Is Sugar Nutritionally Necessary?

sugar-free[1]Q.  I work with girls with eating disorders and the topic of sugar keeps coming up. There is a lot of info in the media targeting sugar, and diets that encourage you to “quit” sugar completely. I’d really like to be able to give the girls I work with an evidence-based explanation for why cutting out sugar completely isn’t a good idea. So far I mostly take the line that food is not simply about nutrition. If you avoid sugar at all costs then you are going to miss out on life (you can’t share a cupcake at a friends birthday, you’re too worried about ingredients to enjoy your food etc.). But I’d love your perspective on whether low to moderate amounts of sugar is OK. 

A.  Our bodies can turn proteins, starches, and fats into glucose for our cells so strictly speaking there would be no need to take in any dietary sugars. Of course, almost 100% of the calories in vegetables are from sugars and we wouldn’t want to eliminate them because they include so many essential nutrients!

I think what you (and they) are really talking about is added or concentrated sweeteners, like white sugar, honey, molasses, etc.  Unlike vegetables, these sources of sugar don’t add much nutritionally to the diet–and consuming these sweeteners in excessive quantities is clearly harmful. But it’s not necessary to eliminate them completely.

The Poison is in the Dose

Epidemiological evidence clearly shows that as sugar intake goes down from >30% of calories to <10% of calories, the risk of many diseases goes down. But at a certain point, the curve flattens. Further reductions in sugar intake don’t seem to lead to significant further reduction in risk. (Although it should be said that because so few modern populations consume very low amounts of added sugar, the data isn’t as robust for the lower end of the scale.)
Based on the existing  data, the World Health Organization (as well as the USDA, AHA, etc.) recommends that added sugars be limited to no more than 10% of total calories and suggests that reducing sugar to 5% of calories may confer additional risk reduction.

Little to Be Gained from a Zero-Tolerance Policy

It’s unclear what’s to be gained by going any lower than that–and, as you say, something may be lost.  I’m with you 100%: getting some (non-nutritional) enjoyment from our food is not a crime. (See also this post on the pitfalls of striving for dietary perfection.)

My other concern about going sugar-free is that it often involves consuming lots of artificial sweeteners–which don’t provide the “free pass” that many think they do.  See also: Artificial Sweeteners and Weight Gain.

Is Sugar Ever Good for You?

The only scenario that I can think of where concentrated sugar might have an actual nutritional function is for endurance athletes. If you’re exercising hard for more than 60 minutes at a time, consuming simple sugars is the most efficient way to provide fuel for depleted muscles.

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