A common assumption by the public is that fruit juices are healthy because they are derived from fruits. This idea is further enforced by fruit juice manufacturers with statements like ‘each glass is the equivalent of ‘X’ fruits’, which implies having a glass of fruit juice is the same as having that many fruits. Fruit juice is actually very different from the actual fruit, and this article will explain the differences, and how this effects your health. Throughout this article oranges will be used as an example because it is a very commonly consumed fruit juice.
Key nutritional comparison
Bellow is a table highlighting the key nutritional differences between fruit juice and the fruit. It is typical for fruit juices to be higher in the vast majority of nutrients (particularly vitamin C and sugar). However, fruit juice has a much lower in fibre.
| Nutrient | 1 Orange | 250ml Orange juice |
|---|---|---|
| Sugar (fructose) | 12g | 20g |
| Fibre | 3.1g | 0.5g |
| Vitamin C | 59mg | 97mg |
There is also a lot of beneficial phenolic compounds found in the pith of oranges, which will not be found in the juice.
Digestion
Fibre is known to slow down the digestion and absorption of nutrients. This is beneficial for the body because it causes a ‘drip-feeding’ effect, which prevents large amounts of nutrients flooding the body. With the example of vitamin C, large spikes in vitamin C absorption doesn’t pose any health problems, but as our body cannot store it, any excess for that moment in time will pass out in urine. Having said this, most people will be able to utilize up to 500mg of vitamin C, so the spike of vitamin C from 250ml of fruit juice is not a problem. However, this nutrient spike is also true for the sugar found in fruit juices, which contains 8g more than one portion of fruit. This results in large amounts of fructose flooding the body in a short space of time.
Fructose & your health
The sugar found in oranges and orange juice is fructose, and this is very quickly absorbed in the digestive system, particularly from fruit juices which lack the fibre whole fruits contain. Unlike other sugars, fructose does not cause an insulin spike, and the only cells in the body which are able to use fructose are cells found in the liver. Here, fructose is converted into an energy storage molecule, called glycogen, or used by the liver as a source of energy.
When the liver uses fructose as an energy source it increase the amount of circulating LDL and triglycerides1 in the body as well as well as causing an increase in insulin resistance2. These are all signs of an increased risk of developing cardiovascular disease and type 2 diabetes. Although these effects will not arise instantly from drinking one glass of fruit juice, the rise in triglycerides and LDL cholesterol is significant after 4 weeks when 30-60g of fructose is consumed regularly each day. This means that after one glass of fruit juice, to avoid these health risks you are limited to no more than 10g of fructose a day. This rules out many commonly consumed foods. To put this into perspective, bellow is the fructose content of some common foods:
| Food | Fructose content |
|---|---|
| A can of coke | 22g |
| Apple | 9g |
| Banana | 5.7g |
| 1 Teaspoon of table sugar (as used in tea/ coffee) | 2g |
| Vegetables soups (such as tomato) | approx 7g |
| Potato | 1g |
Fructose is not only high in fruits and some vegetables, but it is found in large quantities in processed foods (as shown the the fructose content of coke). It is often difficult to find the exact amount of fructose found in processed foods, as nutritional label info often only displays total sugar content.
Summary
Although fruit juices do provide the benefit of an increased amount of many micro-nutrients such as vitamin C, the processing removes all much of the fibre, polyphenols and concentrates the amount of fructose you consume. This amount of fructose in one serving of fruit juice is much more than the body is able to healthily process, and when combines with all other sources of fructose throughout the day, can increase the risk of cardiovascular disease and type 2 diabetes. It is therefore not recommended to consume fruit juices on a regular basis.
Images courtesy of matthewreid, Kikishua and alexblanck.
