Store brands now comprise 25 percent of organic product sales, 20 percent of all products with natural and fat claims and about 40 percent of products with preservative claims in at food, drug and mass merchandise retailers, according to Nielsen Co.

Tom Pirovano, director of industry insights at Nielsen, said in a blog that the fastest growing health and wellness claim among store brands in 2009 was “GMO free” with sales of these items up 67 percent to $60.2 million.

Thousands of organic and natural food products are enrolled in the Non-GMO Project's Product Verification Program (PVP), the nation’s first system designed to scientifically test whether a product has met a set of defined standards for the presence of GMOs.

Some of the companies now eligible to use the verification mark on product packaging include United Natural Foods, Whole Foods Market, organic rice producer Lundberg Family Farms, Eden Foods, Guayaki, SK Food, San-J, and R.W. Garcia.

The second fastest growing claim was “Gluten free,” up 62 percent to $279 million, followed by “Absence of specific fat,” which increased 53 percent in 2009 to $561 million, and “Lowers cholesterol,” up 45 percent to $3.7 million.

Pirovano said grocery chains didn’t waste time launching organic products under their store brands, pointing to the success of Topco’s Full Circle line of over 1,000 products in 90 categories, and the 300 items that Safeway sells under the “O” Organics brand.

However, supermarkets have not been as quick to develop new products under store brands that boast claims such as “high fructose corn syrup free,” which Pirovano said grew 28 percent in 2009 to just $13 million in sales.

He said retailers are “adopting a wait-and-see attitude to determine if a claim has ‘legs’ or is merely the latest blip on the consumer trend screen.”

Another claim, “Hormone/antibiotic free” increased 27 percent in 2009 to $186 million in sales.