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Archive for August 23rd, 2010

High Fructose Corn Syrup: Tasty Toxin or Slandered Sweetener?

The perils of fructose:

High fructose corn syrup (HFCS) has, over the past few decades, gradually displaced cane and beet sugar as the sweetener of choice for soft drinks, candy and prepared foods. In recent years, there have been a growing number claims that HFCS is a significant health risk to consumers, responsible for obesity, diabetes, heart disease and a wide variety of other illnesses. 

In fact, there are large amounts of experimental data supporting the claims that high levels of fructose in the diet can cause hyperlipidemia (high levels of fats — triglycerides primarily — in the blood), obesity and insulin resistance and may lead to cardiovascular disease and type 2 diabetes (for a good recent review, see [1]). A high-fructose diet is thought to cause hyperlipidemia (and probably visceral obesity) because fructose is preferentially “sent”  to fatty acid synthesis and it also reduces the activity of lipoprotein lipase (for a good review, see [2]). The mechanisms by which fructose causes insulin resistance and cardiovascular disease are less clear (see, for example [3], [4] and [5]), but there is no shortage of hypotheses. Despite the fact that some of the underlying mechanisms are not clear, the evidence seems pretty solid that there are real risks to high fructose consumption.

However, the question remains — is HFCS more of a health risk than other sweeteners? Many of the sources that demonize HFCS list alternative sweeteners — cane sugar, honey, agave syrup, etc. — that they claim are healthier than HFCS, but those claims usually rest primarily on the fact that these alternatives to HFCS are “natural” rather than any actual data showing that they are safer than HFCS.  (more…)

Posted in: Nutrition, Public Health

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Does peer review need fixing?

One of the most important aspects of science is the publication of scientific results in peer-reviewed journals. This publication serves several purposes, the most important of which is to communicated experimental results to other scientists, allowing other scientists to replicate, build on, and in many cases find errors in the results. In the ideal situation, this communication results in the steady progress of science, as dubious results are discovered and sound results replicated and built upon. Of course, scientists being human and all, the actual process is far messier than that. In fact, it’s incredibly messy. Contrary to popular misconceptions about science, it doesn’t progress steadily and inevitably. Rather, it progresses in fits and starts, and most new scientific discoveries go through a varying period of uncertainty, with competing labs reporting conflicting results. To achieve consensus about a new theory can take relatively little time (for example, the less than a decade that it took for Marshall and Warren’s hypothesis that peptic ulcer disease is largely caused by H. pylori or the relatively rapid acceptance of Einstein’s Theory of Relativity) to much longer periods of time.

One of the pillars of science has traditionally been the peer review system. In this system, scientists submit their results to journals for publication in the form of manuscripts. Editors send these manuscripts out to other scientists to review them and decide if the science is sound, if the methods appropriate, and if the conclusions are justified by the data presented. This step of the process is very important, because if editors don’t choose reviewers with the appropriate expertise, then serious errors in review may occur. Also, if editors choose reviewers with biases so strong that they can’t be fair, then science that challenges such reviewers’ biases may never see print in their journals. The same thing can occur to grant applications. In the NIH, for instance, the scientists running study sections must be even more careful in choosing scientists to be on their study sections and review grant applications, not to mention picking which scientists review which grants. Biases in reviewing papers are one thing; biases in reviewing grant applications can result in the denial of funding to worthy projects in favor of projects less worthy that happen to correspond to the biases of the reviewers.

I’ve discussed peer review from time to time, although perhaps not as often as I should. My view tends to be that, to paraphrase Winston Churchill’s invocation of a famous quote about democracy, peer review is the worst way to weed out bad science and promote good science, except for all the others that have been tried. One thing’s for sure, if there’s a sine qua non of an anti-science crank, it’s that he will attack peer review relentlessly, as HIV/AIDS denialist Dean Esmay did. Indeed, in the case of Medical Hypotheses, the lack of peer review let the cranks run free to the point where even Elsevier couldn’t ignore it any more. One thing’s for sure. Peer review may have a lot of defects and blindnesses, but lack of peer review is even worse. It’s no wonder why cranks of all stripes loved Medical Hypotheses.
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Posted in: Medical Academia, Science and Medicine

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