While the majority of menstruating women feel some discomfort before their menstrual periods, about 8%-20% experience symptoms debilitating enough to be classified as
premenstrual syndrome (PMS)
. These symptoms begin 7-14 days before menses, and usually subside a few days after menses begins. Ranging from
to weight gain, symptoms of PMS include irritability,
, fatigue, abdominal cramping, breast tenderness,
, and headaches. These symptoms are severe enough to interfere with daily life and relationships.
The cause of PMS is not clear. One theory is that women who experience PMS may be highly sensitive to the hormonal changes that occur during the menstrual cycle. Lifestyle changes, over-the-counter pain relievers, and prescription medications may help minimize symptoms.
Calcium supplementation (1,000-1,300 milligrams [mg] per day), has been shown to be useful in the treatment of symptoms such as water retention, cramps, and back pain. This success has led scientists to consider calcium’s merit as a preventive measure. Researchers from the University of Massachusetts at Amherst studied dietary habits and the subsequent incidence of PMS in a subgroup of women from the Nurses’ Health Study. In this observational study, described in the June 13, 2005 issue of the
Archives of Internal Medicine
, the women who consumed the most dietary calcium and vitamin D had the lowest risk of PMS. Vitamin D is a hormone that regulates the body’s absorption and use of calcium.
About the Study
The researchers enlisted a subgroup of women participating in the ongoing Nurses’ Health Study II (NHS2). The NHS2 is designed to identify risk factors for chronic diseases in women. Since 1989, more than 100,000 female registered nurses have been tracked via questionnaires. Every two years, the women provide information on their health status and health-related behaviors, including eating habits.
The researchers divided their subgroup of NHS2 women into two groups—those who were diagnosed with PMS between 1993 and 2001, and those who were not. Next, they reviewed the women’s food records from the years before diagnoses. The food records, called semiquantitative food frequency questionnaires (SFFQ), asked women to record how often they ate various foods during the previous year; response choices ranged from “less than once per month” to “six or more times per day.” Using this data, researchers calculated each woman’s intake of calcium and vitamin D, and compared the intakes between the two groups.
Women with the highest intake of calcium from foods (about 1,200 mg/day) had a 30% lower risk of PMS than women who consumed 500 mg or less of calcium daily. Likewise, the women who took in the most vitamin D from foods (about 400 IU [International Units]/day) also had a 30% lower risk of PMS than women who ate the least vitamin D (90 IU/day). Those with the highest intake of vitamin D from both foods and supplements (about 700 IU/day) had a 40% lower risk of PMS than women who took in 100 IU/day or less. Supplements alone were not beneficial.
Milk itself, aside from its calcium and vitamin D content, was also associated with a significantly lower risk of PMS. Women who drank four or more glasses of skim or low-fat milk per day had almost half the risk (46% decreased risk) of PMS than women who drank one or fewer glasses per week.
How Does This Affect You?
Are dietary calcium and vitamin D the antidote to PMS? It’s much too soon to say. This is an observational study, which means the researchers identified a group of women who did and did not develop PMS. Then, they reviewed the women’s previous dietary records looking for factors that differed between the groups, surmising that these factors may have affected the risk of PMS. Such a study can only identify associations, that is, factors that occurred at the same time—women in one group consumed a lot of vitamin D and were free of PMS—it cannot say if one factor caused another. In order to determine if calcium or vitamin D actively prevents PMS, a more stringent clinical trial is necessary, one in which women are randomized into two groups and given regulated diets with specific levels of calcium and vitamin D. The authors of this study believe their findings warrant further investigation.
Another consideration is the food frequency questionnaires. These are often used in large observational studies, but are vulnerable to bias as they rely on a woman to accurately estimate her intake of a particular food over the course of an entire year.
Notwithstanding these caveats, calcium and vitamin D are essential nutrients that can help reduce the risk of osteoporosis. Additionally, many women do not consume enough of these nutrients. The level of calcium associated with a decreased risk of PMS—1,200 mg/day—is consistent with the government recommendations for good health (1,300 mg/day for aged 9-18; 1,000 mg/day for aged 19-50; and 1,200 mg/day over age 50) and is well below the safe upper limit (2,500 mg/day). The amount of vitamin D associated with a decreased risk of PMS was 400 IU/day. This is double what the government advises for women ages 9-50, and the exact requirement for women 50 and older. The 400 IUs are well below the safe upper limit of 2,000 IUs.
It is important to note that the decreased rates of PMS in this study were associated with intake of calcium and vitamin D from foods and not supplements. Good food sources of these nutrients are listed below:
Please be aware that this information is provided to supplement the care
provided by your physician. It is neither intended nor implied to be a
substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER
IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the
advice of your physician or other qualified health provider prior to
starting any new treatment or with any questions you may have regarding a