Fructose is a simple sugar found naturally in some foods such as fruits and vegetables.
However, its main consumption occurs through sucrose, a molecule made up of glucose and fructose, commonly known as «table sugar».
Another source of fructose is sorbitol, a sugar-alcohol that, when metabolized by our body, generates fructose. Sorbitol is found naturally in red algae and some fruits.
It can also be obtained artificially by chemical modification of glucose. It is used as a thickener, humectant, and sweetener in various food products.
In case of a correct functioning of the organism, fructose is absorbed in the small intestine and, later, metabolized in the liver, where it is transformed into glucose to be able to be used by the cells.
If there is a problem in absorption or metabolism, it is when intolerance to fructose and sorbitol manifests itself.
Regarding this intolerance, two cases must be differentiated to know which dietary pattern to follow:
It is a relatively common situation. Fructose and sorbitol cannot be absorbed and pass to the colon, where they are fermented by intestinal bacteria.
This gives rise to a release of gases and produces symptoms such as abdominal pain, diarrhea or nausea. It can occur at any stage of life and may or may not be reversible.
Fructosemia or hereditary fructose intolerance (HFI)
It is a rare disease due to a genetic error in metabolism that occurs in only 1 in 20,000 people. Fructose is absorbed by intestinal cells, but the liver is not capable of metabolizing it.
The middle breakdown product of fructose accumulates, which is toxic to the body and causes serious problems in its functioning. IHF is diagnosed in the infant stage and is irreversible.
For both types of intolerances it is key to know which foods contain fructose in order to follow a diet appropriate to the circumstances. But what are these foods?
Fruits: avoid the consumption of most of them.
Vegetables: there are many that contain fructose, the ones with the least amount are chard, and lettuce and cucumber have moderate amounts.
Fish, meat and eggs: they must be fresh.
Legumes: occasional consumption in small amounts.
Cereals and derivatives: you should only avoid whole grains and soy flour.
Dairy products and derivatives: they must not be sweetened.
Oils and fats: avoid commercial sauces.
Sugars, sweeteners and sweets: those allowed are those that do not contain fructose or sorbitol, you can opt for those that contain glucose or artificial sweeteners.
However, apart from the amount of fructose in the food, the ratio of fructose and glucose should also be assessed.
Glucose has been shown to improve the absorption threshold of fructose.
The use of supplementation with vitamin C and folic acid is indicated, because it facilitates the metabolism of carbohydrates, including fructose.
Foods in Fructose Intolerance:
Fructose can be found in three ways:
As free fructose, for example, in honey.
Attached to glucose to form table sugar.
As part of a fructan. Fructans are multiple fructose molecules attached to a glucose molecule, found in: onions, artichokes, asparagus, leeks, garlic, and lettuce, for example.
Fructose malabsorption can be diagnosed using a hydrogen breath test. The hydrogen breath test measures the amount of hydrogen in our breath
Foods Allowed in fructose and sorbitol intolerance:
–Dairy: Milk, cheese, natural yogurt, butter.
-Meats: All without problems.
-Egg: No problem.
-Vegetables: All except those that are prohibited. You can eat them fresh, frozen or canned. Homemade or commercial French fries, carrots (no more than 1 small per day). Onion (no more than 1 teaspoon per day).
-Cereals: Oats, wheat, barley, rye, according to tolerance, rice, tapioca and products made from these. Consumption of white bread should be limited. Homemade cookies made with glucose instead of sucrose.
-Desserts: without fructose, sucrose and sorbitol.
– Sweeteners: Glucose, corn syrup. Artificial sweeteners without fructose, sucrose and sorbitol.
– Soups: Homemade using permitted foods. Extract of meats, concentrated cubes.
-Drinks: Infusions, cocoa (make sure it does not contain sucrose), drinks without sorbitol as a sweetener.
-Condiments: aromatic herbs, spices, essences, dyes, salt, pepper, mustard, curry.
-Fats: Butter, margarine, oils.
Foods prohibited in intolerance to fructose and sorbitol
–Dairy: Milk sweetened with fructose, commercial ice cream with fructose or sorbitol, yogurt with fruit.
– Meats: Sweet ham; stews with vegetables not allowed.
-Vegetables: Peas, lentils, chickpeas, white beans, corn, root vegetables: turnips, beets,), pickles, soybeans, cabbage, tomato.
– Fruits: All, natural or different preparations.
-Cereals: White bread, barley or rye bread is preferable only for toast at breakfast.
– soy flour, muesli, all kinds of cereals made with sugar or honey.
-Desserts: Commercial ice cream, chocolate, pastries, commercial cookies, sweet pastries, especially those that are sugar-free, dietetic or for diabetics.
– Sweeteners: Table sugar, molasses, maple syrup, fructose, sorbitol.
-Jams, sweets: diet sweets, for diabetics, caramels or trinkets, nuts, chocolate, common or sugar-free chewing gum.
– Drinks: All flavored milk, coffee with added sucrose, smoothies, juices, fruit and vegetable smoothies not allowed, fruit liqueurs.
-Condiments: Sauces, dressing, salad, commercial mayonnaise.
IMPORTANT: keep in mind that both sucrose (common sugar) and sorbitol (an artificial sweetener, are sources of fructose),.
If you use a sweetener choose aspartame or cyclamate or others as acesulfame or these others saccharin, sucralose stevia liquid glucose, glucose powder, dextrose, corn sugar, quinoa syrup, maltodextrin, syrup or rice syrup.
Among the polyols, xylitol and erythriol can be chosen.
-See the article «Fructose Consumption—Free Sugars and Their Health Effects» in volume 118 on page 71.
-Heiman ML, Greenway FL (2016). «A healthy gastrointestinal microbiome is dependent on dietary diversity». Mol Metab (Review). 5(5):317–320. doi:10.1016/j.molmet.2016.02.005. PMC 4837298. PMID 27110483
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