Menstrual Pain
Using Foods against Menstrual Pain

Neal D. Barnard, M.D.
Preventive Medicine and Nutrition

What Causes the Pain?

Menstrual pain is significant in about half of women, and in up to 10 percent it is severe enough to interfere with work and other activities for one to two days every month. Sometimes it diminishes after childbirth, but for many it continues.1

In the 1960s, it became clear that chemicals called prostaglandins are a central part of the problem. These chemicals are made from the traces of fat stored in cell membranes and that they promote inflammation. They are also involved in muscle contractions, blood vessel constriction, blood clotting, and pain.

Shortly before your period begins, the endometrial cells that form the lining of the uterus make large amounts of prostaglandins. When these cells break down during menstruation, the prostaglandins are released. They constrict the blood vessels in the uterus and make its muscle layer contract, causing painful cramps. Some of the prostaglandins also enter the bloodstream, causing headache, nausea, vomiting, and diarrhea.2

Researchers have measured the amount of prostaglandins produced by the endometrial cells in women with menstrual pain and found that it is higher than for other women.3 The concentration of prostaglandins circulating in the blood is higher, as well.2

This helps explain why nonsteroidal anti-inflammatory drugs work for menstrual pain. Ibuprofen (Motrin), naproxen (Anaprox), and other NSAIDs reduce the production of prostaglandins.

Using Foods against Pain

There may be a more fundamental approach. Rather than focus on the prostaglandins themselves, it may help to focus on the cellular "factories" that make them. After all, we know that birth control pills reduce menstrual pain, and they apparently do this by reducing the growth of the endometrial cell layer. The smaller this layer of cells is, the less tissue there is to make prostaglandins.

In every monthly menstrual cycle, the amount of estrogens in a woman's body rises and falls. Estrogens are female sex hormones. You can think of them as a sort of hormonal fertilizer, making the cells of your body grow. Estrogens are responsible for breast development at puberty, and each month, they cause the lining of the uterus to thicken in anticipation of pregnancy.

If you were to measure the amount of estrogens in a woman's bloodstream as her period ends and a new cycle begins, you would find that it is gradually rising. For about two weeks, it rises toward a peak and then falls quickly around the time of ovulation. It rises again in the second half of the month and then falls just before her next period. The uterus sheds its lining in a menstrual flow, accompanied by crampy pain.

How Foods Change Hormones

The amount of estrogen in your blood is constantly being readjusted. Some foods push hormone levels up. Others bring them down.

Here's how it works: Fat drives estrogen levels up. Any kind of fat will do it: chicken fat, fish fat, beef fat, olive oil, canola oil—you name it. It does not matter if it is animal fat or vegetable oil; the more of it there is in your diet, the more estrogen your body makes.

If you cut the amount of fat in your diet, the amount of estrogen will be noticeably reduced within the very first month. Cancer researchers have taken a great interest in this phenomenon, because lowering the level of estrogen in your blood helps reduce the risk of breast cancer. Less estrogen means less stimulation for cancer cell growth.

If a woman eating a Western diet cuts her fat intake in half, her estrogen level will be about 20 percent lower.4 If you cut the fat even more, your estrogen level will drop further. That is a good change. If your hormone level does not rise too high, it will have less effect on your uterine cells.

I hypothesized that a change in estrogen is what gets the credit for the newfound comfort that many women experience when they change their diets. In a research study, published in Obstetrics & Gynecology in February 2000, we found that a low-fat, vegan diet significantly reduces pain and PMS for many women.

The diet change was designed to do two things. First, it eliminated all animal fats and nearly all vegetable oils. Less fat in the diet means that less estrogen is produced, which is a good thing.

Second, plant foods also increase the amount of plant roughage (fiber) in your diet, which helps your body to get rid of excess estrogens. Estrogens are normally pulled from the bloodstream by the liver, which sends them through a small tube, called the bile duct, into the intestinal tract. There, fiber soaks them up like a sponge and carries them out with the wastes. The more fiber there is in your diet, the better your natural "estrogen disposal system" works.

Animal products never have any fiber at all. If fish, chicken, yogurt, or other animal products make up any substantial part of your diet, there will be less fiber in the digestive tract. The result is disastrous. The waste estrogens, that should bind to fiber and leave the body, end up passing back into the bloodstream. This hormone "recycling" increases the amount of estrogen in the blood. But you can block it with the fiber in grains, vegetables, beans, and other plant foods that keep waste estrogens headed toward the exit.

So, by avoiding animal products and added oils, you reduce estrogen production. And by replacing chicken, skim milk, and other fiberless foods with grains, beans, and vegetables, you will increase estrogen elimination.

Putting Foods to Work

You can do this yourself. The key is to follow the diet exactly, so that you can see the effect it has for you.

Have plenty of:

  1. Whole grains, such as brown rice, whole grain bread, and oatmeal

  2. Vegetables: broccoli, spinach, carrots, sweet potatoes, Swiss chard, Brussels sprouts or any other

  3. Legumes: beans, peas, and lentils

  4. Fruits

Avoid completely:

  1. Animal products of any type: fish, poultry, meats, eggs, and dairy products

  2. Added vegetable oils: salad dressings, margarine, and all cooking oils

  3. Any other fatty foods: doughnuts, french fries, potato chips, peanut butter, etc.

This sounds like a significant change, and it is. However, we have found that, while everyone feels a bit at sea for the first several days, virtually everyone makes the change in about two weeks. Those who have the best time with it are those who experiment with new foods and new food products and who enlist the support of their friends or partners at home.

As the benefits kick in—reduced menstrual cramps, incredibly easy weight loss, and increased energy—the diet change is so rewarding that you will only wish you had tried it sooner.

It is important to avoid animal products and oily foods completely. Even seemingly modest amounts of them during the course of the month can cause more symptoms at the end of the month.

Be sure to have your foods in as natural a state as possible, choosing brown rice instead of white rice and whole grain bread instead of white bread in order to preserve their fiber.

Give this experiment a careful try for just one cycle, and you will see what it can do for you. You will very likely start to look at the power of foods in a very different way.



1. Merskey H, Bogduk N (eds). Classification of Chronic Pain, 2nd edition. Seattle: IASP Press, 1994, pp. 164-6.
2. Chan WY. Prostaglandins and nonsteroidal antiinflammatory drugs in dysmenorrhea. Ann Rev Pharmacol Toxicol 1983;23:131-49.
3. Ylikorkala O, Dawood MY. New concepts in dysmenorrhea. Am J Obstet Gynecol 1978;130:833-47.
4. Prentice R, Thompson D, Clifford C, Gorbach S, Goldin B, Byar D. Dietary fat reduction and plasma estradiol concentration in healthy postmenopausal women. J Natl Cancer Inst 1990;82:129-34.