Those who read this blog might know that I think fructose, or refined sugar, is ok in moderation. I find that many of sugar’s negative effects hinge on its dose and how it is used and I would never categorize it as a “toxin” as a number of folks seem to. In a blog post entitled Sugar and Diabetes I rallied against the claim that sugar causes the aforementioned disease, pointing out that fructose doesn’t promote insulin resistance except when consumed in doses at or above 100 grams a day or as part of a hyper caloric diet. Thus, if sugar isn’t making you fat and it isn’t displacing important nutrients you can consume quite a bit of it before it incurs any deleterious effects on blood sugar control. However, this is only one aspect of health.
There are no long term controlled studies examining how fructose effects heart disease, for example, although some extrapolations have been attempted via fructose’s effects on biomarkers in short term experiments. One such biomarker is C-reactive protein (CRP), an indicator of inflammation in the body. CRP is, among other things, considered a good predictor of cardiovascular disease.
In 2011 a study was published providing compelling evidence that fructose may dose dependently increase CRP and, therefore, inflammation. This study (1) reported that after 3 weeks 29 young, healthy men had higher CRP the more fructose they were consuming. 6 different fructose intakes were tested, I have plotted a graph of the results below:
As you can see, as fructose intake rose CRP rose as well. Note the R^2 value of 0.5175. The closer an R^2 value is to 1.0 the more linear the association is.
While this seems to make a good case for fructose increasing inflammation, there were some differences between the 6 groups. For one thing, calorie intake varied between groups. Here’s a graph of calorie intake and CRP levels in each of the 6 groups:
Calorie intake also appeared associated with CRP levels, with an R^2 value slightly higher than fructose’s. This could have been from fructose, which could mean fructose increased calorie intake and increased inflammation that way. between groups dietary fat intake varied. Here’s a graph of fat intake and CRP levels:
Look at the R^2 value, dietary fat intake showed a closer fit to CRP levels than either dietary fructose or calorie intake. As fat intake went up CRP seemed to go down. Protein intake also varied between groups. Let’s see how protein intake tracked with CRP levels (excuse the lack of decimal on the numbers on X-axis):
Protein intake also tracked downwards as CRP went up, yielding the largest R^2 value yet.
Does this mean fructose doesn’t increase CRP? No, of course not, it simply weakens the results of this study in my opinion given the dietary differences we did (and thus, likely did not) know about in this experiment.
1. Aeberli I, Gerber PA, Hochuli M, Kohler S, Haile SR, Gouni-Berthold I, Berthold HK, Spinas GA, Berneis K. Low to moderate sugar-sweetened beverage consumption impairs glucose and lipid metabolism and promotes inflammation in healthy young men: a randomized controlled trial. Am J Clin Nutr. 2011 Aug;94(2):479-85