Is Sugar Toxic?

Is sugar toxic? An interview on the CBS news show 60 Minutes gave the star of the anti-sugar movement, Dr. Robert Lustig, a chance to reiterate his idea without facing much opposition. Let’s evaluate it.

Who Is Dr. Robert Lustig?

Dr. Lustig is a pediatric endocrinologist at the University of California, who in the last two years gathered quite a following, which now apparently has enough momentum to give him ever more media presence.

His claim is that sugar – from the little crystals in the bowl on your table to honey and high fructose corn syrup – is behind most of our illnesses, no matter if it’s heart disease, type 2 diabetes, high blood pressure or cancer. He himself explains his position best in the following video, which also fundamentally contributed to his fame as an anti-sugar crusader:

More Calories From Sugar?

Now that was quite impressive, wasn’t it? But is it right? First of all, Dr. Lustig is correct when saying that in the US, overall calorie consumption has increased.

But he very much errs when saying that carbohydrates (“sugars”) are primarily responsible for that increase. Why? Because to make this claim, he used a very narrow sample of data, only spanning the years 1989 – 1995 and coming from persons aged 2 – 17.

Why didn’t he use the much vaster material from the Economic Research Service (ERS), that tracked every food group under the sun from 1970 – 2009?  Looking at that data, which is available for free and already in spreadsheet format, I found the following:

• In 1970, people ate an average of 2,169 kcal / day, in 2009 it was 2,594
• In those 39 years, calories from added sugar went from 402 kcal to 440
• In the form of fruit they went from 70 to 87 kcal
• Added fats increased from 411 to 596 kcal
• Dairy dropped from 267 to 261 kcal
• Flour and cereal rose from 432 to 619 kcal

If you do some quick calculations with this, you should find that the composition of the typical American diet hasn’t changed that much. For example, the two biggest caloric contributors, flour / cereal and added fats, both increased by about 1/3. Therefore Dr. Lustig is clearly wrong when stating that most of the increased calorie consumption now comes from one of the various forms of sugar.

Sedentary Lifestyles

What he also doesn’t give much attention to is people’s daily activity levels. In 1970, the percentage of people working in physically demanding blue-collar jobs was higher, while today 61.9% of the American work force are employed in white-collar jobs. At the same time, people also became less physically active in their spare time: data from 1988 to 2006 shows a decrease of 10%.

If most people now work in jobs that require fewer calories than those 40 years ago, are less physically active on top of it, but actually consume 425 kcal more, it doesn’t take a genius to come the conclusion that more calories – activity = bigger waistlines.

Is Sugar Toxic?

But, a couple of days ago and in the CBS television news magazine 60 Minutes, Lustig went even further and declared sugar as outright “toxic”. “Toxic” as in snake poison, lead or asbestos, substances we usually associate with the word? In an article recently published in Nature, he provides us with the following explanation:

It can also be argued that fructose exerts toxic effects on the liver that are similar to those of alcohol. This is no surprise, because alcohol is derived from the fermentation of sugar.

Yes, alcohol can be toxic, but I’m not sure everybody can appreciate how crude the argument is. To put it simply: If I can use A to produce the toxic B, then A has to be toxic as well. If we follow Dr. Robert Lustig’s skills in logical deduction, then water is at least as toxic as alcohol, because it too is often used in the production of alcoholic beverages.

The Truth About Bad Theories

In light of his rather dubious reasoning and selective use of data we discussed above, you may want to take Dr. Lustig’s arguments with a pinch of salt. So far he published some papers that presented a very convoluted theoretical frame-work for his position, but no hard evidence.

Quite frankly, if a problem can be solved with a very complicated solution or a  rather simple one that has a lot of evidence behind it, I go with the simple one: People are getting fatter and fatter, they eat a lot more calories than 40 years ago while moving less, to lose weight they should therefore do the opposite.

Not that long ago, the big craze of the day was to single out fat as the guilty party in increasing obesity rates. It seems that since then we have learned nothing, as Dr. Lustig now commits the same error, only that it is now sugar that is being singled out. In truth, no single nutrient can inherently be classified as “good” or “bad” – it is the complete picture that counts.

Picture courtesy of “La Melodie“.