Stressing plants to induce their natural defences could lead to a new range of functional foods enriched with a plant’s natural defensive compounds, phytoalexins.

Researchers from the US Department of Agriculture report that stress can lead plants to produce higher levels of these beneficial compounds, which may possess antioxidant and anti-inflammation activity, and maybe even anticancer activity.

Writing in the Journal of Agricultural and Food Chemistry, the USDA researchers state that phytoalexins have been largely ignored as nutritional components in human foods.

“We propose a new area within functional food research called phytoalexin-enriched foods that utilize induced plant compounds or phytoalexins created either pre- or post-harvest that have been traditionally viewed only as plant defensive compounds, but have beneficial health effects,” wrote lead author Stephen Boue.

Global functional foods

The phytoalexin-enriched foods could soon be adding to the growing functional food market, expected to be worth about €175 billion by 2012, according to Euromonitor International data.
In a global health and wellness market, the researcher puts at €450bn, functional foods are the fastest growing sector and second in value to naturally healthy foods (€155bn), both now and in 2012.

By 2012, better-for-you foods will be the third highest selling category, followed by vitamins and food supplements; organic; botanicals; slimming products; food intolerance products
and sports nutrition products.

Phytoalexins science

“Phytoalexin-enriched foods would be defined as foods with health-promoting activities based on phytoalexins and would be a subclass of functional foods,” wrote Boue and his co-workers.

Production of the phytoalexins would be achieved by biotic and abiotic elicitors – substances that elicit the production of the phytoalexins – as well as other stress-inducing techniques. This would be done both before harvest and after harvest, they said.

The various methods for production of such plants include organic cultivation, which reportedly leaves plants more susceptible to pathogen and insect attack. This may subsequently lead to increases in secondary metabolites as the plants defend themselves.

“It is tempting to speculate that in modern agriculture we are limiting at least to some extent the production of health-promoting compounds in our diets that may be present at higher levels in organically grown foods or have been at higher levels in foods grown before the advent of modern agricultural pest control,” wrote the researchers.

Another method is external challenge post-harvest plants such as grapes with UV radiation, which leads to an increase in the levels of resveratrol in grapes.

“These phytoalexin-enriched functional foods would benefit the consumer by providing ‘health-enhanced’ food choices and would also benefit many underutilized crops that may produce phytoalexins that may not have been considered to be beneficial health-promoting foods,” they concluded.

Research: Journal of Agricultural and Food ChemistryPublished online ahead of print, ASAP Article, doi: 10.1021/jf8040403“Phytoalexin-Enriched Functional Foods”Authors: S.M. Boue, T.E. Cleveland, C. Carter-Wientjes, B.Y. Shih, D. Bhatnagar, J.M. McLachlan, M.E. Burow

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