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.
- 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.
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.
- 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 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.
- 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.
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.
- 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.
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.