Fructose is pure sugar (monosaccharide) found in most fruits, such as watermelons, mangoes, oranges, pineapples. Nowadays, fructose is present in large quantities in artificial sweeteners, such as high fructose corn syrup, which is a significant constituent in soda, fruit drinks, cookies, and cereals.
It also constitutes 50 per cent of sucrose, which is the regular table sugar. Honey also comprises approximately 40 per cent of fructose. Also those who take it a habit to mix smoothies with a combination of sweet fruits will be consuming a large amount of fructose.
Fructose is a simple sugar that is mostly absorbed in the small intestine. It is important to note that although it is similar to glucose, which is the sugar found in carbohydrates, it is not as easily absorbed, and it does not utilise insulin.
Fructose intolerance, also known as fructose malabsorption, refers to a condition in which the small intestine cannot efficiently absorb fructose whenever ingested. People who suffer from fructose intolerance genetically lack the chemical carriers of fructose in the intestines. It, therefore, becomes a metabolic problem whenever such people consume fructose, such as eating large quantities of fruits. There is also a condition known as hereditary fructose intolerance, which is due to the deficiency of aldolase B. Aldolase B is necessary for the breakdown of fructose by the liver. This inherited form is usually asymptomatic until the child consumes any fructose-containing substance.
Although fructose is metabolised in the liver, a large daily consumption will create a stress on the liver and then recruit the pancreatic islets for help.
When a fructose-intolerant person consumes fructose, there is a build-up of fructose sugar in the guts. Bacterial action on this sugar in the intestine causes fermentation which, leads to the release of alcohols such as methane, long-term exposure of which can be hazardous to the body.
Fructose intolerance typically presents with gastrointestinal symptoms, such as
- Nausea and vomiting – usually of undigested food particles.
- Bloating – a feeling of fullness due to excessive gas in the stomach
- Increased flatulence.
- Abdominal pain and discomfort, which is usually on and off and occasionally severe.
- Diarrhoea – usually bulky and foul smelling, as a result of poor nutrient absorption.
- Chronic fatigue from lack of sleep due to reduced melatonin, a hormone necessary for sleep.
- Malabsorption of certain nutrients, such as iron. Iron is absorbed in the intestine and needed for the production of red blood cells, which carry oxygen to the different organs in the body. A deficiency of this nutrient will lead to low blood levels and poor oxygenation of the various organs.
- It has been linked to mood disorders like depression due to lower levels of tryptophan. Tryptophan is a precursor for some hormones that help with sleep and mood stabilization. If this amino acid were reduced, it implies that the individual will suffer from lack of sleep and low mood. This will consequently lead to fatigue and mental disturbances, such as depression.
Certain risk factors associated with fructose intolerance such as pre-existing gastrointestinal conditions like irritable bowel disease, stress and most important, high intake of refined and processed food.
Fructose intolerance is diagnosed by a test known as a hydrogen breath test. This test measures the amount of hydrogen in the patient’s breath. Typically the patient fasts for an average of 8 to 12hours before the test.
A baseline test is first performed where the patient is asked to blow into a balloon, and the hydrogen level is measured, next the patients then ingest a little quantity of fructose and the hydrogen test is repeated every 30 minutes for two to three hours. If the level of this gas (hydrogen) in breath is high after this sugar has been consumed, the test is considered positive and a diagnosis of fructose intolerance made.
The Basis of the analysis is that when a fructose intolerant person consumes fructose in foods, such as fruits or sodas, the body is unable to process this sugar. The bacteria in the colon will then act on it. Once the bacteria work on it, the fructose is broken down to release hydrogen, amongst other metabolites. It is the hydrogen produced that is tested with this simple hydrogen breath test.
Although there is no cure, an appropriate diet and elimination of foods that contain high levels of fructose, such as sodas, fruits and honey are usually advised to people suffering from this condition
Some complications may arise as a result of excess fructose, such as the following:
- Deposition of fat in the liver, which could lead to non-alcoholic fatty liver disease – a condition in which the liver accumulates lipids and it is unable to function optimally. This could lead to liver failure.
- There is also insulin resistance, which can lead to obesity and type II diabetes.
- Fructose doesn’t suppress appetite as much as glucose, which could result in overeating. Overeating could result in consuming more than the body needs. The excess carbohydrates stored as fat leading to excessive fat distribution and obesity.
- If consumed in excess, fructose can cause leptin resistance. Leptin is the hormone responsible for fat distribution and regulation, leading to disturbance in body fat regulation and obesity.
- It has been implicated in rising blood level of uric acid, which causes gout. Gout is a form of arthritis that mainly affects the smaller bones of the feet characterised by severe pain and swelling.
However, with the recent advancement in technology, the use of bioenergetics testing, which is a highly sensitive and non-invasive test, has enabled us to diagnose fructose intolerance and several other conditions promptly even before producing symptoms. A healthy meal plan can be drawn to avoid all the possible complications to the various organs.
With the help of the modern Mayr medicine, which takes into cognisance dietary and lifestyle modification, as well as detoxification of harmful by-product of fructose fermentation, a lot of people with fructose intolerance can live a healthy life and it aids the body to regulate the normal physiological functions.
This article was written by Prof Oladapo Ashiru and was first published on The Punch