The New Zealand FERDINAND study found the fruit powder did nothing for weight or blood sugar, but systolic blood pressure improved more than with placebo.

Clinical trials are designed to answer a specific question. Occasionally they answer a different one. That is what happened in a six-month study at the University of Auckland, which set out to test whether powdered feijoa could help prevent type 2 diabetes and instead found a hint that the fruit might help lower blood pressure.

“It’s not what we set out to find,” said Dr Ibrahim Mohamed of the University’s Human Nutrition Unit, “but it’s interesting and certainly warrants more research.”

New Zealand’s favourite import

The feijoa, Acca sellowiana, is a small green fruit native to southern Brazil, Uruguay and parts of Argentina. It has become a fixture of New Zealand back gardens, where its aromatic, tart-sweet flesh is something of a national obsession each autumn. It has also attracted scientific interest. Feijoa is rich in polyphenols and flavonoids, contains vitamin C and is a source of abscisic acid, or ABA, a plant hormone that has been studied for possible effects on blood sugar regulation. These compounds have been linked to antioxidant, anti-inflammatory and potential metabolic effects.

A short-term study in Iran had reportedly suggested benefits for people with type 2 diabetes. The Auckland team wanted to know whether feijoa could do something more ambitious: help people with prediabetes, whose blood sugar is raised but not yet in the diabetic range, avoid progressing to the disease.

Prediabetes is common and often goes undiagnosed. Without intervention, a substantial share of people with the condition go on to develop type 2 diabetes. Landmark trials, most notably the Diabetes Prevention Program in the United States, have shown that lifestyle changes leading to modest weight loss can reduce that risk by more than half. Researchers have hoped that dietary supplements might add to those benefits.

The FERDINAND trial

The study, called FERDINAND, enrolled 97 adults with elevated blood sugar. Each day for six months, participants took about 1 gram of whole-fruit feijoa powder or a placebo, mixed into water or their breakfast. The powder, marketed as Feiolix, was supplied by the company Anagenix.

The trial was built around weight loss, the most effective known way to reduce diabetes risk in people with prediabetes. For the first two months, participants followed a free meal replacement program designed to help them lose weight. The following four months focused on keeping that weight off. The question was whether feijoa would boost the benefits.

It did not. Feijoa powder had no meaningful effect on weight or on blood sugar, the study’s primary concerns. But systolic blood pressure, the top number in a blood pressure reading, improved more in the feijoa group than in the placebo group.

Systolic pressure measures the force of blood against artery walls as the heart beats, and it is the reading most closely linked to cardiovascular risk in older adults. Because participants were losing weight, which itself lowers blood pressure, both groups would be expected to see some improvement. The signal of interest was that the feijoa group appeared to improve more.

The release describes the work, published in Diabetes, Obesity and Metabolism, as the first long-term human clinical trial of feijoa powder supplementation. It was run with AgResearch, the Malaghan Institute and Plant and Food Research.

Why caution is warranted

The blood pressure result needs to be read carefully. It was not the outcome the trial was designed to test, and secondary findings in a trial are more likely to arise by chance than the primary result the study was powered to detect. The release notes that the evidence for an effect on blood pressure was not consistent across all of the analyses, and with 97 participants, the study was modest in size. It does not report how large the improvement was.

The authors acknowledge as much. “Further studies in larger cohorts are warranted,” they write, “to fully evaluate the contribution that whole fruit feijoa powder may make to improved blood pressure.”

There is also a commercial dimension. The trial was funded by New Zealand’s High-Value Nutrition National Science Challenge, known in Māori as Ko Ngā Kai Whai Painga, a government program that aims to grow exports of health foods by validating their health claims scientifically. The powder came from the company that sells it. The authors declare no conflicts of interest, and a randomized placebo-controlled design provides important protection against bias. But a positive signal for a product with export ambitions is exactly the kind of result that benefits from independent confirmation.

A plausible lead

Even so, the finding is biologically plausible. Diets rich in fruits and vegetables are consistently associated with lower blood pressure, and polyphenols, particularly flavonoids, have been shown in some trials to improve the function of blood vessels. High blood pressure affects more than a billion people worldwide, according to the World Health Organization, and is a leading risk factor for heart attacks and strokes. Even small reductions across a population can have meaningful effects on cardiovascular disease.

For now, the study offers a lead rather than a recommendation. Feijoa powder did not help with weight loss or blood sugar, the things it was tested for. Whether it can help with blood pressure is a question that a larger trial, designed with that goal in mind, will need to answer. In the meantime, New Zealanders who enjoy eating the fresh fruit in season have no reason to stop.

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Notes

1. “Evaluating Whole Fruit Feijoa Powder for Type 2 Diabetes Risk Prevention: A Randomised Controlled Trial.” Diabetes, Obesity and Metabolism, 1 September 2026. DOI: 10.1111/dom.71270.
2. University of Auckland. “Clinical trial provides preliminary evidence of blood-pressure effect from feijoa.” EurekAlert!, 30 September 2026. https://www.eurekalert.org/news-releases/1146159.

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