What are phytoestrogens?
Phytoestrogens are natural compounds that exist in many plants and foods, such as dairy, flaxseeds, hops, and soy. These compounds have a similar chemical structure to estrogen.
Estrogen is a hormone that is essential for health in all sexesTrusted Source, although females have higher amounts. It helps keep the bones strong, regulates metabolism, and supports fertility.
Phytoestrogens may have a similar effect on the body to estrogen, which may help those with low estrogen, such as people going through menopause.
However, it is important to note that people have to consistently consume fairly high amountsTrusted Source of phytoestrogens for them to have any measurable effect on the body.
This article explores the health benefits and risks of phytoestrogens. It also lists foods that are high in phytoestrogens.
Phytoestrogens are naturally occurring compounds found in over 300 plantsTrusted Source. They mimic estrogen, which is a hormone that has many functions in the body.
In females, estrogen influences sexual development, menstruation, and libido. In males, adequate estrogen also supportsTrusted Source libido and sexual function, including the ability to get an erection.
In all sexes, estrogen plays a role in regulating the metabolism of fats and glucose, bone strength, and brain health. As a result, having adequate amounts of estrogen is important.
Phytoestrogens may have a similar effect to estrogen in the body. They are also antioxidants and are anti-inflammatory.
However, most foods contain low amounts of phytoestrogens. In comparison to the amount of estrogen the body naturally produces, the intake from everyday foods is usually very small.
How do phytoestrogens work?
Phytoestrogens imitate estrogen because their chemical structure is very similar to that of estradiol. This is a form of estrogen the body produces.
When phytoestrogens enter the body, the body’s estrogen receptors treat them as if they were estrogen. But the body also does not absorb the phytoestrogens from foods very well. As a result, a person has to eat relatively high amounts of them to affect their health.
For example, soy contains a phytoestrogen known as isoflavone. A person needs to consistently consume between 40 and 70 milligrams (mg)Trusted Source per day, or an average of 50 mg per day, of isoflavones to produce health effects.
In Asia, where soy products are a staple food, the average daily intake of isoflavones is between 15 and 50 mg. In the West, the average amount is only around 2 mg per day.
This means most people are probably not eating enough phytoestrogens to have any effect on their health overall.
Foods that contain phytoestrogens
Some foods that contain phytoestrogens include:
Unprocessed soybeans are high in the most well-studiedTrusted Source phytoestrogen, isoflavones. Processing soybeans into different foods, such as tofu, reduces their isoflavone content.
Examples of products containing soy include:
tofu
tempeh
miso
Nuts and seeds
Flaxseeds are one of the main sourcesTrusted Source of a type of phytoestrogen known as lignan. To a lesser extent, many other nuts and seeds also contain phytoestrogens, including peanuts and sunflower seeds.
Grains
Some grains contain also contain lignans. These include:
wheat
rye
oats
barley
Dairy
Dairy products contain phytoestrogens, too. This includes:
cow’s milk
yogurt
butter
Fruits and vegetables
Certain fruits contain phytoestrogens, includingTrusted Source:
apples
pomegranates
grapes
berries
Vegetables that contain phytoestrogens include:
garlic
turmeric
carrots
celery
potatoes
sweet potatoes
broccoli
cabbage
spinach
alfalfa sprouts
collard greens
beans
Herbs
Some plants people use as herbal medicine also contain phytoestrogens, includingTrusted Source:
red clover
hops
chaste berry
Drinks
The following beverages are sources of phytoestrogens:
coffee
tea
beer
red wine
Benefits of phytoestrogens
Scientists are still learning about what the benefits of phytoestrogens may be.
Additionally, a 2020 research reviewTrusted Source indicates that whether phytoestrogens are beneficial depends on the person, their hormone levels, how much they consume, and how much their body absorbs.
Phytoestrogens may:
Reduce menopause symptoms
A 2022 study evaluated the effects of giving 40 mg of soy isoflavones twice daily for 12 weeks to perimenopausal and postmenopausal women. In each group, respectively, the authors recorded the following results:
42.5% and 33.1% reduction in hot flashes
45% and 30.1% reduction in sleep disturbances
37.5% and 40% reduction in symptoms of depression
16.1% and 14.2% reduction in sexual dysfunction
The authors note that while isoflavones cannot completely replace hormone therapy, they have a “good safety profile” and may be suitable for long-term use. Twice daily doses appear to be the most effective.
Lower the risk of osteoporosis
Low estrogen can contribute to weak bones, or osteoporosis. Males and females can both experience osteoporosis, but females can get it earlier in life because of menopause.
A 2019 reviewTrusted Source of previous research notes that results on whether soy isoflavones can prevent osteoporosis are mixed. One meta-analysis found a weak association between them and an increase in bone density.
Another study found that older women who consumed soy milk for over a year had a 2.3% increase in bone density. However, more research is necessary to prove it has a significant benefit.
Reduce the risk of cancer
According to a 2020 reviewTrusted Source of previous research, there is evidence that phytoestrogens in soy reduce the risk of numerous types of cancer, including breast, ovarian, and prostate cancers.
The data so far suggests that the more soy isoflavones a person consumes, the less likely they are to get these conditions.
Improve cancer treatment
There have been some claims that phytoestrogens help with treating cancer, as well as preventing it. They may improve the outcomes for:
Chemotherapy: The 2020 reviewTrusted Source includes previous studies that found certain phytoestrogens may enhance chemotherapy drugs, such as cisplatin, 5-fluorouracil, and topoisomerases. However, this depends on the compound. Some phytoestrogens have shown no effect.
Radiation therapy: The phytoestrogen genistein may increase the sensitivity of leukemia cells to radiation, while also protecting noncancerous cells. The same may also be true for resveratrol.
Hormone therapy: Doctors use hormone therapy to treat tumors with hormone receptors. There is some evidence that certain phytoestrogens may enhance these treatments, but the concept is still controversial.
More research is needed to fully understand whether phytoestrogens could play a useful role in cancer treatment. Additionally, phytoestrogens may not be appropriate for all types of cancer.
******Benefit skin aging********
Estrogen plays a role in skin health, and its reduction in menopause may contribute to the visible signs of aging due to a loss of collagen and elasticity. In addition to changes in appearance, wounds can also heal more slowly.
A 2021 narrative review notes that topical phytoestrogens may be a promising treatment. Some early studies have shown positive results, and the authors argue that phytoestrogens may have similar effects to topical estrogen creams but without as many side effects.
However, more high quality studies are necessary to determine the effectiveness and safety of this approach.
Risks and side effects
Research indicatesTrusted Source that most people in Western countries do not eat enough phytoestrogens for them to have any health effects. However, people may still have concerns about the impact they could have. Here is what the research says.
Thyroid function
According to a 2020 research reviewTrusted Source, some studies have found that isoflavones can contribute to an underactive thyroid in people who already have an iodine deficiency. Iodine is a nutrient that is essential for thyroid function.
However, there are few studies proving this also happens in people with adequate iodine and a healthy functioning thyroid. Those with subclinical hypothyroidism or a thyroid deficiency may need to avoid consuming large amounts.
Summary
For those with low estrogen, adding more sources of phytoestrogens to the diet may reduce symptoms or the risk of osteoporosis. Anyone considering taking phytoestrogen supplements should discuss it with their doctor first.
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