Fructose Levels

What are safe fructose levels on a daily basis?  As you know I discuss extensively many of the evils of fructose overconsumption and how it could effect your weight and your erections.  Caution is definitely in order here because so many people in modern industrialized societies drown themselves in fructose from high fructose corn syrup and sugar.  For example, the average sweetener consumption in the U.S. is, as of 2009, 130 pounds per year. [1] This sounds pretty nasty but translates actually to about 161 grams of added sugar per day.

Almost all sugar, in the U.S. at least, comes from one of three sources:  HFCS-42, HFCS-55 and/or table sugar.  (HCFS stands for high fructose corn syrup.)  All three of these are roughly 50% fructose by weight and thus the above 161 daily grams of sweeteners will translate to approximately 80 grams of fructose per day.  For what its worth, the average American will also eat a (laughable) one piece of fruit and/or juice per day as well [2], which adds approximately 10 grams of fructose to the equation.  (A medium apple has about 10 grams of fructose.)  So total fructose consumption is right around

Before I go on, let me point out that some researchers consider small levels of fructose, say 25-50 grams/day, actually a good thing.  In spite of all of its very dangerous properties, fructose can decrease HbA(1c) [prediabetic] levels, improve hypoglycemia effects [5] and potentially assist athletic performance and fueling. [4]  So notice that a few pieces of fruit is very unlikely to cause you the kind of fructose-related issues that researchers are now highlighting.  Furthermore, the fiber and phytochemicals in fruits conteract many of fructose's negative effects. 

As always, the problems occur when we ingest large amounts of something false and foreign to our systems, in this case table sugar and corn syrup.  But what about the case when average (American) levels of 90 grams/day are consumed?  Is this level of daily fructose good or bad?  Dangerous or harmless? 

To answer those questions, let's start with what is definitely not safe on the high end:  one study of fructose showed that fructose at 200 grams/day raised blood pressure significantly, 6 mm and 3 mm, respectively for the top and bottom readings. [3]  Anything that increases blood pressure this much will raise your risk of stroke, erectile dysfunction, heart disease and all the other long term nasty side effects of hypertension. 

Of course, relatively few people eat 200 grams of fructose per day.  What about those with more "realistic" or average consumption levels?  What I have found is that most experts consider about 50 grams/day of fructose to be completely safe.  For example, one study states that exceeding about 50 grams/day is when you get start noticing fructose's pro-inflammatory, pro-blood-clotting, pro-hypertension, pro-weight-gain and pro-poor-lipids properties. [4]

One prominent blogger, trainer and nutrionist explains that this figure of 50 grams/day probably came from the fact that the liberal and conservative researcher camps say that about 90 and 25-40 grams/day is safe, respectively, and thus moderates split the difference right around 50 grams. 

So the truth is that there is no need to reduce your fructose levels to near zero - a certain amount of fructose is natural and well-tolerated by the body.  However, it is easy to exceed this level without much effort:  one tablespoon of table sugar, for example, has about 12.5 grams of sugar, half of which is sugar. So go easy is my best advice...



1), Table 50.

2) Prev Chronic Dis, Apr 2008 , 5(2):A35, "Trends in Fruit and Vegetable Consumption Among U.S. Men and Women, 1994 2005"

3) Perez-Pozo S, et al "Excessive fructose intake raises blood pressure in humans" AHA BPRC 2009; Abstract P127

4) Current Sports Medicine Reports, Jul/Aug 2010, 9(4):253-258, "Fructose, Exercise, and Health"