17 May Fructose
Lately, one of the most frequently asked questions we get is on the topic of fructose. With increasing information on fruit, fruit sugars (aka fructose) and “added sugars,” all of it can be quite confusing.
Added sugar (is not equal to) sugar,
Sugar (is not equal to) fructose,
Fructose (is not equal to) fruit.
I believe it’s best to start off by emphasising the differences between them.
We shouldn’t say it’s just sugar.
To start, it’s important to look at carbohydrates in detail in order to understand the differences between sugar, added sugar, and fructose.
Carbohydrates represent one of the main groups of nutrients in food. The key purpose of carbohydrates is to provide energy. Digestion of carbohydrates begins in the mouth. Once they are broken down into building blocks called monosaccharides (simple sugars), they are absorbed in the intestines and then into the bloodstream.
Glucose, fructose, and galactose are monosaccharides.
Simple sugars are a quick and easy source of energy for the body.
Disaccharides are formed by the bonding of two of the simple sugars mentioned above.
ie: Glucose + Fructose = Sucrose / Sucrose (table sugar)
For example, granulated sugar is structurally a disaccharide called sucrose. When you consume sucrose, it gets broken down into glucose and fructose, which is then absorbed in the body.
On the other hand, Polysaccharides, are large structures formed by linking many simple sugars.
Glycogen and starch are examples of these structures. Carbohydrates are stored as glycogen in the body.
When digested, carbohydrates that enter our body from food and drinks turn into simple sugars. However, these are not the “harmful” sugars that we are talking about.
Sugars that are added to food during the processing and production stages are called “added sugars,” which are considered to be bad for our health in large quantities.
What would be classified under added sugars?
This group defined as free sugars are not sugars that are naturally found in food, they are sugars which have been added in during the processing and production stages of food.
The sugar we add to cakes and cookies when we bake at home, sugars added to jam and packaged products during production or sugar found in sugary drinks are all examples of added sugars.
*Sugars found in fruit and milk do not fall in this category because they are naturally present in the structure of the food and were not added in later. Therefore, the World Health Organisation does not classify sugar in this category as harmful to our health (1). In other words, we should not be afraid of sugars in the natural structure of food such as fruit.
Why is fruit sugar fructose so feared?
Both fructose and glucose are simple sugars, one of the simplest forms of carbohydrates. The chemical structure of simple sugars and what food source they come from affect how quickly they are digested/absorbed and how they are used or stored in the body.
While excess glucose travels to different parts of the body, excess fructose is mainly stored in the liver due to its distinct structure. When combined with an inactive lifestyle, it can cause fatty liver disease. This can then lead to insulin resistance and later metabolic syndrome, which is the main reason why fructose is feared.
Nevertheless, I feel like we need to approach this topic in a more reasonable way, instead of taking the black and white approach and not consuming fructose at all.
At the end of the day, any food can be beneficial or harmful depending on the amount and frequency of its consumption.
While the harm of fructose is directly proportional to the amount consumed, it’s inversely proportional to the individual’s level of activity.
Although fruit, granulated sugar and high fructose corn syrup contain fructose, their effects on the body are quite different since the speed of digestion and metabolism in the body differs according to the food source from which a nutrient comes from.
IMPORTANCE OF THE AMOUNT
As with everything else, it is worth emphasising the importance of the amount of fructose that is consumed. When the human body is constantly exposed to high amounts of fructose, together with an inactive lifestyle, it will inevitably have a negative affect the individual’s health over time. However, the fructose content that comes from fruit is not enough and its digestion rate cannot be compared to that of a sugary drink, due to its fibre content.
If we are to go over the numbers,
While a medium apple contains 10 grams of fructose (2),
One can (330 ml) of soda, such as coke, contains 17-20 grams of fructose (sugar and fructose contents vary by country) (3).
Fruit is a food rich in fibre and water content. For this reason, eating and digesting fresh fruits is much slower and takes longer than the added sugars in soda, cake, cookies, etc., which are rich in sugar and hence fructose. Therefore, fructose from the fruit does not have a negative effect on the liver.
In addition, fresh fruit is quite satiating compared to many food products that have added sugars. Most people can be satisfied by eating one piece of medium/large fruit. This medium/large piece of fruit contains an average of 10-15 grams of fructose and this amount wouldn’t create a health problem.
In short: We know that high amounts of fructose consumption, combined with inactivity, has negative health effects, but it is not possible to say the same about fructose from fruit.
FRUIT CONSUMPTION AND HEALTH
Fruits (including dried fruits) are rich in many different nutrients such as fibre, vitamins, minerals, antioxidants and phytochemicals that are important for health. For this reason, the World Health Organisation recommends that everyone should eat at least 5 portions of vegetables and fruits daily (a minimum of 400 grams per day) and 10 servings of vegetables and fruits (800 grams per day) if possible, as health benefits increase with increased consumption (4). The WHO groups vegetables and fruits together in this recommendation without distinction.
This recommendation was made when many observational studies saw a decrease in the risk of chronic diseases (type-2 diabetes, cardiovascular diseases, cancer, etc.) with increasing consumption of vegetables and fruits.
Fruit is one of the best food groups you can consume for your long-term health.
Note: Speaking of fresh fruit, even those with a “high sugar content” or higher glycemic load than others have a positive effect on overall health. Unless the specific fruit causes a specific health problem (oral allergy syndrome etc.) for you, fresh fruits should not be feared.
FRESH FRUIT AND WEIGHT MANAGEMENT
Since fresh fruit is rich in water, it has a very low-calorie density compared to foods such as chocolate, cake, etc. Low calorie density means it contains much lower calories per unit volume. This makes fresh fruit a very satiating option considering the number of calories consumed. For those who want to reduce their “junk food” consumption, satisfying their sweet tooth with fruit is a good strategy for both health and weight management.
A systematic review, published in 2019, that compiles all studies to date on fresh fruit consumption, caloric intake and weight status also states that the increase in fresh fruit consumption helps to control weight and achieve weight loss (5).
WHEN TO BE CAREFUL OF FRUIT CONSUMPTION?
Although fruit is generally healthy for you, it is not always possible to say the same for fruit juices.
If we were to compare an orange with a glass of orange juice, while the average person cannot eat 4-5 oranges in one sitting, they can drink 4-5 oranges worth of orange juice in a glass. Therefore, even if the fruit juice is 100% fruit juice, drinking fruit juice is not the same thing as eating the fruit in its natural state.
In addition to this, when the juice is squeezed, it is separated from its fibre. Therefore, a component of the food that, that slows down digestion and increases satiety is removed. This is why it’s important not to equate fruit juice and fresh fruit. The World Health Organisation classifies fruit juices as added sugars, even if freshly squeezed, and recommends limiting their consumption due to this difference (1).
For smoothies, when the whole fruit is put into the blender, unlike fruit juice, the pulp and juice of the fruit are not separated from each other, so the sugars coming from fresh fruit in smoothies are not classified as added sugar. However, my recommendation would be to consume whole fresh fruit daily. But if you want to consume the fruit in liquid form, consuming it in the form of a smoothie seems like a better option than consuming it as fruit juice.
HOW MUCH FRUCTOSE CONSUMPTION PER DAY CAN NEGATIVELY AFFECT HEALTH?
The negative effects of fructose on health are seen in observational studies when consuming more than 150 grams of fructose per day (6). This corresponds to an average of 1.5-2 kilograms of fresh fruit daily. In other words, it is very difficult to consume this amount continuously.
Experts agree that natural sugar in fruit does not have a negative effect on health. In fact, researcher Dr Kimber Stanhope at the University of California, Davis, who has been studying the health effects of sugar for nearly 20 years, said that in a study they conducted, when participants tried to consume amounts of fructose from fresh fruit that would be “harmful” to their health, they stopped the study within a few days as the participants could not consistently eat the necessary amount of fresh fruit (7).
Long story short, if you are worried about your health, there is no need to be afraid of fruit. If you want to do something positive for your health, you can maybe focus on reducing your fruit juice and other ADDED sugar consumption.
Of course, this does not mean that you should never drink fruit juice again; it just means that it is better to eat the fruit instead on a daily basis.
Yes, too much fructose consumption is harmful, but that doesn’t mean that fruit is harmful.
Here are some points I’d like to go over to clear any confusion:
- Fructose does not mean fruit.
- Consuming fructose from fresh fruit that is harmful to your health is very difficult to do.
- Fibre found in fruit slows down the digestion of all nutrients from the fruit. So, eating fruit is not the same as getting fructose in your body from a source like a glass of coke.
- Fruit is one of the best foods you can consume for your long-term health. The World Health Organisation recommends consuming at least 5 portions of fruit and vegetables a day.
1) World Health Organisation. Sugars intake for adults and children. 2015.
2) Mccance., Widdowson. The Composition of Foods. Royal Society of Chemistry; 2015.
3) Fizzy drink sugar levels vary dramatically between countries, says survey [Internet]. beveragedaily.com. 2020 [cited 15 August 2020]. Available from: https://www.beveragedaily.com/Article/2015/10/01/Fizzy-drink-sugar-levels-vary-dramatically-between-countries-says-survey
4) WHO. Diet, nutrition and the prevention of chronic diseases Report of a joint WHO/FAO expert consultation (WHO Technical Report Series 916) [Internet]. 2003. Available from: https://apps.who.int/iris/bitstream/handle/10665/42665/WHO_TRS_916.pdf?ua=1
5) Guyenet S. Impact of Whole, Fresh Fruit Consumption on Energy Intake and Adiposity: A Systematic Review. Frontiers in Nutrition. 2019;6.
6) Tappy L, Mittendorfer B. Fructose toxicity. Current Opinion in Clinical Nutrition and Metabolic Care. 2012;15(4):357-361.
7) SNR #155: Kimber Stanhope, PhD – Effects of Sugar Consumption on Body Composition, Lipid Regulation and Insulin Sensitivity – Sigma Nutrition [Internet]. Sigma Nutrition. 2020 [cited 15 August 2020]. Available from: https://sigmanutrition.com/episode155/