Yet another reason to keep gardening!
http://www.msnbc.msn.com/id/37396355/ns/health-diet_and_nutrition/Chemicals that speed growth may impair ability to absorb soil's nutrientsWhile we've been dutifully eating our fruits and vegetables all these years, a strange thing has been happening to our produce. It's losing its nutrients. That's right: Today's conventionally grown produce isn't as healthful as it was 30 years ago — and it's only getting worse. The decline in fruits and vegetables was first reported more than 10 years ago by English researcher Anne-Marie Mayer, PhD, who looked at the dwindling mineral concentrations of 20 UK-based crops from the 1930s to the 1980s.
It's happening to crops in the United States, too. In 2004, Donald Davis, PhD, a former researcher with the Biochemical Institute at the University of Texas, Austin, led a team that analyzed 43 fruits and vegetables from 1950 to 1999 and reported reductions in vitamins, minerals, and protein. Using USDA data, he found that broccoli, for example, had 130 mg of calcium in 1950. Today, that number is only 48 mg. What's going on? Davis believes it's due to the farming industry's desire to grow bigger vegetables faster. The very things that speed growth — selective breeding and synthetic fertilizers — decrease produce's ability to synthesize nutrients or absorb them from the soil.