What Does Soy Milk Contain?

Soy milk is a nutritious beverage produced by grinding and straining water-soaked soybeans. It can be a milk substitute for lactose intolerant and strictly vegetarian people. Soy milk is a storehouse of a wide range of readily bioavailable nutrients, including protein, vitamins, minerals and a little digestible calcium. For a low-fat diet, soy milk is highly preferred, because it reduces cholesterol levels and, by extension, the risk of coronary heart disease.

Protein

Soy milk is a complete source of protein, containing ample amounts of all nine essential amino acids. The protein content in soy milk is a little over the amount found in cow's milk. Soy milk averages from 7 to 10 g of protein, depending on the brand. It is a "low-glycemic index" food, which means it raises glucose levels slowly and therefore puts less pressure on the pancreas to produce insulin. This helps manage type 2 diabetes and insulin resistance. The suggested daily intake of soy protein for a balanced diet is about 25 g per day.

Fat

One cup of unfortified soy milk contains almost 4.5 g of fat. In addition to energy storage, healthy polyunsaturated fat provides essential fatty acids and serves as a carrier for the absorption of fat-soluble vitamins. Soy milk is naturally cholesterol-free and contains little saturated fat. Thus, people with heart disease and weight problems are advised to drink soy milk to keep cholesterol in check.

Vitamins

Soy milk is rich in B-vitamins and vitamin K. Fortified soy milk may contain even higher amounts of these vitamins. The amount of vitamin B-12 in a cup of processed soy milk is almost 1 mcg, and the RDA for B-12 for adults is 2 mcg per day. The level of vitamin K is a little higher in soy milk than in cow's milk, at 3 mg per 7 ounces. Vitamin K reduces the formation of blood clots, so people with bleeding disorders should consult a physician before consuming soy milk.

Isoflavones

The anticarcinogenic effects of soy milk stem from its isoflavones, compounds with antioxidant and estrogenic properties. Soy milk contains about 10 mg isoflavones per 3.5 ounces. Soy isoflavones may have protective effects against estrogen-induced breast cancer, but this hypothesis is far from definitive, according to J. Lynne Brown, Ph.D., R.D., an associate professor of food science at Penn State University Extension. Soy isoflavones may also offer protection against bone density loss in older men and women. However, this premise has not been clinically confirmed. The maximum safe dietary soy isoflavone intake is 35 to 55 mg per day.