The organic food industry is growing like a weed. It’s not terribly hard to do considering before 2002 there was no such thing as “organic” by FDA standards, but forecasts showed consumption of organic food jumped 11% between 2011 and 2012 – the last known read. That means Americans are shelling out some $28 billion a year on organic food.

But does that mean the companies that deal in organic are a good investment? Brad Lamensdorf from the Ranger Equity Bear ETF says no. As far as specifics, he’s calling out United Natural Foods (UNFI) – a major supplier to Whole Foods (WFM), the godfather of the organic food movement.

“Whole foods has had a lot of trouble recently, though,” points out Lamensdorf.

Wal-Mart (WMT) has announced it will carry organic food in a clear attempt to undercut the prices at chains like Whole Foods, meaning the high-end grocery niche may be getting squeezed.

But the problems at Unify are greater than just whole foods. “This company has six-folded its sales over the last about 10 years, but they have not been able to get any incremental margin expansion,” said Lamensdorf.

UNFI’s inability to grow profit while growing sales is central to Lamensdorf’s short. “We feel like the cap x that they’re having to consistently put into the business is keeping their margins very low,” he said. “We just don’t think it’s a very good business.”

This is a big deal for investors who are looking to invest in organics because they see the writing on the wall as far as consumer trends go. It’s clear organic products are here to stay, with everyone from Wal-Mart to Target focusing their efforts on chemical free goods. But don’t be deceived by the feel-good nature of these companies.

“There’s not any fraud, persay, but the stock is ver, very rich valuation wise, and we just think for a company that looks like its growing, it’s cash flow is actually falling and it’s going cash flow negative,” said Lamendorf. “[It] is really alarming for an investor who would think that they were long a growth stock,” he said.