"We're really puzzled about that because we were looking at post menopausal women and these lignans are known as plant estrogens, so they have a very weak but measurable estrogen effect," Hendrich said. "So potentially, they would have a mild effect for substituting some estrogens in women. It's really hard to know why [there was no effect in women] and whether these substances are counteracting, possibly, some testosterone in men, which of course women don't have. It's definitely something we'd like to investigate further."

Hendrich reports the flaxseed lignan tablets used in this study are not currently available in the U.S. to her knowledge. In the absence of tablets, she says flaxseed can also be sprinkled on cereal, or added in a muffin mix or bread, although whole seeds are not very digestible. Ground flaxseed meal can also provide the desired cholesterol-lowering lignans, according to Hendrich, but it will oxidize over time and could potentially affect the flavor of the foods that it's in. She points out that the oxidation of the product also would diminish the flaxseed's omega-3 fatty acids, which can prevent heart attacks, so freshness is important in the product's impact.

The ISU researcher hopes to publish the study in a professional journal. She also plans further investigation on whether flaxseed can be taken in combination with other known cholesterol-lowering substances, and whether it could prevent high cholesterol in the first place.

Source: Iowa State University