Excess of Fructose

Rich Fructose Foods

Fructose is a widespread monosaccharide in free form in fruit, honey and vegetables. Carrots, figs, plums, peppers, courgettes, bananas and apples are particularly rich. Many sugary drinks, soft drinks, sweets and industrial products enriched with fructose-glucose syrups also abound in fructose.

In addition to being in free form, fructose in foods can also be associated with other sugars or fructose molecules:

• when combined with a glucose molecule, it produces sucrose, which is the white crystalline disaccharide extracted from beet or sugar cane commonly used as "table sugar"; specific enzymes located in the brush border provide for the digestion of sucrose, separating fructose from glucose, which are then absorbed in free form;
• if polymerized in long chains by β-2.1 bonds, it instead forms inulin, a component of the soluble fiber that is NOT easily digestible for humans but still useful for the functioning of the intestine (thanks to the PREBIOTIC function towards physiological Bifidobacteria ). Therefore, the fibers do not represent a source of bioavailable fructose.

Functions and Metabolism

Fructose is a sugar that, at low blood concentrations, boasts a certain "independence" from insulin, the anabolic hormone essential for the transport of glucose, amino acids and many other molecules from the blood inside the tissues (except for the nervous one and a few others).

Insulin, Glycemia and Glycemic Index

Insulin secretion and metabolism can be altered by the presence of metabolic disorders such as insulin resistance and diabetes. In similar cases, drug therapy, nutritional therapy and physical exercise pursue a single goal: the moderation of blood glucose and insulin levels in order to limit metabolic damage in the short, medium and long term.

To reduce blood sugar and insulin levels, it is essential:

1. Improve body composition (lean mass / fat mass ratio)
2. Increase energy expenditure and receptor sensitivity to insulin by exercising
3. Limit high glucose foods and prefer foods with low glycemic index

Fructose, thanks to its characteristic of insulin independence and the need to be converted into glucose before oxidation, has a low glycemic index . For this reason, in the treatment of insulin-resistant and diabetic patients there is often a tendency to promote the consumption of fructose compared to sucrose, glucose and sweeteners (considered unhealthy additives).

Excess and Health

What is still not clear to all professionals in the sector is that EXCESS in the consumption of fructose can be harmful to human health and even more so for dysmetabolic patients.

Excess of Semolina Sugar

First of all, it should be emphasized that fructose is a simple carbohydrate, therefore even eliminating any other source of simple sugars, its overall income should not exceed 10-12% of total kilocalories, an amount that can be easily reached by consuming a couple of portions of fruit and a couple of vegetables, or 3 cans of soft-drinks. How easy it is to understand if fructose consumption is integrated into a similar diet through:

• added drinks and foods
• granular fructose in place of sucrose

excess is inevitable.

Readers could dispute a similar remark by saying:

"... if it is not fructose, it can be sucrose or glucose ... but it is still simple carbohydrates that contribute to raising blood sugar; after all, it would not be healthy to make frequent and massive use of sweetening additives!"

Very true; in fact, the first dietary correction consists in restoring good eating habits by abolishing the simple sugars used as sweeteners. This also facilitates the reduction of the consumption of sweet drinks, desserts and coffee.

Insulin

Fructose is not a totally harmless nutrient : it is true that it boasts insulin-independence BUT ONLY within certain doses; exceeding the consumption of fructose, the increase in insulin secretion is guaranteed.

Liver

It's not all! The conversion of fructose into glucose occurs mainly in the liver; this means that as dietary fructose increases, the liver workload also increases, which in a dysmetabolic patient is certainly not a negligible side effect.

Hypertriglyceridemia

Furthermore, if the hepatic glycogen stores are saturated, the excess fructose is converted into fats (triglycerides) with a negative impact on body weight, triglyceridemia and any problems with hepatic steatosis. Experimental tests on mice and humans have shown the ability of fructose to increase plasma triglyceride levels more than made from a similar amount of glucose. Furthermore fructose would seem to have less satiating power.

Scientific researches

Recently, numerous experimental studies have been carried out on the consumption of fructose in diabetics and the obese, and the results are not good. For example, an experimental1 showed that:

" an excessive consumption of fructose can have deleterious effects on human health (obesity, arterial hypertension, metabolic syndrome, hypertriglyceridemia, hypercholesterolemia and renal damage). In particular, in the common nephrological clinical practice, nephropathic patients are advised to follow a hypoproteic dietary regime running the risk of unconsciously increasing, by way of compensation, the intake of carbohydrates, including fructose. It is therefore advisable to instruct patients with a hypoprotein diet on how to reduce the intake of this sugar . "

Another recent experimental2, highlights that:

" a higher consumption of fructose for 10 weeks leads to significant changes in postprandial utilization of nutrients as well as a significant reduction in lipid oxidation; there is also a reduction in resting energy expenditure compared to the basal values ​​in subjects who consume fructose-sweetened beverages for 10 weeks ".

Fructose is a glycide useful for dietetic therapy but of which it is absolutely not recommended the ABUSE, especially in the treatment of dysmetabolic, obese and nephropathic patients. In people suffering from irritable bowel syndrome even a slight excess of fructose can trigger problems with meteorism, flatulence and abdominal pain.

Bibliography:

1. Johnson RJ, Sanchez-Lozada LG, Nakagawa TJ Am Soc Nephrol - The effect of fructose on renal biology and disease - 2010 Dec; 21 (12): 2036-9. Epub 2010 Nov 29
2. CL Cox, KL Stanhope, JM Schwarz, JL Graham, B Hatcher, SC Griffen, AA Bremer, L Berglund, JP McGahan, PJ Havel and NL Keim - Consumption of fructose-sweetened beverages for 10 weeks overweight / obese men and women - European Journal of Clinical Nutrition 66, 201-208 (February 2012) | doi: 10.1038 / ejcn.2011.159