Barely a week goes by without some new study aiming to demonstrate the efficacy of antioxidant phytochemicals for treating everything from insulin resistance and cardiovascular disease to memory loss and cataracts. Not only is there an enormous list of potential health problems that might benefit, but the array of foods and chemicals under scrutiny is equally bewildering from grapefruit, bilberries and liquorice to ginger, chocolate and olive oil.
And when a new study appears to show a link between a particular food and a health condition, the picture is all too often more complex than it appears at first. The mechanisms involved in the different health effects also vary widely.
As the diverse mountain of evidence continues to accumulate, one thing is certain: functional food manufacturers of the future are going to be looking to optimise the delivery of antioxidant phytochemicals to uncouple the desirable actives from any unwanted components and give consumers more functional 'bang for their buck'.
Now a spin-off firm from Rutgers University, New Jersey, is highlighting a technology that promises to make it easier to include meaningful concentrations of a variety of antioxidant ingredients into food formulations. The spin-off and the technology are known as Nutrasorb.
The first products to include the new ingredients could hit retail shelves as early as next year, according to Professor Ilya Raskin, president of the Global Institute for BioExploration at Rutgers and chief scientist at Nutrasorb.
"One of the most important issues for the food industry is to deliver an effective dose of these compounds in a food matrix. We found that soy protein and pea protein can act as powerful affinity resins magnets that concentrate the active compounds," he says.
The company's defatted soya bean flour delivers standardised concentrations of total polyphenols at between 1% and 10%. What's more, the ingredients don't have the high levels of sugar that normally accompany these compounds in raw materials such as berries.
"Anthocyanins and polyphenols have a very high antidiabetic effect, but the sugar counteracts the effect of those compounds," says Raskin. "As well as enabling us to rapidly isolate the antidiabetic components without the sugar, the process also stabilises and protects them against degradation in the upper gut, making them more bioavailable."
April saw a paper accepted for the Journal of Agricultural and Food Chemistry that demonstrates the ability of a grape polyphenol-based Nutrasorb ingredient to "significantly lower blood glucose levels" in mice.
It looks like adsorption stabilises the compounds outside the body too, with a paper in April's Food Chemistry confirming that defatted soya flour effectively concentrates blueberry and cranberry polyphenols in a shelf-stable format that contrasts sharply with the highly perishable character of the raw fruit.
Nutrasorb is now working with several companies to develop food products, including the big US-based fruit producer, Milne Fruit. Most food types are potential candidates for the new ingredients. The main exception is clear beverages, since the soya proteins are insoluble.
Of course, sugars are not the only unwanted components in some plant products. For instance, Japanese group Kaneka Pharma was at Vitafoods in May to showcase its Glavonoid liquorice extract, which has recently been granted Novel Food status by the European Commission. In this case, the firm's patented process ensures the extract is free from glycyrrhizinic acid, which may have "cortisone-like" side-effects and is the main reason why liquorice has not been used more widely, says Kaneka.
Glavonoid contains 30% liquorice glabra polyphenols, which have been shown to help tackle abdominal obesity and visceral fat. Kaneka says that Glavonoid appears to deliver a "double whammy" in fighting visceral fat. It increases the body's own fat burning ability, as well as decreasing fat synthesis by down-regulating genes that are involved in fatty acid development.
Novel Food status means Kaneka can move Glavonoid into functional foods for weight management and body shaping. Milk, yogurt and fruit- and vegetable-based beverages are all key targets.
For other companies, the obstacles against moving from supplements into food are just too great at least for now. For instance, Italian company Indena makes a number of functional food ingredients, but its flagship Meriva turmeric extract would require Novel Foods status to follow suit.
Meriva's formulation forms a complex between active curcumin and soy phospholipids, which is known as a Phytosome. This was shown last year to make the anti-inflammatory curcuminoids 29 times more bioavailable on average than administering them as a straightforward extract (Journal of Natural Products).
However, it would take a big investment to demonstrate that the same effect is possible when Meriva is used as a food ingredient, according to Indena's marketing director and head of functional food development, Christian Artaria.
"It's not just a regulatory issue. It's also an issue of the food matrix," he explains. "When we create a Phytosome formulation, we carry out extensive animal and human studies. Put them in a food matrix and we'd have to carry out that basic research all over again."
In any case, researchers may be busy trying to discover the next "wonder compound", but clinicians insist that eating well and exercising remains the best strategy to combat many of the conditions being targeted by phytochemical extracts. "We welcome all of the research, but we still steer away from saying that there's any one 'magic' food group. You need a healthy balanced diet and that's the advice we're sticking to for now," says Pav Kalsi, clinical adviser at Diabetes UK.
Eating more fruit and veg may well be the best advice, but plant breeders at Oregon State University see no reason not to give nature a helping hand by working to improve the delivery of beneficial compounds. Their Indigo Rose tomato is the first "true" purple tomato, according to the team, who claim that it offers consumers a hefty dose of anthocyanins, among other benefits.
"It is the first improved tomato variety in the world that has anthocyanins in its fruit," says Professor Jim Myers in the horticulture department. "Other so-called purple and black tomatoes have the green flesh gene, which prevents normal chlorophyll breakdown. A brown pigment called pheophytin accumulates and has a brownish colour that makes a muddy purple when it is combined with carotenoids."