Juicing seems to be a controversial subject.

Advocates say that lots of fruit and vegetable juices represent one of the simplest, fastest and most enjoyable routes to good health.

Critics claim that juicing is the first step on the road to processed food - and that it degrades the produce, gives a more rapid sugar hit - and removes valuable components of the original produce.

This essay is an opinion piece - which gives the author's answer to the question of if and when you should juice produce.

Juicing criticisms

Juicing is very often inferior, in many ways, to consuming produce whole.

Juicing...

• ...leaves fat-soluble compounds bound up with the fibre;
• ...systematically filters out valuable nutrients near the skin;
• ...stops the tongue from detecting rotten, mouldy or parasitised produce;
• ...results in atrophy of the teeth and jaws;
• ...bypasses saliva - the first stage in digestion - and the first line of defense;
• ...eliminates valuable fibre from produce - resulting in:
  • ...increased glycemic index;
  • ...more rapid absorbsion of sugar;
  • ...a sharper insulin spike;
  • ...reduced satieity;
  • ...slower passage through the digestive tract;
  • ...easier absorbsion of excessive doses;
  • ...blood sugar swings;
  • ...lack of benefit of fibre to the colon;

However juicing does have some virtues:

• Eating more fruit and vegetables

  While it is widely agreed that eating more fruit and vegetables is generally a good idea, many find vegetables have palatability problems, and that there is a limit to the volume of celery they can be bothered to munch through.

  By improving the palatability of many vegetables, juicing can result in the consumption of produce which would not be easy or convenient to ingest whole.

  As a result, use of a juicer can increase fruit and vegetable consumption.

  Increased consumption of fruit and vegetable material can displace other less-desirable items from the diet.

• Allowing access to high-quality nutrient sources

  The nutrients in some produce are protected against being eaten by the volume of indigestible fibre they come with.

  Cereal grasses - by most accounts - represent high quality nutritional sources. However the nutrients are practically inaccessible through being bound up with lots of fibre.

  Juicers can liberate the nutrients from the fibre, and allow convenient access to these fine foodstuffs.

• Fibre can trap foodstuffs in between the teeth

  Dental carries can be caused by fibres in fruit becoming stuck between the teeth - and holding bacterial food sources next to tooth enamel.

  By contrast, juice tends not to get stuck between the teeth.

  Indeed, exposure of the teeth, tongue - and the entire mouth - can be minimised - if the juice is consumed using a straw.

The impact of juice on blood sugar spikes can be reduced by diluting it with water - or by using a coarse screen that fails to filter out much fibre.

Reverse juicing

Examining some of the drawbacks of juicing suggests that separating the skin from the sugary pulp of some fruits may have some utility - if the fibrous pulp is eaten and the juice is discarded.

This gives access to the nutrients in the skin - without the burden of all the calories and carbohydrates in the juice.

Grapes are an interesting fruit to try this trick with.

However, this may result in undesirable concentrations of pesticides from the skins if some caution is not taken.

Summary

Juicing has numerous drawbacks - and it is good to be aware of them.

However a good juicer remains one of the most important pieces of food processing equipment for those interested in eating largely-raw diets.

Studies on the effects of blending, chewing and juicing

1. Depletion and disruption of dietary fibre. Effects on satiety, plasma-glucose, and serum-insulin (juicing and disruption)
   
2. The role of dietary fiber in satiety, glucose, and insulin: studies with fruit and fruit juice (juicing)
   
3. Effects of one week juice fasting on lipid metabolism: a cohort study in healthy subjects (juicing and fasting)
   
4. Swallowing food without chewing; a simple way to reduce postprandial glycaemia (disruption)
   
5. Gastric emptying of a solid meal is accelerated by the removal of dietary fibre naturally present in food (juicing)
   
6. Effects of food texture change on metabolic parameters: short- and long-term feeding patterns and body weight (satieity)
   
7. Distribution of multiple pesticide residues in apple segments after home processing (pesticides)
   
8. Behavioral, plasma, and calorimetric changes related to food texture modification in men (blending)
   
9. The physical state of a meal affects hormone release and postprandial thermogenesis (blending)
   
10. Physical state of meal affects gastric emptying, cholecystokinin release and satiety (blending)
    
11. Lycopene in tomatoes: chemical and physical properties affected by food processing (blending)
    
12. Food processing and lipid oxidation (disruption)
    
13. Changes in carotenoids during processing and storage of foods (oxidation)
    
14. A nursing home outbreak of Clostridium perfringens associated with pureed food (blending)