Much Ado About Sugar
Since the 1980's, American soft drinks have been sweetened with high fructose corn syrup (HFCS), and it's rapidly becoming the sweetener of choice in most processed foods. Critics are quick to point a finger at this enigmatic sugar as the root of all evil, claiming its empty calories are contributing to the obesity epidemic, and the numerous chemical processes needed to make it are simply "unnatural". These accusations didn't sit well with "King Corn", and The Corn Refiners Association fired back with a series of TV commercials stating that HFCS was in fact natural, and completely safe in moderation. Government officials have been talking out of both sides of their mouths on the issue, first allowing HFCS to be called natural, then recently proposing it be taxed, thereby equating it to other unhealthy items, such as cigarettes. With all this conflicting information, what should the public think? Should we avoid HFCS at all costs? How does HFCS compare to other sugar sweeteners?
Let's start with the science. I recently came across two blog posts (links below), which centered on a study in the Journal of Clinical Investigation that compared the health effects of consuming different dietary sugars -- one experimental group's sugar of choice was glucose, the other group's was fructose. The study boosted the subject's sugar consumption to 25% of their total daily calories by adding fructose or glucose to unsweetened Kool-Aid. The results showed that both groups put on weight, which is not surprising given the sheer volume of sugar consumed. However, the group with the fructose-based diet had higher visceral fat, triglycerides, plasma LDL and oxidized-LDL levels, plasma glucose level, as well as signs of increased insulin resistance, compared to those in the glucose group, all of which are signs of deteriorating health.
There were some shortcomings of the study, which were pointed out nicely in the blog posts: 1.) it was a small study (n=32), 2.) its only participants were obese people (i.e. will the results hold true for normal weight people?), 3.) subjects consumed much more sugar than the average American (mean=15.8% of total calories), and 4.) fructose is more than 2x sweeter than glucose, so in theory, you'd need less fructose calories to obtain the same level of sweetness. Despite the study's limitations, similar results have been shown in primates, which further substantiate the main finding -- fructose-based sweeteners cause secondary health problems. So what do these results mean to us? First, it seems the sweetener used in this study was either 100% glucose or fructose. We typically don't use such pure sugars, as we primarily satisfy our sweet tooth with either table sugar or the high fructose corn syrup that's hidden in the ingredient list of processed foods. What exactly is the difference between these two sugars, and how does using them affect our health? HFCS is a 55/45 mixture of fructose and glucose, respectively. The Journal of Clinical Investigation study claimed that HFCS may be just as bad for you as pure fructose, as the results of a short-term experiment showed comparable negative health effects between subjects that consumed either of these sugars. Table sugar (sucrose), on the other hand, is a 50/50 mixture of glucose and fructose, which is surprisingly similar in composition to HFCS. The primate study I cited earlier reported that diets high in both HFCS and sucrose increased triglyceride levels. So it seems possible that added fructose, regardless of the source or relative concentration, may be detrimental to our health. So if fructose causes a barrage of negative health effects, does that mean eating an apple is bad for you? After all, fructose is the main sugar in fruits. Michael Pollan address this question best in his book "In Defense of Food" (which I just finished reading, and I hope to get a review posted here soon). Pollan states that, opposed to the fructose in the Kool-Aid given to the study participants, the fructose in an apple is not an isolated monosaccharide -- it exists in a complex micro-environment where it is surrounded by lots of fiber, which prevent the fructose from causing a sugar spike, and allow it to be metabolized slowly. Simply put: with food, context is everything. Mother Nature made fruits sweet for a reason -- they are good for us, and contain vital nutrients. But perhaps fructose was never meant to be isolated in a lab and poured into soft drinks, as the results I've discussed show that processed fructose is rapidly metabolized, and leads to negative health.
While more stringent scientific studies need to be conducted to investigate the effects of HFCS on a diverse population, I think it's safe to say that regardless of the source, the 39 grams of sugar in the average soft drink isn't helping the obesity problem in the United States.
Sources: Some Sugars Worse Than Others? The Bittersweet Fructose/Glucose Debate