Why all the fuss about fructose?

Fructose is not inherently bad. It is a sugar that exists naturally in healthy food items such as fruits and vegetables. For the great majority of people, eating fruits and vegetables is never a bad thing.

However, the availability of fructose in our diet has changed significantly in the past several decades due to the emergence of high fructose corn syrup, which has been widely added to our food supply and is found in great quantities in pops, sodas and other sweetened beverages.

The emergence of high fructose corn syrup in North America mirrored a massive spike in the rates of obesity and several chronic diseases.  For this reason, fructose has garnered a great deal of attention as the potential cause of many of the health issues plaguing modern society. However, opinion in the scientific community is mixed on this isue. Certain health experts have very strong views on fructose as the cause of many modern health woes while others are adamant that it has no unique role in contributing to these issues. 

Why the difference in opinion? It comes down to the fact that, first and foremost, the quality of research available on fructose and its impact on our health is not currently of the highest quality. For this reason, it has been difficult to draw concrete and harmonious conclusions. The same data is essentially being interpreted in different ways by different groups of researchers and there is a disparity in their intrepretations.  

What I plan to do for you today is to outline what we know for certain when it comes to fructose and our health. I will also provide further insights into what makes fructose unique from other sugars and offer guidance on how you should approach fructose in your daily life.

Fructose in Our Food System

The one undeniable reality about fructose is that it  has very widely populated our food system over the past several decades. In the past, sucrose ( another carbohydrate; a 50-50 blend of fructose and glucose – derived from sugar cane and also known as table sugar) was used to sweeten many commercial products such as soft drinks and other sweetened beverages as well treats such as baked goods, ice cream and so on. In order to cut costs, the food industry started using a cheaper alternative to sucrose known as high fructose corn syrup(HFCS). HFCS is chemically different to sucrose and has a higher fructose content. 

Since the introduction of HFCS mirrored the rise in obesity in North America, many blame fructose and HFCS for this issue. However, this is not necessarily a fair argument because many other things have changed in the past several decades that could have contributed just as much or more to the problem ( the introduction of other processed foods, sedentary lifestyles etc).  

With that being said, current data suggests that we currently consume similar amounts of sugar ( primarily fructose) from fruits and vegetables as we do from sweetened soft drinks and other sweetened items liks candy and baked goods. As a public health professional, this is a deeply concerning reality. 

So what does science say about the effects of fructose?

That depends which scientist you ask. There is a great debate as to whether our current consumption level of fructose and other sugars is causing us detriment to our health.  

Some scientists believe that fructose is uniquely responsible for increases in obesity, cholesterol and high blood pressure while others maintain that general overconsumption of calories from any source is a more important consideration. Much of the research that has shown the negative effects of fructose used levels of consumption so high that it would really only apply to a small percentage of the population.

Many pro-fructose scientists will argue that, at average levels of fructose consumption, there is no negative effect to your health and so there is no need to implement fructose recommendations.

However, The World Health Organization believes the current body of evidence is strong enough to recommend that people monitor and restrict their intake of sugars such as fructose, glucose and sucrose in order to reduce their risk of chronic disease.  

Despite this lack of agreement, the reality is that a significant amount of our fructose consumption comes from sugar sweetend beverages such as pops, sodas, juices, energy drinks and so on. The consumption of these foods offers you little to no nutritional benefit and I do not need scientific consesus to tell you that restricting your intake of these foods will be in your best interest. This is especially important for those of you who are frequent and heavy consumers of these items.

What makes fructose so special/potentially harmful?

As I mentioned, the introduction of high fructose corn syrups into our food system is one of the reasons why people blame fructose for obesity and chronic disease, but there is more to the story. 

Before the introduction of high fructose corn syrup (HFCS), sucrose was the most common sweetener. Sucrose, a 50-50 blend of glucose and fructose, is a common carbohydrate  found in most plant-based foods. During digestion, our bodies break down sucrose into equal parts glucose and fructose. What happens next is what makes fructose “special”.

Glucose is absorbed is readily absorbed in  the digestive tract whereas Fructose is not as well absorbed by the digestive tract and may ultimately be fermented by gut bacteria which can lead to gas/bloating etc.  The Fructose that is absorbed, is sent straight to the liver for processing. These are both normal physiological processes but could have important implications for both your liver and digestive system in the context of excessive fructose consumption.

Why does this matter? High fructose corn syrup contains more fructose than glucose ( unlike sucrose which is a 50-50 blend). This means that, with the introduction of HFCS into beverages and other products, our fructose consumption has increased. 

Fructose and your liver

The liver is a very important and often overlooked organ. It cleanses your blood ( drugs/alcohol), manages your energy usage ( fats/carbohydrates) and is responsible for the production and management of a variety of proteins, cholesterol and other hormones.

Liver disease used to be something primarily associated with alcohol abuse but this is no longer the case. You may not have heard about it before, but Non-Alcoholic Fatty Liver Disease ( NAFLD) has “burst” onto the scene as the most common chronic liver disease in adults and adolescents. 

As I mentioned previously, fructose is processed by the liver. This is a normal physiological process but can become an issue in the face of excessive fructose consumption, which can then put a strain on the liver. 

Bottom line: Consuming excessive fructose can lead the liver to produce more fat than it can manage which cam lead to a “fatty liver” ( NAFLD). We cannot say for certain that excess fructose consumption is the sole  cause of NAFLD as obesity and general overconsumption of calories are other massively important considerations. Science will hopefully be better able to anwser this question in the near future.

Fructose and the adolescent liver 

Adolescents consume even more sugar sweetened beverages, and thus more fructose, than the general population. 

If you are a parent or family member of an adolescent, or an adolescent yourself, you should know that greater fructose consumption in this age group ( largely from sweetened beverages like pop) is a very serious issue, especially in obese adolescents.

There are two important things you should know:

1) An obese adolescent who does not have NAFLD will lower their risk of developing NAFLD if they reduce their fructose intake

2) In those who currently have NAFLD, reducing fructose has shown to be beneficial to the health of the liver.

Fructose and your digestive system

According to the Canadian Digestive Health Foundation, about 1 in 6 Canadians currently suffer from Irritable Bowel Syndrome (IBS). The symptoms of IBS include stomach pain, constipation, diarrhea and troubled bowel movements.  

Canada has one of the highest proportion of IBS sufferers globally, and this is very likely down to the way in which we eat. Since fructose is not absorbed in our digestive tract, it may be a dietary component that causes or contributes to IBS. 

It is well known that certain IBS sufferers may have unique difficulties digesting fructose-rich foods and a fructose reduced diet has been shown to be beneficial to symptoms in these people.

Click here to learn more about how limiting fructose and other specific carbohydrates may benefit your IBS symptoms.

Take Home Message

Fructose is not inherently bad and is found in great supply in many fruits and vegetables. The majority of otherwise healthy people reading this post should not limit their fruit and vegetable consumption as a means to control fructose intake. If you have severe IBS that responds poorly to fructose, you may consider selecting fruits and vegetables that are lower in fructose content.

On the other hand, you should absolutely consider restricting your intake of foods rich in added fructose/high fructose corn syrup. The primary foods in this category are soda and other sugar sweetened beverages but also include sugary breakfast cereals, sauces/toppings, ice cream, cakes and other processed fods.  

These foods are contributing calories devoid of nutrients to your diet and may also contribute to straining your liver and digestive system while also potentially contributing to an excessive overall calorie intake which can lead to weight gain and an increase in your risk for numerous chronic diseases. 

Andy De Santis RD MPH