The two have a common goal: to build a better head of lettuce. Specifically, Britz, a research plant physiologist with the US Department of Agriculture's research unit, and Still, a professor of horticulture and plant and soil science at California State Polytechnic University at Pomona, seek to create varieties of lettuce that contain more antioxidants.
Antioxidants are darlings of the nutrition world, valued for their purported health-promoting and disease- busting qualities. But even as Britz and Still toil away, neither is sure antioxidants are all they're cracked up to be.
The body's daily functions, such as metabolizing food, and its exposure to such environmental hazards as pollution, produce stray molecules known as free radicals, which can oxidize, or interact with oxygen molecules, and damage cells.
Antioxidants can engage the free radicals before they do harm. Each antioxidant, from the anthocyanins and caretenoids to isoflavones and lutein, is thought to protect against a certain kind of cell damage. Ascorbic acid and lycopene are thought to reduce DNA damage, while flavonoids are believed to reduce the production of free radicals in the first place, and phenolics may slow heart disease.
One of the great mysteries about antioxidants is whether they can work in isolation or whether their efficacy depends on their interactions with one another and perhaps with other substances.
Another is whether they can do harm: recent research showing that vitamins C and E, taken as supplements, may reduce the health benefits of exercise has cast a pall on antioxidant supplements.
And there's a third mystery: is the disease-fighting capacity of fruits and vegetables directly attributable to antioxidants, or is it based on some other qualities or compounds in these foods?
Victoria Drake, a research associate at the Linus Pauling Institute at Oregon State University, said: "We know that antioxidant-rich foods can reduce the risk of chronic diseases, such as cardiovascular diseases. But evidence that very high doses of individual micronutrients or phytochemicals can do the same is inconsistent and relatively weak. A healthy diet is key; supplements should be used only as 'nutritional insurance.'"
A study in the May 29 issue of the journal PLoS Genetics raises the intriguing question of whether our bodies might benefit from some exposure to free radicals. Trey Ideker, who holds posts in the schools of medicine and engineering at the University of California at San Diego, has found in laboratory tests that limited exposure to oxidants may equip cells to better withstand larger exposures.
Most of the evidence on which antioxidants' reputation is based comes from studies of isolated cells exposed to plant chemicals or from research on rats and mice. While much of the research is compelling, none of it shows how antioxidants actually affect human health.
In any case, Britz and Still both observe that while we have a hunch that antioxidants are good for us, in fact they're not clearly essential to our health. "They're not like vitamins," Britz notes. "They're not necessary in that you don't get a deficiency response if you don't have them."
Yet both continue their work with lettuce, believing that it might lead to development of plants whose high levels of antioxidants may help them grow better and withstand the degradations of shipping and storage.
And altering green lettuce's colors by bumping up the antioxidants might make for a prettier plant. "If the lettuce is more attractive," Briz mused, "people might eat more of it - and less of things that are bad for them."
Source- The Washington Post
No comments:
Post a Comment