The firm was last night served with a notice of intent to sue by consumer advocacy group Center for Science in the Public Interest (CSPI), which alleges that the company deliberately misleads consumers into thinking its products are healthier than they actually are.
According to CSPI, the firm confuses consumers by claiming its Soft & Smooth Made with Whole Grain White Bread combines "the taste and texture of white bread with the goodness of whole grain".
The group said claims such as 'made with whole grain', 'good source of whole grain' and 'now with 25% more whole grain' are "intended to deceive the consumer into thinking the bread is a whole-grain bread, when in fact it is not".
"The claim is particularly misleading because some breads are now made with 'white whole wheat', which really is whole wheat," wrote CSPI in the formal notice sent to the company.
However, Sara Lee said in a statement: "We find the tone of CSPI's letter offensive and much of its content uninformed.
If CSPI had contacted us before they issued their press release and demand letter, they would have seen that we have similar goals."
The company said its product portfolio includes 100 percent whole grain breads, enriched white breads and " nutritionally transitional " products made with a blend of whole wheat and enriched wheat flour.
These different product types help consumers increase their whole grain consumption " without a radical change in taste and consistency ", the company said.
Nutrition group The Whole Grains Council told FoodNavigator-USA.com that 'transition foods' are a good way to help consumers switch over to the nuttier, fuller taste of whole grains.
It added, however, that "most 'beginner' whole grain breads have at least 8g of whole grain per slice, while Sara Lee's Soft and Smooth Made With Whole Grain has just 4g of whole grain per slice.
8g is only about two teaspoons of whole grain flour - an amount that's easily incorporated into bread without sacrificing taste or texture."
Found in products such as whole wheat, oatmeal, popcorn and brown rice, whole grains consist of any grain that has retained its starchy endosperm, fiber-rich bran and its germ after milling.
These grains have long been known to provide high levels of fiber, but new research in recent years has also revealed that they provide vitamins, minerals and high levels of antioxidants.
The grains have also been shown to help reduce the risk factors for a number of diseases, including heart disease, cancer and diabetes.
On the back of this new science, the US government advised in its 2005 Dietary Guidelines that Americans should consume upwards of three ounce-equivalents of whole grain products per day.
Since then, products making whole grain claims have started swarming to supermarket shelves, but a lack of clear FDA guidelines has meant that claims differ - which ultimately leads to consumer confusion.
In an effort to help simplify things for consumers, health and nutrition groups such as the Whole Grains Council and the American Heart Association have released guidelines and symbols of their own.
These can be used on products to flag up the whole grain content, and to indicate whether products are good sources of the healthy grains.
Yet measuring what constitutes whole grains has come with challenges of its own, with internal debate ongoing between nutritionists, scientists and industry.
Variations and inconsistencies have resulted in confusion both at the consumer level, but also at the industry level.
The fine line between a lack of clear guidance and misleading claims can often, as in this case, lead to disagreements and accusations.
In its letter sent to Sara Lee, CSPI said it would seek an injunction prohibiting Sara Lee from claiming any products to be 'made with whole grain' or to have 'the goodness of whole grain' without specifying the percentage of grain that is whole grain.
It would also seek to prohibit claims suggesting that a product is a 'good source' or 'excellent source' of whole grain in the absence of FDA approval of such claims.
The group said it may also seek restitution, damages, disgorgement, and attorneys' fees.
CSPI said it would agree to a settlement before the suit is filed if Sara Lee follows these steps voluntarily.
Sara Lee now has 30 days to respond to CSPI's settlement offer.