Marketing hype

Marketing literature for many super-juices refer to the superior antioxidant capacity of the super-fruits they contain.

For example, a glossy MonaVie brochure claims that on a gram-for-gram basis the antioxidant capacity of the freeze-dried acai berries in MonaVie is more than 15 times higher than blueberries and more than 20 times higher than raspberries.

We think it's unfair to compare freeze-dried acai berries to fresh blueberries and raspberries. The freeze-dried acai contains no moisture so it's a much more concentrated source of antioxidants.

MonaVie contains 25 percent acai: the other 75 percent comprises various fruits and additives. But it's not always clear just how much of the super-fruit a product contains. XanGo lists mangosteen puree as its first ingredient but doesn't say how much - and it also contains nine other fruit juices.

Read carefully and you'll see that the claims and "scientific studies" usually refer to the super-fruit, not the juice product itself. And while some super-fruits have shown promising results in lab studies, what happens in a test tube or lab animal may not occur in the human body.

Some products emphasise the benefits of specific components of the fruit. Mangosteen sets itself apart from other super-fruits as being rich in "xanthones" (a type of antioxidant) and goji is reported to be a unique source of "polysaccharides" (a fancy name for complex carbohydrates). We've simply tested the juices to find out their antioxidant capacity.

The marketing literature is also filled with impressive testimonials. Users of acai juice claim it cures joint pain, lowers cholesterol and controls diabetes among other (even more miraculous) claims. The mangosteen fruit "battles degenerative diseases like cancer, heart disease, diabetes, arthritis, and all forms of brain malfunctions".

Testimonials are the views of one person, not a scientific study. They should be treated like any other unverifiable opinion and given little credence.

Multi-level marketing

Super-juices such as XanGo and MonaVie are sold through multi-level marketing networks. Anyone can become a distributor and earn profits by either building an active customer base (which then buys direct from the parent company) or by recruiting distributors who build a customer base. Distributors can also earn a profit by selling products purchased from the parent company at wholesale prices.

The XanGo and MonaVie websites promise amazing financial rewards and "generous compensation plans" for distributors, but you'll need to sell a lot of juice to make a living. Multi-level marketing schemes are an aggressive sales method - if these products are as amazing as they claim to be, they should be selling themselves.