Harnessing Phytoestrogens in Your Diet

Author: Jessica Lloyd
Senior Naturopath | BHSc(N) | ISSVD, ISSWSH, BSSM, ATMS

Last reviewed: October 19, 2025

Phytoestrogens are plant chemicals, flavonoids, that behave like oestrogen in humans. These plant oestrogens are about 300 times weaker than human estrogen, which can augment the estrogenic effect in the body by weakening regular estrogen (in case of excess) or increasing it from low estrogen (say in postmenopause)¹.

We can use phytoestrogens for a weak and strong relative effect, depending on the person’s needs. We would also be cautious in using phytoestrogens in men, babies, children and those without estrogen imbalances.

Some Sciencey Stuff
Most phytoestrogens are flavonoids, with the most potent being coumestans and isoflavones (genistein and daidzein). Most research has been done on isoflavones, which are found in soy and red clover. Lignan - not a flavonoid - is also a phytoestrogen. These are phenolic phytoestrogens. 

Some other molecules, plant steroids and terpenoids, may also have an estrogenic effect.

Sources of phytoestrogens

While many plants contain phytoestrogens, only some contain enough that we’d use them medicinally.

Foods with phytoestrogens include:^2,3

Flax seeds (high in lignans)
Legume seeds (soy, beans, peas, high in isoflavones)
Soy products (tofu, tempeh, soy milk, soybeans, high isoflavones)
Sesame seeds
Wheat
Berries
Oats
Barley
Dried beans
Lentils
Rice
Alfalfa
Mung beans
Apples
Carrots
Wheat germ
Ricebran
Soy-linseed bread

The amount of phytoestrogens in a particular food varies depending on processing. An intake of 45mg of phytoestrogens daily may have a stabilising effect on hormones.

Searchable phytoestrogens food list

Plant species (Common name)	μg/100 g dry weight	Levels
Plum	5	Very Low
Wheat (white meal)	8	Very Low
Banana	10	Very Low
Apple	12	Very Low
Oatmeal	13	Very Low
Potato (peeled)	16	Very Low
Lentil	23	Very Low
Pea	27	Very Low
Cabbage	33	Very Low
Tritacle (meal)	35	Very Low
Wheat (wholegrain)	36	Very Low
Cabbage, Turnip-rooted	43	Very Low
Poppy seed	51	Very Low
Tritacle (wholegrain, wheat variant)	52	Very Low
Barley (wholegrain)	80	Low
Barley bran	85	Low
Onion	91	Low
Pistachio nut	96	Low
Beetroot	100	Low
Almond	111	Low
Cauliflower	111	Low
Rye meal (wholegrain)	112	Low
Wheat bran	121	Low
Hazelnut	123	Low
Paprika	124	Low
Rasberry	139	Low
Sharon	145	Low
Cabbage, Red	160	Low
Red currant	165	Low
Walnut	173	Low
Oat bran	179	Low
Witloof/Endive	190	Low
Cloudberry	203	Moderate
Caraway seed	235	Moderate
Chickpea/Garbanzo bean	250	Moderate
Black-eyed pea/Cow pea	255	Moderate
Cashew nut	261	Moderate
Rye bran	299	Moderate
Black gram bean	361	Moderate
Carrot (skin on)	370	Moderate
Garlic	380	Moderate
Kidney bean	396	Moderate
Black currant	398	Moderate
Peanut	420	Moderate
Broccoli	451	Moderate
American groundnut (potato bean)	511	Moderate
Pigeon pea	517	High
Clover seed	518	High
Zuccini (skin on)	817	High
Blueberry	835	High
Sesame seed	852	High
Cranberry	1054	High
Strawberry	1210	High
Lingonberry	1510	High
Tea, Yellow label tea-bag	2591	Very High
Sunflower seed	2600	Very High
Tea, Earl Grey tea (Oriental tea mixture)	3212	Very High
Kudzu leaf	3371	Very High
Tea, Pure Lapsang Souchong tea (China)	3520	Very High
Tea, China Gunpowder	3672	Very High
Pumpkin (peeled)	3874	Very High
Tea, Japan Sencha Green tea	4075	Very High
Tea, Nippon Sencha Green tea	5565	Very High
Tea, Prince of Wales, tea-bag	5768	Very High
Tea, China Green tea	5965	Very High
Tea, Green	8000	Very High
Black tea	8500	Very High
Soy bean	88843	Extremely High
Kudzu root	197631	Extremely High
Flaxseed	370987	Extremely High
Flaxseed (crushed)	547300	Extremely High

Herbal medicines with phytoestrogens include:

Red clover
Alfalfa
Hops (what beer is made from)
Liquorice
Turmeric

How plant estrogens work in the human body

Phytoestrogens bind to certain estrogen receptors in select tissues, activating or down-regulating the response of cells.

Breast and uterine tissue have the most ER-alpha estrogen receptors, while metabolic processes for the cardiovascular system and bones tend towards ER-beta receptors.

With other factors in play, the impacts of estrogens can be estrogenic or anti-estrogenic. In breast and uterine tissue, ER alpha receptors are downregulated by phytoestrogens, which may explain the possible anti-cancer benefits.

Phytoestrogens may also impact the balance of estrogen metabolites (the end result of estrogen metabolism), of which three are unfavourable to the body (16 alpha-hydroxy estrone, 4-hydroxy estradiol and 4-hydroxy estrone) and one favourable (2-hydroxy estrone).

Phytoestrogens may protect against cancer in the prostate4, breast and uterus (and others)5 and may offer protection against heart disease and osteoporosis. Soybeans contain multiple anticarcinogens, with isoflavones noteworthy due to soy being the only significant dietary source.

Phyto-oestrogens and the thyroid

Isoflavones in soy and flavonoids from other plants inhibit thyroid peroxidase, an enzyme involved in thyroid hormone synthesis. High intake of phyto-oestrogens may result in worsening hypothyroidism or goitre in iodine-deficient individuals or those with hypothyroidism.⁴

Iodine deficiency increases the thyroid-blocking impact of soy, with iodine reversing this process.

How to use soy products for their phytoestrogens

In postmenopause, phytoestrogens can play a role alongside the adrenals in adding to the overall estrogenic effect on the body, helping to relieve genitourinary symptoms of menopause (GSM) – dry, easily irritated or damaged vaginal and vulvar tissue, urinary incontinence, etc.

We also use phytoestrogens in vaginal treatments such as Fennelope fennel pessaries for a local effect, which has been shown to thicken vaginal epithelial cells⁵. This thickening reduces the vulnerability of cells and can help provide much-needed glycogen in vaginal cells to support protective vaginal flora.

How soy is helpful in other ways

Soy protein can be helpful in some people as a source of complete protein, as soybeans contain all essential amino acids.

People with a history of hormone-related cancers (breast, ovarian, prostate) may benefit from a low animal fat diet and future protection from endogenous estrogens.

Regular intake of soy products can also decrease ‘bad’ cholesterol (low-density lipoproteins or LDL cholesterol) by as much as 10%, with every 1% drop equalling around a 2% drop in heart disease risk. This is significant. The FDA determined that diets with four daily soy servings can reduce levels of low-density lipoproteins.

Soy products may be a valuable dietary addition for some people, beyond the potential benefits for vaginal health.

References

1.
Setchell KDR. Soy Isoflavones—Benefits and Risks from Nature’s Selective Estrogen Receptor Modulators (SERMs). Journal of the American College of Nutrition. Published online October 2001:354S-362S. doi:10.1080/07315724.2001.10719168
2.
Mazur W, Adlercreutz H. Naturally occurring oestrogens in food. Pure and Applied Chemistry. Published online September 1, 1998:1759-1776. doi:10.1351/pac199870091759
3.
Thompson LU, Boucher BA, Liu Z, Cotterchio M, Kreiger N. Phytoestrogen Content of Foods Consumed in Canada, Including Isoflavones, Lignans, and Coumestan. Nutrition and Cancer. Published online July 2006:184-201. doi:10.1207/s15327914nc5402_5
4.
Doerge DR, Sheehan DM. Goitrogenic and estrogenic activity of soy isoflavones. Environmental Health Perspectives. Published online June 2002:349-353. doi:10.1289/ehp.02110s3349
5.
Yaralizadeh M, Abedi P, Najar S, Namjoyan F, Saki A. Effect of Foeniculum vulgare (fennel) vaginal cream on vaginal atrophy in postmenopausal women: A double-blind randomized placebo-controlled trial. Maturitas. Published online February 2016:75-80. doi:10.1016/j.maturitas.2015.11.005