NEW YORK (Reuters) -- Most women know the signs of impending menstruation -- the breast tenderness, food cravings, cramping, and worst of all, the water retention that makes you feel like a float in a Thanksgiving Day parade.
Now, a new study suggests that despite common lore, salt, or sodium chloride, does not increase bloating -- so eating a low-salt diet won't alleviate such premenstrual symptoms.
"Breast tenderness and bloating did not result from sodium retention in the [later stages] of the menstrual cycle," wrote lead study author Dr. Beatriz Olson, of the National Institutes of Health in Bethesda, Maryland.
The 13 women in the new study actually tended to lose sodium in their urine before menstruation, whether on a normal diet or on a low-salt diet, according to a report in this week's issue of Annals of Internal Medicine.
Olson and colleagues recorded the women's menstrual symptoms, food cravings, and blood and urinary sodium levels for one month while on a normal diet, and two months on a salt-restricted diet.
During the first half of the menstrual cycle, the women had a drop in blood and urinary sodium levels while they were on the salt-restricted diet. However, in the second half of the cycle, in the four days before menstruation, the women actually had an increase in sodium in the urine despite a low-salt diet.
The women reported increased ratings of breast tenderness by 6 to 8 times, and there was a two- to three-fold increase in swelling or bloating late in the menstrual cycle compared to the rest of the month.
However, "our study has limitations that prevent us from unequivocally stating that the menstrual symptoms studied are unrelated to sodium balance," Olson said. The study was small and the women reduced sodium intake by only 30%, a difference that may have been too small to see an improvement in symptoms.
SOURCE: Annals of Internal Medicine (1996;125:564-567)
