Feb 06 2014

Fructose vs Glucose

Health conscious individuals have been systematically informed about how important nutrition is to health. This is no doubt true, nutrition is very important. But the nutrition industry, and “natural” health gurus selling vitamins would like you to think that “nutrition is everything,” (in quotes because I have been told that phrase more than once).

Nutrition is important, but it is only one factor among many affecting health. It is not the cause of all problems, and therefore it is not the solution to all health issues.

The overhyping of nutrition, however, creates an obsession with endlessly tweaking one’s diet in the hopes that the perfect combination of “superfoods” will cure all ills and optimize health. The unstated major premise of such claims is that our bodies perform best within very narrow nutritional parameters. It is closer to reality, rather, that our bodies are resilient to a fairly broad range of nutritional parameters. It is helpful to get the broad brushstrokes correct (do not overconsume calories, have a varied diet, etc.), but obsessing over tiny details is likely to be a waste of time.

In the middle of all this is also the ever-present naturalistic fallacy.

One such detail is the distinction between fructose and glucose – two common forms of sugar. Fructose is the form of sugar most commonly found (as the name implies) in fruits. Table sugar, sucrose, is a disaccharide – a combination of one fructose and one glucose molecule.

For years there have been claims that fructose is worse for the body than glucose, and that high-fructose corn syrups (commonly used in processed foods) is partly to blame for the obesity epidemic and other health ills. This, of course, led to the marketing of products with “all natural cane sugar” containing 100% sucrose (which of course is 50% fructose). High fructose corn syrup (HFCS) typically used in food is HFCS55, which has 55% fructose and 45% glucose.

Yeah, that’s it. That’s the dramatic difference. The reasons for using HFCS55 rather than cane sugar are economical and practical – fructose is actually sweeter than glucose so you can use a bit less of it, it is a liquid so it stores and transports well, and its generally cheaper.

Critics of this “unnatural” product site studies showing that fructose has an adverse effect on metabolism. It does – raising triglycerides, for example – but no more than other sugars. Critics often recommend “natural” alternatives based on no evidence, just the fact that they are natural.

Partly they also rely upon basic science studies rather than clinical studies that look at net health effects. This is a common fallacy – extrapolating from basic science data while ignoring or downplaying the clinical data.

A recent systematic review of that clinical data found:

Pooled analyses show that fructose in isocaloric exchange for other carbohydrate does not increase postprandial triglycerides, although an effect cannot be excluded under all conditions. Fructose providing excess energy does increase postprandial triglycerides. Larger, longer, and higher-quality trials are needed.

Consuming too much of any sugar is bad for you, but fructose no more than anything else. Some of the same authors also just published their own clinical trial, looking at a variety of health outcomes. They found:

Depending on the cardiometabolic endpoint in question, fructose has variable effects when replacing glucose. In the absence of clear evidence of net harm, there is no justification to replace fructose with glucose in the diet.

In other words, some of the parameters followed were a little better for fructose, some were a little worse, and in the end it was all a statistical wash.

The best interpretation of all available clinical evidence is that you do not need to worry about how much fructose vs glucose is in the food you eat, and it matters not at all how “natural” the source of the sugar is. You do need to pay attention to the overall amount of sugar in your diet. Simple sugars are calorie dense and high intake does have an adverse effect on numerous metabolic parameters, including cholesterol and insulin.

In the end, when it comes to nutrition, simple advice is often the best. Just don’t overdo the sweets.

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