NEW YORK, NY – SEPTEMBER 22: Actress Maggie Gyllenhaal poses for a photo a she unveils her “got milk?” ad at City Bakery on September 22, 2011 in New York City. (Photo by Jemal Countess/Getty Images)

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If you can drink a glass of milk without feeling bloated, getting gassy, or suffering diarrhea, the chances are your ancestors are from northern Europe. When humans first started milking cows, they processed the milk into fermented cheese, which destroyed the sugar lactose. About 7000 years ago, a gene spread across northern Europe that enabled humans to digest lactose, and thus to drink raw milk. Today, 80% of adults from northern Europe are able to drink milk without digestive distress. But in southern Italy where the lactose gene didn’t spread, only 30% of adults comfortably imbibe milk. And in China, less than 10% of adults are lactose tolerant. Interestingly, although less than a third of humans globally are lactose-tolerant, nearly all children younger than 8 years can digest milk, regardless of where they are from.

Today, lactose intolerant adults can choose from a wealth of plant-based milks such as Oatly, Silk, and Sproud. The global plant-based milk market was estimated at nearly 21 million US dollars in 2024, and was projected to grow by 7.4% a year. But this growth is threatened by the introduction of lactose-free milk, which has spurred an uptick in dairy milk consumption after years of declining sales. Still consumers are curious about milk alternatives, in particular whether they are healthy and for people and the planet.

Are plant-based milks good sources of protein, calcium, and Vitamin D?

Consumers like dairy milk because it is a good source of protein and calcium and is often fortified with Vitamin D and other important nutrients. Plant-based milks vary widely in their protein content depending on the plants they are made from. Oat, almond, and rice milks are low in protein whereas soy and pea milk approach the protein content of dairy. Surprisingly, pea and almond milk have higher calcium than dairy milk. Only some plant-based milks are fortified with Vitamin D, so the wise shopper should look at nutrient labels to compare dairy and plant-based milks. Consumers may also want to check for added sugars and other ingredients in plant-based milks.

According to the Physicians Committee for Responsible Medicine, “There is no apparent health rationale for recommending cow’s milk over plant-based milks.” I would add the caveat that it depends on the particular nutrients one is concerned about and the type of plant-based milk.

Are plant-based milks better for the environment?

Although dairy production has become more efficient thanks to breeding and better quality feeds, it is still a major contributor to water pollution and greenhouse gas emissions. Dairy milk emits about 9.5 kg of greenhouse gases per 100 grams of protein. These emissions are mostly from cows’ unique digestion, manure, and the fertilizers and pesticides used to grow cattle feed.

Fortunately, we have data that compares the overall environmental footprint of dairy milk to plant-based milks. Dairy milk is worse than plant milks on all accounts–it uses a lot more land and water, it emits a lot more greenhouse gases, and it contributes a lot more to water pollution or eutrophication. Although consumers are rightly concerned about the amount of water needed to grow almonds in California, almonds are also grown in areas with more rain, which is why the overall water use for almonds is lower than for dairy.

Note this figure is based on the amount of milk, which is why the greenhouse gas emissions of dairy milk are lower than in the earlier figure that calculates emissions in terms of the amount of protein.

Pea milk is a promising new entry into the plant-based market. Its emissions are even lower than other plant-based milks, about 0.3 g per liter of milk. Its low water use is also impressive, 86% lower than dairy milk. This is in part because the split peas used in pea milk are grown in northern climates with ample rainfall and thus don’t need irrigation.

A leading producer of pea milk is the Swedish company Sproud, which takes its commitment to sustainability seriously. According to CEO Sara Berger, Sproud’s products reduce the climate footprint of dairy by 80 to 85%. Berger also notes that the growth of plant-based milks spurs the dairy industry to reduce its own emissions.

Should humans abandon dairy milk to save the planet?

It depends. In the US and Europe, where dairy consumption is high and people have ready access to plant-based milks and other sources of plant proteins, it makes sense to reduce diary milk consumption for environmental reasons.

In low-income countries the typical farmer has three cows. Those tending the cows are often women, for whom livestock brings income and even independence. Milk and beef may be one of the few sources of protein. Reducing already low milk consumption could threaten basic health.

But here’s the catch. Emissions per pound of milk are declining in North America and Europe thanks to modern farming methods that make cows more efficient. If a single cow produces more milk, we need fewer cows to make the same amount of milk, and fewer cows means lower emissions and lower water use. In addition to breeding and better feeds, innovations such as feed additives that reduce methane in cow burps, will reduce emissions even more. A US or EU dairy operation can produce ten times as much milk per cow compared to a small farm in a low-income country.

So yes, humans in wealthier nations should seek out healthy plant-based milks and other alternatives to dairy milks for environmental reasons. We also need to help women and other farmers in lower-income countries adapt novel dairy practices that increase the efficiency of their milk production. In this way, the Global North and the Global South can work towards a more sustainable food system.