Olive oil – described as “liquid gold” in Homer Iliad – is known for its health benefits. Not only is it delicious, it is also anti-inflammatory, good for the gut, good for the heart and can even help us feel happier and live longer.
However, scientists are now turning their attention to the cloudy, brown and previously discarded byproduct of its production – olive mill wastewater (OMW) – and have discovered that it could be an even more powerful superfood.
OMW is the residue left after olives have been milled and their oil has been separated: a watery residue pressed from the remaining mulch.
Once considered a nuisance because it can contaminate surrounding soil and water if not managed properly, it is now prized for its protective and anti-inflammatory properties.
After hearing stories of olive farmers drinking it for health reasons, researchers became intrigued and began investigating the waste product.
They discovered that this dark, bitter and cloudy liquid is not useless, but just as nutritious, or perhaps even more so, just like its source.
OMW is loaded with healthy plant compounds, or phytochemicals, specifically polyphenols, which contribute to gut health, among other benefits. In fact, OMW is thought to contain at least 10 times the phytochemicals as extra virgin olive oil, which is already considered a rich source.
Italian scientist Adriana Albini, a pioneering professor of cancer research and the first Italian to be elected to the board of directors of the American Association for Cancer Research, has been studying OMW for 10 years.
She and her team have been researching OMW extract and found that it may be useful in both the prevention and treatment of certain types of cancer, including lung, prostate, colon and breast cancer.
Other research has shown that OMW may support recovery after exercise, improve metabolic markers, and potentially help with cardiovascular and neurological conditions.
“Plants can’t run,” Albini said. “Their only defense is to produce secondary or tertiary metabolites, which ward off parasites. Many of these metabolites are poisons, and we know that poisons can be therapeutic at certain concentrations.
“Arsenic, for example, can help treat leukemia. So the idea is that these metabolites can help us defend ourselves against cancer. What plants use for their health, we can also use for ours.”
Eating foods rich in these beneficial plant compounds, such as those in the Mediterranean diet, is associated with a lower risk of developing disease.
OMW contains at least 30 different types of polyphenols, with hydroxytyrosol being the most abundant, Albini said. Also found in both olives and olive oil, hydroxytyrosol has been shown in research to help brain and heart health, and reduce inflammation, which is good for overall health.
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This is what interested Albini in studying the wastewater, along with its consistency. “You can’t drink oil,” she said. “But with this, because it’s liquid, it’s easier to consume.”
Albini added: “It is important to remember that there is no miracle cure (a healthy product derived from food). The overall lifestyle is very important: do not smoke, exercise, eat healthy and drink alcohol in moderation. It is a complex web of things.”
Fattoria La Vialla, a family-run business in Tuscany, sells OMW to customers in the UK. It comes in small “shot” jars and you can choose between sweetened or unsweetened.
Gianni Lo Franco, one of the three brothers who now run the farm, said: “You can think of it as freshly squeezed polyphenol juice.”
His great-grandmother, the matriarch of the family, drank half a glass of what she and the people of Tuscany call “acqua mora” twice a day during the pressing season.“ or “dark water”.
She swore it was the reason for her good health into old age; she lived until the age of 98 without complaint. It made the Lo Franco family curious and led them to send the liquid away for testing and eventually cold filtering so it would be suitable for sale to the public.
“Have you ever, like us, had to reconsider certain customs of our ancestors and admit that the very customs which we looked at with astonishment were in fact the result of ancient wisdom?” said Lo Franco.
“Everyone would have looked at her in surprise, because acqua mora is extremely bitter, but determined as she was, she paid no attention to it – and now it turns out that Nonna Caterina was right. One small jar (25 ml) contains more polyphenols than a whole liter of good extra virgin olive oil. It shows that nature really does not create waste.”