If you've looked for something to help with PMS, you've probably seen the same list again and again: magnesium, vitamin B6, calcium, vitamin D, and often chasteberry at the end. When bloating, irritability or a low mood turns up in the days before your period, it makes sense to wonder whether something on that list could take the edge off.
The short answer is that a few of these have some research behind them for PMS, and calcium has the clearest support. The evidence is more limited than the lists suggest, though, and many of the trials were small.
Why nutrients come up in PMS research
PMS covers the physical and emotional changes that show up during the luteal phase, the stretch of your cycle between ovulation and your period, and ease once your period starts. The Society of Obstetricians and Gynaecologists of Canada (SOGC) lists symptoms such as tender breasts, bloating, headaches, tiredness, irritability, anxiety, sadness and trouble focusing. According to the American College of Obstetricians and Gynecologists (ACOG), up to 90 percent of women notice at least one premenstrual symptom, and roughly 20 to 30 percent have symptoms bothersome enough to count as PMS.
Even though PMS affects so many people, premenstrual conditions remain understudied compared with other mood conditions, and researchers are still working out why PMS happens. Estrogen and progesterone levels look similar in people with and without premenstrual symptoms, so the leading theory is that some people are more sensitive to the normal rise and fall of these hormones. Two brain messenger systems keep coming up in this research: serotonin, which is involved in mood, and GABA, which helps calm nerve activity.
This is where supplements enter the picture. Some nutrients play a part in the body systems researchers are interested in, which makes them worth studying, and trials show whether taking them actually helps.
Calcium: the clearest evidence
Calcium is best known for bones and teeth, but it also helps nerves send signals and muscles move. Researchers began studying it for premenstrual symptoms based on an assumption that changes in how the body handles calcium, influenced by estrogen after ovulation, might play a part. None of the studies so far has enough evidence to fully validate that assumption.
However, ACOG suggests calcium as one option for physical and emotional premenstrual symptoms. It's a conditional suggestion, and ACOG rates the evidence as low quality. Most of that evidence comes from a single trial of 466 women with PMS. By the third cycle, the women taking calcium reported a bigger drop in negative mood than those taking a placebo, along with less bloating, fewer food cravings and less pain. A smaller, earlier trial also found a benefit, while a more recent small study didn't find a significant one. A recent review of 31 nutrition trials found that the calcium studies it included were consistently positive for emotional PMS symptoms.
Food may matter here, too. In one small trial, young women with PMS who weren't getting much calcium added calcium-rich foods, mostly dairy, and their PMS symptoms eased, including low mood and anxiety. For teenagers, ACOG suggests making sure they get enough calcium in their diet, since calcium supplements haven't been studied for PMS in that age group.
So calcium has the best case of anything on the list, and it's still a case built on a handful of trials, with one of them doing most of the work. A word of caution, though: higher amounts from supplements may raise the risk of kidney stones, and calcium supplements can interact with some medicines.
Dietitians of Canada and the US National Institutes of Health both list milk, yogurt and cheese, canned salmon and sardines with the bones, tofu made with calcium sulfate, and leafy greens such as kale among good sources of calcium, along with soy drinks and orange juice fortified with calcium.
Vitamin B6: some positive trials
Vitamin B6 helps enzymes carry out more than 100 reactions in the body, and it's involved in making neurotransmitters, the chemical messengers your brain uses. Serotonin is one of them. Because serotonin is one of the systems linked to premenstrual mood symptoms, researchers have wondered whether B6 could help.
The results lean positive, with caveats. A combined analysis of nine trials, involving 940 women with PMS, found that B6 worked better than a placebo. The same paper notes that most of those trials weren't high quality, so the results are encouraging rather than conclusive. The 31-trial review also found that most B6 trials showed improvements in emotional PMS symptoms. Across all the nutrients it looked at, though, only one of the 31 trials was judged to be at low risk of bias, meaning the rest had problems in their design or reporting that could skew the results. B6 isn't among the options in ACOG's 2023 guideline.
It's worth knowing that with B6, more isn't better. Research has linked very large amounts of B6 from supplements, taken over time, to nerve problems. That hasn't been seen with the B6 in food.
You'll find B6 in chickpeas, tuna and salmon, chicken, potatoes and bananas, as well as fortified breakfast cereals.
Magnesium: popular, but the evidence is thin
Magnesium helps more than 300 enzyme systems do their work, including the ones that regulate muscle and nerve function. You'll often see it recommended for PMS, sometimes in a specific form.
The research hasn't caught up with how often it's recommended. The recent review found too little evidence to say magnesium helps emotional PMS symptoms. In one small trial, magnesium made no difference to mood symptoms, though by the second month it eased fluid-retention symptoms such as bloating, swelling and breast tenderness. That's a single small study, so it can't settle the question. High doses from supplements can also cause diarrhea, nausea and cramping.
You'll find magnesium in pumpkin seeds, chia seeds, almonds and cashews, spinach and black beans.
Vitamin D: unclear, especially if your levels are normal
Vitamin D helps your body absorb calcium and keep the calcium in your blood steady, which is one reason it often appears beside calcium on these lists. In spring and summer, your body also makes vitamin D when your skin is exposed to the sun.
The research is thin and mixed. Three trials looked at people with low vitamin D levels: one found an improvement in PMS symptoms, another found no difference from a placebo, and a third was inconclusive. The review's authors concluded that it's unclear whether vitamin D does anything for people whose levels aren't low. If you're wondering about your own levels, a doctor can check them. Too much vitamin D almost always comes from supplements.
Few foods contain much vitamin D naturally, mainly fatty fish such as salmon and sardines, and egg yolks, so fortified foods do a lot of the work. In Canada, cow's milk must be fortified with vitamin D, according to Dietitians of Canada. In the US, fortification is voluntary, but almost all milk is fortified, according to the National Institutes of Health. In both countries, many soy and other plant drinks are fortified too.
Chasteberry and the other names on the list
Chasteberry, also called vitex, is an herbal supplement made from the fruit of the chaste tree. A 2017 review found that most trials reported fewer PMS symptoms with chasteberry, but most of those trials were at high risk of bias and their results varied widely, so the authors couldn't reach a firm conclusion. ACOG says more research is needed before it can make a recommendation. Side effects tend to be mild, such as nausea, headache or itching, and chasteberry may be unsafe during pregnancy or breastfeeding.
Zinc, a mineral rather than an herb, has a few small positive trials, mostly in university students. Evening primrose oil, another herbal product you may come across, has had mixed results.
Where this leaves you
Nothing on the usual supplement list has strong evidence behind it for PMS, and calcium's support is still limited. Even so, many people use supplements alongside the lifestyle changes that SOGC in Canada and the US Office on Women's Health recommend for PMS, such as eating well, exercising regularly, getting enough sleep and managing stress, and some find them a helpful addition. You might also consider adding more of these nutrients to your diet through the foods above.
Talk to your doctor or pharmacist before starting a supplement, though, and keep in mind that the rules differ by country. In Canada, vitamins, minerals and herbal products must be licensed by Health Canada as natural health products before they're sold, and Health Canada notes that they aren't risk free and can interact with prescription drugs. In the US, the Food and Drug Administration (FDA) doesn't approve supplements before they go on sale, but it does warn that some can interact with medicines.
If PMS is getting in the way of work, sleep or time with people you care about, a doctor can talk through other options, including prescription medication.
If you're curious whether your own symptoms follow a pattern, you can log your period days and symptoms such as bloating in GetMyMood, and select the moods that match how you feel. Over a few cycles, that makes it easier to see whether harder days tend to land before your period.