They saw no change in the already low circulating estrogens in the body. Studies in rats, examining whether circulating estrogen levels were reduced on a high fiber diet, have not seen the decreases reported in women. The reason for this difference is still being debated. These studies present encouraging evidence that diets high in fiber may lower circulating estrogen levels in humans. More studies are needed in this area.
Whole grains are foods of high nutritional value.
They are high in fiber, low in fat, and are good sources of complex carbohydrates, vitamins, and minerals. Besides these benefits toward basic nutrition, whole grains and fiber have been found to decrease the risk of a number of diseases including heart disease and cancers of the stomach, colon, rectum, endometrium, and pancreas. The United States Department of Agriculture's Food Guide Pyramid recommends that most adults eat 9 to 11 servings of grains a day, especially whole grains. Only one study has investigated the use of refined grain products, such as white bread and pasta, and breast cancer risk. This study was conducted in Italy and saw an association of starch from refined grains with increased breast cancer risk.