A diet rich in calcium and vitamin D might banish pre-menstrual syndrome (PMS), US researchers believe.
Milk is a good source of calcium and vitamin D
Many women experience mild emotional or physical symptoms before their period, but 20% have more severe symptoms.
Massachusetts University researchers compared the diets of 1,000 women with PMS and 2,000 women without PMS.
Those without PMS tended to eat more vitamin D and calcium-rich foods like milk, cheese, broccoli and cereals, the Archives of Internal Medicine reported.
Others have already reported that calcium supplements appear to ease PMS, but the new research suggests both calcium and vitamin D might reduce PMS risk in the first place.
Although the authors did not look at what might be behind the link, past studies suggest calcium and vitamin D may influence levels of the female hormone oestrogen.
Researchers have also shown that blood calcium and vitamin D levels are lower in women with PMS.
There are several theories about why PMS occurs, but some believe it is triggered by fluctuations of the sex hormones during the menstrual cycle - a drop in progesterone or the increase in oestrogen during the latter half of the menstrual cycle.
In the current study, after adjusting for factors like the woman's age, how many children she had and whether she smoked, the researchers found the women with the highest intake of vitamin D and calcium were significantly less likely to have PMS.
Scientist Elizabeth Bertine-Johnson said: "We observed a significantly lower risk of developing PMS in women with high intakes of vitamin D and calcium from food sources, equivalent to about four servings per day of skim or low-fat milk, fortified orange juice or low-fat diary foods such as yoghurt."
The amounts consumed were slightly above the current recommended daily amounts in the UK, which are 800 milligrams of calcium and 5 micrograms of vitamin D.
Vitamin D is known to help the body absorb calcium and both are essential for healthy bones.
Professor Shaughn O'Brien, an expert on PMS from Keele University, said the findings provided a basis for clinical trial to see whether this was a real effect.
He said following a healthy, balanced diet was sensible for anyone and that there are drug treatments have been shown to be helpful for women with severe PMS.
These include antidepressants, which appear to ease the physical as well as the psychological symptoms, he said.
The study authors agreed that clinical trials were warranted.
"In the interim, given that calcium and vitamin D may also reduce the risk of osteoporosis and some cancers, clinicians may consider recommending these nutrients even for young women," they said.