Too much fructose: what dangers for the brain?

Too much fructose: what dangers for the brain?


Fructose , contrary to what one might think, is no more harmless than other sugars . Indeed, the sugar that is introduced through the consumption, mainly of fruit, and some vegetables, if consumed in excess, could damage the brain, and represent a risk factor for the onset of the first signs of Alzheimer’s. A study conducted in Colorado would seem to confirm this connection.

To tell the truth, the Italian Society of Human Nutrition (Sinu) has also expressed itself on fructose which, with regard to the recommendations on the intake of sugars, explicitly speaks only of fructose, referring to the maximum quantities of sugars to be introduced with the daily diet . It is recommended to ” limit the consumption of sugars to < 15% » of the energies taken in each day with food and drink”; to ” limit the use of fructose as a sweetener “ and to ” limit the use of foods and beverages formulated with fructose and high fructose corn syrups.”

Fructose: what is it?

Fructose  (or levulose) is a monosaccharide, which has the same molecular formula as glucose (C 6 H 12 O 6 ) but has a different chemical structure Its nutritional properties, which have long been the subject of numerous studies and researches, are also different. Like all carbohydrates  , fructose also provides approximately 4  calories per gram. Fructose is contained in particular in fruit and some vegetables, in variable percentages, as shown in the table below.

FOOD Total glucose
(g/kg of food)
Total fructose
(g/kg of feed)
Oranges 29-39 31-33
Bananas 42-62 41-62
Strawberries 25 20-27
Mandarins 10-11 18-38
Apples 29-32 80
Pears 12.5-16 60
Lemon juice 8-9 9
Greens and vegetables
Garlic 14 8
Carrots 23.5 23
Lettuce 2.4-5.1 3.1
Eggplant 13-16 12-16
Peppers 15-25 13-16
Peas 2.3-19 2.25-10
Fresh tomatoes 13-14 15-19
Zuchinis 9.5-11 8-12

Glycemic index or fructose metabolism?

So what causes damage to the body and favors the onset of diabetes , insulin resistance and brain damage, if we are talking about fructose? A  sugar that is often recommended to diabetics due to its low glycemic index (19-23), which leads to a much lower increase in  blood glucose levels than the intake of a similar quantity of glucose ( glycemic index 100) or of sucrose (glycemic index 68), with a superior sweetening power . There are, however, cons.

The negative aspects, in fact, concern the metabolism of this sugar when it is taken in high doses, i.e. > 40-60 grams per day. This leads to quite serious metabolic effects, such as the onset of metabolic syndrome ; the increase in insulin resistance ; straining the liver , increasing the synthesis of  triglycerides  and  fatty acids. It is a sugar, therefore a carbohydrate, but is metabolised as fat , hence the increase in triglycerides .

Fructose and brain damage: the study

An excess of fructose has deleterious effects on the organism. In particular, it damages the liver, can promote insulin resistance ( a phenomenon directly associated with diabetes) and obesity. According to a study published in the American Journal of Clinical Nutrition , excessive consumption of this sugar could also damage  the brain , even favoring the appearance of the first signs of Alzheimer ‘s .

The research was conducted by a group of US and Mexican researchers from the Anschutz Medical Center at the University of Colorado in Aurora, who highlighted how fructose, unlike glucose, does not provide an immediate energy supply to the body, but rather incentives the intake of food and water slows down the resting metabolism , would favor the accumulation of fat and glycogen (the “spare” form of glucose) and insulin resistance, with serious consequences for the brain.

Here are the effects of perfume on the brain .

Test results

As the scholars explained, the chronic and continued reduction of cerebral metabolism induced by the repeated metabolism of fructose causes progressive cerebral atrophy and loss of neurons . These are characteristics that translate into similar effects of Alzheimer’s disease . Hence the correlation. Therefore, consuming fructose in excessive quantities would trigger some of the early phenomena typical of Alzheimer’s, which manifest themselves, for example, with the reduced metabolism of glucose in the brain, the malfunctioning of the mitochondria , and neuroinflammation. The effects of fructose and one of its derivatives ( uric acidintracellular), as explained by the researchers, are associated with the accumulation, in nerve cells , of proteins associated with the disease.

Brain friendly foods

This study further strengthens the thesis according to which there is a link between diet and Alzheimer’s. A diet rich in sugars and foods with a high glycemic index , in fact, are harmful to brain health, as are salt , fatty meats and eggs .

Among the foods to prefer to keep the brain healthy, we remember:



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