Hypercholesterolemia is an established risk factor for atherosclerotic cardiovascular disease (ASCVD). The National Cholesterol Education Program estimates that 65 million Americans with hypercholesterolemia could be treated with diet and exercise alone. Flaxseed is a potential component of cholesterol-reducing diet regimens. Flaxseed contains significant amounts of soluble fiber and is a rich source of both alpha-linolenic acid and phytoestrogenic ligands, which have been implicated in the prevention of ASCVD. However, flaxseed's phytoestrogenic ligands may have undesirable hormonal effects. This study will systematically evaluate the safety and efficacy of ground flaxseed ingestion in both men and women with hypercholesterolemia.

Participants will be randomized to receive flaxseed or a matching wheat bran control. The test dose of flaxseed will be 40 grams administered in baked products (muffins, bread, or bars). The first 6 study weeks are a diet stabilization phase, followed by a 10-week study phase in which participants are expected to eat two servings of the test food daily. Blood and urine are collected for analysis, which will include measurement of low density lipoprotein cholesterol (LDL-C), post-prandial triglycerides, and urinary isoprostane secretion.