Ever since milk alternatives started trending — making my Starbucks order more unnecessarily complicated than ever — I’ve wondered: What exactly is the difference between them? Obviously, the main distinction is the source from which the “milk” is obtained, but how do they compare in terms of nutrition? Is one better than another in terms of sustainability practices? Which alternative milk is the best? 

Luckily, these quandaries are pretty easily resolved. Here’s the scoop on the different kinds of milk, their nutritional breakdown and environmental impacts. 

The Usual Suspects

cow looking at camera
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Cow’s Milk: Nutritionally Complete, but Environmentally Terrible

Cow’s milk naturally contains a bunch of nutrients that our body requires, including calcium, vitamins D, A, B2 (riboflavin) and B12, and minerals such as magnesium, zinc, potassium and phosphorus. The FDA’s Dietary Guidelines for Americans has flagged three of those nutrients — calcium, potassium and vitamin D — as a public health concern because people aren’t consuming enough of them. Perhaps equally importantly, cow’s milk is high in protein — higher, in fact, than most plant-based milk. 

One of the downsides to cow’s milk (at least from a nutritional standpoint) is that it can be high in saturated fat, which is less heart-healthy than unsaturated fats. If you opt for nonfat (skim) or low-fat milk, however, you can still enjoy dairy milk while consuming less “bad fats” and calories.

But while cow’s milk reigns supreme in terms of nutrition, it is the absolute bottom of the pile when it comes to environmental sustainability. Joseph Poore, a researcher at the University of Oxford, released a study in 2018 that compared greenhouse gasses from over 10,000 farms around the world producing cow, almond, coconut and soy milk. This groundbreaking study concluded that cow’s milk has significantly higher impacts than plant-based alternatives across several metrics. The process of getting cow’s milk on the table creates three times as much greenhouse gas emissions, uses almost 10 times as much land, requires two to 20 times as much fresh water, and creates much higher levels of eutrophication (the pollution of ecosystems with excess nutrients) than any of the milk alternatives.

To further nail this point home, let’s just consider one metric: freshwater usage. According to Poore’s research, it takes 628.2 liters of fresh water to produce one liter of dairy milk. Almond milk, which has been controversial here in the States for its high water usage, uses around 40% less: 371.46 liters of water per liter of almond milk. Oat milk, in comparison, requires just 48.24 liters of water per liter of milk.

Milk sitting in soy nuts
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Soy Milk: The Next Best Thing

Soy milk is probably most comparable to cow’s milk, since it contains similar amounts of protein and typically is fortified with calcium and vitamin D. (Not all soy milk brands are created equal, though, so be sure to read the nutrition label to make sure you’re getting the benefit of these added nutrients.) It is available in both sweetened and unsweetened varieties for those monitoring their sugar intake.

Research suggests that a higher intake of phytoestrogens, the compounds found in soy products, is associated with health benefits like better bone health and a lower risk of cardiovascular disease and some cancers. Other studies have also shown that a diet rich in soy products can reduce menopausal symptoms — another reason to perhaps give soy milk a try.

Soy milk is better than cow’s milk from an environmental standpoint, as well. It uses less than a tenth of the water that almonds require and produces fewer greenhouse gasses than dairy milk production. However, soy production has been shown to contribute to deforestation, especially in the Amazon rainforest. You can avoid being part of that problem if you purchase soy milk made from organic soybeans grown in the United States. (As a side note, it’s also been shown that almost 95% of Brazil’s soy crop is used for animal feed, so the soy that’s problematic is not often found in soy milk imported from Brazil. It’s still wise to be aware of the issue.)

milk surrounded by oats
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Oat Milk: Not Bad, Great for Coffee Drinks

While oat milk has more protein than almond milk, the levels still fall short of cow or soy milk. Like most of the plant-based alternatives, it is usually available fortified with calcium and vitamin D. However, it also contains phytates, which are known to bind to certain minerals — like calcium — and reduce their absorption rate. Oats also contain a functional compound called β-Glucan, which is associated with improved blood glucose and insulin resistance. 

In environmental terms, oat milk is comparable to soy milk. It requires about the same amount of land to produce, just slightly more water, and it produces a smidge fewer greenhouse gas emissions. 

Almond Milk: Meh

Almond milk is popular because it is a lower-calorie option than cow or soy milk, but with fewer calories comes fewer nutrients: Almond milk naturally contains very little protein and carbohydrates (if unsweetened). It does contain vitamin E and small amounts of unsaturated fats, and some almond milk is fortified with calcium and vitamin D. 

milk surrounded by almonds
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Almond milk also contains arabinose, which is a noncaloric sugar that some scientists hope could eventually be helpful for those with metabolic syndrome. (Science has a long way to go before they can prove this with human studies, unfortunately. So far, it’s only been successful in helping obese lab rats.)

When it comes to sustainability, almond milk would rank among soy and oat milk when it comes to emissions and land use, but the water needed to produce it is through the roof. Almonds have one of the largest water footprints in agriculture, requiring 3.2 gallons of water to produce one almond. Put another way, a single glass of almond milk requires 74 liters to make, which is more than used in a typical shower. This is highly problematic, especially considering the fact that 80% of the world’s almonds are produced in California, where water usage continues to be a major issue. All that considered, however, almond milk still uses less water per liter to produce than dairy milk. 

Top image by Anna Puzatykh from Getty Images, via Canva.com

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