Super-food may have been the mainstay of the health industry for a long time, but now researchers are questioning their much promised health promoting properties.
Researchers at London's Kingston University used an approach that allows them to delve deeper into the effectiveness of health-promoting 'super foods' and their elixir-giving ilk.
They found that foods such as broccoli, blueberries and whole grains do contain polyphenols - compounds that have antioxidant and anti-inflammatory properties - but their health-giving properties seldom make it past the gut.
"Polyphenols may well work when cells are exposed to them directly, such as under laboratory conditions, but what needs to be established is how effective they are when consumed as part of a food," said Lucy Jones, Kingston University's deputy dean of the faculty of science, engineering and computing.
"If they don't actually get through the gut membrane and into the rest of the body, then they're not a super food," said Jones in a statement.
Using a model developed in the early 1980s by US cancer research institute Sloane Kettering, Jones and her colleague Dr Elizabeth Opara, adapted it to see if and how medicinal Chinese herbs, known to limit the growth of cancer cells, were absorbed in the body.
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Known as the Caco-2, the model mimics the action of the small intestine, the principal place where nutrients are taken up. Researchers used it to assess what does and doesn't make it through the gut.
"The Caco-2 is a single layer of cells grown in a laboratory environment that develops the characteristics and functions of the micro-villi, the tiny hair-like projections that aid efficient absorption found mainly in the small intestine," Opara said.
"We found that while some compounds may have a local effect in the gut itself, in terms of the rest of the body the impact could be negligible," said Opara.