Soybeans are classified as oil seeds, not as dry beans. While whole dry soy beans contain about 40% protein, much more than most other beans, pulses and seeds, they do contain about 20% fat by weight.
Most of this fat is unsaturated (‘good fat’), but it nevertheless boosts the calorie content of soybeans (170 Calories per 100 g dry weight), to almost twice that of haricot and kidney beans (about 100 Calories per 100 g dry weight).
Whole soybeans are a fabulous source of vitamins and minerals, including folic acid, iron, niacin, riboflavin, thiamin, magnesium, phosphorus, zinc, iron and calcium.
Most people consume soybeans in one of its produced such as tofu, tempeh, miso, vegetable textured protein, soy milk and many other products. The high protein and avriety of amino acids are beneficial for vegetarians and vegans,
The health benefits of soybean products include protection against cancer, alleviation of menopausal symptoms, and benefits for reducing the risk of heart disease, lowering cholersterol and reducing the risk of osteoporosis.
Many of the health benefits of soy are derived from its isoflavones, which is a phytochemical and phytoestrogen with antioxidant properties.
But there has been various concerns raised about possible negative effects of isoflavones linked to the risk of causing goitre and hyperthyroidism. Isoflavones are structurally similar to the female sex hormone estrogen and concern has been raised that these chemicals may mimic the properties of estrogen, the natural female hormone.
This article provides detailed nutritional information about soybeans and soy products and reviews the information on their health benefits.
In many ways the health promoting soybean products are a 'mixed bad' of potential pros and cons.
This article provides an overview to guide your decision about soybeans.
The table opposite compares the macronutrients that contribute to the total energy content of soybeans with Haricot and Kidney beans. The major points are:
The table opposite shows the nutrients in cooked beans. The key points are:
The table below compares the nutrients on 100 g of soy milk, tempeh, tofu and miso. The key differences are:
|Nutrient||Haricot Bean||Kidney Beans||Soybean|
|Nutrient (100 g cooked beans)||Haricot||Kidney||Soy|
|Saturated fatty acids (g)||-||-||1.3|
|Monounsaturated fatty acids (g)||-||-||2|
|Polyunsaturated fatty acids (g)||-||-||5.1|
|Dietary fibre (g)||7.4||5.1||1.6|
|NSP total (g)||8.3||6.7||2.9|
|Soluble NSP (g)||3.7||3.2||0.1|
|Insoluble NSP (g)||4.6||3.5||2|
|Vitamin E (mg)||-||-||0.35|
|Folic acid (micro g)||-||-||54|
Substituting soy protein for animal protein generally reduces cholesterol and saturated fat intakes, indirectly lowering blood cholesterol and helping to reduce the risk of coronary heart disease. Over the last 20 years, a number of human studies have shown a direct effect of soybeans in the diet on lowering cholesterol levels. For example, one study showed that eating 30 - 60 g of soy protein a day decreased LDL cholesterol and total cholesterol by 20% and 10% respectively. In addition, triglycerides were reduced by 10% in another study.
Various epidemiological studies have suggested, without definite proof, that diets based on soybeans provide some protection against breast, prostate and colon cancer. Cell culture experiments have also shown that extracts from soybeans suppressed the induction of tumours in various organs.
Many researchers have discussed the lower incidence of menopausal problems in Japanese women compared to American, Canadian and Finnish women. There is some evidence that easting more soy products may help alleviate some of the symptoms. Research has also shown that high-soy diet increased bone mineral content and bone density in the lumbar region of the spine.
Many people in Asian populations consume 20 mg to 80 mg of the isoflavone, genistein per day, almost entirely derived from soy, whereas the dietary intake of genistein in the United States is only 1 mg to 3 mg per day. It is relatively easy to increase the intake of isoflavone without totally changing the diet. One half-cup of soy beans, one cup of soy beverage or 120 g of tofu provide 30 mg to 40 mg of genistein,
Isoflavones are often referred to as phytoestrogens (that is ‘plant estrogens’) because their chemical structure is quite similar to estrogen, the female sex hormone. But the differences are very significant. These plant estrogens are much weaker than naturally circulating human estrogens and they have less that 1% of the biological activity of synthetic estrogens. Research studies have demonstrated that the compounds in soybeans do not produce estrogen-like responses in humans, do not cause harm at the levels consumed in foods. Many Asian population have been consuming soy products for centuries.
There is some scientific evidence that soybean products may interfere with thyroid function. Thyroid hormones are important for regulation metabolism, brain development, growth, body temperature control and breathing. People with thyroid problems are advised to speak with their doctors before eating lots of soybean products. The general advice is that for other people, soybean products shouldn't have any effect on thyroid function provided people have adequate iodine in their diets.
Various research studies have shown that isoflavones, may disrupt the normal action of thyroid hormones, by inhibited the enzyme thyroid peroxidase, which plays a role in production of the thyroid hormones. However, a 2003 randomized controlled research study conducted by the Harvard Medical School found no difference in thyroid function a group of postmenopausal women subjects, half of which received 90 mg of soy isoflavones in their diet and the other half received a placebo. Eating adequate iodine in the diet can generally reverse or alleviate any effects of soybeans on thyroid function.
Soybeans are one of 5 foods most commonly causing food allergies in children, and one of 8 foods responsible for food allergies in the general population. Soybean allergies can trigger reactions ranging from hives to diarrhea, to serious breathing difficulties. Some people have soy intolerance reactions in their intestines similar to lactose intolerance.
|Product (Serving Size 100 g)||Soymilk||Tempeh||Tofu||Miso|
|Total Fat (g)||1.7||10.8||4.8||6|
|Total Carbohydrates (g)||6.3||9.4||1.9||26.5|
|Dietary Fiber (g)||0.6||0.3||5.6|
|Vitamin C (mg)||0||0||0.1||0|
|Pantothenic Acid (mg)||0.4||0.3||0.1||0.3|
|Vitamin B6 (mg)||0.1||0.2||0||0.2|
|Vitamin B12 (mcg)||0||0.1||0||0|
|Vitamin A (IU)||2.9||0||85.3||89.5|
|Vitamin E (mg)||0.1||0|
|Vitamin K (mcg)||3||29.1|
|Saturated Fat (g)||0.2||2.2||0.7||1.1|
|Monounsaturated Fat (g)||0.4||3||1.1||1.2|
|Polyunsaturated Fat (g)||1||3.8||2.7||3.2|