It would seem safe to assume that products labeled with the words "non-dairy" or "dairy-free" do not contain dairy, right? Surprisingly, that's not always the case. Despite the fact that these two labels are often used interchangeably, the terms can have very different meanings on food labels. So, what's the difference between 'non-dairy' and 'dairy-free?' Turns out they don't actually mean the same thing. And if you're trying to avoid dairy you need to know the difference.

While you can feel pretty sure a product — milk, cream, yogurt, sour cream, ice cream, cheeses — with "dairy-free" on its label contains no form of dairy, other products labeled with "non-dairy" may, in fact, contain some form of dairy, most notably, casein, the main protein in milk. Casein has been linked with the growth of cancer cells, specifically prostate cancer cells, which grew when exposed to casein.

So if you have a dairy allergy, intolerance, or sensitivity or are following a vegan or other dairy-free dietary approach, or want to avoid casein for health reasons, the distinction between dairy-free and non-dairy matters. A lot. It’s definitely confusing, but with a few navigational tips, you can enjoy your favorite plant-based dairy alternatives like plant-based coffee creamers with confidence.

Why avoid dairy

According to Andrew Dole, RDN, Have A Plant Ambassador for the Produce for Better Health Foundation, you should ask yourself if you need or want to avoid all dairy compounds, because the approach to labels will be different. “Someone needing to avoid dairy because of an allergy to a dairy protein like whey or casein doesn’t have a lot of wiggle room for making mistakes,” he says. “Food allergies are dangerous. However, for someone who likes dairy but finds themselves lactose intolerant, the solution is quite easy – choose lactose-free products.”

For those avoiding dairy for any reason, Dole advises replacing the nutrients you’re giving up when omitting dairy. A glass of cow's milk has 13 essential nutrients, so look to plant-based proteins from dairy-free alternatives such as almond milk, soy milk, oat milk, or other types of plant-based milk, and add protein from other plant-based sources like lentils or other legumes, soybean products like tofu, and whole grains like quinoa.

Food labeling terms aren’t always easy for consumers to understand, Dole explains. The terms "dairy-free" and "non-dairy" are two of the more confusing ones. Here’s the breakdown:

What does dairy-free mean?

The Food and Drug Administration (FDA) has no regulatory definition for the term, dairy-free. This means there are no regulations on how it can be used on package labels. (The FDA contends that it keeps this lack of regulation in check by not allowing the use of false and misleading terms on food labels.) Products labeled "dairy-free" should contain no dairy, and you should be able to trust this.

However, it's not an infallible system. An FDA survey on dark chocolate products labeled "dairy-free" found that certain products had detectable levels of milk that had the potential to cause severe reactions in milk allergic consumers. Though researchers found that 90 percent of the dark chocolate products tested with dairy-free claims could be considered safe for most people with milk allergies, the most susceptible could be at risk.

The Food Allergy Research & Resource Program has in past years identified products from small manufacturers labeled dairy-free that contained milk. Some companies use the term on products that are lactose-free, or on products that do not contain dairy ingredients, like milk or cream, but these products may still contain milk derivatives, such as the milk proteins casein and whey. If you’re allergic to milk or dairy, always be cautious and check the ingredients.

What does "non-dairy" mean?

The good news is that the FDA does have a regulatory definition for the term "non-dairy." The not-so-good news is that the definition allows the presence of milk protein, most commonly casein, but also whey, and other derivatives, in products labeled "non-dairy." Because casein (also caseinates) is a major milk allergen, the FDA requires it to not only be listed as an ingredient, it must be followed in parentheses by its source, such as “(a milk derivative).” As an allergen, the product will also include phrasing, such as “Contains: Milk” below the list of ingredients.

Interestingly, the regulatory definition for "non-dairy" began many years ago to protect the dairy industry from contenders that were posing as milk but not including enough milk in the product. This was intended to prevent dairy consumers (looking for real milk products) from being duped by dairy substitutes, or products with very low levels of milk in them, or using dairy-like products, for real dairy products. The FDA did this by requiring a non-dairy label on products that contained 0.5 percent or less milk by weight in the form of casein or caseinates. Times have changed, and now consumers are looking to products without milk.

What is casein?

Casein is the main protein in cow’s milk, which is made up of 80 percent casein protein and 20 percent whey protein. (Human breast milk contains 40 percent casein and 60 percent whey.) Casein is found in dairy products, infant formulas, and a variety of dietary supplements. Casein contains all 9 essential amino acids, making it a complete protein. It is popular among bodybuilders to promote muscle building and recovery and support bone health and prevent osteoporosis. It is also one of the most common food allergens. But casein also has been associated with health risks such as promoting tumor growth in the lab.

Note that lactose-free doesn’t mean a food is dairy-free or non-dairy, Dole explains. “It simply means there is no lactose present, but milk allergens like the proteins casein and whey can still be present. A person can be lactose intolerant or sensitive and not be affected by milk protein allergies at all. They aren’t connected,” he explains.

“There are different types of casein — A1 and A2 — and dairy products contain both. Some individuals are less tolerant of one type of casein and it can cause issues with digestion,” says Dole. This means that while some people can tolerate certain foods (like yogurt) others can't.

Research, such as that published in The China Study (2004), the groundbreaking bestseller co-authored by plant-based advocate T. Colin Campbell, suggests that animal-derived protein, and casein, in particular, cause cancer cells to grow in the lab. In a now-famous experiment, the tumors in lab animals fed casein grow, while tumors in animals given plant-protein shrank. And the results reversed when the diets were switched.

Dole explains that lab studies don't tell the whole story, since foods are not a single nutrient. “Unfortunately for science, but very fortunate for us, we don’t eat that way. There is a complex web of nutrients and interactions involved when we eat a whole food,” says Dole, and “casein is just one of many nutrients found in dairy products.” Still, if the casein study is enough to make someone want to stay away from it, then search the labels or go with "dairy free."

Consumers and dairy labels

“If you need to avoid dairy, start with the label,” says Dole. “The FDA does regulate the labeling of the top nine allergens to keep people safe. Milk and milk allergens will be listed even in the case of non-dairy products using milk protein-based ingredients.”

If you have an allergy to casein or whey, Dole advises caution with a non-dairy label, which does not mean the casein or whey are not present. “Dairy-free is a good visual marker. It can help someone decide which products are worth the time to read the ingredient label. After all, to make sure the manufacturer is providing a truly dairy-free product reading the label is the only way,” says Dole.

Dairy ingredients and derivatives

These are some of the most well-known dairy ingredients and derivatives to avoid on ingredients labels.

  • Milk
  • Cheese
  • Yogurt
  • Cream (heavy cream, sour cream)
  • Ice cream
  • Casein, caseinates
  • Whey, whey powder, whey protein, whey protein isolates
  • Lactose, milk sugar
  • Dry milk powder, non-fat milk powder
  • Butter, butterfat

How to identify products without dairy

  • Scan labels. Familiarize yourself with well-known dairy ingredients so you can spot them quickly.
  • Look for “Contains Milk.” If you spot this easy-to-see dairy indicator below the ingredients list, steer clear, as there’s no need to look further.
  • Buy trusted brands. Research brand websites or call companies before you buy to be certain their products do not contain dairy. Rely on transparent sources.
  • Look for a vegan logo. This is not FDA regulated, but products labeled as vegan means they don’t contain ingredients of animal origin, including milk, eggs, honey, and gelatin. “Certified Vegan” is one such logo. Visit vegan.org for companies that use this logo.
  • Look for Kosher Parve. This certification also denotes products made without dairy.
  • Buy whole foods. Packaged, prepared foods are more likely to have dairy hidden among a long list of ingredients. Choosing plant-based whole foods—produce, whole grains, nuts, and seeds, legumes—are naturally free of dairy.

Bottom Line: "Non-dairy" and "dairy-free" labels are not the same.

People wanting or needing to avoid all dairy should approach alternative dairy products with caution, especially items carrying a "non-dairy" label, which means they could contain dairy ingredients and derivatives. Become familiar with common dairy ingredients so you can spot them on the ingredients label, as well as allergens called out on the label. If you’re swapping dairy with dairy alternatives, be sure to replace those nutrients from other plant-based foods throughout the day.

For more great expert advice, visit The Beet's Health & Nutrition articles.