In the study, researchers looked at men who were about to undergo surgical treatment for prostate cancer. For 30 days prior to surgery the men took 30 grams of flaxseed daily. The tumors revealed how the cells had multiplied. Some men took flaxseed alone, some men took flaxseed in conjunction with a low-fat diet, some men followed a low-fat diet only and took no flaxseed, and some men did nothing and served as a control group.

Researchers found that men in the two groups who took flaxseed had the slowest tumor growth, proving that the flaxseed affected tumor growth rather than the low-fat diet. Each group included 40 participants who ate ground flaxseed (the coating on whole flaxseed is not digestible) sprinkled in drinks and on food.