Fructose has been on trial lately for questions of adverse metabolic outcomes which leaves many people wondering… is fructose bad? How much is too much? Should I avoid fruit?
Fructose (I’m talking specifically about the sugar, not high fructose corn syrup) is a simple sugar found in fruit, table sugar, honey, agave syrup, root vegetables, etc. Glucose, another simple sugar, is the way that our bodies use carbohydrate. So when we consume fructose, it must be converted to glucose in the liver. Excess fructose is thought by some to increase fat storage in the liver, increase circulating insulin levels, and lead to weight gain, visceral fat accumulation and liver damage.
A study by Smajis et al observed the metabolic effects of 150g daily fructose intake from a fructose beverage for 8 weeks in healthy subjects. This would equate to about 12 large apples worth of fructose per day. The data showed no changes to the insulin level/sensitivity, lipid and glycogen accumulation in the liver, and systolic myocardial function from baseline to the end of the study. Another study by Silbernagel et al did not find an association between very high fructose intake on visceral or liver fat accumulation.
Of course, both these studies were performed over a span of weeks, not years, but the results do look promising.
Another thing to note is that studies investigating the effects of fructose generally administer the sugar via a beverage. While many people do drink smoothies or juices that contain fructose, I would argue that most health-conscious individuals don’t get most of their carbs from beverages. Eating a whole fruit leads to much slower digestion/absorption and greater health benefits than from drinking a carbohydrate beverage.
Of course, more research can’t hurt. But my takeaway would be this: If you’re healthy, following a balanced diet and exercising regularly, unless your doctor or health care provider tells you otherwise, this isn’t something you should have to worry about.
-Katy Hair, RD, LDN, CPT
Smajis S, et al. Metabolic effects of a prolonged, very-high-dose- dietary fructose challenge in healthy subjects. Am J Clin Nutr 2019;00:1-9.
Silbernagel G, Machann J, Unmuth A, Schick F, Stefan N, Haring H, Frische A. Effects of 4-week very-high-fructose/glucose diets on insulin sensitivity, visceral fat and intrahepatic lipids: an exploratory trial. British Journal of Nutrition. 14 July 2011; 106(1):79-86