Study: Organic food no more nutritious

>>> back now with health news getting a lot of attention. it's about organic foods . people who buy them and pay more for them do it for a lot of reasons, mostly because they're healthier. but are they? our report tonight from dr. nancy snyderman .

>> reporter: in supermarkets across the country and at farmers markets from coast to coast , increasingly, americans are buying organic. in 1997 , u.s. seals of organic foods topped off at $3.6 billion. fast forward to 2010 . sales total more than $26 billion. the reason?

>> you want to put something on your table that's healthy. and strayed from the farm is the best place to go.

>> whether that's healthy or not, i don't know. it makes even the -- it makes eating more interesting.

>> reporter: more interesting maybe, but a new stanford university study concludes that organic foods are no more nutritious than their conventional alternatives.

>> we didn't find stronger evidence of higher nutritional content in organic foods . we did find differences in the risk of detecting pesticide residues.

>> reporter: according to the report, organic produce is 30% less likely to carry pesticide residues than other fruits and vegetables. and organic chicken and pork are 60% less likely to have bacteria resistant common antibiotics. it may take years to link pesticides and antibiotics to long term health problems, but these are issues we have to consider today.

>> i really think people should be thinking about knowing where their food comes from, how it's grown, that it is economically, that it is environmentally sound.

>> reporter: according to those who study food purchasing preferences, millennials, those under age 30 are driving the trend.

>> they're choosing to want to eat more pure foods and organics is part of that decision process.

>> reporter: organic farmers and ranchers don't claim their foods are healthier, more than half of them in a recent poll believe organic is nutritious. your best advice, buy local . the shorter the distance between farm to table the better it's going to be. and the more nutritious. brian?

>> going to have people questioning a lot of things. nancy, thanks.