Previous studies have suggested that calcium supplements and vitamin D, a hormone that regulates the absorption of calcium, may reduce premenstrual occurrence and severity but it was not clear whether the mineral-vitamin combination could prevent the condition from developing in the first place.
While most women experience mild emotional or physical premenstrual symptoms, as many as 8-20 per cent of women experience symptoms severe enough to meet the definition of premenstrual syndrome, which can substantially interfere with daily activities and relationships.
The new trial, carried out by Elizabeth R. Bertone-Johnson of the University of Massachusetts and a co-author from study funder GlaxoSmithKline, suggests that changing the diet could be beneficial for those in this category.
The researchers compared the diets and supplement use of 1,057 women aged 27 to 44 years old who reported developing PMS over the course of 10 years to 1,968 women who reported no diagnosis of PMS or no or minimal premenstrual symptoms in the same time period.
The women, who participated in the Nurses Health Study, all reported no PMS in 1991, at the beginning of the study period.
Their intake of calcium and vitamin D from diet and/or supplements was calculated from food frequency and standard NHS questionnaires administered in 1991, 1995 and 1999.
"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 dairy foods such as yoghurt," the authors write in the 13 June issue of the Archives of Internal Medicine (165, pp1246-1252).
Women in the highest quintile of total vitamin D intake - those taking on average 706 IU each day - had a relative risk of 0.59 compared with those consuming only 112 IU per day.
Women consuming the most calcium (on average 1283mg per day) had a 30 per cent lower risk of developing PMS than those with a low intake of 529mg daily.
"While previous studies have observed the benefits of calcium supplements for treating PMS, this is the first, to our knowledge, to suggest that calcium and vitamin D may help prevent the initial development of PMS."
The intake of skim or low-fat milk was also associated with a significantly lower risk.
"Our findings, together with those from several small randomized trials that found calcium supplements to be effective in treating PMS, suggest that a high intake of calcium and vitamin D may reduce the risk of PMS," the authors conclude.
They added that clinical trials are needed before the mineral/vitamin combination can be recommended for this condition. However, given that calcium and vitamin D may also reduce risk of osteoporosis and some cancers, clinicians may consider recommending these nutrients even for younger women, they said.