Study Summary – Chronic Fructose Substitution Has Little Effect on Blood Glucose, Insulin, Triglycerides

An article entitled “Chronic fructose substitution for glucose or sucrose in food or beverages has little effect on fasting blood glucose, insulin, or triglycerides: a systematic review and meta-analysis” by Evans et al. was recently published in the American Journal of Clinical Nutrition. The systematic review addressed the effect of isoenergetic fructose replacement of other sugars and its effect on glycated hemoglobin (HbA1c), fasting blood glucose, insulin, and triglycerides.

Evans et al. conducted a literature search of studies using the following criteria: 1) study in humans, 2) clinical trial, 3) fructose as an intervention, and 4) glucose or sucrose as a control. After narrowing the results, researchers included a total of 14 study arms from 11 articles. Outcomes of interest were HbA1c, fasting blood glucose, fasting blood insulin, fasting blood triglycerides, high-density lipoprotein (HDL), low-density lipoprotein (LDL), very low density lipoprotein (VLDL), total cholesterol, apolipoprotein B100, and body weight. The majority of studies were crossover studies in which fructose was substituted for glucose rather than sucrose. The doses of fructose, presentation of fructose, and intervention length varied widely across studies. Five of the 11 studies included only overweight or obese individuals, all others included healthy weight subjects alone or in a combination with overweight and obese participants.  Doses of sugar ranged between 24 and 150g/d.

Evans et al. report the following results:

  • Fasting blood glucose was lowered on average by -0.14 mmol/L for glucose studies and -0.20mmol/L for sucrose studies. However, there was high heterogeneity in the sucrose studies and therefore there was no significant association.
  • Neither glucose nor sucrose replacement by fructose resulted in a change in fasting blood insulin concentrations.
  • 6 studies examined HOMA-IR and found no significant changes after fructose replacement of glucose and a small but significant increase in HOMA-IR in the sucrose replacement study.
  • The 7 studies substituting fructose for glucose showed a small net weight loss. There was no significant change for sucrose substitution.
  • There was no effect of blood triglycerides in the glucose replacement studies and a small but significant reduction in blood triglycerides in the sucrose replacement studies.

o   Meta-analysis of total cholesterol, LDL, DGL, VLDL, and apolipoprotein B100 showed no significant differences.

Evans et al. conclude that “The results of our systematic review and meta-analysis on the isoenergetic exchange of glucose or sucrose by fructose in long-term feeding studies suggest that, as we found with postprandial effects, there may be benefits to long-term fructose consumption.  We found slight reductions in fasting glucose, HbA1c, body weight, and triglycerides, but no change in insulin or other blood lipids. Thus, medical practitioners who think that lowering postprandial glycemia would benefit their patients should feel comfortable in recommending fructose replacement of other sugars, without being concerned about long-term adverse effects.”

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