Gone are the days when non-dairy milk is consumed only by vegans or those with dietary restrictions. Any grocery store offers an array of dairy-free milks: Oat, almond, soy, cashew, coconut, rice, sesame, and pistachio milk, among others. According to a Food Manufacturing Consumer Report from September 2021, non-dairy milk accounts for 10 percent of the total milk market in the US and continues to grow.

The most popular non-dairy milk in the US is almond, with two-thirds of market share, followed by oat milk, the fastest-growing non-dairy milk. But dairy-free doesn’t necessarily mean your dairy-free milk is healthy. Many contain additives like carrageenan as well as added oils. Some are also harmful to the planet.

So which is the healthiest non-dairy milk: almond or oat? Here's what to know before you buy your next non-dairy milk or make that dairy-free latte.

Is carrageenan bad for you?

Carrageenan is an additive used to thicken and emulsify foods and is often used in non-dairy milk. Many vegan products use carrageenan in place of gelatin to avoid the use of animal products, as carrageenan is extracted from a red seaweed called Irish moss. This allows manufacturers to label the ingredient as natural, vegan or plant-based. So one would assume this means carrageenan is safe, right? The research on it is mixed.

“Some small animal studies indicate carrageenan may increase inflammation, but more research is needed in human studies to understand the impact of carrageenan on human health," explains Erin Palinski-Wade, R.D. and author of 2-Day Diabetes Diet. Although this additive is considered safe by the Food & Drug Administration, it was removed from the list of approved foods by the National Organic Standards Board so it’s no longer allowed in foods labeled ‘organic’.”

A 2016 report by the Cornucopia Institute linked carrageenan with multiple gastrointestinal issues, such as inflammation, lesions, and ulcers. This information is based on animal and human cell studies, so the evidence on health is inconclusive. Food & Function concludes more research is needed to indicate whether or not carrageenan is healthy for humans.

Many brands of almond milk and oat milk are carrageenan-free and widely available. If you’re concerned about this additive in your non-dairy milk, be a conscious consumer and read the ingredients list before buying.

Which milks contain oil?

Whether your non-dairy milk of choice is almond or oat, keep an eye out for brands that contain oil. Common oils found in non-dairy milk are canola oil, sunflower oil, rapeseed oil, and palm oil. These oils act as emulsifiers to make the milk more rich and creamy, but it comes at the price of extra calories. The good news is the amount of oil added to non-dairy milk tends to be minimal with only a trace amount of fat and additional calories per serving. However, the oils found in non-dairy milk aren’t necessarily unhealthy. Canola oil for instance has been shown to have numerous health benefits, such as improving cardiovascular risk factors. Here are seven plant-based milks which don't contain added oil.

If you’re on the fence about deciding whether or not to buy non-dairy milk because there’s oil in the ingredients, know that it’s in small amounts with minimal health impacts. What’s more concerning is that many non-dairy milks, including almond and oat, contain added sugars for enhanced flavor. Added sugars (different from natural sugars found in whole foods) should be limited in a healthy diet. Fortunately, most brands of almond milk and oat milk have ‘unsweetened’, ‘unflavored’ or ‘sugar-free’ options. Generally, these are also the brands that offer carrageenan-free non-dairy milk.

What is the most environmentally friendly milk?

Non-dairy milks are hands down better for your health and the planet compared to cow’s milk. They contain less unhealthy fats and fewer calories, use less land and water, and produce lower amounts of greenhouse gases. With that said, non-dairy milks aren’t exactly environmentally friendly. Some require huge quantities of water (almond), are produced in unsustainable environments (coconut), or are grown in massive quantities to feed livestock for meat and dairy production (soy).

Almond milk gets a bad rap as one of the least ‘green’ non-dairy milks because almond trees require large amounts of water. It takes approximately 15 gallons of water to produce only 16 almonds. To its credit though, almond milk has the lowest greenhouse gas emissions of non-dairy milks because almond trees store plenty of carbon dioxide as they grow. Oat milk on the other hand has a smaller environmental footprint. This is because of how oats are grown in rotation to create crop diversity, reduce soil erosion and lower the risk of plant diseases. Another relatively unknown plant milk that has a small environmental footprint is sesame milk, made from sesame plants that are drought-tolerant, self-pollinating, and naturally pest-resistant.

A word of caution: Always choose organic when buying oat-based foods. A 2018 EWG study found the chemical glyphosate present in many non-organic oat products. Don’t panic if oat milk is your favorite addition to your morning coffee. Many non-dairy companies, like Oatly, are certified organic and third-party tested to ensure their product is free from this harmful chemical.

A BBC Science Focus article compared the environmental impact of the top five non-dairy milks. Per one glass (200 milliliters), almond milk requires 74.3 liters of water (oat milk 9.6), 0.1 square meters of land use (oat milk 0.15), and emits 0.14 kilograms of greenhouse gases (oat milk 0.18). All this compared to regular dairy milk, which requires 125.6 liters of water, 1.79 square meters of land use, and emits 0.63 kilograms of gases.

“Any non-dairy milk will, on average, be multiple times more environmentally friendly than the average cow’s milk,” says Dr. Dana Ellis Hunnes, author of Recipe for Survival: What You Can Do to Live a Healthier and More Environmentally Friendly Life. “Cow’s milk also uses twice as much water to produce one gallon of cow’s milk compared with almond or rice milk, and ten times as much water per gallon as soy or oat milk.”

Bottom Line: Both almond milk and oat milk are nutritious non-dairy options that are better for the environment than dairy.

They both have their benefits and drawbacks in terms of health and environmental impact. At the end of the day, choose whichever milk you prefer. Whether you’re vegan or not, the best choice you can make for your health and for the planet is to choose non-dairy milk over cow’s milk.

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