Fructose, friend or foe?

Fructose, otherwise known as the sugar found in fruit, it's in honey and is sweeter than sucrose.  It is used in many foodstuffs and in medicine, mainly in a solution form as an intravenous "nutrient".

Lots of people believe that fructose is "healthier" because... well... it's from fruit and fruit is healthy, right?

Well yes, fruit is healthy when you eat the WHOLE fruit with all that healthy fiber, then the fructose does not have a negative effect on your body.

But, take the fructose out of the fruit and it turns into something different and far more dangerous - think High Fructose Corn Syrup (HFCS).

But first, let's take a look at the differences between the 3 main sugars in our lives:

GLUCOSE:

Glucose is the most important monosaccharide and the body's preferred sugar.  Glucose is also called blood sugar as it circulates in the blood and relies on the enzymes glucokinase and hexokinase to initiate metabolism.  The body processes most carbohydrates into glucose for immediate use or to be stored in the muscles or liver as glycogen for later use.

When elevated blood levels of glucose are detected, insulin is secreted facilitating the entry of glucose into cells.

FRUCTOSE:

As stated above, fructose is found naturally in fruits and vegetables, but it is also added to many foodstuffs including soda and fruit-flavored drinks.  However, it has a different metabolic pathway from other sugars, and is NOT the preferred energy source for brain and muscles.

Fructose is only metabolized in the liver and needs fructokinase to initiate metabolism.  Fructose is also more lipogenic - fat producing, compared to glucose.  It also does not induce the secretion of insulin or stimulate the production of leptin - a key hormone for regulating energy intake and expenditure.  This suggests that fructose behaves more like fat in the body than like other carbohydrates.

SUCROSE:

Also known as table sugar, fruits and vegetables also naturally contain sucrose.  When sucrose is
consumed the enzymes beta-fructosidase separates the sucrose into glucose and fructose.  Once separated, they each follow their particular metabolic pathways.  However, although they are ingested at the same time, the body prefers to use the glucose as its main energy source, and if it doesn't need the energy provided by the fructose, then it will convert it into fat stimulated by the insulin secreted in response to the glucose.

Glucose is essential for life.  Our bodies produce it and every living cell contains it.

Fructose, on the other hand, is NOT essential for life, the body doesn't produce it and throughout history, has only ever consumed it in its natural fruit form - until, that is, they started adding it to food...

So, how can fructose harm you?

Well, having a diet high in fructose can cause problems to your health such as; increased levels of uric acid which in turn leads to gout and high blood pressure.  It can also cause fatty liver which can lead to non-alcoholic fatty liver disease.  Insulin resistance which can lead to type 2 diabetes is another issue and fructose does not affect satiety in the same way that glucose does, leading to eating more than is necessary.  Scientists at the university of Barcelona have found that fructose contributes to raising the risk of obesity, diabetes, heart disease and stroke.

They carried out studies on rats using two types of simple sugars.  The group of rats given fructose water put on more weight than those given glucose water.  Their results were published in the American Journal of Physiology Heart and Circulatory Physiology, stating that the fructose rats suffered more damaging effects on their metabolism and vascular system, fatty liver and an increased risk of obesity.

This means you need to read the labels on the food you buy... in fact, if it has a label, don't buy it!

I can help you improve your health.  If you would like to make an appointment with me either in person or via Skype, just send me an email to lucycarr@socialnutrition.com