An apple keeps the doctor away… but fructose keeps him back

"An apple a day keeps the doctor away". It is a recurring saying, first used by Professor JT Stinson, director of the Missouri fruit experimental station, in a speech given on the occasion of the St. Louis World's Fair in 1904. In reality, it was not all his own because Stinson had drawn on a medical summary of the health benefits of apples that dated back to a XNUMXth-century medical conference given by the prestigious Salerno School of Medicine.

Be that as it may, since then the apple (but not only fruit in general) has been considered the panacea for preventing and treating numerous ailments. Undoubtedly, fruit has many beneficial properties thanks to the content of vitamins, mineral salts, fibers and bioactive molecules. But what we need to focus on most is fructose, the sugar that fruit is naturally rich in.

When we think of fruit, the apple is its representative par excellence thanks to its shape, aroma, colors and juicy texture. The apple tree, in fact, is one of the first trees cultivated since the Neolithic. The remains of an apple tree dating back to 6500 BC have been found in archaeological excavations at Jericho. In 800 BC Homer describes in the Odyssey the garden of Alcinoo with apple, pear, fig and garnet trees; Horace in 100 BC. C writes that the "perfect meal can only end with apples". In 79 d. C Pliny the Elder describes 20 different varieties of apples and in 1100 the Scuola Salernitana extols the therapeutic properties of the apple to treat intestinal, pulmonary and nervous system disorders.

Malus domestica it is the apple tree we know today, while its ancestor appears to be Malus sieversii: a wild apple tree native to the mountainous areas of Kazakhstan, up to 20m tall which produces fruits similar to apples of different sizes and colors but certainly not very sweet compared to our apples. In fact, we had to wait around 2000 A. when grafting was invented in China to reproduce the plants that offered the best fruits and to be able to select, spread and improve them.

Man has always had an idea of ​​paradise as a flourishing garden full of fruit trees. Nor is the example the Garden of Eden in the Bible or the Garden of the Hesperides in Greek mythology. But why? The desire for sweetness is a very deeply rooted desire in us. Anthropologists have discovered that preferences for salty, sour and bitter taste differ greatly in different cultures but the preference for sweet taste is universal for all peoples. The first contact with the sweet taste is that of mother's milk and if we think about how we have fed ourselves for millennia and what was available in nature for 90% of our time, it is easy to understand that reproducing that taste was no small feat . Few things, such as honey and some less acidic fruit, offered that authentic marvel to the palate. What has changed since then? The desire for sweetness has remained intact but the availability of foods that offer this flavor is infinite and this is where our serious troubles begin.

If we think about the fruit of 50 years ago and the fruit we eat now, we realize that it is always bigger, more beautiful, more colorful and sweeter (at the expense of the fibres). Thanks to hybridization the sugar content has increased while the mineral content has decreased (in leafy vegetables the sugar/mineral ratio is in favor of minerals). In fruit there are mainly two sugars: glucose and fructose and we know by now that all the sugar we take in excess is converted into fat and that formed from fructose is much more difficult to dispose of. The problem is actually not the fruit but the fructose that comes from white sugar (sucrose is a sugar in which a glucose molecule is linked to a fructose molecule) and corn syrup (glucose and fructose) now ubiquitous in the majority of products packaged or baked foods and carbonated beverages.

Fructose it is sugar that has the same chemical formula as glucose, but its chemical structure is different, in fact it is metabolized almost exclusively by the liver (like poisons… sic!) and this leads to an overload of work of this organ while glucose can be used by all the cells of our body. Other cells use very little fructose and become saturated very quickly. Once a product that contains fructose has been consumed, it is taken to the liver to be metabolised. The dose makes the difference, if the fructose is excessive compared to the capacity of the intestine to absorb it or the transporters (Glut 5 and 2) are missing, the fructose is fermented by the bacterial flora of the colon and causes bloating, flatulence, diarrhea and dysbiosis. Once in the liver fructose is converted into glucose thanks to the fructokinase enzyme and provided that the liver glycogen stores are not saturated, this usually happens in the morning after an overnight fast. If, on the other hand, the liver glycogen is saturated, the sweet story of fructose ends here, from now on it's just pain. Fructose is converted into fatty acids and large amounts of fructose (see sugary drinks for example) involve the production of large amounts of fat, the production of LDL cholesterol, the increase in intrahepatic (steatosis) and visceral (see cardiovascular diseases) fat, the increase in uric acid (see gout and high blood pressure), the increase in intramuscular fat with the increase in insulin resistance and subsequent hyperinsulinemia. In fact, the metabolic effects of fructose are similar to those associated with ethanol consumption. At this point we also add chronic inflammation which is a good starting point for pathologies of all kinds. At the end of the day all this fructose is absolutely useless to us, not even to make us grow muscles because muscle cells have neither fructose transporters nor the enzyme fructokinase.

In the literature there are now numerous studies that confirm the key role of excessive consumption of fructose and sugar in general in the onset of numerous chronic and degenerative pathologies, which is not linked to the consumption of fruit but of industrial foods and drinks with large quantities of fructose-glucose syrup. Cancers of all kinds, metabolic syndrome, mental disorders, type 2 diabetes, obesity, hypercholesterolemia, autoimmune diseases, and cardiovascular and neurodegenerative diseases are all related in some way to excess sugar intake. Children are most at risk of these excesses. By now snacks, industrial fruit juices and sweets of all kinds have replaced the snacks of the past. Sweet foods have also become a means of consolation or gratification, a reward for doing well in school or a diversion to keep them quiet while we are busy with other matters. According to 2014 data from the "Okkio alla salute" Observatory coordinated by the Istituto Superiore di Sanità in Italy: overweight children are 20,9% and obese children are 9,8%, the highest prevalences are recorded in the Regions of the south and center. Instead, data from the Bambino Gesù Pediatric Hospital in Rome confirm that around 3-12% of children of normal weight are affected by hepatic steatosis and this frequency rises to 70% in overweight or obese children. These are alarming figures and we are talking about a veritable global epidemic of obesity and chronic diseases with all the related consequences: a reduction in the quality of life, an increase in mortality, skyrocketing health care costs and the general impoverishment of the population. Increased sugar consumption goes hand in hand with the increase in disease. It is estimated that in the Paleolithic a person consumed 2kg of honey per year, in 1830 the average consumption was 5 kg of sugar per person and in 2000 it reached 70kg. In Italy in 2013 a consumption of about 27kg per person was estimated. Furthermore, in the USA between 1970 and 1990 the consumption of fructose increased by 1000%.

Sugar consumption should be reduced, especially in sugary drinks, sweets, candies and other packaged products. We must go further and learn to read the labels of all the products we buy in the supermarket. Sugar added to foods can be hidden under numerous terms: sucrose, glucose, fructose, corn syrup, glucose-fructose syrup, dextrose, maltose, maltodextrin, galactose, rice syrup…

Fruit should not be demonized, if there are no particular pathologies, its consumption brings numerous benefits, especially if it is consumed in the morning. In addition to sugars, fruit contains many bioactive substances that cooperate with each other by increasing the absorption of vitamins, mineral salts and regulating the metabolism. Children must go back to snacking on fruit and learn to satisfy their desire for a sweet taste in a natural and healthy way, maybe we adults can do it too.

Let's go back to our apple. An apple a day keeps the doctor away? Apples and pears contain 70% of sugars in the form of fructose, while strawberries, berries, melons, peaches, kiwis and pineapples between 30% and 40%. Bananas also have more glucose than fructose but are higher in calories. Give up industrial products, manipulated, "unmolded" and assembled in the most captivating and imaginative forms in favor of this marvel that nature has offered us and that we have been able to exploit to our advantage, fruit. The best way to consume it is for breakfast, together with walnuts or almonds and a good source of protein such as eggs.

Buon appetito!