Soy Milk Nutritional Value

Soy milk is derived from steeping soy beans in water and extracting the liquid. It functions as a replacement for dairy milk to those with a lactose intolerance, or as an alternative for those who prefer its flavor. Nutritionally it is similar to milk, but being derived from a plant, it offers some different benefits.

Calories

Unsweetened soy milk provides 80 calories per cup. Flavored soy milks are higher in calories, ranging between 100 and 140 calories per cup due to the added sugars. Flavored soy milks designated as "light" provide 80 to 90 calories per cup, but are higher in carbohydrates and lower in fat and protein.

Macronutrients

Soy milk without any added sugar contains only 4 grams of carbohydrates, with 1 gram of fiber. It also provides 4 grams of fat. According to Silk Soy Milk, most of these fats are heart-healthy, with 2.5 grams of polyunsaturated fat, 1 gram of monounsaturated fats and only 0.5 grams of saturated fat. One cup of soy milk also provides 7 grams of protein; unlike most plant-based sources of protein, soy is a complete protein. A complete protein gives you the required amounts of all the essential amino acids.

Vitamins and Minerals

Most soy milk in the market is fortified with vitamins A and D. Unsweetened Silk Soy Milk provides 10 percent of your recommended intake of vitamin A and 30 percent of your recommended intake of vitamin D. It also provides 30 percent of the recommended intake of calcium. Soy milk is also a good source of riboflavin and magnesium, and provides 50 percent of your recommended intake of vitamin B12.

Heart-Healthy Benefits

A clinical study in Stanford, California published in the December 2007 issue of the "Journal of the American College of Nutrition" found that drinking soy milk reduced low-density lipoprotein, or bad cholesterol, 5 percent more than low-fat dairy milk in only four weeks. This reduction is attributed to soy protein and phytosterols. The FDA suggests that 25 grams of soy protein per day as part of a heart-healthy diet can lower your risk of developing heart disease. As an added benefit, soy milk is cholesterol-free. Soy milk contains phytosterols, plant-based nutrients capable of blocking and reducing the absorption of cholesterol. It takes 2 grams of phytosterols per day to reduce cholesterol; soy milk is a rich source, providing a third of that amount in 1 cup.

Soy and Breast Cancer

The Shanghai Women's Health Study, a population study conducted by Vanderbilt's Epidemiology Center and published in the April 2009 issue of the "American Journal of Clinical Nutrition," observed the risk and incidence of breast cancer in women and adolescents as related to their intake of soy. The study found that with long-term consumption of soy, starting from adolescence through adulthood, premenopausal women had the lowest incidence of breast cancer. Soy contains isoflavones, a plant-based phytoestrogen which acts as an anticarcinogenic, or cancer-preventing substance. The activity of isoflavones is what protects women from breast cancer.