You'll find something called noni juice on the shelves of most health food stores. Once sold as a dietary supplement, noni is the fruit of the Morinda tree, native to both the Polynesian islands (especially Hawaii) where its roots, bark, stems, leaves and fruits were used traditionally as a remedy and tonic for thousands of years. The fruit has been described as foul-smelling with a sour taste.
Lately, the juice has found its way into beverages and is being marketed as a cure for all ails of the modern world: cancer, diabetes, heart disease, high blood pressure, arthritis, psoriasis, allergies, sinus infections, ulcers, menstrual cramps, depression, fatigue, chronic pain, and many more conditions.
Any fruit juice backed by such testimonial touting (albeit with disclaimers) must be worth putting up with the high price (the pure juice costs about a dollar an ounce) and the sour taste. At least it must be loaded with nutrients, right?
Well, not really. In fact, noni is relatively low in dietary essentials, such as vitamins or minerals (except for potassium the label warns people with kidney problems to stay away because the high potassium content could damage this organ. Apparently the kidney an organ that noni is powerless to cure.) Websites boast that noni contains 17 amino acids, terpenes, sterols, glycosides, vitamins and minerals.
The catch is all plants carry a vast array of nutrients and phytochemicals, otherwise they wouldn't grow. Every green plant runs photosynthesis, which requires a host of vitamins, minerals, amino acids, along with quinones, and a large variety of antioxidants that protect the plant from oxidative damage.
The question isn't whether noni, like any plant, has the requisite plant chemicals, but whether it's particularly rich in anything to account for the claims.
If noni isn't a particularly rich source of vitamins, minerals, or protein, then its strength must lie in the abundance of phytochemicals: antioxidants (like those found in berries, cherries, grapes, or other exotic fruits including açai), or anti-inflammatories (abundant in ginger and turmeric).
Noni is by no means a rich source of any of the well-studied phytochemicals found in most fruits and vegetables. In fact, much of the research into noni is devoted to determining just what compounds could be responsible for potential cancer prevention suggested in some studies on rats and mice. Several studies report a number of novel glycosides (molecules to which sugar is attached), but there is no convincing evidence they are actively responsible for myriad of purported health benefits to humans from drinking noni. In fact, there aren't any long-term human studies in peer-reviewed journals that demonstrate the miraculous cures alluded to.
There are, however, three reported cases of liver toxicity in persons drinking large amounts of noni over periods anywhere from three weeks to two months.
The power of noni is said to stem from something called xeronine. What is xeronine, and how does it act? According to the noni guru, Ralph Heinicke, Ph.D., xeronine is an unrecognized essential nutrient that makes the immune system work better, though exactly how is unknown. It also allegedly makes our cells absorb more nutrients by binding to specific protein receptors (which are not identified). And of course if the immune system works better, and our cells absorb more nutrients, every system in the body revs up to fight disease (except for the kidneys. And maybe the liver). References to xeronine or its precursor, proxeronine, in literature other than a website promoting noni juice are few.
Despite the uncertainty and unsubstantiated claims, noni is big business - more than $600 million per year in sales, at least according to one of the websites selling it at $168 per 4-bottle case.
Another "noni no-no" involves multi-level marketing schemes that are a lot more robust than the research. One can go online and become a "product consultant" or "distributor" and receive "expert training." Whether a pyramid scheme or not, you don't find this associated with many legitimately researched nutraceutical ingredients. (Hoodia sellers are now some of the worst of the Internet spammers. To see my take on Hoodia, check out "Hoodia Love.")
Ok, maybe this skepticism is less than fair. Noni is a fruit. People have used it therapeutically for a long time (as they have apples, oranges, berries, etc.). Still, research demonstrating it benefits to humans must be reported in peer-reviewed journals. A little double-blind testing ought to be a snap.
If noni juice is special, it should be proven so in an unbiased, open and respectable manner. Until then, the cost and the taste seem to make it hardly more than a passing fad.