Is soy or almond milk truly milk? It depends on the definition of milk, and it looks like that definition could receive similar consideration that the definition of mayonnaise received when Unilever asked the Federal Drug Administration to look into Hampton Creek's use of the word "mayo" on its eggless "Just Mayo" product. Unilever argued that labeling an eggless product as mayo was false advertising.

Along those lines, 32 members of Congress, many of them from large dairy states, have written a letter to the FDA telling the agency to "order manufacturers of plant-based drinks to find some other name," according to NPR. With the backing of the National Milk Producers Federation, an organization that represents dairy farmers, the letter says it is "illegal and misleading" for these products to be called milk and cites the FDA's definition of milk as "the lacteal secretion, practically free from colostrum, obtained by the complete milking of one or more healthy cows (21 CFR 131.110)."

Looking at that definition, I wonder if it's time to change it. This definition not only excludes plant-based milks, it excludes goat milk, sheep milk and other mammal milk that humans consume as traditional milk, to say nothing of ingredients in foods, particularly cheese. A strict interpretation of that definition would not only make it illegal for makers of almond milk to label their product as milk, it would also make it illegal for the ingredients list on goat cheese to list "goat milk" as an ingredient.

Should only cow's milk be labeled as milk, or should the definition include other kinds? If so, should it include only milk from animals or should it also include plant-based liquids that are used like animal milk?

Making milk political

The FDA has not yet responded to the letter sent by members of Congress, but as we saw with the Just Mayo labeling, when a big food manufacturer applied enough pressure, the FDA suddenly took notice.

Dairy milk sales have been in decline in recent years. According to Mintel, its sales decreased 7 percent in 2015 and are expected to continue to drop through 2020. Sales of non-dairy milk were up 9 percent in 2015 and are expected to continue to increase.

If sales of milks like soy, almond, coconut and hemp continue to increase while dairy milk sales continue to decrease, it wouldn't be surprising if this letter from members of Congress isn't just the first step in pressure being put on the FDA to limit the use of the word "milk."

Personally, I'm not mislead when I see alternative milk products labeled as milk. I know they don't come from an animal. The word "milk" has been associated with them for a long time, and the practice is accepted by consumers.

Perhaps the FDA does need to look into the use of the world "milk," but the agency should look at it from all sides and consider expanding the definition instead of making it illegal for plant-based milks to use the term.

If you feel differently, please tell us why in the comments.

Robin Shreeves ( @rshreeves ) focuses on food from a family perspective from her home base in New Jersey.