Among the proposed changes in the more than 500 pages revising the Nutrition Facts label are tweaks to the daily values, or reference daily intakes, of a range of nutrients.

The RDI for calcium, based on a 2,000-calorie diet, would go up from 1,000 milligrams to 1,300 milligrams, for example, and for potassium from 3,500 milligrams to 4,700 milligrams. The reference intake for fiber would go up to 28 grams from 25 grams.

These differences could complicate matters for food manufacturers and change the claims they can make on packages about whether a product is a “good” or “excellent” source of a nutrient.

“As FDA changes the daily values, it’s indirectly, but very significantly changing its rules for health claims and disclosure rules for nutrient content claims,” said Bruce Silverglade, an attorney who represents the food industry at OFW Law. “That’s the elephant in the room that few people have recognized as of this point.”

Some segments of the food industry, however, are looking at these changes closely.

“The requirements for vitamin D are doubling, so milk will no longer be an excellent source. It will still be a good source,” said Cary Frye, of the International Dairy Foods Association. “That was a big surprise to us.”

So, while FDA has estimated that the food industry will spend about $2 billion on the new label, some estimate that costs will be much higher — and go beyond the label itself.

“There’s going to be a huge investment to changing their whole marketing strategies,” said Jillian Wein Riley, an associate with the global law firm Reed Smith, and a former FDA attorney. “One cup of milk would have 23 percent of the percent daily value [for calcium], whereas it’s 30 percent now. From a marketing perspective, a fifth doesn’t sound nearly as good as a third.”

Corrected to say Reed Smith is a global law firm.