点击显示 收起
June 20, 2000 -- Forget Midol, aspirin, or ibuprofen. For period cramps and other menstrual symptoms, such as headaches, nausea and fatigue, women may find lasting relief from daily doses of fish oil and vitamin B-12, according to a small Danish study.
The Danish researchers recruited 78 women with menstrual pain and randomly assigned them to take capsules filled with one of four oils: seal oil, fish oil alone, fish oil plus vitamin B-12, or a placebo of "regular" oil -- those fatty acids typically found in Danish diets. The women, who took five capsules each day throughout three menstrual cycles, filled out questionnaires rating their pain every month during the study, and for three months after they had stopped taking the capsules.
The researchers found that women taking seal oil, fish oil, and fish oil plus B-12 reported fewer symptoms and less pain than those taking the regular oil. Those who took the fish oil plus B-12 reported the most improvement, and unlike the effects of seal oil or fish oil alone, the effects of fish oil plus B-12 lasted for at least three months after the women had stopped taking the capsules.
The findings support what researchers already know about omega-3 fatty acids, an important fat found in fish oil.
"A lot of people have found that omega-3 fatty acids decrease inflammation and clearly there is inflammation that goes on [during menstruation]. So the findings would be consistent with everything we know about omega-3 fatty acids," Ernst Schaefer, MD, tells WebMD. "It is a small study, but it would suggest that this is a potentially useful form of therapy." Schaefer, who is chief of the lipid metabolism laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, was not involved in the study.
"I think it's very interesting, but you always have to consider the numbers; it is actually a small study, and when you have subjective symptoms, you can sometimes see some curious results," he says. Nevertheless, he says, the findings are potentially important.
Neither Schaefer nor the Danish researchers are quite clear on why vitamin B-12 seems to help, but Schaefer can take a guess. "Vitamin B-12 has been shown to lower homocysteine levels ... and homocysteine can cause inflammation as well," he says. "But whether this is the mechanism whereby it decreases menstrual cramps, I don't know."
Interestingly, the Danish researchers found that when they compared the diets of the women in their study to the diet of Danes in general, the women tended to eat less fish and more carbohydrates. The researchers suggest that these women may be more prone to cramps because their omega-3 intake was out of balance with their intake of omega-6, another essential important fat found primarily in plant oils, such as canola, soybean, and corn oils.
"Omega-3 decreases inflammation, and omega-6 increases inflammation, so there has to be a balance there," Schaefer says.
Zeev Harel, MD, a professor of pediatrics at Brown University, has done his own studies on menstrual cramps in adolescents and omega-3 intake. He says an ideal diet should be made up of 50% carbohydrates, 20% protein, and about 30% fat, which includes saturated, monounsaturated, and polyunsaturated fats.
"Among the polyunsaturated fat, we have two families: omega-3 and omega-6," he tells WebMD. "There is a competition in the body between omega-3 and omega-6: They use the same enzymes and everything. We have more omega-6 in our Western diet; unfortunately, the ratio is almost 25:1. Ideally, it should be should be 5:1 in favor of omega-6. If we supply the diet with more omega-3, we incorporate more of those in every tissue of the body," Harel says.
Why is that important? Because these fats affect the body's production of chemicals called prostaglandins, Harel says. Prostaglandins can cause inflammation and also affect uterine contractions and blood flow, both of which are involved in cramps.
"The findings don't surprise me," he says.
So, should women of childbearing age stock up on vitamin B-12 and fish oil to foil menstrual cramps? While some studies have shown that as your consumption of fish or fish oil and/or B-12 goes up, that menstrual pain goes down, you're unlikely to find a doctor to prescribe them just yet.
But Schaefer says fish oil supplements can't hurt. "Fish oil is certainly innocuous, and people can buy it over the counter," says Schaefer, adding that fish oil has been shown to be beneficial for a number of other conditions as well. "People have used [fish oil] for a variety of conditions, including rheumatoid arthritis, for example. Also, it has been reported in a large prospective study that two fish oil capsules a day reduces the risk of heart disease."
"At this point, we just recommend encouraging fish intake, especially those rich in omega-3 fatty acid, such as salmon, herring, tuna, mackerel, and sardines," Harel says. "For those who don't like fish, they may consider fish supplements."
For more information from WebMD, visit the Living Better Healthy Women page or the Diet and Nutrition page.
Vital Information: