Understanding and using phyto-oestrogens in food

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

We can use phyto-oestrogens for a weak and strong relative effect depending on the person’s need. We would also be cautious in using phyto-oestrogens in men, babies, children and those without oestrogen imbalances.

Some Sciencey Stuff
Most phyto-oestrogens 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 phyto-oestrogen. These are phenolic phyto-oestrogens. 

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

Sources of phyto-oestrogens

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

Foods with phyto-oestrogens 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 phyto-oestrogens in a particular food varies depending on processing. An intake of 45mg of phyto-oestrogens daily may have a stabilising effect on hormones.

Searchable phyto-oestrogens food list

Plant species (Common name)μg/100 g dry weightLevels
Plum5Very Low
Wheat (white meal)8Very Low
Banana10Very Low
Apple12Very Low
Oatmeal13Very Low
Potato (peeled)16Very Low
Lentil23Very Low
Pea27Very Low
Cabbage33Very Low
Tritacle (meal)35Very Low
Wheat (wholegrain)36Very Low
Cabbage, Turnip-rooted43Very Low
Poppy seed51Very Low
Tritacle (wholegrain, wheat variant)52Very Low
Barley (wholegrain)80Low
Barley bran85Low
Onion91Low
Pistachio nut96Low
Beetroot100Low
Almond111Low
Cauliflower111Low
Rye meal (wholegrain)112Low
Wheat bran121Low
Hazelnut123Low
Paprika124Low
Rasberry139Low
Sharon145Low
Cabbage, Red160Low
Red currant165Low
Walnut173Low
Oat bran179Low
Witloof/Endive190Low
Cloudberry203Moderate
Caraway seed235Moderate
Chickpea/Garbanzo bean250Moderate
Black-eyed pea/Cow pea255Moderate
Cashew nut261Moderate
Rye bran299Moderate
Black gram bean361Moderate
Carrot (skin on)370Moderate
Garlic380Moderate
Kidney bean396Moderate
Black currant398Moderate
Peanut420Moderate
Broccoli451Moderate
American groundnut (potato bean)511Moderate
Pigeon pea517High
Clover seed518High
Zuccini (skin on)817High
Blueberry835High
Sesame seed852High
Cranberry1054High
Strawberry1210High
Lingonberry1510High
Tea, Yellow label tea-bag2591Very High
Sunflower seed2600Very High
Tea, Earl Grey tea (Oriental tea mixture)3212Very High
Kudzu leaf3371Very High
Tea, Pure Lapsang Souchong tea (China)3520Very High
Tea, China Gunpowder3672Very High
Pumpkin (peeled)3874Very High
Tea, Japan Sencha Green tea4075Very High
Tea, Nippon Sencha Green tea5565Very High
Tea, Prince of Wales, tea-bag5768Very High
Tea, China Green tea5965Very High
Tea, Green8000Very High
Black tea8500Very High
Soy bean88843Extremely High
Kudzu root197631Extremely High
Flaxseed370987Extremely High
Flaxseed (crushed)547300Extremely High

Herbal medicines with phyto-oestrogens include:

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

How plant oestrogens work in the human body

Phyto-oestrogens bind to certain oestrogen receptors in select tissue, activating or down-regulating the response of cells.

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

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

Phyto-oestrogens may also impact the balance of oestrogen metabolites (the end result of oestrogen 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).

Phyto-oestrogens may protect against cancer in the prostate​4​​, 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 major 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 or those with hypothyroidism.​6​

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

How to use soy products for their phyto-oestrogens

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

We also use phyto-oestrogens in vaginal treatments such as Fennelope fennel pessaries for a local effect, which has been shown to thicken vaginal epithelial cells​7​. This thickening reduces the vulnerability of cells and can help provide much-needed glycogen in vaginal cells to support healthy vaginal flora.

Soy protein can be useful 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 protections from endogenous oestrogens. Regular intake of soy products can also decrease ‘bad’ cholesterol by as much as 10 per cent, with every one per cent equalling around a two per cent drop in heart disease risk.

As a result, soy products are a good substitute. The FDA determined that diets with four daily soy servings can reduce levels of low-density lipoproteins, the so-called bad cholesterol that builds up in blood vessels, by as much as 10%.

This number is significant because heart experts generally agree that a 1% drop in total cholesterol can equal a 2% drop in heart disease risk.

References

  1. 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. 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. 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. 4.
    Castle EP, Thrasher JB. The role of soy phytoestrogens in prostate cancer. Urologic Clinics of North America. Published online February 2002:71-81. doi:10.1016/s0094-0143(02)00019-8
  5. 5.
    Adlercreutz H. Phyto-oestrogens and cancer. The Lancet Oncology. Published online June 2002:364-373. doi:10.1016/s1470-2045(02)00777-5
  6. 6.
    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
  7. 7.
    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


Original price was: USD $9.95.Current price is: USD $0.00. ex GST/VAT/TAX
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Jessica Lloyd - Vulvovaginal Specialist Naturopathic Practitioner, BHSc(N)

Jessica is a degree-qualified naturopath (BHSc) specialising in vulvovaginal health and disease, based in Melbourne, Australia.

Jessica is the owner and lead naturopath of My Vagina, and is a member of the:

  • International Society for the Study of Vulvovaginal Disease (ISSVD)
  • International Society for the Study of Women's Sexual Health (ISSWSH)
  • National Vulvodynia Association (NVA) Australia
  • New Zealand Vulvovaginal Society (ANZVS)
  • Australian Traditional Medicine Society (ATMS)
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