Foods high in oestrogen: what phytoestrogens can and cannot do

You cannot eat your way back to the oestrogen levels you had at 35. That is the honest starting point, and it is worth saying before the list of foods, because a lot of what is written about “oestrogen-rich foods” quietly implies otherwise.

What you can do is eat in a way that takes the edge off some symptoms for some women, protects your bones and heart through the years when falling oestrogen puts both at risk, and sits comfortably alongside HRT if you take it. This article is about what the food can and cannot do, and how to tell the difference.

What phytoestrogens are

Phytoestrogens are plant compounds shaped enough like oestradiol, the main human oestrogen, to attach to the same receptors in your cells. There are three families that matter in food:

• Isoflavones, mainly in soya and to a lesser extent in other legumes
• Lignans, highest in flaxseed (linseed) and sesame, with smaller amounts in wholegrains, berries and some vegetables
• Coumestans, in sprouted beans such as alfalfa and mung bean sprouts

Two things make them different from the oestrogen in HRT. They are very weak: an isoflavone sitting on an oestrogen receptor does a small fraction of what oestradiol would do there. And they are not the same molecule, so they do not replace what your ovaries have stopped making. The oestrogen in modern HRT, by contrast, is body-identical oestradiol, usually through the skin as a patch or gel.

The foods, from strongest to mildest

Food	Main phytoestrogen	How much it takes
Flaxseed (linseed), ground	Lignans	One to two tablespoons a day
Soya: tofu, tempeh, edamame, soya milk, miso	Isoflavones	One or two portions a day
Sesame seeds and tahini	Lignans	A tablespoon or two
Chickpeas, lentils, beans	Isoflavones (small amounts)	A portion most days
Oats, barley, rye, wholegrain bread	Lignans (small amounts)	Part of normal meals
Dried apricots, dates, prunes	Lignans and isoflavones (small)	A handful
Berries, apples, pears	Lignans (small)	Normal fruit intake
Broccoli, cabbage, kale, Brussels sprouts	Lignans (small)	Normal vegetable intake
Alfalfa and bean sprouts	Coumestans	A handful in salads

Flaxseed needs grinding, or it passes straight through. Soya counts whether it is fermented or not, but highly processed soya products such as some protein bars and “meat” alternatives vary a great deal in how much isoflavone survives manufacturing. Whole soya foods are the reliable sources.

What the evidence shows for hot flushes

This is the claim most women are interested in, and it is the one with the most research behind it.

Trials of soya isoflavones, whether from food or supplements, show a modest reduction in how often hot flushes happen in some women, typically after eight to twelve weeks of daily intake. The effect is real but small, and clearly smaller than HRT. A Cochrane review of phytoestrogens for menopausal symptoms found no conclusive evidence overall, while noting that preparations rich in genistein, one of the soya isoflavones, performed better than the rest.

Part of the reason results are so mixed is biology. To get the most oestrogen-like effect from soya, your gut bacteria have to convert one isoflavone, daidzein, into a compound called equol. Roughly a third of women eating a Western diet can do this. The rest get much less from the same bowl of edamame, and no amount of trying harder changes that.

NICE, in its menopause guideline, takes a careful line: isoflavones and black cohosh may relieve flushes and sweats, but the preparations vary, their safety is uncertain and they can interact with other medicines. That is a reasonable summary.

What it will not fix

Phytoestrogens have no meaningful effect on vaginal dryness, which needs local treatment, usually vaginal oestrogen. They do not restore bone density, although a diet built around legumes, wholegrains, vegetables and oily fish is good for bones and heart for other reasons. And the evidence for brain fog, mood, joint pain and sleep is thin to non-existent.

If those are your main symptoms, food is a supporting act. The main treatment is covered in our guide to HRT in the UK.

Who should be careful

For almost everyone, phytoestrogens in food amounts are safe, and populations that eat soya daily from childhood have lower rates of several hormone-related conditions, not higher.

After breast cancer. Eating soya foods has not been shown to raise the risk of breast cancer or of recurrence, and several large studies in survivors point the other way. Concentrated isoflavone supplements are a different matter, because the doses are far higher and the studies are smaller. If you have had breast cancer, or you take tamoxifen or an aromatase inhibitor, talk to your oncology team before adding supplements, and keep soya to food.

Thyroid medication. Soya can reduce how much levothyroxine you absorb. Leave a gap of around four hours between the tablet and a soya-heavy meal.

Supplements generally. Isoflavone, red clover and black cohosh supplements are sold as natural, which tells you nothing about dose or safety. Black cohosh in particular has been linked to rare cases of liver damage. If you want to try a supplement, tell your doctor, exactly as you would with any other medicine.

How to use this sensibly

If you want to see whether phytoestrogens help your flushes, give it a fair trial: a portion or two of whole soya foods most days, a tablespoon of ground flaxseed, and two to three months before you judge it. Keep a simple count of flushes per day before you start, because memory is unreliable and the change, if it comes, is gradual.

Build the rest of your plate for the long term rather than for flushes. Our menopause diet guide sets out what to eat for bones, heart, sleep and mood, with portion sizes and a day planner.

When food is not enough

If flushes, sweats, broken sleep or mood changes are affecting your work, your relationships or your sleep, dietary change on its own is unlikely to be enough, and you do not have to wait it out. For most women HRT is the most effective treatment and the risks are smaller than the headlines of twenty years ago suggested. Many of these symptoms begin in perimenopause, while periods are still regular, which is when women are most often told it is too early.

At Arc, your doctor goes through diet, non-hormonal options and HRT together and builds a plan around your symptoms, which can include food and HRT side by side. There is no requirement to choose one or the other.

The bottom line

Soya, flaxseed and legumes are good foods and a reasonable thing to try for mild flushes, with a modest effect in perhaps a third of women after two or three months. They are safe in food amounts for nearly everyone, including most women after breast cancer. They are not oestrogen replacement, they will not treat vaginal dryness or protect your bones on their own, and if your symptoms are affecting your life, they are not the main answer.