reproduced from Physicians Committee for Responsible Medicine - URL:
Physicians Committee for Responsible Medicine  

(articolo in italiano)
Menstrual Pain/PMS
Nutritional Factors in Menstrual Pain and Premenstrual Syndrome
Neal D. Barnard, M.D.

Disorders of menstrual function can be taxing and sometimes even disabling. Up to 10 percent of women in their teens and early twenties suffer from severe menstrual pain. In most cases, there is no identifiable cause. However, for some women, the pain is a symptom of endometriosis (a condition in which cells that normally line the uterus have ended up in the abdominal cavity), adenomyosis (the existence of islands of uterine lining cells deep within the uterine muscle), fibroids (the presence of overgrown muscle cells in the wall of the uterus), or other conditions.1 Nutritional factors appear to play an important role in managing menstrual pain.

Premenstrual syndrome includes feelings of moodiness, tension, or irritability, as well as physical symptoms, such as water retention. Like menstrual pain, it appears to be influenced by nutrition.

One of the treatments we are testing is the use of a very-low-fat, vegetarian diet. We are using this diet because, when it is properly followed, it has the very helpful effect of reducing the amount of estrogen in the blood, sometimes to a striking degree.2-12 For some individuals at least, diets that avoid animal products and keep vegetable oils to a bare minimum cause a marked reduction in menstrual pain, presumably because of the diet’s effect on hormones.

There are several reasons why this diet affects hormones. First of all, reducing the amount of fat in the food you eat reduces the amount of estrogen in your blood. This appears to be true for all fats—animal fats and vegetable oils.

Second, plant products contain fiber (roughage), which tends to carry estrogens out of the body. Here is how it works: The liver filters estrogens out of the blood and sends them down a small tube, called the bile duct, into the digestive tract. There, fiber from grains, beans, vegetables, and fruits soaks up the estrogens like a sponge. If plant foods are a major part of your diet, you’ll have plenty of fiber. But the amount of fiber in your diet is reduced when you have yogurt, chicken breast, eggs, or other animal products, because fiber comes only from plants. Without adequate fiber, the estrogens in your digestive tract end up being reabsorbed back into the bloodstream.

Certain foods that are common in vegetarian diets have special effects. Soy products, for example, contain phytoestrogens, which are very weak plant estrogens that reduce your natural estrogens’ ability to attach to your cells. The result is less estrogen stimulation of cells.

In addition to individual reports that low-fat, vegetarian diets can cause dramatic reductions in menstrual pain, vegetarians also have fewer ovulatory disturbances. Some researchers have found that excess estrogen plays a role in PMS symptoms, too, and that shifting the balance of the diet away from fatty foods and toward high-fiber plant foods is helpful.13

A Dietary Approach

The diet that has been extremely helpful in individuals excludes animal products completely and also keeps vegetable oils very low. Our experience is that the diet must be followed closely in order for it to work. This means no animal products at all—not even skim milk or eggs. It also means keeping vegetable oils to a bare minimum in the diet. Even though olive oil or peanut butter are better than chicken fat or beef fat when it comes to cholesterol levels, the effect on hormones is what we are concerned about here, and all fats—animal fats and vegetable oils—have to be avoided, because they all cause extra estrogen to be made by your body.

So, in addition to keeping animal products out of the diet, it is important to avoid oily salad dressings, french fries, potato chips, butter, margarine, cooking oils, and the shortening that is in many cookies and pastries. It also appears to be important to make this change for the entire month, not just before your period.

This is a big change in the diet, of course. However, a very short test will show whether it works for you. Its effects have been noticeable in the very first month or two after women have made this change. It is also a great way to lose excess weight without counting calories. Some people also note that other problems, such as migraines, are less common with this kind of diet. To test whether a change in diet will help you, we suggest that you follow a low-fat, vegetarian diet very strictly for two months.

Let us look briefly at getting complete nutrition. It is a simple matter, but please pay particular attention to the issue of vitamin B12.

Protein is not a problem on vegetarian diets, because plant foods have plenty of protein. Any normal variety of plant products contains more than enough protein for the body’s needs.

Calcium is found in abundance in green leafy vegetables and beans. You’ll also find a very rich source of calcium in fortified orange juice. Also, plant-based diets actually reduce the amount of calcium that is lost through the kidneys each day.

Iron balance tends to be better on pure vegetarian diets than on other diets. Green leafy vegetables and legumes (beans, peas, and lentils) are rich in a form of iron that is more absorbable if your body needs more iron and less absorbable when your body already has plenty of iron. Avoiding dairy products helps, because they contain virtually no iron and can actually inhibit iron absorption.

Vitamin B12 is needed for healthy nerves and healthy blood. Vegetarian sources, such as fortified soymilk or cereals, are not very common, so we recommend supplementing with any typical daily multivitamin or other reliable source of vitamin B12. While most authorities believe that it is only necessary to take B12 supplements if you have been on a pure vegetarian diet for more than three years or in childhood, pregnancy, or lactation, we suggest that you begin B12 supplementation within the first few months of beginning a vegetarian diet, mainly to get in the habit of ensuring complete nutrition.

For menus, recipes, and additional information, we suggest that you look at Eat Right, Live Longer or Food for Life by Neal Barnard, M.D., The Peaceful Palate by Jennifer Raymond, any of the nutrition books by John McDougall, M.D., or cookbooks by Mary McDougall.


Other nutritional factors affect menstrual symptoms, too, and are described below:

Essential Fatty Acids

As you know, different kinds of fats act differently in your body. Animal fats contain a great deal of saturated fat, which is the kind of fat that is solid at room temperature, while vegetable oils contain more unsaturated fats, which are liquids. But there are actually many more subtle differences between different kinds of fat.

Fats influence the production of prostaglandins in your body. These natural chemicals are involved in inflammation, pain, muscle contractions, blood vessel constriction, and blood clotting. Prostaglandins are suspected of playing a role in menstrual pain, migraines, and gastrointestinal pains, particularly since many of the pain-killing medicines that are commonly used to treat menstrual pain inhibit the effects of prostaglandins.14

People whose diets are balanced in favor of certain fats, called omega-3 fatty acids, rather than other fats, tend to have milder menstrual symptoms. Some people adjust their fat balance by adding extra omega-3-rich oils, such as flax oil or fish oils, to the diet, to try to counteract the “bad” fats in meats and dairy products. Unfortunately, this strategy tends to increase the amount of fat in the diet, which can be risky from several health standpoints.

A better strategy is to keep your diet rich in green, leafy vegetables and legumes (beans, peas, and lentils) and to eliminate meats and dairy products. The result is a new diet balance that favors omega-3s.14

Vitamin B-6

Vitamin B-6 (pyridoxine) has been shown to reduce pain in some research studies. It has been used to increase resistance to pain in people who are withdrawing from overused headache remedies and has helped people with carpal tunnel syndrome, nerve pains of diabetes, and temporomandibular joint pain (TMJ).15

In a way, this is no big surprise, since the vitamin has long been known to be used in the body to make neurotransmitters, the chemicals that conduct our nerve messages, including those that affect the way we feel pain.

Vitamin B-6 appears to affect the pain itself, not the underlying condition. For example, when researchers check the nerve functions of patients with carpal tunnel syndrome or diabetes, vitamin B-6 does not seem to affect them, but it does appear to work against pain. Vitamin B6 has also been shown to help in reducing depression, irritability, and other symptoms in some research studies.16,17

B-vitamins appear to play a role in controlling estrogens, by facilitating their removal in the liver. Presumably, if your diet is low in B-vitamins, the amount of estrogen in the blood may rise.18

The healthiest B-6 sources are whole-grains, beans, bananas, and nuts. Refined grains lose much of their B-6 along with their fiber. People on typical European and North American diets are more likely to be deficient in vitamin B-6, because their high protein intake from meats, dairy products, and eggs, requires extra B-6.

VITAMIN B-6 (content in milligrams)




 Soybean flour






 Potatoes (raw)


 Whole wheat bread


 Peas (raw)




Studies using B-6 supplements generally use doses in the range of 50 to150 milligrams per day. It should be used under the guidance of your physician. Higher amounts must be avoided as they can actually cause nerve problems. B-6 supplements typically take three months or more to work.


Simple sugars can contribute to irritability and depressed mood. Researchers have found that sugar increases the amount of certain brain neurotransmitters that control moods. In our experience, individuals are affected by sugar very differently. For some women, especially just before a period is due, a bar of chocolate or any other sugary food—even orange juice—can cause a dramatic increase in irritability, while other people have a much more mild reaction.16

While sugary foods, especially chocolate, are often craved during the premenstrual period, it is well worth avoiding them as an experiment to observe the differences in how you feel.

Foods that are rich in complex carbohydrates and fiber, such as whole wheat bread, brown rice, oatmeal, vegetables, and beans, do not seem to cause moodiness, and higher protein foods, such as beans or tofu, tend to help block the effect of sugar on moods.


Some evidence suggests that getting into better calcium balance can help reduce both menstrual pain and PMS. The effect is probably not a large one, however, and not all women notice an effect.

Most people think that improving calcium balance means ingesting more calcium either through supplements or dairy products. And, indeed, calcium carbonate supplements have been shown to reduce PMS symptoms.19

But potentially much more important is to reduce the amount of calcium your body is losing minute by minute. Researchers have clearly established that animal proteins increase the loss of calcium by increasing the amount of calcium your kidneys remove from the blood and excrete in the urine. When people avoid animal proteins, their calcium losses are cut to less than half of what they had been.20

Calcium losses can be further reduced by avoiding excess sodium, limiting caffeine intake to no more than two cups of coffee per day, avoiding tobacco, having regular exercise, and assuring that you get vitamin D, either from regular sun exposure or from a typical multiple vitamin.


Manganese is associated with reduced moodiness and menstrual pain.21


Caffeine aggravates PMS, and the more caffeine you consume—in coffee, tea, colas, or chocolate—the worse your PMS is likely to get.22 Although individual brands vary, here is a guide to the approximate amounts of caffeine in various products:

CAFFEINE CONTENT (in milligrams)



 Percolated or drip coffee, 1 cup


 Brewed coffee, 1 cup


 Instant coffee, 1 cup


 Black tea, 1 cup


 Coca-Cola, 20 ounces


 Pepsi, 20 ounces


 Chocolate, 1 ounce



Please Share Your Experiences

In contrast to the number of women who are struggling with menstrual pain and PMS, the amount of research on this subject is surprisingly meager. You can help by sharing your individual experiences with nutritional or other factors that have helped you. Such experiences often lead researchers in useful directions. If you would like to do so, please contact Neal D. Barnard, M.D., 5100 Wisconsin Avenue, Suite 400, Washington, D.C. 20016. Thank you.

1. Mersky H, Bogduk N (eds). Classification of Chronic Pain, 2nd edition. IASP Press, Seattle, 1994, pp. 164-6.
2. Goldin BR, Adlercreutz H, Dwyer JT, Swenson L, Warram JH, Gorbach SL. Effect of diet on excretion of estrogens in pre- and postmenopausal women. Cancer Res 1981;41:3771-3.
3. Goldin BR, Gorbach SL. Effect of diet on the plasma levels, metabolism, and excretion of estrogens. Am J Clin Nutr 1988;48:787-90.
4. Shultz TD, Leklem JE. Nutrient intake and hormonal status of premenopausal vegetarian Seventh-day Adventists and premenopausal nonvegetarians. Nutr Cancer 1983;4:247-59.
5. Barbosa JC, Shultz TD, Filley SJ, Nieman DC. The relationship among adiposity, diet, and hormone concentrations in vegetarian and nonvegetarian postmenopausal women. Am J Clin Nutr 1990;51:798-803.
6. Adlercreutz H. Western diet and Western diseases: some hormonal and biochemical mechanisms and associations. Scand J Clin Lab Invest 1990;50, Suppl 201:3-23.
7. Barr SI, Janelle KC, Prior JC. Vegetarian vs nonvegetarian diets, dietary restraint, and subclinical ovulatory disturbances: prospective 6-month study. Am J Clin Nutr 1994;60:887-94.
8. Prentice R, Thompson D, Clifford C, Gorbach S, Goldin B, Byar D. Dietary fat reduction and plasma estradiol concentration in healthy postmenopausal women. J Nat Cancer Inst 1990;82:129-34.
9. Ingram DM, Bennett FC, Willcox D, de Klerk N. Effect of low-fat diet on female sex hormone levels. J Natl Cancer Inst 1987;79:1225-9.
10. Rose DP, Boyar AP, Cohen C, Strong LE. Effect of a low-fat diet on hormone levels in women with cystic breast disease. I. Serum steroids and gonadotropins. J Natl Cancer Inst 1987;78:623-6.
11. Boyar AP, Rose DP, Loughridge JR, et al. Response to a diet low in total fat in women with postmenopausal breast cancer: a pilot study. Nutr Cancer 1988;11:93-99.
12. Woods MN, Gorbach SL, Longcope C, Goldin BR, Dwyer JT, Morrill-LaBrode A. Low-fat, high-fiber diet and serum estrone sulfate in premenopausal women. Am J Clin Nutr 1989;49:1179-83.
13. Abraham GE. Nutrition and the premenstrual tension syndromes. J Appl Nutr 1984;36:103-24.
14. Deutch B. Menstrual pain in Danish women correlated with low n-3 polyunsaturated fatty acid intake. Eur J Clin Nutr 1995;49:508-16.
15. Bernstein AL. Vitamin B6 in clinical neurology. Ann NY Acad Sci 1990;585:250-60.
16. Abraham GE, Rumley RE. The role of nutrition in managing the premenstrual tension syndromes. J Reprod Med 1987;32:405-22.
17. Kleijnen J, Ter Riet G, Knipschild P. Vitamin B6 in the treatment of premenstrual syndrome—a review. Br J Obstet Gynaecol 1990;97:847-52.
18. Biskin MS. Nutritional deficiency in the etiology of menorrhagia, metrorrhagia, cystic mastitis and premenstrual tension: treatment with vitamin B complex. J Clin Endocr Metab 1943;3:227.
19. Thys-Jacobs S, Ceccarelli S, Bierman A, Weisman H, Cohen M, Alvir A. Calcium supplementation in premenstrual syndrome. J Gen Intern Med 1989;4:183-9.
20. Remer T, Manz F. Estimation of the renal net acid excretion by adults consuming diets containing variable amounts of protein. Am J Clin Nutr 1994;59:1356-61.
21. Penland JG, Johnson PE. Dietary calcium and manganese effects on menstrual cycle symptoms. Am J Obstet Gynecol 1993;168:1417-23.
22. Chou T. Wake up and smell the coffee: caffeine, coffee, and the medical consequences. Western J Med 1992;157:544-53.