The tonic they oversold

Few plants have been sold as hard as noni. Search for it and you'll be told the fruit treats cancer, diabetes, arthritis, fatigue and high blood pressure — often in one breath, usually with very little behind it. That overselling is worth naming first, because the real plant, used the way it has actually been used for a very long time, is more interesting than the sales pitch.

Noni is the fruit of Morinda citrifolia, a small evergreen tree native to Southeast Asia and Australasia and carried across the ocean by Polynesian voyagers as one of their "canoe plants" — the useful species worth taking on a long journey. The fruit is knobbly, pale yellow, and frankly pungent; two of its common names are cheese fruit and hog apple, which tells you most of what you need to know about the smell. In the places that grow it, the fruit and the leaves have long been used as food and as a folk remedy. The leaf, in fact, is the part more often eaten as a vegetable, and it appears in regional food-composition tables as a genuine food.

What the science actually shows is narrower than the marketing. Laboratory and animal studies point to antioxidant and anti-inflammatory activity from noni's polyphenols. That is real, and it is also a long way from proof that drinking it treats any disease in a human being. There is no reliable clinical evidence that noni cures cancer or anything else, and anyone telling you otherwise has run well ahead of the evidence.

There is one caveat that deserves honesty rather than burial. There have been a small number of case reports of liver injury linked to noni. Looked at closely, these involved people drinking large volumes of concentrated juice — litres over weeks — sometimes alongside other risk factors, and the concern was serious enough that European food-safety bodies reviewed it. The sensible reading is not "noni is dangerous." It is that concentrated anything, taken in excess, is a different proposition from a modest traditional drink. Dose is the whole story.

Which is exactly how we treat it: a modest infusion, for the taste and the ritual of a warm cup, not as a medicine. We are not going to tell you it fixes anything. It's an old Pacific tonic with a strong character — worth meeting on honest terms.