In the past few decades, Americans have moved gradually away from traditional cows’ milk in favor of several non-dairy alternatives such as almond milk, coconut milk, hemp milk, and oat milk.[1] Americans today drink 37 percent less dairy milk than they did in 1970. Since 2011, annual dairy milk sales have dropped from $15 billion to $11 billion, while sales for popular non-dairy alternatives rose from $900 million to $1.4 billion. Some cite health concerns for these shifting preferences, including lactose intolerance, caloric content, and dairy allergies.[2]

Non-dairy milks in the "milk" aisle at Whole Foods. Since 2011, annual sales for non-dairy milks have risen from $900 million to $1.4 billion
Non-dairy milks in the “milk” aisle at Whole Foods. Since 2011, annual sales for non-dairy milks have risen from $900 million to $1.4 billion. Photo from Sarah Cardwell-Smith.

Official government and medical stances on cows’ milk remain positive—pointing to cow’s milk’s superior nutritional profile.[3] A 2018 literature review concluded that “the totality of available scientific evidence supports that intake of milk and dairy products contribute to meet nutrient recommendations, and may protect against the most prevalent chronic diseases, whereas very few adverse effects have been reported.”[2]

Despite these glowing reviews of cows’ milk, the public seems to remain unconvinced, as non-dairy milk sales continue to rise. Further, while there exists an array of studies investigating milk’s effects on nutrition and mortality risk, the evidence remains conflicting and inconclusive.[4]As non-dairy milk alternatives rise in popularity, it is important to consider both the health and the environmental implications of all available options. Many types of milk—as do many types of food—require a large amount of water and energy for their production. Excessive water use depletes the natural environment, while excessive energy use in general emits large quantities of carbon dioxide. Excessive carbon dioxide in the atmosphere contributes to climate change, which affects human health in the form of natural disasters, water shortages, compromised air quality, and more. Certain crops must also be treated with high levels of pesticides to protect them from disease. Excessive pesticide use ultimately decreases crops’ ability to survive extreme environmental and climate changes and infectious diseases, which puts them at a greater risk of extinction.Below is a summary of milk and four of its common alternatives—and their respective impacts on human health and the natural environment.

The milk aisle at Whole Foods
The milk aisle at Whole Foods. Photo by Sarah Cardwell-Smith.

Cows’ Milk

Cow’s milk’s major claim over its non-dairy competitors is an overall more diverse nutrition profile. Cow’s milk also has naturally more protein and anti-microbial properties than most plant-based milk options–leading many researchers to deem plant-based milks “nutritionally inferior” to dairy milks.[5] Compared to plant-based milks, cows’ milk tends to have a higher calcium content—unless the plant-based milks are fortified, in which case they often contain higher amounts of calcium than bovine milk.[6]

Some scientists, however, question the assumed value of milk as an important source of calcium. A 2013 analysis pointed out that cows’ milk is, evolutionarily, a recent addition to the human diet, and that we actually have no nutritional requirement for animal milk. These researchers point out that while milk’s importance is often justified by a need to obtain adequate dietary calcium, there are many other significant food sources of calcium besides milk.[7]

While cow’s milk may not take a toll on our health, the production of cow’s milk certainly takes a toll on the environment.

While cow’s milk may not take a toll on our health, the production of cow’s milk certainly takes a toll on the environment.[2] Dairy cows produce about 150 billion gallons of methane each day—and methane is 25 to 100 times more harmful to the atmosphere than carbon dioxide. Globally, raising livestock is responsible for 18% of greenhouse gas emissions. Nitrous oxide from both manure and fertilizer, as well as carbon dioxide emissions from changes in land use and the machinery and vehicles required to produce and transport dairy products, all contribute to climate change.[8] Dairy milk does, however, have the highest nutrient density per its greenhouse gas emissions, compared to non-dairy milks.

Some estimates say that producing a single gallon of cow’s milk requires more than 600 gallons of water. Approximately 55 percent of the United States’ freshwater supply is used for raising animals for food.

Despite its nutritional strength, health and environmental concerns with dairy milk have become considerable enough to drive consumers to explore other options.

Almond Milk

Almond milk is the fastest-growing non-dairy milk in North American, European, and Australian beverage markets.[5] In the past five years, almond milk sales have grown more than 250 percent. Almond milks tend to have the lowest average protein content and calorie content compared to both milk and non-dairy alternatives—and a low calorie content is exactly what some consumers are looking for in a milk.[6] Almonds also have a high monounsaturated fatty acids (MUFA) content, which can be helpful in weight loss and weight management. They also contain vital nutrients such as vitamins E and A, manganese, and fiber.[5] On the other hand, some brands of almond milk contain a stabilizer and thickening agent called carrageenan, which may be associated with digestive issues. 

While almond milk’s low-calorie content and considerable nutrient content has made it a popular dairy alternative, the environmental impact of its production poses a significant concern. (One 2016 article made the dramatic claim that “almond milk, the ever-popular soy-free, dairy-free, vegan-friendly milk substitute now found everywhere from hip restaurants to coffee shops, is ruining the world.”) Growing almonds requires large amounts of water and pesticides—sixteen gallons of water are required to produce just fifteen almonds. Further, 23,000 acres of natural lands, primarily in California where 80% of the world’s almonds are grown, have been converted to almond farms. Sixteen thousand of those acres were lands formerly classified as wetlands.

One study notes the environmental “trade-offs” of dairy milk production versus almond milk production. Researchers at UCLA pointed out that while almond milk production emits fewer greenhouse gasses than does cow’s milk production, cow’s milk production uses less water than almond milk production. They concluded that “these two products present a trade­off where consumers must decide which environmental impact is more important: water usage or climate change.”

Coconut Milk

Coconut milks are generally less calorie-dense than dairy milks, although the majority of these calories come from saturated fats.[5] This milk substitute boasts a generally good taste, but also contains no protein, no calcium (unless added), and high levels of saturated fats.[6] Some studies have found that the lauric acid in coconut fats can increase one’s HDL (high-density lipoprotein) levels, which help reduce LDL (low-density lipoprotein) levels in the blood stream.[6]

Traditional coconut farming is relatively easy on the environment as it requires little fertilizer or pesticides. Because most coconuts are grown in southeast Asia, however, the carbon footprint of transporting the product to the United States is large.

Soy Milk

Soy milk is rich in protein and fat compared to other common milk substitutes and contributes to an overall balanced diet. Because it contains comparable amounts of nutrients to cow’s milk, some researchers say it is “the best alternative for replacing cow’s milk in human diet.”[6]

Soy and soy milk contain isoflavones, which have been shown to exhibit anti-cancer properties.[7] Some argue, however, that the benefits of isoflavones are offset by soy’s potential role in breast cancer. Further, many consumers complain of soy milk’s “beany” taste, which has led them in search of other vegan milk alternatives such as almond and coconut.[5]

Compared to other milks, manufacturing soy milk requires one of the lowest amounts of fossil fuel energy—it takes only 1 kilo-calorie (kcal) of fossil fuels to produce 3.2 kcal of soybeans, while it takes 14 kcal to make just one kcal of dairy milk. This “carbon footprint,” however, does not account for the amount of water used to produce the product. Further, growing soy tends to require intensive farming and pesticide use.

Hemp Milk

One serving of hemp milk provides nearly half of the daily recommended calcium intake. It also contains vitamins A, B12 and D, iron, potassium, riboflavin, magnesium, and linoleic acid, an essential omega-3 fatty acid. It does not, however, contain the other essential omega-3 fatty acids such as EPA and DHA.[6]

Hemp milk is a fast-growing crop that naturally suppresses weeds and resists many diseases, thus eliminating the need for most pesticides, herbicides, and fungicides. It requires little space and little watering to grow, and actually enriches the soil, making it possible to grow other food crops immediately after harvesting hemp. These qualities make hemp-based products among the most sustainable to produce.

Hemp milk at a grocery store
Hemp milk at a grocery store. Photo via Flickr by Jeepers Media.

Once a staple of the American diet, cows’ milk may someday be left behind for its vegan alternatives. Existing studies evaluating milk’s impact on health, however, are conflicting, inconclusive, and often operate on the assumption that dairy milk is a necessary part of the human diet.

While food journalist and activist Michael Pollan would advise us to eat more plants and fewer animal products, many doctors continue to warn patients against possible consequences of substituting plant milks for animal milks. As the future of milk consumption in America is uncertain, it is important to consider environmental impacts of milk production along with health impacts. Failure to do so may lead us to make health decisions that are beneficial in the short term, but are ultimately unsustainable. Further comprehensive studies are needed to assess the nutritional and health impacts of plant milks versus animal milks, as well as their associated impacts on the natural environment.

References:
[1] McCarthy, A., Parker, M., Ameerally, A., et al. (2017). Drivers of choice for fluid milk versus plant-based alternatives: What are the consumer perceptions of fluid milk? Journal of Dairy Science, 100(8): 6125-6138.
[2] Thorning, T., Raben, A. et al. (2016). Milk and diary products: good or bad for human health? An assessment of the totality of scientific evidence.  Food & Nutrition Research, 60: 32527.
[3]Marangoni, F., Pellegrino, L., et al. (2018). Cow’s Milk Consumption and Health: A Health Professional’s Guide. Journal of the American College of Nutrition. DOI:10.1080/07315724.2018.1491016
[4] Lu, W., Chen, H. et al. (2016). Dairy products intake and cancer mortality risk: a meta-analysis of 11 population-based cohort studies. Nutrition Journal, 15(1):91.
[5] Vangs, S., Raghavan, V. (2018). How well do plant based alternatives fare nutritionally compared to cow’s milk? Journal of Food and Science Technology, 55(1): 10-20.
[6] Chalupa-Krebzdak, S., Long, C., Bohrer, B. (2018). Nutrient density and nutritional value of milk and plant-based milk alternatives. International Dairy Journal, 87:84-92.
[7] Ludwig, D., Willett, W. (2013). Three Daily Servings of Reduced-Fat Milk: An Evidence-Based Recommendation? JAMA Pediatrics, 167(9): 788-789.
[8] Makinen, O., Wanhalinna, V., et al. (2016). Foods for Special Dietary Needs: Non-dairy Plant-based Milk Substitutes and Fermented Dairy-type Products. Critical Reviews in Food Science and Nutrition. 56(3): 339-49.

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