Soy has been around longer than most other plant-based options and is more popular due to taste, texture and a similar nutrition profile to cow’s milk, the only plant-based alternative to be recognized by the Dietary Guidelines for Americans. So how does it truly compare?
Unlike real milk, which is simply pasteurized and fortified after being produced by a cow, soybeans are usually soaked in water and ground before boiling the resulting slurry. Once strained, then other ingredients (like vitamins for fortification) are blended in to create a “milk”.
Further, a quick search online shows that while soy milk is the most comparable in price to real milk of plant-based alternatives, a half-gallon of soy milk is still over 11/2 times more expensive than a half-gallon of real milk.
Sustainably, greenhouse gas (GHG) emissions associated with soy’s production are about equal to almond milk, with the big difference being that soybeans use much less water than almonds do. Soybeans also have a lower impact on soil and need fewer nitrogen fertilizers. However, soybeans require more land than almonds, a possible challenge if the popular alternative to milk continues to increase in popularity.
On the nutrition front, soy milk has added calcium, vitamin A, vitamin D, riboflavin and vitamin B12, but it does not offer the same nutritional value as dairy milk, which has nine essential nutrients: calcium, vitamin D, phosphorous, protein, riboflavin, niacin, pantothenic acid, vitamin B12 and vitamin A. Soy milk may also contain added ingredients like sea salt, sugar, natural flavors and thickeners which are added to improve its consistency and shelf life. The ingredients and nutrition will vary according to brand, but soy milk can have up to 10 added ingredients. Meanwhile, milk has only two added ingredients, vitamin A and vitamin D, only bumping the added ingredient list total up to three for lactose-free milk (it includes an enzyme that breaks down lactose).
Soy milk is the closest alternative to be considered comparable to real milk, but not identical. Soy can be a good alternative choice if you cannot drink real milk due to a rare milk allergy, but dairy is still the superior choice.