How (Un)Harmful is Fruit Sugar?

Fructose is a popular sweetener for drinks, sweets, and various processed foods. It occurs naturally in fruits and also artificially. Here it is known as glucose-fructose syrup, HFCS, isoglucose, corn syrup, invert sugar (syrup), or fruit sweetener.

However, there are significant differences between these two forms in how the body handles them. And artificially produced fructose is not without problems, as some studies suggest.

Fructose hat den Vorteil, dass sie eine höhere Süßkraft als Saccharose (Haushaltszucker) hat und damit eine geringere Menge den gleichen Süß-Effekt hat. Zudem ist sie billiger. Sie wird außerdem langsamer vom Körper aufgenommen, ist im Gegensatz zu Glucose weniger wichtig für den Körper und gelangt außerdem ohne Insulin in die Zellen.

Potential problems associated with fructose

Fructose is described as the most concerning of all sugars – but only in its artificially produced form.

• Fructose inhibits the feeling of satiety and promotes fat formation. A dangerous combination if you want to lose weight.
• it can exacerbate insulin resistance and thus lead to diabetes in the long term
• it increases uric acid levels, which can result in gout and kidney stones
• furthermore, blood fat levels and blood pressure rise, affecting the entire cardiovascular system
• Fructose has a negative impact on gut flora
• and can lead to fatty liver
• new findings also link it to brain damage such as Alzheimer's, Parkinson's, depression, and ADHD

Although fructose is also found in fruits, these adverse effects only concern the industrial form, most commonly known as HFCS, high fructose corn syrup, or corn syrup.

Excessive sugar consumption

Since the industry generously uses this corn syrup for all sorts of consumer goods (soft drinks, sweets, sauces, etc.), practically everyone who does not actively pay attention consumes about 60 grams of fructose daily.

And table sugar is only slightly better, as it also consists of 50% fructose.

If you calculate the daily sugar consumption, which varies depending on age, you come to 60 grams x 365 days = 21,900 grams, or nearly 22 kilograms of fructose per person per year. The total sugar intake is even higher, as the 22 kg refer to fructose.

Die WHO empfiehlt maximal zwischen 25 – 50 Gramm Zucker pro Tag zu sich zu nehmen. Ausgehend von einer Kalorienaufnahme von 2.000 Kalorien pro Tag. Man muss die WHO nicht mögen und ihre Empfehlungen sind nicht immer sinnvoll, aber dass die allermeisten Menschen tatsächlich zu viel Zucker konsumieren, kann jeder beobachten.

Fructose study and brain regulation

In this study researchers examined the effects of fructose on the brain.

The researchers wanted to know: Can what we eat change our genes in the brain in such a way that we are more likely to develop metabolic diseases (e.g., obesity, diabetes) or psychological/neurological problems? They examined mice and attempted the following:

• One group received normal food
• One group received a lot of fructose (i.e., fruit sugar, as found in soft drinks, ready meals, and sweets)
• A third group received fructose + DHA (an omega-3 fatty acid)

Key findings:

• A lot of fructose changes hundreds of genes and their switches (epigenetics = genes are turned on or off without changing the DNA sequence) in the brain (especially in the hypothalamus = metabolism control and in the hippocampus = learning & memory)
• This creates networks of genes that become disordered – and these networks are associated with obesity, diabetes, inflammation, depression, memory problems, and other diseases (also in humans – this was matched with large genetic databases)
• Two genes are particularly involved (Bgn and Fmod), which act like "conductors" and amplify the negative effects of fructose
• DHA reverses almost all these changes – effectively a protective mechanism at the gene level

In summary: Too much fructose, as in the modern diet, can seemingly reprogram the brain on a molecular level in the long term and make it more susceptible to metabolic and brain diseases.

Good omega-3 fats (especially DHA) can largely reverse this damage according to this study.

This is another reason why nutrition not only influences the stomach but also the brain and psyche significantly – and why an individually optimal diet ("nutrigenomics") might help predict or reduce disease risks in the future.

Avoiding fructose

The answer to high fructose consumption cannot be to mitigate the effect with high doses of DHA, but first and foremost to reduce fructose consumption.

The simplest ways to do this are:

• avoiding processed foods
• avoiding sweet lemonades, soft drinks, etc.

In contrast, real fruits are not a problem, as they contain other ingredients alongside fructose that, in combination, can well balance the already low fructose content. Note: this does not apply to dried fruits, in which the sugar is more concentrated.

Sofern man Nahrungsergänzungsmittel konsumiert, deren Hauptbestandteil oder Trägerstoff (Frucht-)Zucker ist, darf man dies also bewusst einmal hinterfragen, da der generelle Zuckerkonsum schon oberhalb der empfohlenen Mengen liegt und Fruchtzucker überraschende Auswirkungen auf Gehirn, Herz-Kreislauf, Leber und Gewicht haben kann, wie die oben verlinkte Studie in Aussicht stellt.

Transparency notice

The fact that I, as the author of this text, present plant-based supplements without added sugars on this website should not overshadow the legitimate health concerns regarding increased (fruit) sugar consumption!

You may attribute a self-interest to me with the critical examination of fructose, but that cannot be a reason to dismiss questions about sugar consumption or to look for alternatives that better fit the personal dietary plan and Wellness Goal fit.

The Answer

To answer the initial question:

Fructose in its natural form within fruits, alongside all the other substances a fruit contains, is generally harmless.

However, industrially produced fructose consumed in large quantities can lead to the negative effects described above, as studies show.

Wherever possible, fructose should be avoided. And supplements that rely on fructose as a main ingredient should ideally opt for a different composition.

There are companies that demonstrate it can be done differently, by producing products 100% from plants. And if someone still wants to take a vitamin pill to address a specific deficiency, they can certainly find products without a high fructose content.

Given the potential difficulties, this is certainly a good decision.