Millions of women know the pain and emotional tumult of premenstrual
syndrome, or PMS. But a new study finds that diets full of iron from plant-based
sources might help ease the condition.
Women who ate in this way were about one-third less likely to develop PMS
than women who consumed less iron, the researchers found. Non-meat sources of
iron include dried beans and green leafy vegetables.
Another mineral makes a difference, the study found. Higher levels of zinc
were also associated with less PMS over the 10-year study period. Zinc occurs in
many fresh fruits and vegetables.
"It does look like a range of minerals are important for menstrual cycle
health and for PMS. Women should consume a balanced diet, and if they're not
getting enough nutrients from their diet, they should take a multivitamin,"
recommended senior study author Elizabeth Bertone-Johnson, an associate
professor at the University of Massachusetts Amherst.
Bertone-Johnson said the researchers don't know exactly why iron might be
associated with less PMS, because iron is involved in many processes in the
body. They think higher levels of iron might reduce the pain and emotional
symptoms of PMS by boosting levels of a brain chemical called serotonin. Low
serotonin levels play a role in clinical depression, and Bertone-Johnson said
that serotonin has been linked to PMS symptoms in other research.
As with iron, Bertone-Johnson said it wasn't clear how higher levels of zinc
might protect against PMS.
What the study found
PMS affects between 8% and 15% of women in their reproductive years,
according to study background information. Symptoms can be physical or
emotional, and may include breast tenderness, abdominal bloating, appetite
changes, depression and anxiety.
The current research followed about 3 000 women enrolled in the US Nurses'
Health Study II. None of the women reported having PMS at the start of the
Over 10 years, the women completed three food-intake questionnaires. At the
end of the study, 1 057 women reported PMS, and the remaining 1 968 women did
After adjusting the data for calcium intake and other factors, the
researchers found that the women who consumed the most non-heme iron had up to a
40% lower PMS risk compared to the women who consumed the least non-heme iron.
Non-heme iron is iron that comes from plant-based sources or supplements, rather
than from meat.
The risk of developing PMS dropped significantly for women who consumed more
than 20 milligrammes (mg) of iron daily. The lowest risk was seen in women
consuming nearly 50 mg of iron daily. However, the recommended daily intake for
premenopausal women is 18 mg per day, according to Bertone-Johnson.
As for zinc, a slightly protective effect for women consuming more than 10 mg
daily was also seen.
But, Bertone-Johnson cautioned, both of these minerals can be harmful if
taken at above average levels.
The researchers found that higher potassium levels were linked to higher
levels of PMS, although Bertone-Johnson said these and other findings from this
research need to be confirmed in other studies. Interestingly, the researchers
didn't find a connection between sodium, which can make you retain water, and
"PMS is probably multi-factorial, and it's probably way more complicated than
one or two supplements or mineral deficiencies might cause," said Dr Fredric
Moon, medical director of general obstetrics and gynaecology at Winthrop
University Hospital in Mineola, NY.
Ask your doctor
Moon advised women to check with their doctors before starting any type of
supplements. Iron levels can be checked with a simple blood test, he said.
Clinical nutritionist Samantha Heller, at the NYU Center for Musculoskeletal
Care, agreed. "It's important to speak with your physician before supplementing
with any minerals," she said. "Too much iron can cause serious problems, and
supplementing with something like zinc can knock your copper balance off.
There's a delicate balance in the body, and women need to be very thoughtful
before they start using supplements."
Heller explained that it's difficult to tease out the effect of any one
particular nutrient. But, she added, "If a woman wants to shift to a more
plant-based diet, it may contribute overall to reduced oxidative stress and
inflammation, which may help reduce the symptoms of PMS, and heart disease and
While the study found an association between dietary iron and zinc and
decreased PMS symptoms, it did not prove a cause-and-effect relationship.
Learn more about premenstrual syndrome from the US
Office on Women's Health.