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It's estimated that three out of every four women experience premenstrual syndrome (PMS) to some degree, with about one-third seeking help from a health-care provider.

According to a new U.S. study published in the online edition of The American Journal of Clinical Nutrition, boosting your intake of foods rich in B vitamins can significantly lower the odds you'll suffer from PMS.

The list of symptoms associated with PMS is long but the most common include irritability, depression, crying spells, increased hunger, food cravings, headache, fluid retention, bloating and breast tenderness. Most women with PMS will experience only a few of these symptoms.

The hallmark of PMS is timing: Symptoms occur up to 14 days before a woman's period and typically go away once menstruation starts.

Interactions between hormones and brain chemicals called neurotransmitters, stress and poor eating habits are thought to trigger or worsen PMS.

In the study, U.S. researchers followed 6,000 healthy women for 10 years during which time they were asked about their diet, supplement use and presence of PMS symptoms. After 10 years, 1,057 women were confirmed to have PMS.

A high intake of two B vitamins from foods - thiamin (B1) and riboflavin (B2) - was associated with a significantly lower risk of developing PMS.

Women who consumed the most thiamin (1.93 milligrams a day) compared with the least (1.2 mg) were 25 per cent less likely to suffer PMS.

Those whose diets provided the most riboflavin (2.52 mg a day) had a 35 per cent reduced risk of PMS compared with women who consumed the least (1.38 mg).

B vitamins may guard against PMS by helping synthesize brain neurotransmitters. Riboflavin, for example, is needed to activate vitamin B6, which in turn is used to generate serotonin. (Low serotonin may lead to depression, anxiety, headaches and overeating.)

Thiamin is required to synthesize a neurotransmitter called gamma-amino butyric acid (GABA); low levels of GABA are linked with anxiety.

Women with high intakes of thiamin and riboflavin consumed more than the current recommended daily intake (1.1 mg for each B vitamin).

A daily intake of 1.93 mg of thiamin can be achieved by eating two to three servings of thiamin-rich foods a day. These include fortified breakfast cereals, legumes, peas, nuts and lean pork.

To consume 2.52 mg of riboflavin each day, you need to eat one to two servings of fortified breakfast cereal or six to seven servings of riboflavin-rich foods daily. Good sources of riboflavin include milk, yogurt, cottage cheese, soy beverages, eggs, almonds and spinach.

B vitamin supplements did not impact PMS risk, a finding that may be explained by the form of these vitamins found in foods.

For almost all women who experience PMS, the following diet and lifestyle modifications can help ease symptoms.

Include carbohydrates

A higher carbohydrate diet tends to improve mood and reduce food cravings. It's thought these foods help increase the level of serotonin in the brain.

Choose healthy carbohydrates at every meal such as whole grain breads and cereals, pasta, brown rice, sweet potato, legumes, fruit and starchy vegetables.

Reduce salt

Cutting salt can reduce fluid retention, bloating and weight gain. Limit processed foods high in sodium such as deli meats, frozen meals, soups and snack foods. Eat home prepared meals more often than high-sodium restaurant meals.

Increase calcium

Women who consume about 1,200 mg of calcium a day from their diet have a 30 per cent lower risk of developing PMS symptoms. Clinical trials have also shown that giving women 1,000 to 1,200 mg of supplemental calcium a day for three months significantly improved mood swings, fluid retention, food cravings and painful cramps.

Women with PMS tend to have low levels of calcium at the time of ovulation, which can affect hormones that regulate mood.

Women aged 19 to 50 need 1,000 mg of calcium a day. One cup of milk, 3/4 cup plain yogurt and 1.5 ounces of cheese all contain roughly 300 mg of calcium. Other sources include fortified soy beverages (300 mg in one cup), sardines with bones (3 ounces = 325 mg), canned salmon with bones (3 ounces = 188 mg), cooked Swiss chard (one cup = 102 mg), cooked broccoli (one cup = 62 mg) and almonds (1/4 cup = 92 mg).

If you can't get enough calcium from food, take a supplement. Do not take more than 500 mg at one time since absorption from calcium supplements is best in doses of 500 mg or less; if you need to take more, divide your dose over the course of the day.

Get more magnesium

Women who take 360 mg of supplemental magnesium a day report better mood and less fluid retention. The mineral may also reduce premenstrual migraines.

Magnesium is involved in the activity of serotonin and other neurotransmitters and plays a role in blood vessel contraction.

There is less evidence for magnesium than calcium, but it may be worthwhile trying for three months if you suffer headaches, fluid retention and mood swings. The upper safe limit for magnesium supplementation is 350 mg; higher doses can cause diarrhea.

Magnesium-rich foods include spinach, Swiss chard, kale, almonds, peanuts, cashews, lentils, soybeans, tofu, wheat bran and yogurt.

Consider vitamin B6

Taking 100 mg of B6 a day seems to decrease overall PMS symptoms, especially depression. B6 is needed for the production of neurotransmitters that effect mood.

Daily doses of more than 100 mg don't have additional benefit and may have toxic effects if taken for an extended period of time. The safe upper daily limit is 100 mg of supplemental B6.

What doesn't work

There are plenty of products marketed to help fight PMS, but most have little, if any, reliable evidence that they work. Based on studies conducted to date, the following supplements have not been shown to ease PMS symptoms - don't waste your money.

• Evening primrose oil

• Dong quai

• Black cohosh

• Red clover

• Natural progesterone

• Soy

Leslie Beck, a Toronto-based dietitian at the Medcan Clinic, is on CTV's Canada AM every Wednesday. Her website is

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