Sugar is a dietary carbohydrate commonly found in foods such as fruit, starchy vegetables, and milk. It serves as a source of quick energy for cells but carries downsides. Manufacturers also add sugar to packaged foods to improve taste and make them more crave-worthy.
There are other reasons manufacturers add sugar to processed foods too. One is that sugar makes foods taste better. Sugar also helps to preserve foods and make them last longer. Additionally, sugar adds texture and bulk to foods.
Regardless of sugar’s appeal, the American Heart Association recommends that less than 10% of daily energy intake should come from added sugars. Despite these guidelines, many Americans consume twice that amount.
One reason Americans consume so much sugar is that it’s in so many processed foods. Sugar is a cheap way for food manufacturers to add flavor and sweetness to their products. Unfortunately, this means that Americans are unwittingly consuming copious amounts of sugar every day.
The Harms of Sugar
Why is sugar harmful? Sugar is empty calories and overconsuming it can lead to weight gain and problems associated with obesity, such as insulin resistance and type 2 diabetes. Not to mention, sugar contributes to tooth decay.
There is some evidence that sugar may be addictive. A study in rats found that those fed a high-sugar diet were more likely to keep eating it, even when given the option of other food. Other research shows sugar may affect the brain in a way that is similar to drugs like cocaine. Sugar can cause a release of dopamine, which is a neurotransmitter that is associated with pleasure and reward. It is unclear if sugar is truly addictive, but it is possible that it may be for some people.
For these reasons, you should avoid added sugar in packaged foods, especially high-fructose corn syrup, but what about the natural sugar in fruit? Is it harmful, too?
Types of Sugar
The main types of sugar are sucrose (table sugar), fructose (a component of fruit), and glucose (a component of starchy foods such as bread). Table sugar is a combination of half fructose and half glucose. Although all sugars contain the same number of calories — 16 calories per teaspoon — your body metabolizes them differently.
A teaspoon of granulated sugar contains 4 grams of sugar (with 16 calories). Because your liver metabolizes fructose in its entirety, foods high in fructose may increase the risk of non-alcoholic fatty liver disease (NAFLD) and are more likely to cause insulin resistance.
Fruit Contains Glucose and Fructose
Like sugary packaged foods, fruit contains glucose and fructose, but it’s packaged differently in a piece of fresh fruit. Most processed food is made with white flour and contains little fiber. Therefore, your gut quickly absorbs the sugars in these foods, causing glucose and insulin spikes that are harmful to your metabolic health.
In contrast, the sugar in fruit is bundled with fiber. Since fiber slows the absorption of sugar in the gut, you don’t get the glucose and insulin spikes that come from consuming sugar from low-fiber packaged foods. Therefore, sugar gets into your system more slowly, leading to a slower rise in blood glucose.
So, even though both fruit and packaged foods contain sugar, the delivery system is different, and the effects on blood sugar are, too. Therefore, biting into a piece of whole fruit affects your blood glucose and metabolic health differently than eating a packaged cookie. Plus, there’s evidence that the antioxidants in fruit help tame the blood sugar response.
Fruit Juice Is an Exception
Many people see fruit juice as healthy because it contains vitamins, minerals, and antioxidants. But it can have a similar effect on blood sugar as a soft drink. That’s because fruit juice lacks the fiber that whole fruit contains, so the delivery system is different. There’s no fiber to slow down entry into your gut, so you get blood sugar spikes.
Studies link consuming sugar-sweetened beverages and fruit juice with a higher risk of type 2 diabetes and obesity. While fruit juice contains nutrients, water often dilutes it during juicing. In addition, due to the processing, most of these nutrients are present in lower concentrations than in whole fruit.
Therefore, eating whole fruit is best for your metabolic health. Plus, when you eat whole fruit, you’ll feel fuller after eating it, which makes you less likely to overeat later in the day.
Fruit Differs in Its Fiber and Sugar Content
If you have type 2 diabetes or want to limit the amount of sugar in your diet, you can do so by watching your portions. Stick to one or two servings of fruit each day and choose fruits that are naturally lower in sugar and contain more fiber. One of the best options is berries since they contain less sugar than other fruits and contain significant fiber. Blueberries, strawberries, blackberries, and raspberries are low in sugar and are less likely to cause blood sugar spikes than a fruit higher in sugar and low in fiber, like bananas.
In the case of bananas, a riper banana will cause a sharper rise in blood glucose than a less ripe one with more resistant starch. What you eat with fruit affects the blood glucose response, too. Adding a source of protein and healthy fats, like spreading peanut butter on an apple or banana, will reduce your blood sugar level when you eat it.
Other fruits to limit for better blood sugar control include grapes, mangoes, prunes, kiwifruit, apples, guava, oranges, pomegranate, and pears. These fruits are rich in nutrients, but their sugar-to-fiber ratio is at the higher end. However, eating them is still easier on your blood sugar than drinking fruit juice.
The Bottom Line
The sugar in whole fruit is less problematic than the sugar in fruit juice due to the fiber in whole fruit. Still, some fruits have lower sugar and fiber content than others. Berries are among the best fruits for metabolic health and blood sugar control. So, enjoy a bowl of berries but skip the glass of fruit juice.
References:
- “Healthy eating for blood sugar control – Harvard Health.” 15 Feb. 2021, health.harvard.edu/diseases-and-conditions/healthy-eating-for-blood-sugar-control.
- “Low Sugar Fruits: For Diabetes and Health.” 26 Jun. 2017, healthline.com/health/best-low-sugar-fruits.
- “Fruit Juice and Diabetes – What Juice Can Diabetics Drink.” 08 Sept. 2022, diabetes.co.uk/food/juice-and-diabetes.html.
- Xi B, Li S, Liu Z, Tian H, Yin X, Huai P, Tang W, Zhou D, Steffen LM. Intake of fruit juice and incidence of type 2 diabetes: a systematic review and meta-analysis. PLoS One. 2014 Mar 28;9(3):e93471. doi: 10.1371/journal.pone.0093471. PMID: 24682091; PMCID: PMC3969361.
- “Daily Intake of Sugar — How Much Sugar Should You Eat Per Day?.” 10 Jun. 2021, healthline.com/nutrition/how-much-sugar-per-day.
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