Fructose is a simple sugar found in fruits, honey and some root vegetables. Fructose is the sweetest natural sugar and is used commonly in commercial food preparation. Excess fructose consumption in processed foods has been associated with development of metabolic syndrome -- a combination of conditions that predisposes some people to develop diabetes and cardiovascular disease, including altered levels of LDL cholesterol.
Fructose versus Glucose
Fructose and glucose have different effects on blood sugar and cholesterol levels, according to a study published in the June 2009 issue of the "Journal of Nutrition." Glucose, which is removed from the bloodstream by the lever earlier than fructose, results in elevated blood glucose and lower triglyceride levels. Fructose, which is removed from circulation rapidly, results in elevated triglyceride production in the liver, which also leads to higher LDL levels. In the study, diets consisting of 20 percent fructose for four to six weeks caused significant elevations in triglycerides and LDL cholesterol, while diets of 20 percent glucose did not cause the same elevations in cholesterol levels. The researchers noted diets that limited fructose to between four and twelve percent of calories did not impair cholesterol levels.
Total Cholesterol
A fructose-rich diet is known to cause metabolic syndrome in some people, according to a study published in the January 2011 issue of the journal "Lipids in Health and Disease." In the study on laboratory animals, a high-fructose diet consisitng of 60 percent fructose led to insulin resistance and elevated total cholesterol and triglycerides. Fructose did not impair aerobic capacity of muscle, leading the researchers to question the potential influence of exercise on elevated cholesterol and blood sugar levels associated with metabolic syndrome.
Metabolic Syndrome
A study published in the February 2010 issue of the journal "Archives of Physiology and Biochemistry," found that fructose consumption early in life may be a contributing factor in the development of metabolic syndrome. In the study on laboratory animals, three weeks of a 10 percent fructose diet resulted in elevated triglycerides and elevated VLDL -- a type of LDL cholesterol that is has a strong influence on the development of atherosclerosis and increased oxidative damage to lipids. The researchers concluded that fructose in the diet early in life may have a detrimental effect on blood sugar and cholesterol levels.
Triglycerides and Total Cholesterol
Fructose raises triglycerides and lowers total cholesterol, without elevating total or LDL cholesterol, according to a study published in the October 2009 issue of the journal "Diabetes Care." In the meta-study -- a review of previously published research -- including 16 studies and 236 participants, diets containing fructose increased triglycerides and lowered total cholesterol compared to diets that contained an equal calorie allotment of another carbohydrate.
References
- "Diabetes Care"; Heterogeneous Effects of Fructose on Blood Lipids in Individuals with Type II Diabetes: Systematic Review and Meta-Analysis of Experimental Trials in Humans; Sievenpiper JL, et al.; October 2009
- "Journal of Nutrition"; Dietary Fructose and Glucose Differentially Affect Lipid and Glucose Homeostasis; Schaefer EJ, et al.; June 2009
- "Archives of Physiology and Biochemistry"; Glycoxidative Stress-Induced Damage on Lipid Profile in a Fructose Enriched Diet Model of Insulin Resistance in Rats; García Me, et al.; February 2010
- "Lipids in Health and Disease"; Impact of Early Fructose Intake on Metabolic Profile and Aerobic Capacity of Rats; Ghezzi AC, et al.; January 2011
