As goes Whole Foods (WFM) , so goes United Natural Foods (UNFI) - Get Report . It's a correlation that isn't necessarily constructive as United Natural Foods heads into its fiscal first quarter earnings release, due out after the close of trading Wednesday.

United Natural Foods, the Providence-based distributor of natural and organic mostly branded food products, is slated to post adjusted EPS of 62 cents for its Oct. 29 ended fiscal first quarter. That would be a decline of 1% over last year's result. Revenues are expected to rise - and by a healthier 15% - to $2.3 billion, but some of that year over year increase is a reflection of the company's acquisitions, rather than organic demand improvements.

While United Natural doesn't have the same business model as food retailers, such as Kroger (KR) - Get Report or SuperValu (SVU) , the food distributor isn't inoculated against the headwinds buffeting the grocery segment, which include deflation in food prices, robust competition, a heavy promotional environment, and a decline in foot traffic in retail stores.

Like all players in the food segment, United Natural Foods' grocery customers have felt the impact of increased pressure from a resurgent Walmart (WMT) - Get Report , which continues to bolster its market share in the grocery sector.

Unlike, say, fast food restaurant operators, which have been challenged by consumers' changing tastes, United Natural does at least offer a line of products that satisfy those consumers' demands for healthier, natural food options. The characteristic has helped the company put up positive earnings surprises in three of the last four quarters. Nevertheless, its healthier pedigree hasn't keep the food distributor from the pressure on margins, as it feeds into the traditionally low-margin grocery sector. When its customers gets spanked, United Natural cries.

It's correlation with Whole Foods is unimpeachable. A comparison chart of the two stocks shows that both stocks topped out for the latest cycle back in February 2015: United Natural at $83, Whole Foods at $56.

Since, the stocks have lost 35% and 36%, respectively, and the two year stock charts resemble two skiers tacking each other on the way down a steep mountain. United Natural stock is down 28 cents at $49.08 in Tuesday's intraday trading.

The correlation isn't some kind of quirk. United Natural Foods is the top vendor into Whole Foods, and Whole Foods is the distributor's top customer, accounting for 30% of sales. In its latest fiscal fourth quarter, Whole Foods reported that same store sales declined 2.6%, as the retailer tried to distance itself from its long-standing "whole wallet" reputation.

United Natural Foods has tried to offset some of the pressures stemming from the weak operating environment that confronts its grocery customers by undertaking several acquisitions, including its recent purchase of the Global Organic business. That's helped the top line remain relatively robust, but it's served to continue to compress margins in its core business.

When it reported its fiscal fourth quarter results, United Natural Foods management projected relatively modest top line growth for the whole of fiscal 2017, pegging its sales at $9.4 to $9.7 billion, with EPS expected to come in at $2.53 to $2.63.

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