Several supplements can support estrogen levels or ease the symptoms of low estrogen, though their strength varies widely. The most studied options are soy isoflavones, red clover, boron, vitamin D, and flaxseed. None of these match the potency of prescription hormone therapy for every symptom, but some come surprisingly close for specific complaints like hot flashes and mood changes.
How Low Estrogen Is Measured
Estradiol, the primary form of estrogen, is measured through a blood test. Normal levels for premenopausal women range from 10 to 300 pg/mL, while postmenopausal women typically fall below 10 pg/mL. Levels that drop lower than expected for your age can result from menopause, perimenopause, rapid weight loss, eating disorders, or premature ovarian failure. Knowing your baseline number helps you and your provider gauge whether supplements, lifestyle changes, or hormone therapy makes the most sense.
Soy Isoflavones
Soy isoflavones are the most researched plant-based option for low estrogen. They contain compounds, primarily genistein and daidzein, that bind to estrogen receptors in your body. These compounds attach more strongly to one type of estrogen receptor (beta) than the other (alpha), which gives them a milder, more selective effect compared to your body’s own estrogen. The binding strength of genistein is comparable to natural estradiol at these beta receptors, which explains why soy can produce real, measurable effects.
A meta-analysis of 17 clinical trials found that 54 mg of soy isoflavones per day, taken for six weeks to 12 months, reduced hot flash frequency by about 21% and improved severity by 26% compared to placebo. In one head-to-head trial, women taking 90 mg of soy isoflavones daily for 16 weeks experienced a 49.8% reduction in hot flashes, nearly matching the 45.6% reduction seen with low-dose prescription hormone therapy. That’s a notable result for a supplement.
Mood benefits appear as well. A pilot study of 50 perimenopausal and postmenopausal women given 100 mg of soy isoflavones for 12 weeks found a 32% improvement in depressive symptoms. A separate two-year Italian study of 200 women found that 54 mg per day of genistein improved mood significantly more than placebo. The effective dosage range across studies falls between 54 and 100 mg daily, with benefits often emerging after several weeks of consistent use.
Red Clover
Red clover contains the same core isoflavones found in soy (genistein and daidzein) plus two additional ones: biochanin A and formononetin. These compounds act as selective estrogen receptor modulators, meaning they can activate estrogen pathways in some tissues while having neutral or blocking effects in others. In animal research, red clover supplementation raised estradiol levels by roughly 45% compared to controls, with a dose-dependent pattern. While animal results don’t translate directly to humans, red clover is widely available in standardized extracts and is often used by women who prefer it over soy.
Black Cohosh
Black cohosh is one of the most popular menopause supplements, but it works differently than most people assume. Despite decades of marketing as a “natural estrogen,” the commercially available forms of black cohosh do not actually bind to estrogen receptors or act as estrogen in the body. The National Cancer Institute notes that purported estrogenic effects have been refuted by current laboratory and clinical studies of the standard extracts sold to consumers.
What black cohosh does do is influence serotonin activity in the brain. This is relevant because serotonin plays a key role in regulating body temperature, and disrupted serotonin signaling is one reason hot flashes happen. Researchers have also proposed that black cohosh may affect the brain’s central opioid system, another pathway involved in temperature regulation. So while it can genuinely help with hot flashes and possibly mood, it’s not raising your estrogen levels. If your goal is specifically to support estrogen, black cohosh isn’t the right tool. If your goal is symptom relief regardless of mechanism, it remains a reasonable option.
Vitamin D
Vitamin D plays a direct role in estrogen production. When vitamin D binds to its receptor inside ovarian cells, it activates genes responsible for key enzymes in the estrogen-making pathway. In laboratory studies on ovarian cells, vitamin D treatment increased the expression of three critical steroid-producing enzymes and boosted estradiol production up to threefold compared to untreated cells.
This matters practically because vitamin D deficiency is extremely common, particularly in women over 50. If your vitamin D levels are low, your body may struggle to produce estrogen efficiently even when the ovaries still have some capacity. Getting your vitamin D level checked is a simple first step. Many women with low estrogen discover they’re also deficient in vitamin D, and correcting that deficiency can support the hormonal picture overall.
Boron
Boron is a trace mineral that flies under the radar but has solid evidence behind it. In a clinical trial, postmenopausal women who took just 3 mg of boron daily for seven weeks experienced significant increases in both estradiol and testosterone levels. The effect was especially pronounced in women whose magnesium intake was also low, suggesting boron and magnesium work together in steroid hormone metabolism.
Boron is found naturally in foods like avocados, nuts, and dried fruits, but most people don’t get much from diet alone. Supplemental doses in studies range from 3 to 10 mg per day. At 10 mg daily for four weeks, even men showed significant increases in estradiol, confirming that boron’s effect on estrogen production is robust and not limited to one population.
Flaxseed
Flaxseed works differently from the other options on this list. Its primary active compounds are lignans, which gut bacteria convert into enterolactone and enterodiol. These metabolites have a structure similar to estrogen, but rather than simply boosting estrogen levels, they shift how your body processes estrogen. Flaxseed lignans alter the activity of liver enzymes responsible for estrogen metabolism, changing the balance of estrogen byproducts in your body.
Flaxseed lignans can also increase production of sex hormone-binding globulin (SHBG), which binds to circulating hormones and affects how much free estrogen is available. This means flaxseed is better understood as an estrogen modulator than an estrogen booster. For women with low estrogen, the weak estrogenic activity of enterolactone may provide a mild supportive effect, but flaxseed is more commonly recommended for women looking to balance estrogen metabolism rather than raise total levels.
How Supplements Compare to Hormone Therapy
Prescription hormone therapy remains more potent for most symptoms. In one direct comparison, genistein (a soy isoflavone) reduced hot flashes by 22% after 12 weeks, while hormone replacement therapy reduced them by 53% over the same period. However, not every study shows such a wide gap. The trial comparing 90 mg soy isoflavones to low-dose estrogen-progesterone therapy found nearly identical hot flash reductions (49.8% vs. 45.6%), suggesting that at higher doses and with longer use, plant-based approaches can narrow the difference considerably.
For women who can’t or prefer not to use prescription hormones, a combination approach often works best: soy isoflavones or red clover for direct receptor activity, vitamin D to support the body’s own production, boron as a low-cost cofactor, and black cohosh layered on top for additional symptom control through serotonin pathways.
Safety Considerations
Phytoestrogens are generally well tolerated, but they are not risk-free at high doses. In a clinical case report from SUNY Downstate Medical Center, three women aged 35 to 56 developed abnormal uterine bleeding and endometrial changes from consuming very high amounts of soy. All three saw their symptoms resolve after reducing soy intake. The youngest, who had been eating a soy-heavy diet since age 14, experienced secondary infertility that resolved once she cut back, eventually becoming pregnant.
Women without serious risk factors or a family history of hormone-sensitive cancers can generally incorporate soy and other phytoestrogens into their routine without significant concern. But if you have a personal or strong family history of breast cancer, endometriosis, or uterine fibroids, the decision is more nuanced. Estrogen-mimicking compounds can theoretically stimulate hormone-sensitive tissue, so working with a provider to weigh the tradeoffs is worth the effort.