What are the health benefits of soy?

What is soy? 
Soybeans were one of the first foods to be grown by humans. Soy is a subtropical plant, native to southeastern Asia. This member of the pea family (which includes beans, dried peas, lentils and chick peas.) grows from one to five-feet tall and forms clusters of three to five pods, each containing two to four beans per pod.

Soy

Soy has been a dietary staple in Asian countries for at least 5,000 years, and during the Chou dynasty in China (1134-246 B.C.), fermentation techniques were discovered that allowed soy to be prepared in more easily digestible forms such as tempeh, miso, and tamari soy sauce.

Tofu was invented in 2 nd -Century China. Soy was introduced to Europe in the 1700s and to the United States in the 1800s. Large-scale soybean cultivation began in the United States during World War II. Currently, Midwestern U.S. states produce approximately half of the world's supply of soybeans.

Soy contains protein, isoflavones, and fiber, all thought to provide health benefits. Soy is an excellent source of dietary protein, including all essential amino acids. Soy is also a source of lecithin or phospholipid. Soy isoflavones and lecithin have been studied scientifically for numerous health conditions. Isoflavones such as genistein are believed to have estrogen-like effects in the body, and as a result are sometimes called "phytoestrogens.

Nutritional value of soy
250 ml (1 cup) of cooked soybeans contains as much protein as 100 g of cooked meat, chicken or fish. The quality of soy proteins can be compared to meat proteins, while other legumes are not considered complete sources of protein.
All legumes, including soy, have no cholesterol. Even though soy is a little higher in fat than other legumes, it’s only good fat (monounsaturated and polyunsaturated fats, including omega-3 fatty acids)!
Soy is also an excellent source of minerals including calcium, iron and zinc:

• Calcium is essential for building and developing strong bones and teeth.
• Iron is used to carry oxygen to tissue and muscle cells.
• Zinc is important for growth, immunity, healing wounds and perceiving taste.

Our bodies don’t absorb plant iron (from legumes, grains, vegetables, nuts, tofu) as well as animal iron. Eat a source of vitamin C with meals to help your absorption of plant iron. Some examples of vitamin C-rich foods are citrus fruits, red peppers, strawberries and broccoli.

Soy protein has also been investigated for benefit in terms of other cardiovascular disease risk factors, reducing menopausal symptoms, weight loss, arthritis, brain function, and exercise performance enhancement. Dietary soy may decrease the risk of breast cancer in women and prostate cancer in men, as well as other types of cancers. 

In general, the supportive evidence for use of phytoestrogens as treatments for menopause, cardiovascular disease, osteoporosis (weak bone mass), and cancer is limited. The use of soy formula has been investigated in the treatment of diarrhea in infants and is an effective and safe alternative to cow's milk formula in most infants. Due to limited human study, there is currently not enough evidence to recommend for or against the use of soy for weight reduction.  

Soy products
Soy products are made from soybeans. Common sources of soy isoflavones include roasted soybean, green soybean, soy flour, tempeh, tofu, tofu yogurt, soy hot dogs, miso, soy butter, soy nut butter, soy ice cream, soy milk, soy yogurt, tofu pups, soy cheese, bean curd, seitan, and soy noodles. Soybean flour is found in Spanish sausage products (chorizo, salchichon, mortadella, and boiled ham), doughnuts, and soup stock cubes. Grocery stores carry many different kinds of soy products. Once you become familiar with them, they can become part of your regular eating habits. Some include:

• Tofu – Firm or extra-firm tofu can be used in vegetable stir-fries, soups and pasta sauces. Silken tofu is good for preparing smooth sauces, dips, creamy desserts, shakes or soups.
• Roasted soybeans - Soybean can be soaked in water then roasted in oil or using dry heat. Roasted soybeans taste like peanuts and are sold plain, salted or seasoned.  They are a nice alternative to peanuts and contain less fat ; 11 g per 60 ml versus 18 g for the same amount of peanuts
• Soy beverages - Soy beverages are made using ground-up soybeans. The grinding extracts a liquid that looks like milk.  You can drink a soy beverage ‘as is’, or you can use it to replace cow’s milk in tea, pour it into a bowl of cereal or even use it for cooking sauces and soups.   Soy beverages usually contain between 5 g to 9 g of protein per 250 ml (1 cup). Milk contains about 8.5 g of protein per 250 ml, so try to choose a soy beverage that has over 7 g of protein per 250 ml.   However, soy beverages can’t really place milk unless they are fortified.
• Fortified soy beverages have just as much calcium, vitamin D, B2, A and zinc as milk and can even contain more vitamin B12 than milk. Soy beverages also provide an average of 8 to 14% of the recommended daily iron intake (1 to 2 mg of iron per cup of drink).