"The increasing popularity of the juice today has necessitated this review," said the authors.
Noni juice, from the fruit of the Morinda citrifolia L. plant was authorised for sale in the European Union under novel foods legislation, but case reports have continued to surface claiming adverse events after consumption of the juice.
The authors, from Tahitian Noni International in collaboration with the University Medical School of Hamburgs Department of Toxicology, reviewed data from animal studies on toxicology, allergenicity and genotoxicity, and human clinical safety studies. Case reports of adverse events were also analysed.
"This review has drawn together, for the first time, documented food usages and formal safety studies. It appears that noni juice is as safe as other common fruit juices," wrote lead author Brett West in the Institute of Food Technologists' Journal of Food Science (Vol. 71, pp. R100-R105).
The animal data on toxicology found no pathological changes at high doses in any of the 55 animal organs studies, and led the reviewers to determine the no observable adverse effect level (NOAEL) as more than 80 millilitres of juice per kilogram of body weight.
The allergenicity studies, using both rats and guinea pigs, showed that "no positive allergic reactions were noted in any of the animals," said West.
A review of the genotoxicity data also reported a negligible risk for the juice.
Human clinical trials used double-blind, placebo-controlled designs, one of which used Tahitian Noni Juice and the other a noni fruit extract. The first study, said the authors indicated that "drinking up to 750ml of Tahitian Noni Juice per day is safe."
Case reports of potential adverse effects of the juice were described as "disparate" by the reviewers, and, due to confounding factors such as other ingredients in the juice, and people also taking Chinese herbs or prescription drugs, could not establish a direct link between noni juice consumption and potential harm.
"This review article will compensate for the lack of information and context in the published literature, and will thus assist health professionals and scientists in assessing the wholesomeness of noni fruit juice," said the authors.
Noni juice comes from the fruit commonly known as 'noni'. But it is also known as 'Indian Mulberry' and 'nonu'. It is believed to have originated in Southeast Asia and to have been distributed subsequently by ancient voyagers or other means into the Pacific islands, including Tahiti and Hawaii.
Today, it is one of a number of antioxidant fruits, including pomegranate, guarana, mangosteen, goji berries and blueberries, which are increasingly seen by food and beverage makers as up and coming ingredients.
Leatherhead Foods predicts that sales of such heart health foods will rise nearly 60 per cent over the 2004-2009 period to reach nearly $5.7bn by 2009. Although it said in its recent "Heart Benefit Foods" report that, until now, juice drinks have tended to have a general health positioning due to their antioxidant content, there are signs that this may be about to change.