As a general rule, we don't recommend foods that have lost a significant amount of their natural, whole food value. Unfortunately, many soy milks are characterized by exactly this quality—they bear little resemblance to natural, whole soybeans and they have lost many of the health benefits associated with whole soybeans. Soy milks are often made with the use of soy protein isolate (SPI), an industrially-created component that provides no whole food benefits. Many soy milks are also sweetened with unwanted amounts of added sugar, and they have been produced with other additives and flavorings. For these reasons, soy milk as an overall beverage group contains many products that we don't recommend.
It is possible, however, to find commercial, prepackaged soy milks that are produced directly from whole soybeans. The process of making soy milk from whole soybeans typically starts with the soaking of the dry beans, followed by some mixture of grinding, boiling, and filtering. When soy milk products have been produced in this way, you will usually find the words "whole soybeans" high up on the list of ingredients, often in second place right after the words "filtered water." If you are purchasing prepackaged soy milk, we recommend that you purchase products that have been made from whole soybeans as indicated on the ingredient list.
Of course, we also recommend that you purchase organic soy milk to avoid unwanted contaminants and genetically engineered soybeans. On organic soy milk products, you will find the words "whole organic soybeans" high up on the ingredient list, usually in second place right after "filtered water."
Most full-fat soy milks have been made from whole soybeans according to the steps described above. For this reason, we typically recommend full-fat soy milks as higher-quality options. Some low-fat and "lite" soy milks have also made in this way and can also make good options, but be sure to check their ingredient lists for the words "whole soybeans" or "whole organic soybeans" (as well as absence of the words "soy protein isolate" or "soy concentrate") before purchasing.
From a research perspective, there is a difference in documented health benefits from whole soybeans versus processed soybean components (like soy protein isolates). In repeated research findings, whole food soybeans have been shown to provide us with better cardiovascular support than dietary supplements containing soy components. "Better" in this case means not only more consistent but also more in-depth cardiovascular support.
Another difference between soy milk made from whole soybeans and soy milk made from processed components like SPI involves phytate levels. Phytates are substances found in soybeans (and many other foods) that can lessen the absorption of certain nutrients, especially minerals. Soy products in general (including products that are minimally processed) typically contain 1.4 - 3.0% phytates. Soy isolates (commonly used production of low-fat soy milk) usually contain a minimum of 2.89% phytates. Therefore, you're more likely to get better nourishment from soy (especially mineral nourishment) if you consume it in whole food versus processed form.
Note that soy milks may claim that they are rich in certain vitamins and minerals. Yet, it's usually because they are fortified with those nutrients rather than being naturally concentrated in them.
While we are confident in recommending the purchase of lesser-processed soy milks made from whole soybeans, we would still like point out the difference between whole soybeans and soy milks made from them. When you consume whole soybeans, you get a complete range of nutrient and health benefits. This result is especially true if whole soybeans have been fermented in traditional versions of miso, natto, soy sauce, or tofu. In the world of soybeans, you cannot do better than whole soybeans in fermented form. However, since a large portion of the whole soybean is removed by filtration during the production of most commercial soy milks, you cannot get the full range of health and nutrient benefits from soy milk that you can get from whole soybeans, even when that soy milk has been produced from whole soybeans. But you can still get many valuable nutrient and health benefits from lesser-processed, whole bean soymilks, and many people find soy milk to be a very helpful and tasty addition to their meal plan.