Spend time hanging around alternative health spaces, and you’ll undoubtedly come across seed cycling. This popular protocol aims “balance women’s hormones” and help with all sorts of issues related to sex hormones and the menstrual cycle. Proponents use seed cycling for everything from PMS symptoms, dysmenorrhea (painful menstruation), and irregular cycles to PCOS, infertility, ovarian cysts, and menopausal symptoms like hot flashes and night sweats.
Testimonials abound from women who credit seed cycling with changing their lives. No shortage of holistic doctors, naturopaths, dietitians, and bloggers promote it as a helpful tool, or even a miracle cure, for women. There are also plenty of skeptics.
While it’s great to keep an open mind, we also want interventions that actually work. Nobody wants to throw valuable time and money after remedies that don’t do anything or, worse, that cause harm. When you dig into the claims, they seem a little too good to be true, but that doesn’t mean they’re not. Let’s look at the evidence.
What is Seed Cycling?
Seed cycling is a program where you eat certain seeds during different phases of the menstrual cycle. According to proponents, if you diligently follow the protocol for several months, you can expect to see improvements in whatever symptoms or malady you’re hoping to address.
Seed cycling looks like this:
During the follicular phase (first day of menses to ovulation), consume one tablespoon of flax seeds and one tablespoon of pumpkin seeds per day.
During the luteal phase (day after ovulation to day before menses), consume one tablespoon of sunflower seeds and one tablespoon of sesame seeds per day.
Don’t know when you ovulate? No problem, you can do flax and pumpkin for the first half of your cycle (approximately days 1 to 14) and sunflower and sesame in the second half (days 15 to 28, or however long your cycle is). Women who don’t menstruate are advised to use the moon cycle as a guide. New moon to full moon corresponds to the follicular phase, full moon to new moon is luteal.
For digestibility, it’s important to grind the flax seeds and sesame seeds. Usually, seed cyclers grind all the seeds using a spice mill or coffee grinder, or you can buy premade seed blends. Sprinkle the ground seeds over yogurt or salads, mix it into smoothies or soups, or just make a sludgy shot of seed water.
How Does Seed Cycling (Supposedly) Work?
Seed cycling advocates claim that it balances your hormones, meaning that sex hormones (mostly estrogen and progesterone) are at appropriate levels at different points of the menstrual cycle. When sex hormones plummet during menopause, seed cycling allegedly helps mitigate those effects, too. Supposedly, this works for a number of reasons.
First and foremost, seeds contain compounds called lignan precursors. When you eat them, bacteria in the gut metabolize them to create lignans. Lignans are phytoestrogens, like the isoflavones in soy. Because their chemical structures are similar to estrogens the body produces naturally, lignans can bind to estrogen receptors and mimic the effects of estrogen. Proponents say that lignans help create an ideal balance of estrogen and progesterone in the body, boosting estrogen when it is too low and binding it to facilitate detoxification when it is too high. (We’ll return to this claim later.)
Other alleged benefits come from vitamins and minerals in the seeds. Specifically:
Zinc, mostly from pumpkin seeds and sesame seeds, is meant to prime the body to produce progesterone.
Vitamin E in sunflower seeds is likewise meant to encourage progesterone synthesis.
Selenium from sunflower seeds is supposed to help clear (or “detox”) the body of excess estrogen.
But does it actually work like that?
That’s the million-dollar question.
As discerning health consumers, we need to understand that a theory can be “mechanistically plausible,” which means that when you explain why it could work, it totally makes sense. However, it still might not be true. In science, hypotheses usually start with ideas that are mechanistically plausible, but then those hypotheses have to be tested. Some hypotheses that seem completely valid and sensible don’t bear out under scrutiny. That’s why empirical research is vital.
Seed cycling is mechanistically plausible. Lignans are phytoestrogens, and flax and sesame seeds are both significant dietary sources of lignans. Zinc is important for reproductive health.1 Selenium does promote glutathione synthesis.2 Glutathione is a critical antioxidant and an important component of the body’s natural detoxification system. The body does excrete excess estrogen.
So you can see where the idea for this protocol might have come from. The problem is, there really isn’t any solid evidence that seed cycling actually does what it purports to do.
Yes, lignans are phytoestrogens, but scientists are still working to understand how, exactly, lignans affect sex hormone levels. They can be either estrogenic or anti-estrogenic, but it’s not yet clear how and when they exert different effects.3 There’s definitely no concrete evidence that they work like smart drugs, increasing or decreasing estrogen on an as-needed basis to create optimal hormone balance.
Proponents of seed cycling rely heavily on one small study from 1993 that asked 18 women to consume flax seeds for three months.4 In this study, flax seed consumption led to fewer anovulatory menstrual cycles (cycles where an egg is not released as expected) and a more favorable progesterone-to-estradiol ratio during the luteal phase. However, most of the effects on sex hormone levels were not significant. Perhaps tellingly, this study has never been replicated, suggesting the findings couldn’t be reproduced with more powerful studies or other researchers didn’t think this was worth following up on.
Overall, there is only scant evidence that lignans directly affect sex hormone levels. Plenty of studies find that they don’t.5 Moreover, remember that lignans are created in the gut. Not everyone has the microbes needed to convert high levels of lignans. 6 So even if seed cycling does work as proponents claim, we’d expect that some people would benefit much more than others.
Zinc, vitamin E, and selenium are undoubtedly important for overall health and reproductive health in particular. However, there’s still a lot to learn about how supplementing affects the outcomes we’re interested in here. For example, a 2020 review entitled “The Role of Zinc in Selected Female Reproductive System Disorders” concluded that zinc supplements may help with PCOS and dysmenorrhea, but there is a dearth of evidence when it comes to issues like endometriosis and menopause.7 Similarly, a 2016 review of antioxidants concluded, “Given the complexities of hepatic processing and the contribution of diet and lipoprotein metabolism, additional research is needed to further explore the potential relations and mechanisms between particular vitamin E concentrations and reproductive outcomes.”8
In short, we still have much to learn about all these processes. Furthermore, the seed cycling hypothesis relies on mechanistic pathways (A leading to B) that aren’t currently well-supported by data.
Seed Cycling Has Never Really Been Put to the (Empirical) Test
The bottom line is that this protocol has never been rigorously tested. I couldn’t find any studies where participants followed this exact regimen and scientists compared their outcomes to a control group. Even if the evidence for all the mechanistic pathways was strong—and it isn’t—the entire protocol would still need to be put to the test.
Currently, all the evidence is anecdotal. To be clear, I’m not discounting the reports from women who feel like seed cycling worked for them. Anecdotes can be informative, but we can’t rely solely on them. They leave too many questions unanswered.
For those who have success with seed cycling, is it because lignans, vitamins, minerals, and fatty acids are optimizing hormone balance? Maybe. Or maybe it’s due to other compounds or different mechanisms like reducing inflammation.
Could it be a placebo effect? Perhaps (and you might be ok with that as long as you get the results you want).
Is there a better way to use seeds and/or the compounds they contain to achieve the same goals? We don’t know.
These are all questions that well-designed, well-controlled laboratory studies could answer. Studies that we don’t currently have.
The Verdict: Is Seed Cycling Worth Trying?
On the one hand, I’m tempted to say it can’t hurt, might help. Seeds offer lots of other benefits. They are good sources of nutrients like B vitamins, magnesium, manganese, and copper, as well as fiber and the aforementioned vitamin E, zinc, selenium, and fatty acids. Lignans have known antioxidant, anti-inflammatory, and anti-cancer properties. Flax and sesame seeds seem to have cardioprotective effects.9 10 11 Pumpkin seeds can improve blood glucose levels.12
On the other hand, many women turn to things like seed cycling after conventional doctors have been unable, or even unwilling, to help them. PCOS and endometriosis sufferers notoriously struggle to get properly diagnosed and treated. We don’t have great solutions for menopausal women dealing with common symptoms like hot flashes, night sweats, and depression. These women have been let down so many times. I’m therefore reluctant to give an enthusiastic thumbs up to something that has no solid evidence behind it. There’s a risk, too, of delaying or avoiding medical treatment in favor of alternative therapies that ultimately aren’t what you need.
Although the risks of seed cycling seem low, you should be aware of a few things:
Seeds are high in phytates and can be allergenic, so they don’t work for everyone.
They’re also high in fiber, leading to gastrointestinal issues for some folks.
Seeds aren’t allowed during the elimination phase of the AIP plan.
If your doctor has advised you to limit your intake of phytoestrogens, make sure you talk to them first.
Finally, if hormone health is your goal, the first step is to make sure you’re nailing the big-ticket items: nutrition, sleep, stress management, and healthy movement.
So what’s YOUR verdict? Are you interested in seed cycling or not so much? Have you tried it already?