Superfruit juices review and compare

Can juice from 'super' fruits — goji, noni, mangosteen or açai — really cure cancer?
 
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  • Updated:16 Aug 2007
 

01 .Introduction

Orange

In brief

  • So-called "superfruits" — goji, noni, mangosteen and açai — are rich sources of antioxidants, but some of the marketing hype exaggerates the benefits of their juices. There’s no good evidence that drinking them will cure diseases such as cancer or diabetes.
  • You can pay as much as $85 for a 1L bottle of one of these juices. On a serve-by-serve basis, many common fruits such as strawberries and apples, contain more antioxidants, and are cheaper.

CHOICE sets out the facts about our testing and responds to the industry's claims about our approach.

Forget about an apple — if you really want to keep the doctor away, you need to knock back a daily dose of juice from goji, mangosteen or some other even more exotic "superfruit". Or so say the distributors of these products. Most suggest having at least one 30mL serve a day.

Açai (pronounced ah-sigh-ee), goji, mangosteen and noni fruits have a long history of traditional use. But it’s only in relatively recent times that they’ve gained the "superfruit" tag, been actively marketed and entered the mainstream. You can even find packs of dried goji berries adorning the aisles in Woollies.

So why buy them? The marketing message that’s common to all superfruits is that they — and their derivative products — are packed full of antioxidants. But when CHOICE tested the antioxidant activity of nine juices, we found it wasn’t as high as the marketing hype had led us to expect.

Please note: this information was current as of August 2007 but is still a useful guide to today's market.


Brands tested

We tested the following açai, goji, mangosteen and noni juices:

  • Nu Açai and Guarana, from RioLife
  • Absolute Red NingXia Wolfberry Purée
  • Himalayan Goji Juice from FreeLife
  • Medicines From Nature Goji Juice
  • Tree of Health Goji Juice Blend
  • Xango Whole Fruit Beverage
  • Xanberry
  • Tahitian Noni Juice
  • Tree of Health Noni Juice

The CHOICE verdict

Superfruit juices contain a range of nutrients, but marketing spin has vastly exaggerated their health benefits. Until there’s much better scientific evidence, it’s cheaper and wiser to get antioxidants from other fruit (and veg) sources. A wide variety of types and colours of fruit and veg can help protect against diseases such as cancer, heart disease and type 2 diabetes — in part due to phytochemicals such as antioxidants, but also due to other nutrients they contain, including fibre.

Look into the claims and you’ll find there’s very little evidence to back them up. Testimonials abound, but they’re purely anecdotal. Marketers occasionally cite long lists of lab studies as ‘proof’ of the health benefits claimed. While some of the results of these studies are promising, there are few clinical trials, and what happens in a test tube or animal may not occur in humans. CHOICE looked in more detail at the scientific evidence for each fruit and has summarised our findings in Juices compared.

Health and therapeutic claims for food are currently prohibited under the Australia New Zealand Food Standards Code. Several websites for superfruit products pay lip-service to this fact by posting a disclaimer such as “this product is not intended to diagnose, treat, cure or prevent any disease”. But the health claims that appear above the disclaimer tell a different story. It’s clear that the regulation isn’t being effectively enforced for these products.

 
 

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CHOICE tested the total antioxidant capacity (TAC) of nine different superfruit products:

  • four goji
  • two noni
  • two mangosteen and
  • one açai.

We've given the TAC (measured in μmol of trolox equivalents) of a single serve of each product, and shown this as a percentage of the TAC of a Red Delicious apple (5900*) for comparison. We examined the different brands' websites as well as the marketing literature on display where they were sold. We also reviewed the evidence for health benefits of these products.

* Source: Journal of Agricultural and Food Chemistry. 2004, 52, 4026-4037.

Açai

Nu Açai Brand tested:

  • Nu Açai and Guarana, from RioLife (contains 14% açai pulp).
  • TAC: 1800 per 30 mL — 31% of the TAC of a Red Delicious apple

Price paid: $12 for 500 mL.

The lowdown

Amazonian açai, the cherry-sized purple berry fruit of the açai palm, deteriorates rapidly after harvest. This "amazing energy berry" is usually only available outside the Amazon as juice or pulp that's been frozen, dried or freeze-dried. Pulp can be added to juices or smoothies. The Boost juice bar chain sells an açai and guarana combo juice as the 'açai NRG shooter'.

Açai is reported to contain high levels of anthocyanins, compounds with antioxidant activity that are also responsible for its deep purple colour. According to RioLife's marketing literature, açai was rated by a doctor on the TV show Oprah as "the #1 food for anti-aging benefits". Nu Fruits' website says açai berries have "six times the antioxidant level of blueberries" and touts them as a great source of essential fatty acids and energy, but holds back from making specific health claims.

Research confirms açai's high antioxidant levels, and lab studies suggest it may have anti-cancer and anti-inflammatory effects, as well as a possible use in treating heart disease. But human studies on its health effects are yet to be published.

Goji

Goji JuicesBrands tested:

  • Absolute Red NingXia Wolfberry Purée (100% puréed goji berries).
    TAC: 2025 per 25 mL — 34% of the TAC of a Red Delicious apple.
  • Himalayan Goji Juice from FreeLife (90% goji juice from concentrate).
    TAC: 570 per 30 mL — 10% of the TAC of a Red Delicious apple.
  • Medicines From Nature Goji Juice (90% goji juice from concentrate).
    TAC: 690 per 30 mL — 12% of the TAC of a Red Delicious apple.
  • Tree of Health Goji Juice Blend (90% goji juice from concentrate).
    TAC: 1440 per 30 mL — 24% of the TAC of a Red Delicious apple.

Price paid: From $45 to around $85 for 1 L.

The lowdown

The goji berry, or wolfberry, has been cultivated and eaten in Himalayan regions for centuries. According to Absolute Red, goji is "the greatest natural source of antioxidants on the planet". Dr Earl Mindell, the 'face' of FreeLife and reported to be "the world's foremost authority on the goji berry", is quoted as saying, "I believe goji juice will have a more powerful benefit on health, well-being and anti-aging than any other product I have seen in the last 40 years."

Cellular and animal studies have investigated the impact of goji on the growth of human leukemia cells, aging, vision, insulin resistance and infertility, among other things. Results from many show a positive effect, and it's suggested that polysaccharides unique to goji may play a key role. But good-quality clinical studies providing evidence for reported benefits in humans are lacking. If you take warfarin, see your doctor before drinking goji, as they may interact.

Mangosteen

Mangosteen juicesBrands tested:

  • Xango Whole Fruit Beverage (an undisclosed % of mangosteen, from concentrate).
    TAC: 1020 per 30 mL — 17% of the TAC of a Red Delicious apple.
  • Xanberry (an undisclosed % of puréed mangosteen).
    TAC: 1710 per 30 mL — 29% of the TAC of a Red Delicious apple.

Price paid: Approx. $50 for 750 mL.

The lowdown

Mangosteen, Asia's so-called 'queen of fruits', is a tropical fruit with a thick purplish rind and segmented white flesh. It's purported to contain more xanthones — a compound that may have antioxidant properties — than any other fruit.

Literature given to us by a Xango distributor makes strong claims about the fruit, including, "Lab studies show that mangosteen xanthones outperform current chemotherapy drugs in killing liver, lung and stomach cancer cells." Xanberry marketing talks more generally about the antioxidant power of mangosteen fruit and the benefits of xanthones and antioxidants, but it claims that one bottle of Xanberry has over double the antioxidant levels of goji juice.

Scientific research confirms that a variety of xanthones can be isolated from mangosteen plants and fruits. There are also a number of lab studies that suggest mangosteen extracts may have a use in the treatment of some cancers. But clinical trials on real people are lacking.

Noni

Noni juicesBrands tested:

  • Tahitian Noni Juice (89% noni fruit juice purée).
    TAC: 540 per 30 mL — 9% of the TAC of a Red Delicious apple.
  • Tree of Health Noni Juice (100% noni fruit juice).
    TAC: 525 per 25 mL — 9% of the TAC of a Red Delicious apple.

Price paid: Approx. $40 to $60 for 1 L.

The lowdown

Noni, a lime-green Polynesian tropical fruit, has a long history of medicinal use. Typically it's the roots, bark and leaves that are used for different remedies, usually by applying them externally to the skin or to wounds.

The website of market leader Tahitian Noni Juice refrains from making extravagant claims about its product. It says the fruit "provides powerful antioxidants, boosts the immune system and increases energy", the inference being that the juice will too.

Tree of Health, however, doesn't hold back. It quotes a contemporary Hawaiian healer as saying, "I have used noni to help people with cancer, kidney problems, diabetes and tumors." It also lists dozens of testimonials from people who found that drinking noni juice resulted in lower blood pressure, stronger nails and even improvements to their golf game. Noni fruit and juice derivatives have shown anti-tumour activity in rats and mice, but clinical data is scant. Of most interest is a trial in which cancer patients were given daily capsules (not juice) containing noni fruit extract. No tumour regressions were observed, but quality of life (as measured by a decrease in pain interference with activities) improved.


Claims about antioxidants

Woman with juice drinkAntioxidants are groups of chemicals found in foods, especially fruit and vegetables, that help protect the body’s cells from the harmful effects of free radicals. The damage caused by free radicals has been associated with the development of cancer, heart disease, Alzheimer’s and Parkinsons, and is linked to the aging process.

Marketing literature for many superfruit juices refers to their superior antioxidant activity (compared with other fruits), as measured using the oxygen radical absorbance capacity (ORAC) assay. For example, goji berries have 10 times and açai berries six times the antioxidant capacity of blueberries — or so it’s claimed. This might well apply to the whole fruit, but what about the juice products on sale?

We used the ORAC assay to determine the total antioxidant capacity (TAC, measured in μmol of trolox equivalents) of nine products; the results are shown in Juices compared. We then compared the results with the TAC of some common fruits*.

It turns out that if it’s antioxidants you’re after, you’re probably better off eating an apple, or many other more common fruit.

  • You’d need to drink almost five 30mL serves of Tahitian Noni Juice to match the TAC of a navel orange (2540).
  • Three 30mL serves of Xanberry Mangosteen Juice Plus would still fall short of matching the TAC of a cup of strawberries (5938), raspberries (6058) or cultivated blueberries (9019).
  • And the TAC of the humble Red Delicious apple (5900 for one medium-sized apple) is roughly equivalent to ten 30mL serves of Himalayan Goji Juice.

* Source: Journal of Agricultural and Food Chemistry. 2004, 52, 4026-4037.

Extreme marketing

The hype for some superfruit products goes beyond touting their antioxidant capacity, and could leave you believing they’re nothing short of a miracle.

One marketing brochure for goji juice lists no fewer than 34 reasons to drink it every day, including to “enhance libido and sexual function”, “treat menopausal symptoms”, ”improve your memory” and even “inhibit tumor growth”.

And how about this from a promotional pamphlet for mangosteen. An unnamed doctor is quoted as saying: “In my opinion, the mangosteen equals or outperforms the following prescription and over the counter drugs”, and the pamphlet goes on to list 46 medicines including Celebrex (arthritis medication), Lipitor (cholesterol-lowering medication), Methadone (a painkiller that’s used to treat heroin addiction) and Valium (used to treat anxiety disorders).

It’s not surprising health professionals are concerned that people may be misled by this sometimes overzealous marketing, and buy expensive juice in the mistaken belief that it will act as a cure-all.

Of even greater concern is the potential for vulnerable people to be exploited — someone with cancer, say, who’s desperate to try anything that might help. Not only can unsubstantiated health and therapeutic claims give people false hope and lead to disappointment if expectations for recovery or cure aren’t met, but it may be dangerous, if a superfruit juice or product is substituted for prescribed conventional medication.

Pomegranate

We didn’t come across straight pomegranate juice when we were doing our research, but given its popularity in the UK and the US (in the form of brands such as Pom and Pomegreat), it’s bound to be similarly popular here soon.

Just like other superfruits, ads for pomegranate juice refer to it as an antioxidant superpower. There’s some preliminary human evidence that the juice may help to reduce your cholesterol levels and keep your circulatory system healthy. However, it also appears to interfere with an enzyme that’s critical to the proper metabolism of many common medications. So if you take any drugs on a regular basis, check with your pharmacist or GP before you try pomegranate juice.

Where to buy superfruit products

Most superfruit products are still sold in Australia via a multi-level (network) marketing system. You can buy bottles of juice direct from distributors (or ‘independent marketing executives’), who hand out samples and marketing brochures behind promotional displays in shopping malls, healthfood stores and gyms, and earn commissions on sales. Superfruit juices and related products are also sold online.

You’ll pay anything from $40 to around $85 a bottle if you buy your superjuice this way. If you sign up as a member or become a distributor yourself, you’ll get a discount.

04.Our response to industry criticism

 

The superfruit juice industry is fighting back after CHOICE awarded a Shonky award to superjuices in December 2007.

You may have heard criticism of CHOICE’s tests on superjuices and our approach to the science. We stand behind our test method and findings. Here are the key facts in defence of our position:

  • CHOICE tested the antioxidants in the juices (using a measure called ORAC) because that’s what most of the juice manufacturers talk about in their marketing.

The one message that consistently stood out in the marketing literature for superfruits in general was the claim of their superior antioxidant capacity. The total antioxidant capacity (TAC) can be measured using an ORAC (oxygen radical absorbance capacity) test.

The testing allowed CHOICE to compare the TAC of a serve of superjuice (the ones we’d purchased were tested to provide examples) with serves of more common fruits. We used the TAC of a red delicious apple as a point of reference given that it’s a relatively cheap fruit, that’s commonly available in Australian supermarkets and greengrocers.

Total antioxidant capacity is just one feature of superfruits, however. A high antioxidant score doesn’t necessarily guarantee benefits in the body. In addition, antioxidant capacity can also be artificially boosted by preservatives (which can have antioxidant activity) that are sometimes present in superfruit juices.

This means that for some of the juices, the antioxidant capacity attrituable to the preservative-free component could actually be somewhat lower than the total antioxidant capacity of the product as a whole which we reported.

  • CHOICE carefully sought out and assessed the medical literature on the various superfruits and their components. Some evidence has greater weight than other evidence – it’s not just about the number of published studies, but their quality and findings.

Our research wasn’t restricted to testing antioxidant capacity. CHOICE also looked at the claims made in both generic marketing material and for specific products, where present. Some products place more emphasis on the benefit of specific components of the fruit. Examples include xanthones (in mangosteen) and polysaccharides (in goji).

CHOICE used the PubMed database (from the US National Library of Medicine and National Institutes of Health) to conduct a search for studies on superfruits and their products that have been published in the scientific literature. This included evidence for specific components of superfruits. We then assessed the evidence in a thorough and scientifically rigorous way.

Two highly respected Australian bodies, the National Health and Medical Research Council (NHMRC) and Food Standards Australia and New Zealand (FSANZ) have developed frameworks for assessing the quality of scientific evidence. In both these frameworks, the highest level of evidence is from systematic reviews of intervention studies, such as randomised controlled trials.

This is followed by randomised controlled trials themselves, cohort studies and case control studies, and then finally experimental studies (cellular and animal studies).

As we state in this report, some of the results of published studies on superfruits are promising. But there are few clinical trials, and what happens in a test tube or animal may not occur in humans. CHOICE would be interested in seeing more good quality research being carried out on superfruits. But our current position on superfruit juices is framed taking the totality of evidence into account, for the fruits as well as fruit components, rather than on the basis of individual studies.