If you’ve ever made fresh juice at home, you’ll know that much of the fruit or vegetable is wasted when you extract the liquid juice from the pulp. But what exactly is in this pulp?
I used to think that the pulp was 'just' fibre, but a number of studies published in the past few years have shown that there are a whole host of additional polyphenolic antioxidants bound to the fibre in fruits and vegetables – precisely what we’re missing out on if we’re drinking juice – and that these polyphenols act in a different way to the polyphenols found in the liquid component of juice.
These fibre-bound polyphenols are known as non-extractable polyphenols (NEPPs), which aren’t absorbed in the small intestine and as such make their way to the large intestine, where they are fermented by friendly bacteria, which produces a wide range of health benefits (1) (2).
Of the plant foods, fruits in particular have been shown to have very high levels of these NEPPs, so if you drink fruit juice, you’re missing out on all these wonderful polyphenols which feed your gut bacteria and exert numerous positive effects on colonic and systemic health (1).
Furthermore, the soluble fibre in fruit actually slows down the digestion and absorption of the sugar, which blunts the blood glucose response. The body also doesn’t send the same satiety signals for liquids as it does for solids (even if a liquid meal and a solid meal contain equal calories/kilojoules), which makes it very easy to drink large volumes of juice without feeling full.
So, in summary, fruit juice ain't a health food, in my opinion. If you do like drinking fresh juice, I’d recommend sticking to a mixed vegetable juice (which is much lower in sugar than fruit juice) every now and again, and eating your fruit whole, just as nature intended.
1. Arranz S, Silván JM, Saura-Calixto F. Nonextractable polyphenols, usually ignored, are the major part of dietary polyphenols: A study on the Spanish diet. Mol Nutr Food Res. 2010;54(11):1646–58.
2. Saura-Calixto F. Concept and Health-Related Properties of Nonextractable Polyphenols: The Missing Dietary Polyphenols. J Agric Food Chem. 2012 Nov 14;60(45):11195–200.