Freshly made fruit and vegetable juices can boost your performance, says Dave Reavely

An ever-increasing number of runners and athletes are getting into the juice habit.

But I'm not talking about buying a carton of orange or apple juice – I'm referring to extracting freshly-made fruit and vegetable juices in your own home using a juicer specifically designed for the purpose.

The big advantage of this is that you can extract juice that is rich in nutrients, phytochemicals (naturally occurring compounds that have disease-fighting and cell-protective properties) and enzymes. All of these factors add up to a potent health-promoting drink that is absorbed via the digestive system in about 15-20 minutes.

A shop-bought juice is likely to have been depleted of many of its nutrients and lacking in enzymes as a result of storage. Many of those juices – even the organic versions – may have been pasteurised to preserve their shelf-life, resulting in the destruction of much of their nutritional value.

Next time you purchase a carton of juice have a careful look at the label to see if it is made from concentrate. If so, it means it has been reconstituted from concentrated juice and mains water - in other words, there is no substitute for the freshly-made stuff.

Why freshly-made juices?

Optimum performance can often be related to supplying the body with a high level of nutrients while keeping the level of toxicity within the body at a low level. Ingesting freshly-made juices helps you to achieve both of these objectives because juices help to eradicate toxins from the body. They are also an excellent source of vitamins, minerals and other helpful natural chemicals which the body needs to resist disease and function at its best.

The high chlorophyll content in green juices helps to oxygenate the blood

This is best summed up in the following simple equation: low toxicity + optimum nutrition = optimal performance. Contrast this with: high toxicity + poor nutrition = impaired performance.

Juices and smoothies

Many people seem to be confused about the difference between freshly extracted juices and smoothies. There are a few differences: smoothies are mainly made from fresh fruits which are placed in a blender to produce a delicious drink. This is a far cry from an extracted juice because the smoothie still contains all of the fibre present in the whole fruit. However, place that same fruit in a juice extractor and you end up with the juice being separated from the fibre.

The advantage of this is we can consume large quantities of nutrient-rich juice without taxing our digestive systems with all of that fibre. Imagine juicing three or four medium size carrots – approximately a glassful of carrot juice. Once drunk, the carrot juice would be absorbed into your system in about 15 minutes. Now imagine eating all of those carrots with all of that fibre. It would take some time to break them down and the energy required from your digestive system to do so would be much greater.

So freshly-extracted fruit and vegetable juices can virtually by-pass the digestive system and be absorbed very quickly into your body.

Understandably, some people question the wisdom of losing all of that fibre, reasoning that we need fibre for our digestive systems to function properly and fend off diseases such as colon cancer. Of course, this is perfectly true. However, I am not advocating that runners and other athletes should drink juices at the expense of fibre-rich foods, merely that juices form an adjunct to a high fibre diet. Therefore, in this way, you get the best of both worlds.

Top tip

When selecting a juicer choose a model that is easy to clean, has a good quality motor – preferably 750W or above and is efficient at extracting juice from fruits, vegetables, leafy greens and wheatgrass.

Green juices

Although all juices have benefits, in my opinion the green juices are the best as their high chlorophyll content helps to oxygenate the blood. Green leafy vegetables are also high in minerals such as magnesium, iron and calcium, which are essential for optimum health. What's more, the green juices have the least impact in terms of blood sugar as they don’t cause blood sugar spikes which can be followed by a sudden energy slump.

Bearing this in mind, I recommend that athletes and all those engaged in sports should try to consume the higher sugar containing juices such as those that contain carrots, fruit and beetroot in moderation compared to the green juices.

» David Reavely is a nutritional therapist, book author and a qualified fitness instructor, see fooddetective.co.uk