The Lowdown on Fructose

What Is Fructose?

Fructose (also known as fruit sugar) is a form of sugar belonging to the hexose class of sugars, which include any sugar that contains six carbon atoms. (Source)

Fructose is a sugar that is found naturally in most fruits and certain vegetables, and is one of the least carcinogenic nutritive sugars.

Fructose is found in significantly higher quantities in fruits than in vegetables. Reducing sugars, which are a combination of glucose and fructose, are the primary source of soluble carbohydrates found within most fruits as well as seedless raisins.

Although certain vegetables do contain fructose, it is in much lower quantities than fruits. The only vegetable that has a relatively high quantity of fructose is the sugar beet.

Fructose is also a major food and beverage ingredient in the form of high fructose corn syrup (HFCS), a potent sweetener that is an ingredient in sodas, processed juices, candy bars and sweets, canned fruits and white or whole-wheat breads.

HFCS is produced by subjecting corn to wet-milling in order to extract the starch. The second stage of the procedure is liquefaction and saccharification, the process from which grain-based starches are converted into monomer dextrose (a fermentable sugar).

The dextrose is then converted to fructose through isomerization (essentially re-arranging the atoms to form a new compound), and lastly goes through fractionation, a process that involves separating and enhancing the fructose concentration. (Source)

History Of Fructose

In the 1970’s and 80’s, fructose was believed to be a form of sweetener that was considered to have less negative effects than glucose, particularly on blood sugar. At the time, fructose was marketed as being a diabetic-friendly alternative to sugar.

Fructose has a low glycemic index (GI) – the number value given to the amount of carbohydrates in a certain food or beverage that will affect blood glucose. Compared to glucose (GI value of 100), fructose has a GI value of 20.

Unlike other commonly used sugars such as sucrose, glucose, starches and malt sugars, fructose does not require insulin in order to metabolize.

This facet of fructose was associated with reducing the risk of insulin surges that could eventually lead to insulin resistance and conditions such as diabetes and metabolic syndrome.

From 1970 onwards, fructose was declared as a healthier alternative – in moderation – to other forms of sugar by the American Diabetes Association.

High Fructose Corn Syrup

The general perception of fructose as a less harmful sugar came to an abrupt end in 2004, when a study was published linking increased incidence of obesity to the increased popularity of HFCS as a staple sweetener in sugary drinks, processed foods, and candies.

The authors of the review noted that the fact that fructose does not require insulin to metabolize was not a benefit but a liability, as insulin surges are the body’s warning system when too much sugar is being consumed.

The sugar industry attempted to reclassify HFCS as a type of corn sugar in 2012, a proposition that was rejected by the Food & Drug Administration.

A study published in July 2017 in the American Journal of Nutrition revealed that naturally-occurring fructose may improve the liver’s ability to metabolize sugar, which could potentially help diabetic individuals convert sugar to fuel. (Source)

Is Fructose Good Or Bad For You?

You may have read cautionary articles or heard warning tales about how fructose is inherently bad for your health, particularly in the last decade.

It is important to differentiate between fructose that occurs naturally in fresh fruits and (to a lesser degree) vegetables, and HFCS, which is most commonly found in heavily processed foods, sugary drinks, and snacks.

In the United States, the bulk of the average individual’s fructose consumption is not from the naturally occurring fructose found in nutrient-rich fruits, but HFCS. As mentioned above, HFCS is typically found in foods and beverages with few if any nutritional benefits – sodas, candy, etc.

The vast majority of popular soft drinks consumed today contain HFCS, and soda consumption has increased dramatically over the past 60 years, rising from approximately two servings per week to two servings per day.

Although fructose does a play a role in the metabolism of glucose, there is no specific dietary need for fructose in and of itself. Unlike glucose, fructose cannot enter most cells as it does not stimulate the release of insulin when consumed. (Source)

Diets that advocate eliminating processed, grain-based and high-sugar foods such as the Paleolithic diet and ketogenic diet allow mild to moderate consumption of fruits, but eliminate nearly all products that contain HFCS.

Read our guide to the keto diet here. 

Unless you have an allergy or condition that prevents you from eating certain foods, most nutritionists would not recommend entirely eliminating dietary components from your diet entirely.

Similarly, there is no one single component (i.e. saturated fat, grain-based products, etc) that can be blamed as the exclusive reason for a particular disease or condition, although consuming any type of component or food item to excess can have negative consequences in the long-term.

On that note, an excess of fructose that comes from HFCS products that tend to have little to no nutritional benefits isn’t a healthy option. The natural fructose found within fruits and natural sweeteners, such as honey and maple syrup, is generally not harmful in moderation as these items contain other minerals, vitamins, and nutrients that are beneficial. (Source) 

What Is Fructose Intolerance?

Fructose intolerance is a condition that results in the digestive system being incapable of absorbing fructose, which leads to such disruptive symptoms as bloating, abdominal pain, gas, and diarrhea.

Individuals with fructose intolerance must avoid or limit their consumption of foods that are fructose-rich. Certain fruits and vegetables such as apples, watermelon, sugar beets, grapes, zucchini and peas contain high amounts of natural fructose.

Fruits and vegetables such as lettuce, strawberries, bananas, blueberries, avocados and green beans may be consumed in limited quantities as long as they do not cause any digestive irritation.

For individuals with fructose intolerance, product labels – particularly of processed foods and drinks – must be read carefully. Any food or beverage containing HFCS, fructose, agave syrup, maple syrup, molasses, honey, coconut sugar or palm sugar should be avoided. (Source)