Soy bean products are growing more and more popular — from milk to tofu, there is an entire spectrum of foods available. However, there are still some controversies over soy. So just how safe is it? And how much should you be eating? Dietitian separates t
SOY comes from soybean plants, which are part of the legume family. As soy is closely related to the likes of beans, peas and lentils, it too is a great source of plant protein. You will find the same amount of protein in 1.5 cups of cooked soy beans as you would find in 150g of meat. Unlike most other plant proteins, soy is considered a complete protein — meaning that it contains all the essential amino acids or building blocks that make up a really good source of protein.
Not only is it a good source of protein, but it’s also jam-packed full of vitamins and minerals. Most notable micronutrients include calcium and iron, making soy an excellent choice for vegans who omit the likes of iron-containing meats and calcium-containing dairy from their diet.
Like most legumes, soy beans are also an excellent source of fibre. Soy provides both soluble and insoluble fibre in excellent quantities. Soluble fibre is the gel-like fibre that helps soften the stool, while insoluble fibre is the roughage that bulks it out. Therefore soy beans can act like a sweeping brush, cleaning our gut and keeping things moving!
There are two things that make soy beans unique among their legume pals — how much fat they contain and their isoflavone content. Soy beans are about 20pc fat. Most other beans, peas and lentils are relatively fat-free. However, their fat content is certainly not a negative — the fat they provide is healthy fat, with about 60pc being polyunsaturated, and 30pc monounsaturated fatty acids. Soy beans are a rich source of isoflavones, which are antioxidants that have many health benefits. Each gram of soy protein is associated with approximately 2.2mg to 3.3mg of isoflavones. Isoflavone content can vary depending on soil and growing conditions.
There are many kinds of soy foods that are made from soy beans, such as tofu, soy milk, textured vegetable protein (TVP) and soy sauce. They are not created equal — their level of processing changes their nutrient profile.
Firstly, the fat content of soy foods differs depending on whether the whole bean is used. For example, TVP is fat-free, while other soy foods such as tofu and soymilk contain a little more fat.
Secondly, their isoflavones content varies, depending on how processed the food source is and how the soy protein was extracted from the soy bean. Tofu, soymilk, soy nuts, tempeh, edamame, soy flour and textured soy protein all contain significant amounts of isoflavones. Very processed soy-containing fast foods like soy burgers contain considerably less isoflavones than the more whole food varieties, while the likes of soy sauce contains none (see panel to the right).
Dietitian Orla Walsh gets to the core of common food myths