rapidly accessible, extrinsic sugars

What happens to the excess fructose?

Almost every cell in the body is able to utilise glucose, however only the cells of the liver are able to process fructose. When consumed in excess, our bodies cannot break down fructose and it is stored as triglycerides (fat).

The relationships between high extrinsic sugar diets and poor health have yet to be conclusively proven. However studies have linked the rise in refined sugar consumption to health conditions such as non-alcoholic liver disease1, diabetes2 and cardiovascular disease3. Unhealthy insulin levels (such as the constant peaks and troughs triggered by extrinsic sugar consumption) have been linked to breast cancer4 and colon cancer recurrence5. Excessive sucrose consumption has been positively linked to obesity levels in a number of studies6,7.

How much sugar should we eat?

The UK recommendations on sugar consumption are set by the Scientific Advisory committee on Nutrition (SACN). A recent draft report suggests that free sugar consumption should be around 5% or daily energy. The World Health Organization also suggests that reducing sugar intake to 5% of total calories would have significant health benefits, adding that there is no need for added fructose or any added sugars in diet. The sugar guidelines refer to extrinsic sugars, not the intrinsic sugars present in whole foods.

5% of sugar intake equates to approximately 25 grams of sugar (6 teaspoons). To put this further into context, a tablespoon or tomato ketchup contains approximately 4 grams (1 teaspoon) of extrinsic sugar. A can of cola contains 40 grams (10 teaspoons) of extrinsic sugar.

Cut it out

Since refined sugar has no nutritional value, but can contribute significantly to poor health conditions such as diabetes and obesity, the best thing that you can do is to cut it out completely. The Green Apple Club 28 DAYS Meal Challenge will give you the tools and support that you need to follow a refined sugar free diet.

 

References:

  1. http://www.ncbi.nlm.nih.gov/pubmed/23390127
  2. http://www.mayoclinicproceedings.org/article/S0025-6196(15)00040-3/abstract
  3. http://ajcn.nutrition.org/content/86/4/895.full
  4. http://www.webmd.com/breast-cancer/news/20150115/unhealthy-insulin-levels-may-boost-breast-cancer-risk
  5. http://news.harvard.edu/gazette/story/2012/11/insulin-and-colon-cancer-linked/
  6. http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9570430&fileId=S1368980015000300
  7. http://www.bmj.com/content/346/bmj.e7492

 

Related articles:

Why a Low Fat Diet May Not be the Answer

Cancer Fighting Foods: Research Strides Ahead of Western Doctors

 

About the author: 

Sonia Nicholas is a Biomedical Scientist and Freelance Clinical Science Writer & Editor. She has been working in the field of clinical science for fifteen years.

Sonia believes that everyone can improve their health by eating a clean diet – a claim that scientific research increasingly supports. Sonia also believes that healthy, clean eating is accessible to all and doesn’t have to be an expensive lifestyle choice.

All of the information on The Green Apple Club website is in line with current, recommended Government guidelines. All of the articles are evidence based and fully scientifically referenced.

Article tags: sugar free diet, natural sugars, refined sugars


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