You’ve probably heard it countless times, especially in low-carb circles: sugar is sugar is sugar. This is true in principle – the glucose, fructose, and sucrose found in table sugar or high fructose corn syrup (HFCS) are the same molecules as the glucose, fructose, and sucrose in honey, fruit, and starchy vegetables. But when it comes to the way your body uses these sugars, these foods are hardly comparable. In this article, I’ll show you why all sugar is not created equal, and why you should care.
Does sugar from fruit and starchy vegetables have the same impact on your health as a candy bar?
Fructose and High Fructose Corn Syrup Are Not The Same
In my previous post in this series, I compared HFCS with white sugar and concluded that these two sweeteners are more or less metabolically equivalent. In the comments section, a few people brought up research showing that fructose is metabolized very differently from glucose; in fact, it’s metabolized more like alcohol.
I’ll address that research in a second, but first, understand this: high fructose corn syrup is not the same thing as fructose. Fructose is a simple sugar molecule with a specific chemical structure, while HFCS is a mixture of fructose and glucose in a roughly 1:1 ratio.
Now, there are certainly some scary studies about the metabolic effects of pure fructose. In animal models, fructose administration can cause dyslipidemia, non-alcoholic fatty liver disease, insulin resistance, and even type 2 diabetes. (1)
But these harmful effects result from animals being fed large amounts of pure, isolated fructose. In this form, fructose does act much like a toxin in the body, and it would be a terrible idea to start sweetening your food with pure fructose. But because fructose isn’t found in isolation in nature or even in our food supply, these studies are largely irrelevant to practical nutrition.
Already, we’re beginning to see that all sugar is not created equal, and that form and “packaging” makes a huge difference in metabolic effect. In this case, pure fructose does not affect the body the same way as fructose in sugar or HFCS. Now, what about fructose in fruit?
Fruit: More Than Just a Hit of Sugar
Although conventional wisdom holds that fruit is unquestionably a health food, the push to avoid sugar and excess carbohydrates has in many cases left people hesitant, even afraid to eat fruit. While it’s typically acknowledged that eating an apple is better than eating a bag of candy, fruit is still often seen as a source of sugar that should be consumed in strict moderation, and the phrase “sugar is sugar” is a common refrain, especially in Paleo or low-carb communities. The problem with this viewpoint is that added sweeteners and fruit have completely different metabolic effects.
First of all, the fiber and water found in whole fruit increase satiety, which makes it less likely that you’ll go into caloric excess. Studies going back more than forty years have shown that naturally occurring sugars in fruits are beneficial to health and do not promote weight gain, and we can see these effects in traditional cultures such as the Kuna, who obtain a significant percentage of their calories from fruit while remaining lean. (2, 3)
And despite some claims to the contrary, there’s no evidence that we should avoid whole fruit simply because it contains fructose. (4) Far from being a health hazard, like pure fructose or added sweeteners, studies overall suggest that eating whole, fresh fruit may actually decrease the risk of obesity and diabetes. (5) Additionally, randomized controlled trials have shown that eating fruit reduces oxidative stress markers and blood glucose in diabetics. (6) Further, limiting fruit intake has no effect on blood sugar, weight loss, or waist circumference. (7)
For most people, 3-5 servings of fruit per day is perfectly fine, although certain people with insulin resistance, diabetes, or metabolic syndrome may see improvements by restricting fruit intake to one to two servings a day, and by choosing fruits that are lower in sugar. Additionally, some benefits of fruit restriction for digestive issues come more from avoiding high FODMAP fruits as opposed to fruits altogether.
Solid Sugar vs. Liquid Sugar
Another angle to consider is the issue of sweeteners in beverages versus sweeteners in solid foods. Countless studies have demonstrated that drinking your sugar has uniquely harmful effects, primarily because most people fail to reduce their caloric intake to compensate for the extra calories they’re consuming in sweetened drinks. (8)
For example, a study of 323 adults found that subjects who increased the number of calories they obtained from sugar-sweetened beverages didn’t decrease their caloric consumption from other sources. (9)
Another study showed that total calorie intake among sixteen patients was greater on the days that sugar-sweetened beverages were given at lunch than on the days they weren’t. So even when the sweetener used is the same (usually sugar or HFCS), consuming it in a beverage will have different health effects than consuming it in a food.
Real Honey vs. Fake Honey
I’ve already written about the unique metabolic effects of honey, and there have been studies comparing the effects of honey and “artificial honey” on blood lipids, insulin response, and blood sugar. Although artificial honey is a mixture of glucose and fructose in the same ratio as was found in natural honey, its metabolic effects are completely different.
In one study, supplementation with real honey decreased triglycerides and LDL cholesterol, increased HDL cholesterol, and even decreased plasma homocysteine. (10) On the contrary, the artificial “honey” raised triglycerides and LDL cholesterol. Other similar studies have found that natural honey results in more stable postprandial blood sugar and insulin response when compared with artificial honey. (11, 12)
There are further examples that I won’t get into, but I hope I’ve demonstrated that the phrase “sugar is sugar” is simply not accurate when it comes to nutrition and “real” food. The source of sugar does make a difference, and we as a community need to be careful about generalizing study results where they may not apply, and demonizing foods that don’t deserve to be demonized.
If you missed any of the previous articles in this series on sweeteners, be sure to check them out below, and stay tuned for the final post where I’ll tie everything up and give you some practical tips on where sweeteners should fit in a healthy diet.