The major phytoestrogen groups are isoflavones, flavones, coumestans and lignans. The former three are flavonoids. Isoflavones are found in high concentration in soy bean and soy bean products (eg. tofu) where as lignans are mainly found in flax seed.

Some studies indicate that phytoestrogens have health benefits including potential reduction in breast cancer, prostate cancer and cardiovascular disease risks, possible protection against osteoporosis (bone loss) and menopausal symptoms. Besides, both flavonoid and lignan phytoestrogens have antioxidant activity.

Estrogen is available in medically formulated pills. However, dietary estrogen (phytoestrogen) can be also found in wide variety of food products (including herbs), even though the level varies depending on the source. Below is a short list of phytoestrogen food sources analyzed by researchers in Canada. The Canadian researchers analyzed 121 food samples, of which the food samples with the highest total phytoestrogen content are presented below. The food samples with the highest total phytoestrogen content were nuts and oil seeds followed by soy products.

Total phytoestrogen content presented below is the sum of isoflavones (genistein, daidzein, glycitein, formononetin), lignans (secoisolariciresinol, matairesinol, pinoresinol, lariciresinol), and coumestan (coumestrol).

Table 1. Foods high in phytoestrogen content.

Phytoestrogen food sources	Phytoestrogen content (µg/100g)
Flax seed	379380
Soy beans	103920
Tofu	27150.1
Soy yogurt	10275
Sesame seed	8008.1
Flax bread	7540
Multigrain bread	4798.7
Soy milk	2957.2
Hummus	993
Garlic	603.6
Mung bean sprouts	495.1
Dried apricots	444.5
Alfalfa sprouts	441.4
Dried dates	329.5
Sunflower seed	216
Chestnuts	210.2
Olive oil	180.7
Almonds	131.1
Green bean	105.8
Peanuts	34.5
Onion	32
Blueberry	17.5
Corn	9
Coffee, regular	6.3
Watermelon	2.9
Milk, cow	1.2