WHAT ARE THE ISOFLAVONES?
The isoflavones are a selection of health boosting nutrients that are mainly found in soybeans and soy products. They are part of the flavonoid sub-class of phytonutrients (a group of chemical compounds which occur naturally in plants and have numerous health benefits but are not considered essential nutrients).
The isoflavones and the other flavonoids were discovered and isolated by the Hungarian biochemist Albert Szent-Györgi in 1938. At first he named the flavonoids vitamin P but it was later discovered that they are not essential to human health and therefore not technically vitamins.
Whilst the isoflavones are not believed to be essential nutrients in humans there are still plenty of reasons to consume them regularly. They act as powerful antioxidants and protect your body’s cells from free radicals (harmful by-products that are released during oxygen related reactions), prevent cancer and much more.
In this article I will be discussing 2 of the main isoflavones and their health benefits in greater detail:
Functions:- Daidzein is a powerful antioxidant and phytoestrogen (a compound which regulates estrogen levels in the body and can help prevent cancer, heart disease, osteoporosis (reduced bone mineral density) and negative menopausal symptoms). It can also prevent cancer (particularly breast cancer and prostate cancer) and stimulate the formation of osteoblasts (cells which produce bone mass and reduce your risk of developing osteoporosis).
Recommended Daily Allowance (RDA):- There is currently no official RDA for daidzein. However, research suggests that you should try to consume between 50 milligrams (mg) and 100mg of isoflavones each day to take advantage of daidzein’s health benefits. Consuming up to 200mg of isoflavones per day is believed to be safe but you should try not to exceed this limit.
Food Sources:- Daidzein can be found in various beans and peas with soy based products being the richest source. Some of the best foods for getting this isoflavone are green soybeans (67.79mg per 100 grams (g)), natto (21.85mg per 100g), soybeans (9.27mg per 100g), soy cheese (11.24mg per 100g), soy protein isolate (33.59mg per 100g) and tempeh (17.59mg per 100g).
Overdose Symptoms:- There are currently no reported overdose symptoms associated with daidzein consumption. However, some people are allergic to isoflavones and for these people consuming high levels of isoflavones can cause interference with mineral absorption and thyroid function.
Deficiency Symptoms:- There are currently no reported deficiency symptoms associated with daidzein consumption.
Functions:- Genistein is a powerful antioxidant, anthelmintic (a substance which removes parasitic worms from the body) and phytoestrogen. It can also prevent atherosclerosis (a condition where hard plaques form in the artery walls and restrict the flow of blood which ultimately increases your heart disease risk), cancer (particularly breast cancer and prostate cancer) and diabetes (by minimising insulin resistance and regulating blood glucose levels).
RDA:- There is currently no official RDA for genistein. However, research suggests that you should try to consume between 50mg and 100mg of isoflavones each day to take advantage of genistein’s health benefits. Consuming up to 200mg of isoflavones per day is believed to be safe but you should try not to exceed this limit.
Food Sources:- Green soybeans (72.51mg per 100g), miso (24.56mg per 100g), natto (29.04mg per 100g), soy cheese (20.08mg per 100g) and soy protein isolate (59.62mg per 100g) are some of the best genistein foods available. Black chickpeas (0.64mg per 100g), soybeans (9.84mg per 100g), soy milk (6.06mg per 100g) and white beans (0.74mg per 100g) are also good sources of this isoflavone.
Overdose Symptoms:- Provisional research has suggested that consuming extremely high levels of genistein may destroy male testicular cells (although there is contradictory research which suggests genistein has no effect on male testicular cells) and increase your cancer risk (by increasing the growth rate of certain breast cancers, interfering with certain cancer fighting drugs and reducing the body’s ability to fight cancer cells). However, further evidence is required before these overdose symptoms can be confirmed.
Deficiency Symptoms:- There are currently no reported deficiency symptoms associated with genistein consumption.
Most UK and USA diets contain very few if any isoflavones. However, by neglecting these important nutrients you are missing out on some serious health benefits. In particular, the cancer fighting properties of these phytonutrients is very impressive. This is illustrated best by comparing cancer rates in the UK and USA (where consumption of isoflavones and soybeans is very low) against Japan (where the average diet contains between 100mg and 200mg of isoflavones and cancer rates are much lower).
Fortunately, the isoflavones can easily be added to your diet. Try cooking with soybeans, purchase soy milk instead of regular milk and occasionally switch your whey protein isolate for soy protein isolate. This will keep your body topped up with isoflavones and give it the nutrients it needs to fight cancer, diabetes, oxidative damage and more.