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Could the iron in women’s diet be tied to PMS?

By Lilian Anekwe

A new study has linked the amount of iron in the foods women eat to their risk of having premenstrual syndrome (PMS). But women who had the lowest risk of PMS ate more iron than is recommended. We don’t know if this is safe.

What do we know already?

It’s thought that between 8 and 15 in 100 women have PMS at some point in their lives. There are different definitions, but PMS generally describes the physical and emotional symptoms that happen during the second half of a woman’s menstrual cycle (days 14 to 28), such as stomach bloating and feeling anxious.

Researchers have tried to find out if PMS symptoms are linked with the amount of certain vitamins and nutrients in a woman’s diet. Some studies have looked at minerals like magnesium and potassium, but they have been quite small and found inconclusive results.

In this study researchers asked 3,000 women about their premenstrual symptoms, how often they ate different mineral-rich foods, whether they took any multivitamins or supplements, and general questions about their health.

The women were divided into two groups - those who had PMS (defined as at least one physical and one emotional premenstrual symptom that affected their daily life or their relationships), and those who didn’t have PMS. The researchers then compared the two groups to see if there was a link to the amount of minerals in their diet.

What does the new study say?

There was a link between the amount of iron in the women’s diet and their likelihood of having PMS. Women who had the most iron (around 50 milligrams a day, or the equivalent of eight bowls of fresh spinach) were less likely to have PMS than women who had the least iron. When the researchers looked at iron in food and dietary supplements separately, only the link with iron in food remained strong enough to rule out the effect of chance.

Women who had the most zinc in their diet were also less likely to have PMS than women who had the least. But the link was only just strong enough to rule out being down to chance.

In contrast, women who had the most potassium were more likely to have PMS than women who had the least potassium.

There was no link between the likelihood of PMS and how much sodium, magnesium, or manganese a woman had.

How reliable is the research?

The researchers accounted for things that might have affected whether women had similar symptoms to PMS, such as whether they had anxiety or depression. This helps to make the results more accurate. However, they relied on women to accurately fill in questionnaires on their diet and PMS symptoms, which leaves room for error. For example, the women may not have accurately remembered or recorded what they ate, or what symptoms they had.

What does this mean for me?

This study suggests women who have a lot of iron in their diet are less likely to have PMS than women who have less. The results show there’s no benefit from having iron supplements, though, as you can get the iron you need from your diet. But bear in mind that the women who had the highest amount of iron in this study, and the lowest risk of PMS, did eat more iron than is usually recommended. Doctors recommend most women have around 15 to 20 milligrams of iron a day from their diet. We’re not sure if it’s safe to regularly have more iron than this.


Chocano-Bedoya PO, Manson JE, Hankinson SE, et al. Intake of selected minerals and risk of premenstrual syndrome. American Journal of Epidemiology. Published online 26 February 2013.

Feb 27, 2013