Smoothie, Squash Or Juice?

Fruit juice or smoothie?

The first distinction is whether a drink is a fruit juice or a smoothie. Technically a juice can be made from any fruit or vegetable with high water content and consists of juice and water-soluble nutrients, particularly carbohydrates, without any of the structure of the fibre.

A smoothie is made of blended whole fruits and although the food is pulverised and structurally changed, you still end up consuming the food in its entirety. So, if you blend up a pear and a cup of spinach, your body digests an entire pear and a whole cup of spinach. In theory, this makes a smoothie more nutritious, as it may contain all the goodness from the skin and core of the fruit, which often has higher concentrations of beneficial phytonutrients and will contain more fibre.

Fruit juice or squash?

So considering the juice, as it is little or no fibre does this mean that drinking a bottle of fruit juice is no better than drinking squash or cordial? In one way yes, as you can see from the table below, the calories, sugar and fibre content are surprisingly similar across a whole range of popular drinks, including both pure unsweetened fruit juices and Coca Cola. The World Health Organisation’s advice on free sugar is that it should ideally make up less than 5% of total energy in our diets (1), though a more realistic goal currently is 10%. 5% would equate to just 25g or 6 teaspoons in a 2500kcal/day diet less than in most of these drinks. The sugar in a fruit juice or cordial should be considered as free sugar. Data from the last UK National Diet and Nutrition Surveys shows that in the UK adults get around a quarter of all the free sugar in their diets from non-alcoholic drinks (2).

Fruit juice will almost certainly contain more beneficial minerals, vitamins, antioxidants and phytonutrients than squash or cordial. The exact amount will depend on the type of juice, the level of pasteurization and processing and the length of time it has been sitting about, as many nutrients degrade over time. It would be fair to guess that the freshly squeezed shop bought orange juice would be the most nutritious but it is worth noting that a serving of Ribena contains 40% of your daily requirement of vitamin C, as well as good quantities of anthocyanin and that Lucozade Sport has added Niacin, Vitamin C, B6, B12, Pantothenic acid and carotene. Fruit juice will also generally have a lower Glycaemic Index (GI), a foods GI is the measure of how quickly the sugar it contains reaches the bloodstream. The GI of Coca Cola is 63 and original sparkling Lucozade has a GI of 95, whereas fresh orange juice has a GI of around 50 and fresh apple juice contains the phytochemical phloridzin, which has been found to lower the speed of glucose transport (3) – apple juice has a GI of around 40. A GI of below 55 is considered to be below. Medium GI is 56-69 and a high GI food is over 70 (4).

Smoothies

Smoothies can also be high sugar (see below), but research has shown that this sugar is not absorbed as quickly as in juices. Innocent have GI tested their smoothies and found average scores of around 40, which is considered to be a low GI food (5).

The list above shows that the fibre content of shop-bought smoothies can vary widely. The government published guidelines on recommended fibre intake in July 2015. These give the recommended fibre intake for adults is 30g a day. On average, we consume much less than this – about 18g per day. Intakes of fibre in children are also too low. Recommendations for all age groups are given below. 250ml of the highest fibre smoothie I could find, the Love Smoothies breakfast smoothie, provides just under half of an adult daily fibre requirement (14.5g), which doesn’t sound bad but foods need to contain over 6g fibre / 100g before they are considered to be high fibre and most of the smoothies I looked at contained very little fibre.

Bought or homemade?

The ingredient list of shop-bought smoothies is impressive and it is difficult to have lists of ingredients available in small amounts at home. As an example, Naked’s Green Machine Smoothie contains apple Juice (64%), Pineapple Juice (10%), Banana Puree, Kiwi Puree (8%), Mango Puree, Botanical Extracts (Powdered Spirulina, Chlorella, Broccoli, Spinach, Barley Grass, Wheat Grass, Parsley, Ginger Root, Blue-Green Algae and Odourless Garlic) and Natural Flavourings. But notice how many of these ingredients are actually juices or purees. It’s little wonder the fibre content is quite low. You may add fruit juice to a homemade smoothie but you don’t need to and making smoothies at home means you know exactly what is in them, your ingredients will be fresh and you won’t lose nutrients over time. It’s reasonably easy to include spirulina, or herbs and spices.

Is it better to just eat the fruit/vegetables?

Most nutritionists and dieticians would say it is better to eat food rather than drink it and that the change in the structure of foods when we pulverize them makes them less beneficial for us. There is also evidence that the chewing action is important as it lowers anxiety, producing calming signals to the brain (6). However, research does show that in some cases we get more of the good things from fruits or vegetables when they are processed, as the phytonutrients, vitamins and minerals can become more bioavailable and easier to get from the food (7,8). It’s also better to drink your vegetables than not eat them at all.

My feeling is there is a role for juices and smoothies in our diets but care should be taken when choosing that you are getting what you think you are. Many juices and smoothies are very high in sugar / low fibre.

Learn more with our Nutrition & Weight Management course

References:

(1) http://www.who.int/nutrition/publications/guidelin…

(2) Understanding Free sugars (2014). British Nutrition. https://www.nutrition.org.uk/attachments/article/8…

(3) Johnston, Sharp, Clifford and Morgan (2004) Dietary polyphenols decrease glucose uptake by human intestinal Caco-2 cells. FEBS Letters 579 (7) 1653-1657 http://www.sciencedirect.com/science/article/pii/S…

(4) Glycaemic Index. University of Sydney http://www.glycemicindex.com and also covered in Nutrition and Weight Management lesson 6.

(5) http://www.prnewswire.co.uk/news-releases/innocent…

(6) Sasaki-Otomaru et al 2011. The effect of regular gum chewing on levels of anxiety, mood and fatigue in healthy young adults. Clin Pract Epidemiol Ment Health 7: 133-139.

(7) Ashcoff et al (2015) In Vitro Bioaccessibility of Carotenoids, Flavonoids and Vitamin C from differently processed Oranges and Orange Juices. J Agric Chemistry 63(2). 578-587

(8) Dewanto et al (2002) Thermal Processing Enhances the Nutritional Value of Tomatoes by increasing total antioxidant activity. J Agric Chemistry (50(10). 3010-3014.