Soy isoflavones: information of properties and studies

ORIGEN AND DESCRIPTION
The use of soya as food for human consumption has been linked to the Chinese nation since its origin, as it has made up their principal source of protein.
Soya originates from the eastern region of the Asian continent. According to ancient literature, it has a high nutritional value widely disseminated in China, which then moved on to other Asian nations and subsequently to European nations. It was brought to the New World at the end of the 19th century, but its commercial importance was given during the transitional period between the First and the Second World War in which the normal supplies of coconut and African palm oil, from the Far East, were suspended causing the vegetable oil industry to resort to substitutes, such as soya.
In Central and South America, the countries where it is mostly grown are Brazil and Argentina.

BENEFITS OF SOY ISOFLAVONES

They possess a mild oestrogenic action, since isoflavones have a chemical structure which allows them to act in the same places as oestrogens, so that their behaviour partially supplies the role of these. They help relieve the symptoms produced during climacteric syndrome.
Isoflavones are also involved in the prevention of bone decalcification as they avoid, due to the oestrogenic effect, the mobilization of calcium from the bones. They also avoid the blockage of calcium absorption which is caused when blood plasma oestrogen levels descends.
During menopause is when the use of calcium, vitamin D and isoflavones are particularly recommended. In this phase of a woman’s life, a series of important changes happen in the body.
Due to hormonal changes, it is necessary to take into account a few recommendations regarding health and diet. During this stage of change, women are at a higher risk of osteoporosis, alterations in blood lipids and atherosclerosis, as well as an increase in weight.
For this reason, correct eating habits prior to the beginning of these processes can produce a decline in the effect of these hormonal changes, and of the prevalence of determined pathologies.

HOW DO SOY ISOFLAVONES WORK IN OUR ORGANISM?
Alleviate the symptoms of menopause.
Reduce the risk of suffering cardiovascular diseases: Inhibit muscle contractility of blood vessels. Act in platelet aggregation processes reducing the risk of thrombus formation. Produce a moderate decline in LDL (bad cholesterol) concentrations, especially in people with high cholesterol levels.
Beneficial effect on bone loss.
Anti-oxidant action, comparable to that of vitamin E, produces effects such as the relaxation of blood vessels, the decrease in the oxidation of proteins which transport cholesterol from the liver to different parts of the body and activates its metabolism with which the risk of atheromatous formation in the arteries is diminished. Amongst the isoflavones, genistein has the greatest anti-oxidant ability.
Increase in hyaluronic acid production, produces an improvement in the appearance of the skin.
Selective Oestrogen Receptor Modulators. There are two types of oestrogen receptors:
Alpha-receptors: present in the breasts, uterus, ovaries, testicles and liver. The continuous union of oestrogens to these receptors predispose the development of tumours; they are carcinogenic. The phytoestrogens that join to the alpha-receptors avoid oestrogen from joining them, working as alpha-receptor blockers; therefore, helping reduce the risk of cancer.
Beta-receptors: present in some blood cells, lungs, prostate, bladder, bones and the thymus, they are responsible of the beneficial effects. The phytoestrogens join to these receptors when the quantity of oestrogen is low. They work by imitating the action of oestrogens.
The affinity of isoflavones to these receptors is determined by the chemical structure, which although isn’t derived from cholesterol, is very similar to animal oestrogen. The affinity of phytoestrogens to beta-receptors is 30 times greater than to alpha-receptors, which is why they are considered selective modulators of said receptors.

CHEMICAL COMPOSITION OF SOY ISOFLAVONES
Soya is a protein-rich food; it contains almost all of the essential amino acids that the body needs to manufacture its own proteins. It is rich in lecithin and both omega-3 and omega-6 fatty acids. It provides minerals such as iron, copper, magnesium, phosphorus, potassium and manganese and vitamins such as vitamin K, thiamine, riboflavin and folate. Its sodium content is low. Its fibre content is high, which facilitates the intestinal transit.
Soya is one of the richest foods in isoflavones, vegetable derived compounds with beneficial health effects.

SCIENTIFIC STUDIES ON SOY ISOFLAVONES
A recent study showed that isoflavones have powerful anti-oxidant properties, comparable to that of vitamin E. These anti-oxidant benefits can help reduce the risk of cancer in the long run. Genistein is the most powerful anti-oxidant amongst soy isoflavones, followed by daidzen.
Scientists of the IMABIS Foundation of Malaga, made available to the Spanish Biomedical Research Centre in Physiopathology of Obesity and Nutrition (Centro de Investigación Biomédica en Red-Fisiopatología de la Obesidad y Nutrición: CIBERObn), have revealed the protective properties of soy isoflavones against weight gain, the activation of thermogenic brown fat, or the reduction of associated hepatic steatosis.
These facts are the results of a study tested on animals published by the “British Journal of Pharmacology”. If its similarity to humans is accepted, it would suppose “a new therapeutic path against obesity using, rather than pharmaceuticals, this active ingredient of soya”, explains IMABIS. For many years natural elements have been considered beneficial towards health and this finding “reinforces this theory”. Furthermore, isoflavones have anti-oxidant powers, anti-carcinogenic and protective properties of the osseous or coronary system. Isoflavones act as analogues of determined hormones that are secreted by the human body, such as oestrogens.
Studies carried out on mice were headed by Fernando Rodríguez Fonseca, doctor of the Hospital Universitario Carlos Haya of Malaga and group leader of CIBERObn. During the process the rats were nutritionally induced to gain weight with a diet rich in carbohydrates and fats. Because of this, the animals began to suffer obesity, diabetes and fatty liver. After that, the scientists dispensed the isoflavone diadzien during two weeks. Past this time, the animals were sacrificed and it was found that “the higher the doses of diadzein in the diet, the lower the weight gain and the lower the presence of hepatic fat. Apart from witnessing the beneficial role that it plays in obesity and diabetes, by improving glucose control and the resistance to insulin”, points out Rodríguez de Fonseca. This was not the only conclusion obtained as high levels of leptin, known as the hormone of thinness as it inhibits appetite, and low levels of adiponectin appeared. Because of these results, scientists recommend isoflavones in one’s diet, “Especially when hepatic steatosis is present”.
Epidemiological studies suggest that the differences in diet could explain the lower incidence of cardiovascular disease in Japan compared to countries such as the U.S.A. and the United Kingdom, which have the lowest dietary consumption of isoflavones. The action mechanisms of isoflavones in relation to cardiovascular health include hypocholesterolemic effects, anti-oxidant properties and vascular effects on the platelets and cytokines. The potential anti-atherogenic effects of isoflavones include the reduction of high density lipoprotein cholesterol, modulation of pro-inflammatory cytokines, cell adhesion proteins and the formation of nitric oxide, protection of low density lipoproteins against oxidation, inhibition of platelet aggregation and the improvement of vascular reactivity. Isoflavones could have an effect against skin damage caused by the sun, which include cancer and skin aging. In animals and human beings, the topical application of genistein before UV exposure seemed to protect the skin.
The Sociedad Iberoamericana de Información Científica (SIIC) 2002 mentions that the studies on humans confirm that isoflavones can exercise beneficial hormonal effects to prevent many illnesses observed in western populations (breast cancer, menopausal symptoms, osteroporosis and cardiovascular disease), whose diet usually lacks these natural compounds.

PRECAUTIONS
In numerous studies on human beings, the ingestion of foods or supplements rich in isoflavones with exposure between 1-6 months of 3 Mg/D up to 131 Mg/D of aglycone equivalents, no adverse effects have been reported, which gives supporting evidence of the safety of chronic consumption of isoflavones at this level of exposure.