What is fructose and its sweetness?
Fructose is a monosaccharide(simple sugar) just like glucose and fructose sweeteners cause diabetes more than glucose. Fructose has a slightly different shape and weight from glucose. It is a naturally occurring simple sugar found in many plants, especially in ripe fruits, vegetables, and honey. This is the reason these foods taste so sweet. Fructose is the sweetest tasting naturally occurring simple sugar.
Fructose usually appears bonded /joined with glucose to form sucrose. Sucrose is the scientific name for table sugar.
Fructose in commons foods
If you check on most food labels, be it on your bread or drinks you will see added sugar, this is most likely fructose. Fructose before the age of food processing was available in the human diet in low concentrations as ripened fruit and honey. Today that has changed due to commercial food processing.
Fructose has become abundantly available and is found in high concentrations in almost all processed foods.
High fructose corn syrup as sweeteners.
In the years gone by, sucrose obtained from plants like sugarcane was the preferred sweetener in processed food. However, the discovery of High fructose Corn syrup(HFCs) has surpassed the use of sucrose as a sweetener. HFCs are cheap to make from readily available corn starch1
Fructose in a ripe fruit represents about 1% of the fruit weight while in the HFCS sweetener, fructose can be up to 50% of the sweetener weight. High Fructose Corn Syrup is about 55% fructose to 45% glucose, while natural sucrose is 50% fructose and 50 % glucose.
Fructose and metabolic disease research
Fructose when eaten in any form is metabolized by the body just like Glucose, but its metabolism occurs mainly in the liver. Human and animal research studies have demonstrated that too much fructose intake decreases an energy chemical in the liver called Adenosine triphosphate(ATP).
When ATP in the liver decreases it causes a reduction in the amount of insulin receptors in the liver. Remember that insulin receptors are the gates that allow Insulin to enter all body cells and carry out its work of metabolizing glucose.
Reduction of Insulin receptors causes insulin resistance in the liver cells. Research shows that fructose loads in the liver increase the formation of fat and reduce the process of breakdown of fats to provide energy for the cells a process called fat oxidation. This eventually leads to the accumulation of fat in the liver2
Fat in the liver
High and abnormal levels of fat in the liver trigger inflammation of the liver cells, this chronic inflammation destroys the insulin receptors(gates) even more, thereby worsening insulin resistance. As insulin resistance increases in the liver, it causes an increase in the production of Glucose in the blood.
The insulin-producing cells in the pancreas overwork to counteract the high glucose levels in the blood. This causes them to deteriorate and eventually, lose the functional ability to produce enough insulin.
Dysfunctional pancreatic cells
An increase in the number of dysfunctional insulin-producing cells in the pancreas over time is a primary cause of type 2 diabetes3
A research was conducted among healthy volunteers to compare the effect of the consumption of pure glucose and pure fructose. It was found that fructose intake resulted in a decrease in the bidding of insulin to insulin receptors in body cells called monocytes and a 25% reduction in insulin sensitivity in muscles compared to intake of pure glucose4
In another research, the consumption of isolated fructose had a very bad effect on the amount of glucose, insulin, and fat in the blood compared to glucose consumption. Isolated fructose intake promoted greater food intake and an increase in body weight, and liver weight in rats.
Fructose effects can be reversed
A lot of research evidence out there has shown that added fructose from sucrose or HFCs affects the liver and body’s glucose metabolism negatively resulting in insulin resistance both in humans and animals. There is hope, research further shows that these fructose-induced body changes; insulin resistance, high insulin in the blood, high fats in the blood and liver, and diabetes can be reversed by reducing the sources of added fructose in people’s diets.
Fructose in the human diet
Processed foods, mostly beverages are usually sweetened with HFCs. HFCs are found in candies, jams, bread, soft drinks, fruit drinks, other baked goods, and sweets.
Observations in various research studies have revealed that consumption of fructose in processed foods and beverages is associated with higher fasting blood glucose levels, type 2 diabetes, obesity, and metabolic syndrome.
Even 100% fruit juice though not sugar-sweetened has a high concentration of fructose, removed from its natural state. Consumption of this juice is also associated with increased body weight and a higher risk of diabetes.
Chronic overnutrition of fructose causes a loss of insulin receptors in the liver which leads to liver insulin resistance. It also increases fats in the liver and fat toxicity causes dysfunctional insulin producing cells and eventually to type 2 diabetes.
Frequency of intake is crucial
The next time you pick up a sweetened beverage or concentrated fruit juice use this knowledge to your health benefit. Amount and frequency of intake, combined with other factors like your age and metabolism also determine how fast you may develop diabetes.
Observations in various research studies have revealed that consumption of fructose in processed foods and beverages is associated with higher fasting blood glucose levels, type 2 diabetes, obesity, and metabolic syndrome.
References
- Basciano H, Federico L, Adeli K. Fructose, insulin resistance, and metabolic dyslipidemia. Nutr Metab (Lond). 2005 Feb 21;2(1):5. doi: 10.1186/1743-7075-2-5. PMID: 15723702; PMCID: PMC552336
- Bocarsly ME, Powell ES, Avena NM, Hoebel BG. High-fructose corn syrup causes characteristics of obesity in rats: increased body weight, body fat and triglyceride levels. Pharmacol Biochem Behav 2010;97:101–106
- Johnson RJ, Perez-Pozo SE, Sautin YY, et al. Hypothesis: could excessive fructose intake and uric acid cause type 2 diabetes? Endocr Rev 2009;30:
- Teff KL, Elliott SS, Tschöp M, et al. Dietary fructose reduces circulating insulin and leptin, attenuates postprandial suppression of ghrelin, and increases triglycerides in women. J Clin Endocrinol Metab 2004;89:2963–2972.