If you’re lactose intolerant, allergic to milk, or follow a dairy-free diet, you’ve probably tried countless milk alternatives—and may even have a favourite brand or variety. But if you rely on milk for nutrients like calcium and protein, you should choose your plant-based alternative wisely.

Despite the fact that milk alternatives are often marketed as appropriate equivalents to cow’s milk, not all varieties provide equivalent macronutrients, according to a just-published meta-analysis. To come to this finding, the researchers at McGill University in Canada used existing research to compare the nutritional makeup of several unsweetened soy, almond, rice, and coconut “milks.” In the end, they found that soy milk was the most nutritionally similar to cow’s milk, which researchers consider to have an ideal ratio of proteins, fats and carbs. The other milks reviewed lack nutrients the researchers say are essential for overall health.

But just because it’s the closest to cow’s milk doesn’t mean that soy milk is the best option for everyone.

“Some news outlets reporting on this study are saying that soy is the ‘healthiest,’ but that’s a bit misleading,” says dietitian Rebecca Ditkoff. “What the study actually uncovered is that in terms of nutrition, soy milk is most comparable to cow’s milk. It contains the same essential nutrients and roughly the same amount of protein per 250mL serving. But as with many nutrition recommendations, there isn't a single milk alternative that’s healthiest for everyone."

“When choosing [between] cow’s milk or a non-dairy milk, one has to consider how their milk of choice fits into the context of their overall diet, needs, and personal taste preferences,” says Ditkoff. Here are a few things to consider when selecting your next carton:

Do you have any allergies?

Soy milk is not suitable for anyone with a soy or milk protein allergy, cautions dietitian Isabel Smith. “Milk and soy proteins look the same to the body.”

Do you rely on milk for protein and calcium?

“Yes, soy milk has more protein than other milk alternatives, but not all brands are fortified with calcium, so make sure you read your labels,” says Smith. This is important if you rely on milk for your daily dose of the bone-building mineral or regularly use it as a base for a snack or meal. (Think: smoothies, soups, etc.) “If you have at least a cup of ‘milk’ daily, and don't want to sip soy, try an unsweetened pea milk. Like milk, a 250mL serving has 8 grams of protein. It’s also fortified with calcium and vitamin D,” Smith says.

If you aren’t looking for a protein- or calcium-rich alternative because you get plenty of those nutrients elsewhere throughout the day, unsweetened coconut or almond milk are both fine, says dietitian Sarah Koszyk.

Do you only add a splash to your coffee?

If you only use milk to lighten up your morning cup of joe, then what you use isn’t all that important. “Whatever non-dairy milk you choose, use one that’s unsweetened, free of artificial sweeteners, and has some protein or healthy fat,” Smith says. (You could even use cow's milk so long as you don't have an allergy.)

Do you only avoid cow’s milk because you’re lactose intolerant?

You might not have to.

“Many people who consider themselves lactose intolerant, actually aren’t. The issue is that they cannot tolerate a type of casein protein in milk called A1,” Koszyk says. The other type of casein protein in milk, called A2, can often be tolerated without side effects, likely because of a small difference in the proteins' amino acid make-up.

What’s all this have to do with which milk you buy? “There’s now a milk on the market which is a cow's milk that is missing the A1 protein,” Koszyk says. “a2 Milk can give you the same benefits as dairy milk such as calcium, vitamin D, and protein, without the discomfort.”

Among all the milks on the market, the study researchers say that cow’s milk has the best composition of nutrients for humans (it's the closest to human breast milk), so keeping it part of your diet certainly has its benefits. Especially since the authors note that “further research is needed to establish the consequences of added calcium in the human body.” Simply put, it’s best to get nutrients naturally, rather than from fortified sources or supplements, and this milk allows you to do just that.

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