Before you assume we’ve gone all Alan Titchmarsh on you, a shrub in the drinking context is a blend of vinegar, fruit and a sweetener, infused over time to make a concentrated fermented ‘cordial’ of sorts.
Like its fermented beverage fellows kombucha and kefir , as a shrub steeps, its levels of good bacteria (probiotics) increase, alongside its tangy taste. It’s the nutritious potential of said probiotics, plus the tart, almost alcoholic taste, that has foodies and drinks experts predicting that shrubs will catch on in a big way in 2018. They are already huge Stateside.
Nonsuch already has three flavours of 'shrub' including 'sour cherry and mint' and Soupologie is launching its own drinking vinegar (based on apple cider vinegar , with the 'mother', the cloudy bit that contains probiotics) and the end of January.
This isn’t the first time that the shrub has fermented its way its way into fashion, however, as fermented fruit 'liquors' were all the rage in the 15th century, which is handy given that fridges weren’t yet invented and freshwater supplies could be somewhat questionable. They enjoyed a resurgence in the Victorian era, and now that more and more of us are both sober curious and looking to nourish our guts , they’re making quite the comeback, although you can’t quickly whip one up in the Nutribullet - the fermentation process can take up to two weeks. You also won’t be downing this in one - another reason for the alcohol comparison is that shrubs can be a fairly potent acquired taste - think sip, not chug.
As for possible health benefits, apart from the probiotic content, shrubs are said to be a source of vitamins B and C, but cold (pressed), hard evidence is still rather sketchy on this.
Obviously, if drinking them as an alternative to alcohol, there’s an inherent health plus there, but the sugar content, even if you use honey or an unrefined sweetener, could undo some of gut-friendly shrubs’ good work. That said, many shrubs are lower in sugar than say, squash, so ye olde shrub could be the lesser of two sugar “evils” in this regard. Also, a fruit-infused fermented elixir drunk in moderation is hardly a health dealbreaker: if you like the taste, go forth and ferment (or wait for ready-made ranges to hit the shelves).